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idal power is taken from the Earth's oceanic tides; tidal forces are periodic variations in gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans

Because the Earth's tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and classified as a renewable energy resource

Because the Earth's tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and classified as a renewable energy resource

The report finds that in 2011, roughly 6,800 megawatts (MW) of new wind power capacity was added to the U.S. grid, a 31 percent increase from 2010 installations.  The United States’ wind power capacity reached 47,000 MW by the end of 2011 and has since grown to 50,000 MW, enough electricity to power 13 million homes annually or as many as in Nevada, Colorado, Wisconsin, Virginia, Alabama, and Connecticut combined. The country’s cumulative installed wind energy capacity grew 16 percent from 2010, and has increased more than18-fold since 2000.  The report also finds that six states now meet more than 10 percent of their total electricity needs with wind power.

The fossil fuels are then burned to heat water.

A generator is basically an electric motor working in reverse.

Biodiesel from soybeans costs an estimated $2 to $2.50 per gallon to produce. Biodiesel from yellow grease is about $1 a gallon cheaper, but the available supply in the U.S. is much smaller – enough to make 100 million gallons per year. Producers of biodiesel from pure vegetable oil are eligible for a federal excise tax credit of $1 for every gallon blended with conventional diesel. Biodiesel from used cooking oil earns a credit of 50 cents per gallon.

When a visible light photon strikes a solar cell it can do one of three things: pass straight through, be reflected, or be absorbed. If the photon is absorbed, its energy is absorbed by an electron in an atom of the solar cell enabling it to escape from its normal position (photon excitation), cross the junction and fill a hole. Since electrons are physically moving across the PN junction, the positive charge carrying holes are effectively moving in the opposite direction around the load circuit (a rechargeable battery or light bulb etc). This completes the circuit providing more holes for the electrons to combine with and providing usable electricity.

The first electricity-generating wind turbine was a battery charging machine installed in July 1887 by Scottish academic James Blyth to light his holiday home in Marykirk, Scotland.[7

There were 140,000 fuel cell stacks shipped globally in 2010

although, as of 2010, no public company in the industry had yet become profitable

The theory of global warming is nothing new. The Nobel Prize-winning chemist Svante Arrhenius first proposed the idea of global warming in 1896. Carbon dioxide, he knew, traps heat in the Earth's atmosphere. He also knew that burning coal and oil releases carbon dioxide (CO2).

A benefit is very little pollution. However, there is a very serious potential draw back. It can be very hard of fish populations. The proposal for tidal power is to put turbines on the bottom of a bay and let the water rushing in and out with the tide turn them and generate electricity. However, along with the water will come fish and other marine animals. What do you think will happen when these critters get sucked into the turbines. Can you say sushi, boys and girls? Putting some kind of screen in front of the turbine to prevent this would just mean that the animals would be sucked up against the screens, obstructing the flow of water through the turbines.

A quick search on TreeHugger shows that ' solar power ' most often occurs in connection with producing electricity and only secondarily in connection with solar water heaters

Compared to electrically heated Water , Solar Water Heating is 57% of the internal rate of return, the scientists found

first tidal energy turbines

Both technologies require room for periodic ship-borne maintenance and repair access, with subsurface equipment which could impinge on the other facility if they're too close. And if one of the turbines breaks, as happened in 2010 with an earlier tidal turbine in the Bay of Fundy, PC Landing worries it could damage the nearby cable.

This ultimately reduces the cost these power plants can sell their electricity

most all biofuels used today cause more greenhouse gas emissions than conventional fuels if the pollution caused by producing these "green" fuels is taken into account, two studies published Thursday have concluded.

The benefits of biofuels have come under increasing attack in recent months as scientists have evaluated the global environmental cost of their production. The new studies, published by the journal Science, are likely to add to the controversy.

When you take this into account, most of the biofuel that people are using or planning to use would probably increase greenhouse gasses substantially," sai

First of all, biofuels come in many varieties, but in general, there are two main products, those that replace (or blend with) gasoline, and those that replace (or are blended with) middle distillate fuels, such as diesel fuel, or home heating oil.

A fuel cell is a device that uses a source of fuel, such as hydrogen, and an oxidant to create electricity from an electrochemical process.

Most fuel cells in use today, however, use hydrogen and oxygen as the chemicals.

Although hydrogen is the most abundant element in the universe, it is difficult to store and distribute. Canisters of pure hydrogen are readily available from hydrogen producers, but as of now, you can't just fill up with hydrogen at a local gas station.