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Clean Energy

Clean energy

Green energy is a term used by some environmentalists to describe what they deem to be environmentally friendly sources of power. In particular green energy must be renewable and non-polluting. Green energy is generally considered to include:
- Geothermal power
- Wind power
- Small-scale hydropower
- Solar power
- Biomass power
- Tidal power
- Wave power Some versions may also include power derived from the incineration of waste. Somewhat controversial is nuclear energy's claim to be green. It is possibly sustainable, arguably renewable and produces virtually no atmospheric pollution during the energy production stage. The mining, transport and pre- and post-production require a large amount of energy, some of which emits carbon dioxide and other greenhouse gasses. One advocate of nuclear is ex-Greenpeace organizer Patrick Moore [http://www.checkbiotech.org/root/index.cfm?useaction=news&doc_id=9574&start=1&control=207&page_start=1&page_nr=101&pg=1], although Greenpeace itself does not support the use of Nuclear energy. For green energy to be truly "ecological electricity" it must not include medium or large-scale hydroelectric power or sources of air pollution such as burning biomatter or petroleum. In several countries, current electricity retailing arrangements make it possible for consumers to buy green electricity, either by purchasing their electricity from a generating company that uses only renewable technologies, or by buying from a general supplier who undertakes to buy at least as much power from renewable sources as their "green" customers purchase. Generally green electricity commands a price premium compared with standard supplies. Obviously this option is only available where common carrier arrangements have been put in place to allow competitive supply of power. Renewable energy certificates, or green tags, are currently the most convenient way for consumers and businesses to support "green power". Over 35 million homes in Europe, and 1 million in the United States, are purchasing green tags. No power source is impact-free. For instance, concerns are raised over bird kills and in some cases noise pollution by windmills and over heavy metal use and associated mining damage by solar cells.

External links

- [http://www.greenmountain.com Green Mountain]
- [http://www.cus.net/renewableenergy/subcats/solar/solar.html Renewable Energy]
- http://www.epa.gov/greenpower
- http://www.foe.co.uk/campaigns/climate/press_for_change/choose_green_energy Friends of Earth Green Energy Guide
- http://www.electricitylabels.com/
- http://www.greenprices.com
- http://www.green-e.org
- [http://www.greenelectricity.org Green electricity marketplace].
- http://www.greenpower.gov.au/
- [http://www.ems.org/renewables/green_tags.html Green Tags: A Renewable Energy Option Available to Everyone] Category:Sustainability

Environmentalist

Environmentalist is a person or a group that supports any goal of the environmental movement. Most politically inclined environmentalists identify themselves as greens and they have strong views on issues that concern the environment. The Green Parties are generally applied to those in the environmental movement working as volunteers, activists or paid staff. However, the term could also be applied to environmental scientists. Typically, environmentalists have conservationist views - in general, they advocate for the preservation, restoration, or enhancement of the natural environment. Environmentalists are sometimes given names in a derogatory context such as watermelon, tree hugger, eco-terrorist, or greeny (greenie). Eco-terrorism is sometimes used to describe the act of violence, sabotage, vandalism, property damage and intimidation both against people and against property committed in the name of environmentalism.

Renewable energy

Renewable energy (sources) or RES capture their energy from existing flows of energy, from on-going natural processes, such as sunshine, wind, flowing water, biological processes, and geothermal heat flows. The most common definition is that renewable energy is from an energy resource that is replaced rapidly by a natural process such as power generated from the sun or from the wind. Most renewable forms of energy, other than geothermal and tidal power, ultimately come from the Sun. Some forms are stored solar energy such as rainfall and wind power which are considered short-term solar-energy storage, whereas the energy in biomass is accumulated over a period of months, as in straw, or through many years as in wood. Capturing renewable energy by plants, animals and humans does not permanently deplete the resource. Fossil fuels, while theoretically renewable on a very long time-scale, are exploited at rates that may deplete these resources in the near future (see: Hubbert peak). Renewable energy resources may be used directly, or used to create other more convenient forms of energy. Examples of direct use are solar ovens, geothermal heating, and water- and windmills. Examples of indirect use which require energy harvesting are electricity generation through wind turbines or photovoltaic cells, or production of fuels such as ethanol from biomass (see alcohol as a fuel). A parameter sometimes used in renewable energy is the tonne of oil equivalent (toe). This is equal to 10,000 Mcal or 41,868 MJ of energy.[http://www.iea.org/Textbase/stats/unit.asp] For aspects of renewable energy use in modern societies see Renewable energy development. For a general discussion, see future energy development.

Modern sources of renewable energy

Geothermal energy

Geothermal energy ultimately comes from radioactive decay in the core of the Earth, which heats the Earth from the inside out, and from the sun, which heats the surface. It can be used in three ways:
- Geothermal electricity
- Geothermal heating, through deep Earth pipes
- Geothermal heating, through a heat pump. Usually, the term 'geothermal' is reserved for the thermal energy from the core of the Earth. Geothermal electricity is created by pumping a fluid (oil or water) into the Earth, allowing it to evaporate and using the hot gases vented from the earth's crust to run turbines linked to electrical generators. The geothermal energy from the core of the Earth is closer to the surface in some areas than in others. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such geothermal power sources exist in certain geologically unstable parts of the world such as Iceland, New Zealand, United States, the Philippines and Italy. The two most prominent areas for this in the United States are in the Yellowstone basin and in northern California. Iceland produced 170 MW geothermal power and heated 86% of all houses in the year 2000 through geothermal energy. Some 8000 MW of capacity is operational in total. Geothermal heat from the surface of the Earth can be used on most of the globe directly to heat and cool buildings. The temperature of the crust a few feet below the surface is buffered to a constant 7 to 14 °C (45 to 58 °F), so a liquid can be pre-heated or pre-cooled in underground pipelines, providing free cooling in the summer and, via a heat pump, heating in the winter. Other direct uses are in agriculture (greenhouses), aquaculture and industry. Although geothermal sites are capable of providing heat for many decades, eventually specific locations cool down. Some interpret this as meaning a specific geothermal location can undergo depletion. Others see such an interpretation as an inaccurate usage of the word depletion because the overall supply of geothermal energy on Earth, and its source, remain nearly constant. Geothermal energy depends on local geological instability, which, by definition, is unpredictable, and might stabilise. The present consumption of geothermal energy does not in any way threaten or diminish the quality of life for future generations, consequently, it is considered a renewable energy source.

Solar energy

heat pump Since most renewable energy is ultimately "solar energy" this term is slightly confusing and used in two different ways: firstly as a synonym for "renewable energies" as a whole and secondly for the energy that is directly collected from sunlight. In this section it is used in the latter category. Solar power can be used to:
- generate electricity using solar cells
- generate electricity using thermal power plants
- generate electricity using solar towers
- heat buildings, directly
- heat buildings, through heat pumps
- heat foodstuffs, through solar ovens. Obviously the sun does not provide constant energy to any spot on the Earth, so its use is limited. Solar cells are often used to power batteries, as most other applications would require a secondary energy source, to cope with outages. Some homeowners use a solar system which sells energy to the grid during the day, and draw energy from the grid at night; this is to everyone's advantage, since power demand for air conditioning is highest during the day.

Wind energy

As the sun heats up the Earth unevenly, winds are formed. The kinetic energy in the wind can be used to run wind turbines, some capable of producing 5 MW of power. The power output is a function of the cube of the wind speed, so such turbines generally require a wind in the range 5.5 m/s (20 km/h), and in practice relatively few land areas have significant prevailing winds. Luckily, offshore or at high altitudes, the winds are much more constant. There are now many thousands of wind turbines operating in various parts of the world, with utility companies having a total capacity of over 47,317MW.[http://www.ewea.org/documents/Thefacts_Summary.pdf] Capacity probably means maximum possible output which does not count load factor. It is worth noticing that this number suggests a much higher real percentage of power supply than it really has. New wind farms and offshore wind parks are being planned and built all over the world. This has been the most rapidly-growing means of electricity generation at the turn of the 21st century and provides a complement to large-scale base-load power stations. Most deployed turbines produce electricity about 25% of the time (load factor 25%), but some reach 35%. The load factor is generally higher in winter. It means that a 5 MW turbine can have average output of 1.7 MW in the best case. Global winds long-term technical potential is believed to be 5 times current global energy consumption or 40 times current electricity demand. This requires 12.7% of all land area, or that land area with Class 3 or greater potential at a height of 80 meters. It assumes that the land is covered with 6 large wind turbines per square kilometer. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy.[http://www.stanford.edu/group/efmh/winds/global_winds.html][http://www.ens-newswire.com/ens/may2005/2005-05-17-09.asp#anchor6] This number could also increase with higher altitude ground based or airborne wind turbines.[http://www.wired.com/news/planet/0,2782,67121,00.html?tw=wn_tophead_2] There is resistance to the establishment of land based wind farms owing initially to perceptions that they are noisy and contribute to "visual pollution," i.e., they are considered to be eyesores. Many people also claim that turbines kill birds, and that they in general do little for the environment. Others have argued that they find the turbines beautiful, that turbines out at sea are invisible to anyone on the shore, that cars kill more birds annually and that turbines are continuing to evolve. Wind strengths vary and thus cannot guarantee continuous power. Some estimates suggest that 1,000MW of wind generation capacity can be relied on for just 333 MW of continuous power. While this might change as technology evolves, advocates have suggested incorporating wind power with other power sources, or the use of energy storage techniques, with this in mind. It is best used in the context of a system that has significant reserve capacity such as hydro, or reserve load, such as a desalination plant, to mitigate the economic effects of resource variability. Wind power is renewable.

Water power

Energy in water can be harnessed and used, in the form of motive energy or temperature differences. Since water is about a thousand times heavier than air is, even a slow flowing stream of water can yield great amounts of energy. There are many forms:
- Hydroelectric energy, a term usually reserved for hydroelectric dams.
- Tidal power, which captures energy from the tides in horizontal direction. Tides come in, raise waterlevels in a basin, and tides roll out. The water must pass through a turbine to get out of the basin.
- Tidal stream power, which does the same vertically, capturing the stream of water as it is pushed around the world by the tides.
- Wave power, which uses the energy in waves. The waves will usually make large pontoons go up and down in the water.
- Ocean thermal energy conversion (OTEC), which uses the temperature difference between the warmer surface of the ocean and the cool (or cold) lower recesses. To this end, it employs a cyclic heat engine.
- Deep lake water cooling, not technically an energy generation method, though it can save a lot of energy in summer. It uses submerged pipes as a heat sink for climate control systems. Lake-bottom water is a year-round local constant of about 4 °C. Hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations with the potential for harnessing gravity in this way are either already being exploited or are unavailable for other reasons such as environmental considerations. Building a dam often involves flooding large areas of land, changing habitats, and while hydroelectric energy produces essentially no carbon dioxide, recent reports have linked hydroelectric power to methane, which forms out of decaying submerged plants which grow in the dried up parts of the basis in times of drought. Methane is a potent greenhouse gas. The other methods of energy generation (and cooling) have had varying degrees of success in the field. Wave and tidal power prove hard to tap, while OTEC has not been field tested on a large scale. The general public mostly considers water power energy to be renewable.

Biomass

Plants use photosynthesis to store solar energy in the form of chemical energy. Biofuel is any fuel that derives from biomass - recently living organisms or their metabolic byproducts, such as manure from cows. It is a renewable energy. Typically biofuel is burned to release its stored chemical energy. Research into more efficient methods of converting biofuels and other fuels into electricity utilizing fuel cells is an area of very active work. Biomass, also known as biomatter, can be used directly as fuel or to produce liquid biofuel. Agriculturally produced biomass fuels, such as biodiesel, ethanol and bagasse (often a by-product of sugar cane cultivation) can be burned in internal combustion engines or boilers. A drawback is that all biomass needs to go through some of these steps: it needs to be grown, collected, dried, fermented and burned. All of these steps require resources and an infrastructure. However, since the government passed legislation that requires the integration of 7.5 billion U.S. gallons (28,000,000 m³) of ethanol into the gasoline supply experts estimate that six million dollars of investment will be created along with 200,000 additional jobs in the United States. Biomatter energy, under the right conditions, is considered to be renewable.

Liquid biofuel

Liquid biofuel is usually bioalcohol such as methanol, ethanol and biodiesel. Biodiesel can be used in modern diesel vehicles with little or no modification and can be obtained from waste and crude vegetable and animal oil and fats (lipids). A major benefit of biodiesel is lower emissions. The use of biodiesel reduces emission of carbon monoxide and other hydrocarbons by 20 to 40 percent. In some areas corn, sugarbeets, cane and grasses are grown specifically to produce ethanol (also known as alcohol) a liquid which can be used in internal combustion engines and fuel cells. Ethanol is being phased into the current energy infrastructure. E85 is a fuel composed of 85% gasoline and 15% ethanol that is currently being sold to consumers. The EU plans to add 5% bioethanol to Europe's petrol by 2010. For the UK alone the production would require 12,000 square kilometres of the country's 65,000 square kilometres of arable land assuming that no biofuels are created using waste produces from other agriculture.

Solid biomass

Direct use is usually in the form of combustible solids, either firewood or combustible field crops. Field crops may be grown specifically for combustion or may be used for other purposes, and the processed plant waste then used for combustion. Most sorts of biomatter, including dried manure, can actually be burnt to heat water and to drive turbines. Sugar cane residue, wheat chaff, corn cobs and other plant matter can be, and is, burnt quite successfully. The process releases no net CO₂. Solid biomass can also be gasified, and used as described in the next section.

Biogas

Many organic materials can release gases, due to metabolisation of organic matter by bacteria (fermentation). Landfills actually need to release this gas to prevent dangerous explosions. Animal feces releases methane under the influence of anaerobic bacteria. Also, under high pressure, high temperature, anaerobic conditions many organic materials such as wood can be gasified to produce gas. This is often found to be more efficient than direct burning. The gas can then be used to generate electricity and/or heat. Biogas can easily be produced from current waste streams, such as: paper production, sugar production, sewage, animal waste and so forth. These various waste streams have to be slurried together and allowed to naturally ferment, producing methane gas. We just need to convert current sewage plants to biogas plants, build more locally centered smaller biogas plants and plan for the future. Biogas production has the capacity to provide us with about half of our energy needs, either burned for electrical productions or piped into current gas lines for use. It just has to be done and made a priority. Besides, when a plant has extracted all the methane it can, we are left with a better fertilizer for our farms than we started with.

Small scale energy sources

There are many small scale energy sources that generally cannot be scaled up to industrial size. A short list:
- Piezo electric crystals generate a small voltage whenever they are mechanically deformed. Vibration from engines can stimulate piezo electric crystals, as can the heels of shoes
- Some watches are already powered by kinetics, in this case movement of the arm
- Electrokinetics generate electricity from the kinetic energy in water that is pumped through tiny channels
- Special antennae can collect energy from stray radio waves or theoretically even light (EM radiation).

Issues

Aesthetics, habitat hazards and land use

Some people dislike the aesthetics of wind turbines or bring up nature conservation issues when it comes to large solar-electric installations outside of cities. Some people try to utilize these renewable technologies in an efficient and aesthetically pleasing way: fixed solar collectors can double as noise barriers along highways, roof-tops are available already and could even be replaced totally by solar collectors, amorphous photovoltaic cells can be used to tint windows and produce energy etc. Some renewable energy capture systems entail unique environmental problems. For instance, wind turbines can be hazardous to flying birds, while hydroelectric dams can create barriers for migrating fish - a serious problem in the Pacific Northwest that has decimated the numbers of many salmon populations. Burning biomass and biofuels causes air pollution similar to that of burning fossil fuels, although it causes a lower greenhouse effect since the carbon placed in the atmosphere was already there before the plants were grown, rather than being "new" carbon from fossil fuels . Another problem with many renewables, especially biomass and biofuels, is the large amount of land required, which otherwise could be left as wilderness.

Concentration

Another inherent difficulty with renewables is their variable and diffuse nature (the exception being geothermal energy, which is however only accessible in exceptional locations). Since renewable energy sources are providing relatively low-intensity energy, the new kinds of "power plants" needed to convert the sources into usable energy need to be distributed over large areas. Electrical power consumption in Western countries averages about 100 watts per person (i.e. about 1 MWh per year). In cloudy Europe this would require about eight square meters of solar panels, assuming a below-average solar conversion rate of 12.5%. Systematic electrical generation requires reliable overlapping sources or some means of storage on a reasonable scale (pumped-storage hydro systems, batteries, hydrogen fuel cells, etc). So, because of current costs of such energy storage systems, a stand-alone system is only economic in rare cases, or where a connection to a public grid would be impractical.

Proximity to demand

The geographic diversity of resources is also significant. Some countries and regions have significantly better resources than others in particular RE sectors. Some nations have significant resources at distance from the major population centers where electricity demand exists. Exploiting such resources on a large scale is likely to require considerable investment in transmission and distribution networks as well as in the technology itself.

Availability

One recurring criticism of renewable sources is their intermittant nature. Solar insolation, for example can only be expected to be available during the day (50% of the time). Wind energy is somewhat more available, while geothermal and wave energy are available all of the time, although the intensity of the waves varies season to season. A wave energy scheme installed in Australia is generating electricity with an 80% availability factor.

Fossil fuels

Renewable energy sources are fundamentally different from fossil fuel or nuclear power plants because the Sun will 'power' these 'power plants' (meaning sunlight, the wind, flowing water, etc.) for the next 4 billion years. They also do not directly produce greenhouse gases and other emissions, as fossil fuel combustion does. Most do not introduce any global new risks such as nuclear waste. Fossil fuels are not considered a renewable energy source, but are often compared and contrasted with renewables in the context of future energy development. The traditionally, though not universally, held Western (biogenic) theory postulates that fossil fuels are the altered remnants of ancient plant and animal life deposited in sedimentary rocks. They were formed millions of years ago and have rested underground, mostly dormant, since that time. In contrast, the Abiogenic petroleum origin theory states that petroleum (or crude oil) is primarily created from non-biological sources of hydrocarbons located deep in the Earth. This view was championed by Fred Hoyle in his book The Unity of the Universe. Though it is possible to produce complex hydrocarbons artificially by using the Fischer-Tropsch process, this process does not generate energy, and cannot be considered a large scale solution to the energy problem. The coal industry in the US is publicly claiming coal is renewable energy because the coal was originally biomass. However, the biomass of fossil fuels was produced on the time scale of millions of years through a series of events and it is considered to be a deposit of energy, not an energy flow. Some scientist hold the view that the formation of fossil fuels was a one-time event, made possible by unique conditions during the Devonian period, such as increased oxygen levels and huge swamps. When the term renewable was introduced (see Defining renewable within this article), it was a generally held belief that the Earth's sources would be depleted within some 50 years. Since then, large deposits of deep-Earth oil have been found, which has extended this timetable. Because the current rate of consumption exceeds the rate of renewal (if, indeed, there is renewal of fossil fuels), the Earth will eventually run out of fossil fuels (see peak oil).

Transmission

If renewable and distributed generation were to become widespread, electric power transmission and electricity distribution systems might no longer be the main distributors of electrical energy but would operate to balance the electricity needs of local communities. Those with surplus energy would sell to areas needing "top ups". That is, network operation would require a shift from 'passive management' - where generators are hooked up and the system is operated to get electricity 'downstream' to the consumer - to 'active management', wherein generators are spread across a network and inputs and outputs need to be constantly monitored to ensure proper balancing occurs within the system. Some Governments and regulators are moving to address this, though much remains to be done. One potential solution is the increased use of active management of electricity transmission and distribution networks. This will require significant changes in the way that such networks are operated. However, on a small scale, use of renewable energy that can often be produced "on the spot" lowers the requirements electricity distribution systems have to fulfill. Current systems, while rarely economically efficient, have proven an average household with a solar panel array and energy storage system of the right size needs electricity from outside sources for only a few hours every week. Hence, advocates of renewable energy believe electricity distribution systems will become smaller and easier to manage, rather than the opposite.

Historical usage of renewable energy

Throughout history, various forms of renewable and non-renewable energies have been employed.
- Wood was the earliest manipulated energy source in human history, being used as a thermal energy source through burning, and it is still important in this context today. Burning wood was important for both cooking and providing heat, enabling human presence in cold climates. Special types of wood cooking, food dehydration and smoke curing, also enabled human societies to safely store perishable foodstuffs through the year. Eventually, it was discovered that partial combustion in the relative absence of oxygen could produce charcoal, which provided a hotter and more compact and portable energy source. However, this was not a more efficient energy source, because it required a large input in wood to create the charcoal.
- Animal power for vehicles and mechanical devices was originally produced through animal traction. Animals such as horses and oxen not only provided transportation but also powered mills. Animals are still extensively in use in many parts of the world for these purposes.
- Water power eventually supplanted animal power for mills, wherever the power of falling water in rivers was exploitable . Water power through hydroelectricity continues to be the least expensive method of storing and generating dispatchable energy throughout the world. Historically as well as presently, hydroelectricity provides more renewable energy than any other renewable source.
- Animal oil, especially whale oil was long burned as an oil for light.
- Wind power has been used for several hundred years. It was originally used via large sail-blade windmills with slow-moving blades, such as those seen in the Netherlands and mentioned in Don Quixote. These large mills usually either pumped water or powered small mills. Newer windmills featured smaller, faster-turning, more compact units with more blades, such as those seen throughout the Great Plains. These were mostly used for pumping water from wells. Recent years have seen the rapid development of wind generation farms by mainstream power companies, using a new generation of large, high wind turbines with two or three immense and relatively slow-moving blades. Today, wind power is the fastest growing energy source in the world.
- Solar power as a direct energy source has been not been captured by mechanical systems until recent human history, but was captured as an energy source through architecture in certain societies for many centuries. Not until the twentieth century was direct solar input extensively explored via more carefully planned architecture (passive solar) or via heat capture in mechanical systems (active solar) or electrical conversion (photovoltaic). Increasingly today the sun is harnessed for heat and electricity.
- Attempts to harness the power of ocean waves appears in drawings and patents back to the 19th century. Modern attempts to capture wave power began in the 1970's by Professor Steven Salter who started the Wave Energy Group at the University of Edinburgh in Scotland. There are several pilot plants generating power into the grid, and many new and curious designs are in various stages of development and testing.

External links

- [http://www.greenmountain.com Green Mountain Energy]
- [http://www.renewableenergyaccess.com Renewable Energy News from around the world]
- [http://www.futurecrisis.com/alternative-energy-plans.php Renewable Energy Projects and Daily News]
- [http://www.cus.net/ Renewable Energy]
- [http://groups.yahoo.com/group/worldoilboycott World Oil Boycott Grassroots Organization]
- [http://www.greenprogress.com/alternative_energy.php Green Progress - alternative energy news]
- [http://www.solardrome.com SolarDrome Renewable Energy from Around the Web]
- [http://www.greenfuelonline.com/enterprise4.htm Technology turns greenhouse gas emissions to clean air biofuels]
- [http://www.ief-energy.org/ International Energy Foundation]
- [http://www.inboxrobot.com/news/AlternativeEnergy Alternative Energy newsletter for Research Professionals]
- [http://www.nrel.gov/ National Renewable Energy Laboratory (American)]
- [http://www.GenomeNewsNetwork.org/categories/index/energy.php Genome News Network (GNN) Energy News] Collection of articles about how advances in genomics is leading to advances in energy production.
- [http://www.cat.org.uk/ Centre for Alternative Energy (European)]
- [http://www.activistmagazine.com/index.php?option=content&task=view&id=120 Carbon Activism for Beginners].
- [http://www.ecoresearch.net/election2004/report/sentence?s=1 Renewable Energy Media Analysis] — US Election 2004 Web Monitor
- [http://europa.eu.int/comm/energy/intelligent/index_en.html EU Intelligent Energy], energy efficiency and renewables.
- [http://www.ademe.fr/ French Agency for the Environment and Energy Management], fields of activity : air quality, wastes, energy-efficiency and renewables, environmental management, polluted soils, transportation
- [http://www.itdg.org/ Intermediate Technology Development Group]
- [http://www.thehydrogenexpedition.com/ The Hydrogen Expedition] Renewable energy world record
- [http://www.aapg.org/explorer/2002/11nov/abiogenic.cfm Abiogenic Gas Debate] On the possible abiogenic origin of fossil fuels
- [http://wiki.greenpowered.org Green Wiki] Collective articles on renewable energy and other topics related to sustainable living
- [http://energy.sourceguides.com/index.shtml The Source for Renewable Energy] A directory to more than 9000 renewable energy businesses worldwide
- [http://environmental-finance.com Environmental Finance magazine]
- [http://climatechangeaction.blogspot.com/2005/09/energy-efficiency-vs-small-scale.html Renewables vs Energy Efficiency] Where should i spend my money if i want to have a low carbon home?
- [http://europa.eu.int/comm/energy/res/index_en.htm European Union website about renewable energy]
- [http://www.rengen.info/?p=6 The wide world of renewable energy]

References

- [http://eia.doe.gov/ U.S. Energy Information Administration] provides a wide range of statistics and information on the industry.
- Boyle, G. (ed.), Renewable Energy: Power for a Sustainable Future. Open University, UK, 1996.
- [http://www.eere.energy.gov/ U.S. DOE Energy Efficiency and Renewable Energy (EERE) Home Page] Category:Climate change Category:Sustainability ja:再生可能エネルギー

Pollution

Environmental Pollution is the release of harmful environmental contaminants, or the substances so released. Generally the process needs to result from human activity to be regarded as pollution. Even relatively benign products o

POOP

f human activity are liable to be regarded as pollution, if they precipitate negative effects later on. The nitrogen oxides produced by industry are often referred to as pollution, for example, although the substances themselves are not harmful. In fact, it is solar energy (sunlight) that converts these compounds to smog. Pollution can take two major forms: local pollution and global pollution. In the past, only local pollution was thought to be a problem. For example, coal burning produces smoke, which in sufficient concentrations can be a health hazard. One slogan, taught in schools, was "The solution to pollution is dilution." The theory was that sufficiently diluted pollution could cause no damage. In recent decades, awareness has been rising that some forms of pollution pose a global problem. For example, human activity (primarily nuclear testing) has significantly raised the levels of background radiation, which may lead to human health problems, all over the world. Awareness of both kinds of pollution, among other things, has led to the environmentalism movement, which seeks to limit the human impact on the environment. Whether something is pollution depends almost entirely on context. Blooms of algae and the resultant eutrophication of lakes and coastal ocean is considered pollution when it is fueled by nutrients from industrial, agricultural, or residential runoff in either point source or nonpoint source form (see the article on eutrophication for more information). Heavy metals such as lead and mercury have a role in geochemical cycles (i.e. they occur as within 'nature'). These metals may also be mined and, depending on their processing, may thus be released in large concentrations into an environment previously not playing host to them. Just as the influences of anthropogenic release of these metals to the environment may be considered as 'polluting', such pollution could also occur in some areas due to either autochtonous or historic 'natural' geochemical activity. Carbon dioxide is sometimes referred to as a pollution, on the basis that these emissions have led, or are leading, to raised levels of the gas in the atmosphere and, furthermore, to harmful changes in the Earth's climate. Such claims are strongly disputed, particularly by political conservatives in Western countries and most strongly in the United States. Due to this controversy, in many contexts carbon dioxide from such sources are labelled neutrally as "emissions." See global warming for a very extensive discussion of this topic. Traditional forms of pollution include air pollution, water pollution, and radioactive contamination while a broader interpretation of the word has led to the ideas of ship pollution, light pollution, and noise pollution. Serious pollution sources include chemical plants, oil refineries, nuclear waste dumps, regular garbage dumps (many toxic substances are illegally dumped there), incinerators, PVC factories, car factories, plastics factories, and corporate animal farms creating huge amounts of animal waste. Some sources of pollution, such as nuclear power plants or oil tankers, can release very severe pollution when accidents occur. Some of the more common contaminants are chlorinated hydrocarbons (CFH), heavy metals like lead (in lead paint and until recently in gasoline), cadmium (in rechargeable batteries), chromium, zinc, arsenic and benzene. Pollution is often a serious side effect in natural disasters. For example hurricanes almost always involve sewage pollution, and petrochemical pollution from overturned boats or automobiles, or even damage from coastal refineries is common. Pollutants are thought to play a part in a variety of maladies, including cancer, lupus, immune diseases, allergies, and asthma. Some illnesses are named in relation with certain pollutants: for example, Minamata disease, which is caused by mercury compounds.

Regulation and Monitoring

International

The Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty on global warming. It also reaffirms sections of the UNFCCC. Countries which ratify this protocol commit to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases. A total of 141 countries have ratified the agreement. Notable exceptions include the United States and Australia.

United States

The United States Environmental Protection Agency (EPA) was supposed to establish "acceptable" levels of exposure to contaminants. One of the ratings chemicals are given are carcinogenicity, or how likely they are to cause cancer. Levels range from, not carcinogenic, likely carcinogen, known carcinogen, and unknown. But some scientists have said that most of these levels are far too high and people should be exposed less to them. The CalEPA Office of Environmental Health Hazard Assessment has a different list of levels. ([http://www.oehha.ca.gov/prop65/prop65_list/Newlist.html OEHHA]). The U.S. has a maximum fine of US$25,000 for dumping toxic waste. However, many large manufacturers plead guilty, as they can easily afford this relatively small fine.

External links

- [http://www.scorecard.org/chemical-groups/one-list.tcl?short_list_name=tri00ry Toxic Release Inventory] - tracks how much waste companies release into the water and air. Gives permits for releasing specific quantities of these pollutants each year. [http://toxmap.nlm.nih.gov/toxmap/main/index.jsp Map]
- [http://www.scorecard.org/chemical-groups/one-list.tcl?short_list_name=hs Superfund] - manages Superfund sites and the pollutants in them (CERCLA).
- [http://www.osha-slc.gov/SLTC/pel/index.html OSHA limits for air contaminants]
- [http://atsdr1.atsdr.cdc.gov:8080/atsdrhome.html Agency for Toxic Substances and Disease Registry] - found out top 20 pollutants, alias for chemicals, how they affect people, what industries use them and what products they are found in.
- [http://ntp-server.niehs.nih.gov/ National Toxicology Program] - from National Institutes of Health. Reports and studies on how pollutants affect people.
- [http://toxnet.nlm.nih.gov/ Toxnet] - more databases and reports on toxicology. From NIH
- [http://www.scorecard.org Scorecard.org] - lots of information about pollution in the US. Just enter your zip code. Colored maps also show how bad certain types of pollution are in your area.
- [http://www.epa.gov Environmental Protection Agency]
- [http://www.oehha.ca.gov/prop65/prop65_list/Newlist.html OEHHA]
- [http://ntmc0.tripod.com National Toxic Mold Coalition and Foundation]
- [http://www.edf.org Environmental Defense Fund]
- [http://www.rachel.org Rachel's Environment and Health News] - Weekly news about how the polluted environment affects people, and what corporations and governments are doing (or not doing) about it. Also in Spanish.
- [http://www.essential.org Essential.org] - Some organizations related to consumers and consumer protection, including pollution.
- [http://www.cleanupge.org CleanUp GE.org] - Info about GE's shady dumping practices on the Hudson river.
- [http://www.Pollution.net Pollution.net] - Good starting point for environmental jobs, environmental news, articles and books. Plus blogs on environmental issues
- [http://ace.orst.edu/info/extoxnet/newsletters/ghindex.html Extoxnet newsletters] - environmental pollution news. Last update 1998.
- [http://www.enn.com/ Environmental News Network] - more news
- [http://www.ewg.org/ Environmental Working Group]
- [http://www.ejnet.org/sludge/ Sewage Sludge] - in the U.S. it is perfectly legal to fertilize food crops with solids from the sewer, which include lots of heavy metals and toxins.
- [http://dir.yahoo.com/Health/medicine/toxicology/ Yahoo - Toxicology] - another great starting point.
- [http://sis.nlm.nih.gov/Tox/ToxTutor.html The ToxTutor from the National Library of Medicine] - An excellent resource to review human toxicology.
- [http://the-raw-prawn.blogspot.com/2004/10/pollution-and-development-as-seen-from.html Pollution and development, as seen from space]
- [http://www.choosevegetarian.com/earth_overview.asp Overview of the possible environmental benefits of a plant-based diet]
- [http://airspace.bc.ca/Airspace Action on Smoking and Health]
- [http://www.cigarettelitter.org/ CigaretteLitter.Org - The Facts About Cigarette Butts and Litter - Cigarette Litter] ja:公害 th:มลพิษ

Geothermal power

Geothermal power is electricity generated by utilizing naturally occurring geological heat sources. It is a form of renewable energy.

Types of geothermal sources

renewable energy Geothermal power is generally harnessed in one of three ways. Large scale electrical generation is possible in areas near geysers or hot springs by utilizing naturally occurring steam, superheated ground water or using geothermal heat to heat a heat-transfer fluid. Experiments are in progress to determine if a fourth method, deep wells into "hot dry rocks", can be economically used to heat water pumped down from the surface. A hot dry rock project in the United Kingdom was abandoned after it was pronounced economically unviable in 1989. HDR programs are currently being developed in Australia, France, Switzerland and Germany. Magma (molten rock) resources offer extremely high-temperature geothermal opportunities, but existing technology does not allow recovery of heat from these resources.

Electrical generation

Geothermal-generated electricity was first produced at Larderello, Italy, in 1904. Since then, the use of geothermal energy for electricity has grown worldwide to about 8,000 megawatts of which the United States produces 2700 megawatts. The largest dry steam field in the world is The Geysers, about 90 miles (145 km) north of San Francisco began in 1960 which produces 2000 MWe. Calpine Corporation now owns 19 of the 21 plants in The Geysers and is currently the United States' largest producer of renewable geothermal energy. The other two plants are owned jointly by the Northern California Power Agency and Santa Clara Electric. Since the activities of one geothermal plant affects those nearby, the consolidation plant ownership at The Geysers has been beneficial because the plants operate cooperatively instead of in their own short-term interest. Another major geothermal area is located in south central California, on the southeast side of the Salton Sea, near the cities of Niland and Calipatria, CA. As of 2001, there were 15 geothermal plants producing electricity in the area. CalEnergy owns about half of them and the rest are owned by various companies. Combined the plants produce about 570 megawatts. Geothermal power is very cost-effective in the Rift area of Africa. Kenya's KenGen has built two plants, Olkaria I (45MW) and Olkaria II (65MW), with a third private plant Olkaria III (48MW) run by Israeli geothermal specialist Ormat. Plans are to increase production capacity by another 576MW by 2017, covering 25% of Kenya's electricity needs, and correspondingly reducing dependency on imported oil. Geothermal power is generated in over 20 countries around the world including Iceland (producing 17% of its electricity from geothermal sources), the United States, Italy, France, New Zealand, Mexico, Nicaragua, Costa Rica, Russia, the Philippines, Indonesia and Japan. Canada's government (which officially notes some 30,000 earth-heat installations for providing space heating to Canadian residential and commercial buildings) reports a test geothermal-electrical site in the Meager Mountain - Pebble Creek area of B.C, where a 100 MW facility might be developed at that site.

Desalination

Douglas Firestone began working with evaporation/condensation air loop desalination about 1998 and proved that geothermal waters could be used as process water to produce potable water in 2001. In 2003 Professor Ronald A. Newcomb, now at San Diego State University Center for Advanced Water Technologies began to work with Firestone to enhance the process of using geothermal energy for the purpose of desalination. In 2005 testing was done in the fifth prototype of a device called the “Delta T” a closed air loop, atmospheric pressure, evaporation condensation loop geothermally powered desalination device. The device used filtered sea water from Scripps Institute of Oceanography and reduced the salt concentration from 35,000ppm to 51ppm. [http://aquagenesis.us/testing.html]

Water injection

In some locations, the natural supply of water producing steam from the hot underground magma deposits has been exhausted and processed waste water is injected to replenish the supply. Most geothermal fields have more fluid recharge than heat, so re-injection can cool the resource, unless it is carefully managed. In at least one location, this has resulted in small but frequent earthquakes (see external link below). This has led to disputes about whether the plant owners are liable for the damage the earthquakes cause.

Heat depletion

Although geothermal sites are capable of providing heat for many decades, eventually they are depleted as the ground cools. [http://www.geothermie.de/egec-geothernet/ci_prof/australia_ozean/new_zealand/0080.PDF] The government of Iceland states It should be stressed that the geothermal resource is not strictly renewable in the same sense as the hydro resource. It estimates that Iceland's geothermal energy could provide 1700 MW for over 100 years, compared to the current production of 140 MW. [http://eng.idnadarraduneyti.is/ministries/homepage//nr/1191]

Cost

Currently there are few geothermal resource areas in the U.S. capable of generating electricity at a cost competitive with other energy sources, particularly natural gas. Internationally geothermal power is more competitive in those countries that have limited hydrocarbon resources, such as Iceland, New Zealand, and Italy. Not all areas of the world have a usable geothermal resource, though many do. Also, some geothermal areas do not have a high enough temperature to produce steam. In those areas, geothermal power can be generated using a process called binary cycle technology, though the efficiency is lower. Other areas do not have the water to produce steam, which is necessary for current plant designs. Geothermal areas without steam are called hot dry rock areas and methods for exploiting them are being researched. Also, instead of producing electricity, lower temperature areas can provide space and process heating. As of 1998, the U.S. has 18 district heating systems, 28 fish farms, 12 industrial plants, 218 spas and 38 greenhouses that use geothermal heat.

External links

- [http://www.cus.net/renewableenergy/subcats/geothermal/geothermal.html Geothermal Energy]
- [http://hotrock.anu.edu.au/ Australian National University Hotrock website]
- [http://www.geodynamics.com.au/IRM/content/default.htm Geodynamics - Australian Company developing Geothermal Electricity in Australia]
- [http://www.eere.energy.gov/geothermal/ US Department of Energy pages on geothermal energy]
- [http://www.uaf.edu/energyin/webpage/pages/renewable_energy_tech/geothermal.htm A University of Alaska article on geothermal energy]
- [http://quake.wr.usgs.gov/recenteqs/FaultMaps/122-38.htm Earthquakes due to geothermal energy production] - A real-time one week duration earthquake map that always shows a number of small earthquakes due to water injection and geothermal production - observe the upper left corner (Cloverdale) - this is the site of a geothermal plant called "The Geysers"
- [http://www.ees4.lanl.gov/hdr/ Hot Dry Rock Geothermal Energy Technology]
- [http://aquagenesis.us/ \Geothermal Desalination and Water Reclamation]
- [http://www.kengen.co.ke/content.asp?id=9&catid=2 KenGen Geothermal power generation page]
- [http://www.ormat.com/projects_kenya.htm Ormat page on the Olkaria III project], which uses air instead of water for cooling Category:Energy conversion Category:Renewable energy Category:Alternative energy ja:地熱発電

Wind power

Wind power is the kinetic energy of wind, or the extraction of this energy by wind turbines. This article deals mainly with the intricacies of large-scale deployment of wind turbines to generate electricity.

Wind energy

An estimated 1 to 3 percent of the energy from the Sun is converted into wind energy. This is about 50 to 100 times more energy than what is converted into biomass by all the plants on earth through photosynthesis. Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) are common. Eventually, the wind energy is converted through friction into diffuse heat all through the earth's surface and atmosphere. While the exact kinetics of wind are extremely complicated and relatively little understood, the basics of its origins are relatively simple. The earth is not heated evenly by the sun. Not only do the poles receive less energy from the sun than the equator does, but dry land heats up (and cools down) more quickly than the seas do. The differential heating powers a global atmospheric convection system reaching from the earth's surface to the stratosphere which acts as a virtual ceiling. The change of seasons, change of day and night, the Coriolis effect, the irregular albedo (reflectivity) of land and water, humidity, and the friction of wind over different terrain are some of the many factors which complicate the flow of wind over the surface.

Wind variability and turbine nameplate power

The power in the wind can be extracted by having it act on moving wings, connected to a rotor, which converts some of that power into torque on the rotor. The amount of power transferred depends on the wind speed (cubed), the swept area (linearly), and the density of the air (linearly). The mass flow of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15 °C (59 °F) day at sea level, air density is about 1.22 kilograms per cubic metre (it gets less dense with higher humidity). An 8 m/s breeze blowing through a 100 meter diameter rotor would move about 76,000 kilograms of air per second through the swept area. The kinetic energy of a given mass varies with the square of its velocity. Because the mass flow increases linearly with the wind speed, the wind energy available to a wind turbine increases as the cube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 megawatts. As the wind turbine extracts energy from the air flow, the air is slowed down, which causes it to spread out and diverts it around the wind turbine to some extent. A German physicist, Albert Betz, determined in 1919 that a wind turbine can extract at most 59% of the energy that would otherwise flow through the turbine's cross section. The Betz limit applies regardless of the design of the turbine. More recent work [http://mystic.math.neu.edu/gorban/Gorlov2001.pdf] by Gorlov shows a theoretical limit of about 30% for propeller-type turbines. Actual efficiencies range from 10% to 20% for propeller-type turbines, and are as high as 35% for three-dimensional vertical-axis turbines like Darrieus or Gorlov turbines. kinetic energy Windiness varies, and an average value for a given location is not in itself a clear indication of the amount of energy a wind turbine could yield there. The distribution model most frequently used is the Raleigh model, an example of which is plotted to the right against an actual measured dataset. Because so much power is generated by higher windspeed, much of the average power available to a windmill comes in short bursts. The 2002 Lee Ranch sample is telling: half of the energy available arrived in just 15% of the operating time. Since wind speed is not constant, a wind generator's annual energy production is never as much as its nameplate rating multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. A well-sited wind generator will have a capacity factor of as much as 35%. When comparing the size of wind turbine plants to fueled power plants, it is important to note that 1000 kW of wind-turbine potential power would be expected to produce as much energy in a year as approximately 350 kW of fuel-fired generation. Though the short-term (hours or days) output of a wind-plant is not completely predictable, the annual energy of output tends to vary only a few percent between years.

Wind power density classes

Wind maps in the United States and Europe classify areas into seven arbitrarily defined classes of wind power density, analogous to the five classes of hurricane force. This [http://rredc.nrel.gov/wind/pubs/atlas/tables/A-8T.html table] is taken directly from [http://rredc.nrel.gov/wind/pubs/atlas/ Wind Energy Resource Atlas of the United States]. Each class is a range of power densities, so that an area rated as class 4, for example, would have average power density from 200 to 250 W/m² at 10 m above ground. Generally, economic development of wind power for electricity generation takes place in areas rated Class 3 or higher.

Table 1-1 Classes of wind power density at 10 m and 50 m^(a).
Wind Power Class	10 m (33 ft)		50 m (164 ft)
Wind Power Class	Wind power density (W/m²)	Speed^(b) m/s (mph)	Wind power density (W/m²)	Speed^(b) m/s (mph)
1	0	0	0	0
1	100	4.4 (9.8)	200	5.6 (12.5)
2	100	4.4 (9.8)	200	5.6 (12.5)
2	150	5.1 (11.5)	300	6.4 (14.3)
3	150	5.1 (11.5)	300	6.4 (14.3)
3	200	5.6 (12.5)	400	7.0 (15.7)
4	200	5.6 (12.5)	400	7.0 (15.7)
4	250	6.0 (13.4)	500	7.5 (16.8)
5	250	6.0 (13.4)	500	7.5 (16.8)
5	300	6.4 (14.3)	600	8.0 (17.9)
6	300	6.4 (14.3)	600	8.0 (17.9)
6	400	7.0 (15.7)	800	8.8 (19.7)
7	400	7.0 (15.7)	800	8.8 (19.7)
7	1000	9.4 (21.1)	2000	11.9 (26.6)

(a) Vertical extrapolation of wind speed based on the 1/7 power law. (b) Mean wind speed is based on Rayleigh speed distribution of equivalent mean wind power density. Wind speed is for standard sea-level conditions. To maintain the same power density, speed increases 3%/1000 m (5%/5000 ft) elevation.

Turbine siting

power plant As a general rule, wind generators are practical where the average wind speed is greater than 20 km/h (5.5 m/s or 12.5 mph). Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year, and wouldn't suffer too many sudden powerful bursts of wind. The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and the reduced viscosity of the air. The variation in velocity with altitude, called wind shear is most dramatic near the surface. Typically, the variation follows the 1/7th power law, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10% and the expected power by 34%. Wind farms or wind parks often have many turbines installed. Since each turbine extracts some of the energy of the wind, it is important to provide adequate spacing between turbines to avoid excess energy loss. Where land area is sufficient, turbines are spaced three to five rotor diameters apart perpendicular to the prevailing wind, and five to ten rotor diameters apart in the direction of the prevailing wind, to minimize efficiency loss. The "wind park effect" loss can be as low as 2% of the combined nameplate rating of the turbines. Utility-scale wind turbine generators have low temperature operating limits which restrict the application in areas that routinely experience temperatures less than −20 °C. Wind turbines must be protected from ice accumulation, which can make anemometer readings inaccurate and which can cause high structure loads and damage. Some turbine manufacturers offer low-temperature packages at a cost of a few percent of the turbine cost, which include internal heaters, different lubricants, and different alloys for structural elements, to make it possible to operate the turbines at lower temperatures. If the low-temperature interval is combined with a low-wind condition, the wind turbine will require station service power, equivalent to a few percent of its output rating, to maintain internal temperatures during the cold snap. For example, the St. Leon, Manitoba project has a total rating of 99 MW and is estimated to need up to 3 MW (around 3% of capacity) of station service power a few days a year for temperatures down to −30 °C. This factor affects the economics of wind turbine operation in cold climates.[1]

Onshore

Onshore turbine installations tend to be along mountain ridges or passes, or at the top of cliff faces. The change in ground elevation causes the wind velocities to be generally higher in these areas, although there may be a lot of variation over relatively short distances (a difference of 30 m can sometimes mean a doubling in output). Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed. For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that is permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable. Sea shores also tend to be windy areas and good sites for turbine installation, because a primary source of wind is convection from the differential heating and cooling of land and sea over the course of day and night. Winds at sea level carry somewhat more energy than winds of the same speed in mountainous areas because the air at sea level is more dense. Unfortunately, windy areas tend to be picturesque, and so there is a great deal of opposition to the installation of wind turbines on what would otherwise appear to be ideal sites.

Offshore

prospecting Offshore wind turbines are considered to be less unsightly (they can be invisible from shore), and because the winds are usually more potent offshore, such turbines don´t need to reach quite as high into the air. However, offshore conditions are harsh, abrasive, and corrosive, and it is often impossible or near-impossible to repair a broken down turbine in open waters. In stormy areas with extended shallow continental shelves and sand banks (such as Denmark), turbines are reasonably easy to install, and give good service - Denmark's offshore wind generation provides about 20% of total electricity demand in the country, while generating more than 20,000 jobs [http://www.windpower.org/media(775,1033)/Annual_report_2004.pdf]. At the site shown, the wind is not especially strong but is very consistent. The largest offshore wind turbines in the world, are installed in a small group of seven off the coast of Wicklow in Ireland, and are located on a sand bank. As of 2005, the largest offshore wind farm is Horns Rev which is located 15km west of Jutland, Denmark [http://www.hornsrev.dk/Engelsk/default_ie.htm].

Airborne

It has been suggested that wind turbines might be flown in high speed winds at high altitude. No such systems currently exist.

Utilization

Large scale

There are now many thousands of wind turbines operating in various parts of the world, with a total capacity of over 47,317 MW of which Europe accounts for 72% (2005). It was the most rapidly-growing means of alternative electricity generation at the turn of the century and provides a valuable complement to large-scale base-load power stations. World wind generation capacity quadrupled between 1997 and 2002. 90% of wind power installations are in the US and Europe. Denmark, Ireland, and Germany have made considerable investments in wind generated electricity. Denmark is especially a leader in the production and use of turbines, with a commitment made in the 1970s to eventually produce half of the country's power by wind. General Electric recently constructed the world's largest offshore wind turbine park in Ireland, and plans are being made for more such installations on the west coast, including the possible the use of floating turbines. Germany already produces 40% of the entire world's wind power, and the hope is that by 2010, wind will meet 12.5% of German electricity needs. Germany has 16,000 wind turbines, mostly concentrated in the north of the country, near the border with Denmark - including the biggest in the world, owned by the Repower company. While the United States government lost interest when the price of oil dropped after the 1970s oil crisis, the Danes and Germans continued their efforts and now are a leading exporter of large turbines (each generating 0.66 to 5.0 megawatt). Wind accounts for 0.4% of the total electricity production on a global scale (2002). Germany is the leading producer of wind power with 35% of the total world capacity in 2005 (10% of German electricity). The United States and Spain are next in terms of installed capacity. According to the American Wind Energy Association, wind generated enough electricity to power 0.4% (1.6 million households) of total electricity in US, up from less than 0.1% in 1999. Germany's Schleswig-Holstein province generates 25% of its power with wind turbines. Denmark generates over 20% of its electricity with wind turbines, the highest percentage of any country and is fourth in the world in total power generation. Today (2005) Germany produces more electricity from wind power than from hydropower plants. After Denmark, Germany, the United States, and Spain, India ranks 5th in the world with a total wind power capacity of 3500 MW. Almost half of this capacity (1600 MW) was added in the last two years, and of new electricity capacity additions in the country, wind power accounted for over 20% of the total in that period. Currently wind power generates 3% of all electricity produced in India. Unlike the others in the top 5, India's estimated wind power potential is pretty low at just 45 gigawatts, while world wide potential is estimated at 72 terawatts, with the US and Northern Europe among the regions with the maximum potential. On August 15, 2005, China announced it would build a 1000-megawatt wind farm in Hebei for completion in 2020. China reportedly has set a generating target of 20 million kilowatts by 2020 from renewable energy sources - it says indigenous wind power could generate up to 253 million kilowatts.[http://news.yahoo.com/s/ap/20050815/ap_on_sc/china_wind_power] Another growing market is Brazil, with a wind potential of 143 GW.[http://www.cresesb.cepel.br/atlas_eolico_brasil/atlas-web.htm] The federal government has created an incentive program, called Proinfa[http://www.eletrobras.gov.br/EM_Programas_Proinfa/default.asp], to build production capacity of 3300 MW of renewable energy for 2008, of which 1422 MW through wind energy. The program seeks to produce 10% of Brazillian electricity through renewable sources. Brazil produced 320 TWh in 2004.

Small scale

TWh Wind turbines have been used for household electricity generation in conjunction with battery storage over many decades in remote areas. Household generator units of more than 1 kW are now functioning in several countries. To compensate for the varying power output, grid-connected wind turbines utilise some sort of grid energy storage. Off-grid systems either adapt to intermittent power or use photovoltaic or diesel systems to supplement the wind turbine. Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind; while the larger ones generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. As technology progresses, large generators are becoming as simple as small generators. Direct drive generators and aeroelastic blades for large wind turbines are being researched and direct current generators are sometimes used. In urban locations, where it is difficult to obtain large amounts of wind energy, smaller systems may still be used to run low power equipment. Distributed power from rooftop mounted wind turbines can also alleviate power distribution problems, as well as provide resilience to power failures. Equipment such as wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid and/or maintaining service despite possible power grid failures. Distributed power The Lakota turbine by Aeromax is approximately 7 feet (2 m) in diameter and produces 900 watts of three phase power. It uses a three phase rectifier and charge controller so that it is free to spin at whatever speed is optimal for a given wind condition. Lightweight materials (the entire turbine weighs only 16kg (35 pounds)) allow it to respond quickly to the gusts of wind typical of urban settings. It attaches to a size 9 structural pipe (similar to a TV antenna mast). The Lakota is very quiet. Even when standing up on the roof right next to the mast it is inaudible. Climbing up the mast, it is still inaudible from just a few feet under the turbine. A dynamic braking system regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building, so that the 'heat loss' will heat the inside of the building (i.e. during high winds when more heat is lost by the building, more heat is also produced by the braking resistor). The proximal location makes low voltage (12 volt, or the like) energy distribution practical, e.g. in a typical installation the braking resistor can be located just inside to where the mast is attached to the building. Such small-scale renewable energy sources also impart a beneficial psychological effect on building owners, so that they begin to take on a keen awareness of electricity consumption, possibly reducing their consumption down to the average level that the turbine can produce.

Controversy

The debate around wind energy is heated and often emotional. Arguments of both parties are listed below.

Arguments of opponents

dynamic braking

Economics

- Wind power depends on operational subsidies. In the United States, wind power receives a tax credit of 1.9 cents per kilowatt-hour produced, wiht a year inflationary adjustment. Another tax benefit is accelerated depreciation. Many American states also provide incentives, such as exemption from property tax, mandated purchases, and additional markets for "green credits." Countries such as Canada and Germany also provide tax credits and other incentives for wind turbine construction. Although other energy sources are also subsidized, the amount per kilowatt-hour may be much higher for wind.
- Maintenance of wind turbines can be difficult and expensive. Repairs require a much more complicated and expensive operation than ground based generation.
- Many potential sites for wind farms are far from demand centers, requiring substantially more money to construct new transmission lines and substations.

Yield

- The goals of renewable energy development are reduction of reliance on fossil and nuclear fuels, reduction of greenhouse gas and other emissions, and establishment of more sustainable sources of energy. Some critics question wind energy's ability to significantly move society towards these goals. They point out that 25-30% annual load factor is typical for wind facilities. The intermittent and nondispatchable nature of wind turbine power requires that "spinning reserves" are kept burning for supply security. More frequent ramping of such plants means lower efficiency and possibly greater emissions.
- Another charge is that output figures, such as "Denmark produces over 20% of its electricity from wind," do not account for electricity that is simply absorbed by the international grid because it is produced when demand is already being met by other sources that can't be turned off, such as base load and combined heat and power plants.
- Electric power production is only part (about one to two fifths) of a country's energy use, and wind power does nothing to mitigate the larger part of the effects of energy use. For example, despite aggressive installation of wind facilities in the U.K., that country's CO₂ emissions continued to rise in 2002 and 2003 (Department of Trade and Industry). Greenhouse gas emissions in Denmark rose 6.2% in 2003 (National Environmental Research Institute).
- Groups such as the UN's Intergovernmental Panel on Climate Change state that the desired mitigation goals can be achieved at lower cost and to a greater degree by continued improvements in general efficiency — in building, manufacturing, and transport — than by wind power. A study by the Irish Grid into expanding wind power similarly concluded that, "The cost of CO₂ abatement arising from using large levels of wind energy penetration appears high relative to other alternatives."

Ecological footprint

- The construction of a large facility is also far from ecologically neutral if the location has no previous development. It requires roads, foundations, clearing of trees, and construction of power lines. The clearing of trees is necessary since obstructions within a distance ten times the height of the turbine reduce yield dramatically. A distance of twenty times is preferred.
- A wind farm that produces the energy equivalent of a conventional power plant would have to cover an area of approximately 300 square miles. [http://wired-vig.wired.com/wired/archive/13.02/nuclear.html?pg=2&topic=nuclear&topic_set=]
- Offshore sites eliminate some of these objections, but raise others such as dangers to navigation and the possible adverse effect of low-frequency vibration and shadow flicker on aquatic mammals.
- Another important complaint is that windmills kill too many birds, especially birds of prey, and bats. Siting generally takes into account bird flight patterns, but most paths of bird migration, particularly for birds that fly by night, are unknown. Although a Danish survey in 2005 (Biology Letters 2005:336) showed that less than 1% of migrating birds passing a wind farm in Rønde, Denmark, got close to collision, the site was studied only during low-wind non-twilight conditions. A survey at Altamont Pass, California conducted by a California Energy Commission in 2004 showed that turbines killed 4,700 birds annually (1,300 of which are birds of prey). Radar studies of proposed sites in the eastern U.S. have shown that migrating songbirds fly well within the reach of large modern turbines. The numbers of bats killed by existing facilities has troubled even industry personnel [http://vawind.org/Assets/Docs/BCI_ridgetop_advisory.pdf].

Scalability

- The large number of turbines required for a viable wind plant, and the huge number of plants required to meet the ambitious goals of the wind industry and governments, ensures that more people and wildlife habitat will be affected by them.

Aesthetics

- There is resistance to the establishment of land based wind farms owing to perceptions that they are noisy and contribute to "visual pollution." Moving the turbines offshore mitigates the problem, but offshore wind farms are more expensive to maintain and there is an increase in transmission loss due to longer distances of power lines.
- The large installations of a modern wind facility are typically 100 m high to the tip of the rotor blade, and, besides the continuous motion of the 35-m-long rotor blades through the air, each time the blade passes the tower a deep subsonic thump is produced, which is a form of noise pollution.
- Some residents near windmills complain of "shadow flicker," which is the alternating pattern of sun and shade caused by a rotating windmill casting a shadow over residences. Efforts are made when siting turbines to avoid this problem.

Arguments of supporters

noise pollution Supporters of wind energy state that:

Yield

- Wind power is a renewable resource, which means using it will not deplete the earth's supply of fossil fuels. It also is a clean energy source, and produces no carbon dioxide, sulfur dioxide, particulates, or any other type of air pollution, as do conventional fossil fuel power sources.
- Wind's long-term technical potential is believed 5 times current global energy consumption or 40 times current electricity demand. This requires 12.7% of all land area, or that land area with Class 3 or greater potential at a height of 80 meters. It assumes that the land is covered with 6 large wind turbines per square kilometer. Offshore resources experience mean wind speeds ~90% greater than that of land, so offshore resources could contribute substantially more energy.[http://www.stanford.edu/group/efmh/winds/global_winds.html][http://www.ens-newswire.com/ens/may2005/2005-05-17-09.asp#anchor6]. This number could also increase with higher altitude ground based or airborne wind turbines [http://www.wired.com/news/planet/0,2782,67121,00.html?tw=wn_tophead_2].

Coping with intermittent energy

- Electricity demand is very variable although in general quite predictable. Because conventional powerplants can drop off the grid within a few seconds (owing to equipment failures etc.), in most systems the output of some coal and/or gas powerplants is intentionally part-loaded to follow demand and to replace rapidly lost generation. The ability to follow demand, and thus maintain constant frequency (usually 50 or 60 Hz) is termed response. The ability to quickly replace lost generation, typically within timescales of 30 seconds to 30 minutes, is termed reserve. Nuclear power plants in contrast are not very flexible and are not part-loaded. Power plant that operates in a steady fashion (usually for many days continuously) is termed "base load" plant. As a consequence the production system is already equipped with an array of substantial, quickly adjustable back-up techniques. As the fraction of energy produced by wind (penetration) increases, different technical and economic factors affect the electric power network. Large networks, connected to multiple wind plants at widely separated geographic locations, may accept a higher penetration of wind than small networks or those without economical methods of compensating for the variability of wind. In systems with significant amounts of existing pumped storage (e.g. UK, eastern US) this proportion may be higher; isolated, relatively small systems with only a few wind plants may only be stable and economic with a lower fraction of wind energy (e.g. Ireland). This may still a reasonable proportion - perhaps over 10%.
- Existing European hydroelectric power plants can store enough energy to supply one month's worth of European energy consumption. Improvement of the international grid would allow using this at relatively short term at low cost, supplementing wind power. Excess wind power could even be used to pump water up into collection basins for later use.
- In energy schemes with a high penetration of wind energy, secondary loads, such as desalination plants and electric boilers are included because their output (water and heat) can be stored.
- Energy Demand Management or Demand-Side Management refers to the use of communication and switching devices which can release deferrable loads quickly to correct supply/demand imbalances. An increase in such systems, in conjuction with price-triggers, can allow consumers with large loads to take advantage of renewable energy by shifting their loads to coincide with resource availability.
- An ice storage device has been invented which allows cooling energy to be consumed during resource availability, and dispatched as air conditioning during peak hours.
- The creation of a "burst electricity" industry, where excess electricity can be used extremely cheaply on windy days for opportunistic production would greatly improve the efficiency of wind turbines. Applications such as electrolysis for hydrogen fuel, and other processes that are efficient with intermittent electricity usage can use the intermittent energy provided by wind turbines, preventing windmills from being forced to idle during days of excess power availability.
- Geographically-spread wind turbine parks used together produce power much more constantly.
- Electricity produced from solar energy could be a counter balance to the fluctuating supplies generated from wind. It tends to be windier at night & during cloudy / stormy weather, so there is more likely to be more sunshine when there is less wind.

Ecological footprint

- The energy consumption for production, installation, operation and decommission of a wind turbine is usually earned back within 3 months of operation.
- After decommissioning wind turbines, even the foundations are removed.
- Studies show that the number of birds and bats killed by wind turbines is negligible compared to the amount that die as a result of other human activities such as traffic, hunting, power lines and high-rise buildings and especially the environmental impacts of using non-clean power sources. For example, in the UK, where there are a few hundred turbines, about one bird is killed per turbine per year; [http://www.bwea.org/media/news/birds.html 10 million] per year are killed by cars alone. Another study suggests that migrating birds are somewhat smarter than we give them credit, those birds which don't modify their route and continue to fly through a wind farm are quite capable of avoiding windmills[http://www.newscientist.com/channel/life/mg18625045.500], at least in the low-wind non-twilight conditions studied. In the UK, the Royal Society for the Protection of Birds (RSPB) concluded that "The available evidence suggests that appropriately positioned wind farms do not pose a significant hazard for birds" (see [http://www.rspb.org.uk/policy/windfarms/index.asp RSPB statement on wind farms]). It notes that climate change poses a much more significant threat to wildlife, and therefore supports wind farms and other forms of renewable energy.
- Clearing of wooded areas is often completely unnecessary for grounded turbines, as the practice of farmers leasing their land out to companies building wind farms is becoming ever more common. The annual royalties farmers receive are often up to four thousand dollars. What's more, the land can still be used for farming and cattle grazing.
- The ecological and environmental costs of wind plants are entirely paid for by those using the power produced, with no long-term effects on climate or local environment left for future generations.
- Less than 1% of (the land) would be used for foundations and access roads, the other 99% could still be used for productive farming. [http://www.bwea.com/ref/faq.html]

Economic feasibility

- Conventional and nuclear power plants receive massive amounts of direct and indirect governmental subsidies. If a comparison is made on real production costs, wind energy is competitive in many cases. If the full costs (environmental, health, etc.) are taken into account, wind energy is competitive in most cases. Furthermore, wind energy costs are continuously decreasing due to technology development and scale enlargement.
- Nuclear Power plants receive special immunity from the disasters they may cause, which prevents victims from recovering the cost of their continued health care from those responsible, even in the case of criminal malfeasance.
- Conventional and nuclear plants also have sudden unpredictable outages (see above). Statistical analysis shows that 1000 MW of wind power can replace 300 MW of conventional power.

Aesthetics

- It is possible to hold a conversation directly underneath a modern wind turbine without any difficulty whatsoever and without raising one's voice. The modern turbine is quieter than its predecessors owing to improvements in the blade design.
- Newer wind farms have their turbines spaced further apart, due to the greater power of the individual wind turbines. They no longer have the cluttered look of the early wind farms.
- Wind turbines can be positioned alongside motorways, which significantly reduces aesthetic concerns as there are nowhere near as many calls for the improvement of the aesthetic quality of motorways as there are to remove fossil fuel consuming power plants.

Sources

Technical

- [http://www.futurecrisis.com/alternative-energy-plans.php Wind Energy Projects and Daily News]
- [http://www.stanford.edu/group/efmh/winds/global_winds.html 2005 Stanford Wind Potential study] Global wind potential maps
- [http://rredc.nrel.gov/wind/pubs/atlas/maps/chap2/2-01m.html Average annual wind power map for the U.S.]
- [http://www.windatlas.dk/ Wind Atlases of the World – The World of Wind Atlases]
- [http://www.windpower.org Danish Organisation of wind-turbine manufactures] Extensive technical information on windenergy.
- [http://www.fieldlines.com/section/wind Homebrewed windenergy]
- [1] [http://www.hydro.mb.ca/issues/transmission_projects/wuskwatim/exhibits_1031.pdf Discussion of application of wind turbines in cold climates]

Political

- [http://www.bwea.org The British Wind Energy Association]
- [http://www.awea.org American Wind Energy Association]
- [http://www.ewea.org European Wind Energy Association] Extensive information and myth debunking in the report: windenergy the facts.
- [http://www.canwea.ca/en/ Canadian Wind Energy Association]
- [http://www.saveoursound.org/ Alliance to Protect Nantucket Sound] Citizens group opposed to plans for USA's first offshore wind facility.
- [http://www.capewind.org/ Capewind] -- Website of USA's first offshore wind facility.
- [http://www.countryguardian.net/ Country Guardian] -- A UK NGO opposed to the construction of wind turbines.
- [http://www.windwatch.org/ National Wind Watch] -- A US coalition of citizens and grassroots groups to promote knowledge and raise awareness of the damaging impacts of industrial wind turbine development.
- [http://www.aweo.org/ Industrial Wind Energy Opposition] -- Resources for debunking claims, documenting ill effects, and fighting the spread of industrial wind power
- [http://www.gardnermountain.org Gardner Mountain NH USA] -- "A public community site" trying to stop some local wind turbine development.
- [http://www.iberica2000.org/Es/Articulo.asp?Id=1228 Iberica 2000.org] - On the serious impact of wind farms on birds.
- [http://www.newscientist.com/channel/life/mg18625045.500 "Wind turbines a breeze for migrating birds"] - Birds avoid windmills.
- [http://kirbymtn.blogspot.com/2005/06/migrating-birds-forced-to-lengthen.html Commentary on preceding paper] - Birds have to fly farther to avoid windmills, fair-weather study finds.
- [http://gristmill.grist.org/story/2005/7/18/1459/58709 "We Must Increase Our Gust"] - On wind power's ability to replace other sources, with lively forum discussion.
- [http://www.inthesetimes.com/site/main/article/2302/ "Shooting Down the Breeze"] - On wind power industry's ambivalent concern about wildlife impacts, also with lively forum discussion.
- [http://www.wind-works.org/ Wind Works] --An extensive personal site on windpower. Nuanced pro wind energy.
- [http://www.yes2wind.org yes2wind] -- A website by [http://www.greenpeace.org/international_en/ Greenpeace], [http://www.foe.org Friends of the Earth] and the [http://www.wwf.org/ WWF] in support of wind energy and debunking claims of the anti-wind energy lobby.
- [http://www.wind-farm.org wind-farm] -- A website for news, articles, and discussion of wind facilities.
- [http://www.externe.info/ ExternE] -- The European research project about the external costs of energy production in general.
- [http://www.greenhouse.gov.au/yourhome/technical/pdf/fs48.pdf Wind systems] - On the site of the Australian Greenhouse Office.
- [http://www.windpower-monthly.com/ Windpower Monthly] -- Wind Energy Magazine.
- [http://www.enertrag.de/index_en.php Enertrag.de] -- A German energy company investing in wind turbines. Owns 13 wind parks as of October 2004.
- [http://www.AfriWEA.org African Wind Energy Association] -- AfriWEA is a non-profit organisation formed in 2002 to encourage manufacturers, developers, governments, renewable energy owners and individuals to promote and support wind energy development on the African continent

Wind Power projects

- [http://www.billingsgazette.com/index.php?display=rednews/2005/07/10/build/state/30-ropin-the-wind.inc Judith Gap Wind Farm] (Montana)
- [http://www.windiberica.com Windiberica Wind Farm Projects] (Spain)
- [http://www.aad.gov.au/apps/operations/electrical.asp Mawson Station] - High Penetration (>90%) Wind Diesel at Mawson Station in Antarctica.
- [http://www.daws.com.au/Projects/Denham.html Denham] - Wind Diesel in Western Australia.

External links

- [http://www.greenmountain.com Green Mountain]
- [http://www.canadiangeographic.ca/magazine/ND05/indepth/resources.asp "Wind versus water: Measuring the potential of our renewable resources"] from Canadian Geographic
- [http://www.climatechange.com.au/2005/04/07/offshore-wind-energy-could-supply-10-of-europes-electricity-by-2020/ Climate Change Chronicles article about offshore wind energy in Europe]
- [http://www.cnn.com/2005/TECH/science/07/15/wind.power/index.html?section=cnn_latest Wind farms could meet energy needs]
- [http://www.thewatt.com/modules.php?name=News&new_topic=16 Wind Power Related News]
- [http://www.cus.net/ Wind power] Category:Energy conversion Category:Renewable energy Category:Turbines Category:Alternative energy ja:風力発電

Hydropower

. ]] Hydropower is energy obtained from flowing water. Energy in water can be harnessed and used, in the form of motive energy or temperature differences. The most common application is the dam, but it can be used directly as a mechanical force or a thermal source/sink. Prior to the widespread availability of commercial electricity, hydropower was widely used for milling, textile manufacture, and the operation of sawmills. In the 1830s, at the height of the canal-building era, hydropower was used to transport barge traffic up and down steep hills using the technology of inclined plane railroads.

Types of water power

There are many forms of water power:
- Hydroelectric energy, a term usually reserved for hydroelectric dams.
- Tidal power, which captures energy from the tides in horizontal direction
- Tidal stream power, which does the same vertically
- Wave power, which uses the energy in waves
- Ocean thermal energy conversion, which uses the temperature difference between the warmer surface of the ocean and the cool (or cold) lower recesses.
- Deep lake water cooling, not technically an energy generation method. It uses submerged pipes to cool things.

Hydroelectric power

Main article: Hydroelectricity Aside from dams, the term also refers to a number of systems in which flowing water drives a water turbine or waterwheel. Hydroelectric power from potential energy of the elevation of waters, now supplies about 715,000 MWe or 19% of world electricity, and large dams are still being designed. Apart from a few countries with an abundance of it, hydro power is normally applied to peak-load demand, because it is so readily stopped and started. Nevertheless, hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations with the potential for harnessing gravity in this way are either already being exploited or are unavailable for other reasons such as environmental considerations. Hydroelectric energy produces essentially no carbon dioxide, in contrast to burning fossil fuels or gas, and so is not a significant contributor to global warming through CO₂. Recent reports have linked hydroelectric power to methane, which forms out of decaying submerged plants which grow in the dried up parts of the basis in times of drought. Methane is a greenhouse gas. Hydroelectric power can be far less expensive than electricity generated from fossil fuel or nuclear energy. Areas with abundant hydroelectric power attract industry with low cost electricity. Recently, increased environmental concerns surrounding hydroelectric power, have begun to outweigh cheap electricity in some countries. The chief advantage of hydroelectric dams is their ability to handle seasonal (as well as daily) high peak loads. When the electricity demands drop, the dam simply stores more water. Some electricity generators use water dams to store excess energy (often during the night), by using the electricity to pump water up into a basin. The electricity can be re-generated when demand increases. In practice the utilization of stored water in river dams is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.

Tidal power

Main article: Tidal power Harnessing the tides in a bay or estuary has been achieved in France (since 1966), Canada and Russia, and could be achieved in certain other areas where there is a large tidal range. The trapped water can be used to turn turbines as it is released through the tidal barrage in either direction. Worldwide this technology appears to have little potential, largely due to environmental constraints. See: tidal power. Another possible fault is that the system would generate electricty most efficiently if it were to generate electricity in bursts, every six hours (once every tide). Obviously, this limits the applications for which tidal energy can be used.

Tidal stream power

A relatively new technology development, tidal stream generators draw energy from underwater currents in much the same way that wind generators are powered by the wind. The much higher density of water means that there is the potential for a single generator to provide significant levels of power. Tidal stream technology is at the very early stages of development though and will require significantly more research before it becomes a significant contributor to electrical generation needs. Several prototypes have however shown some promise. For example, in the UK in 2003, a 300 kW Seaflow marine current propeller type turbine was tested off the north coast of Devon, and a 150 kW oscillating hydroplane device, the Stingray, was tested off the Scottish coast. Another British device, the Hydro Venturi, is to be tested in San Fransisco Bay. The Canadian company Blue Energy has plans for installing very large arrays tidal current devices mounted in what they call a 'tidal fence' in various locations around the world, based on a vertical axis turbine design.

Wave power

Main article: Wave power Harnessing power from ocean surface wave motion is a possibility which might yield much more energy than tides. The feasibility of this has been investigated, particularly in the UK. Generators either coupled to floating devices or turned by air displaced by waves in a hollow concrete structure would produce electricity for delivery to shore. Numerous practical problems have frustrated progress. A prototype shore based wave power generator is being constructed at Port Kembla in Australia and is expected to generate up to 500 MWh per annum. The Wave Energy Converter has been constructed (as of July 2005) and initial test results have exceeded expectations in terms of energy production during times of low wave energy. The energy of waves crashing against the shore is absorbed by an air driven generator and converted to electricity. For countries with large coastlines and rough sea conditions the energy density of breaking waves offers the possibility of generating electricity in utility volumes. Excess power in periods of rough sea could be used to generate renewable hydrogen.

Ocean thermal energy conversion

Main article: Ocean thermal energy conversion Ocean thermal energy conversion is a relatively unproven technology, though it was first used by the French engineer Jacques Arsene d'Arsonval in 1881. The difference in temperature between water near the surface and deeper water can be as much as 20 °C. The warm water is used to make a liquid such as ammonia evaporate, causing it to expand. The expanding gas forces its way through turbines, after which it is condensed using the colder water and the cycle can begin again. Read the Millennial Project for more information.

Deep lake water cooling

Main article: Deep lake water cooling Deep lake water cooling is the use of cold water piped from a lake bottom and used for cooling. Energy measures work or heat exchange; although this technology doesn't generate energy that can do wo

Clean energy

See also

External links

Environmentalist

See also

Renewable energy

Modern sources of renewable energy

Geothermal energy

Solar energy

Wind energy

Water power

Biomass

Liquid biofuel

Solid biomass

Biogas

Small scale energy sources

Issues

Aesthetics, habitat hazards and land use

Concentration

Proximity to demand

Availability

Fossil fuels

Transmission

Historical usage of renewable energy

See also

External links

References

Pollution

POOP

Regulation and Monitoring

International

United States

See also

External links

Geothermal power

Types of geothermal sources

Electrical generation

Desalination

Water injection

Heat depletion

Cost

See also

External links

Wind power

Wind energy

Wind variability and turbine nameplate power

Wind power density classes

Turbine siting

Onshore

Offshore

Airborne

Utilization

Large scale

Small scale

Controversy

Arguments of opponents

Economics

Yield

Ecological footprint

Scalability

Aesthetics

Arguments of supporters

Yield

Coping with intermittent energy

Ecological footprint

Economic feasibility

Aesthetics

See also

Sources

Technical

Political

Wind Power projects

External links

Hydropower

Types of water power

Hydroelectric power

Tidal power

Tidal stream power

Wave power

Ocean thermal energy conversion