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biofuel

a gaseous, liquid, or solid substance of biological origin that is used as a fuel

By the time it reaches Earth's surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day. Averaged over the entire surface of the planet, 24 hours per day for a year, each square meter collects the approximate energy equivalent of almost a barrel of oil each year, or 4.2 kilowatt-hours of energy every day. Deserts, with very dry air and little cloud cover, receive the most sun—more than six kilowatt-hours per day per square meter. Northern climates, such as Boston, get closer to 3.6 kilowatt-hours. Sunlight varies by season as well, with some areas receiving very little sunshine in the winter. Seattle in December, for example, gets only about 0.7 kilowatt-hours per day. It should also be noted that these figures represent the maximum available solar energy that can be captured and used, but solar collectors capture only a portion of this, depending on their efficiency. For example, a one square meter solar electric panel with an efficiency of 15 percent would produce about one kilowatt-hour of electricity per day in Arizona.

global potential is enormous: over 400 billion liters annually, well more than double the amount of diesel the US burns every year.

Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol.

How Does Wind Energy Work? The diagram below shows a simplified version how a wind turbine converts the kinetic energy in the wind to electrical energy around the country. If you can't see the diagram you will need to download flash to see it. The wind blows on the blades and makes them turn. The blades turns a shaft inside the nacelle (the box at the top of the turbine) The shaft goes into a gearbox which increases the rotation speed enough for... The generator, which uses magnetic fields to convert the rotational energy into electrical energy. These are similar to those found in normal power stations. The power output goes to a transformer, which converts the electricity coming out of the generator at around 700 Volts (V) to the right voltage for distribution system, typically 33,000 V. The national grid transmits the power around the country.

One of the main disadvantages is the initial cost of the equipment used to harness the suns energy

A solar energy installation requires a large area for the system to be efficient in providing a source of electricity

pollution can degrade the efficiency of photovoltaic cells. Clouds also provide the same effect, as they can reduce the energy of the suns rays

Price projections vary among fuel cell developers, but most are targeting costs below $1,500/kW

Maintenance costs of a fuel cell are expected to be comparable to that of a microturbine, ranging from $0.005-$0.010/kWh (based on an annual inspection visit to the unit).

At the current price, units are only used in high value, "niche" markets where reliability is premium, and in areas where electricity prices are very high and natural gas prices are low.

A wind turbine is a rotating machine which converts the kinetic energy in wind into mechanical energy. If the mechanical energy is used directly by machinery, such as a pump or grinding stones, the machine is usually called a windmill.

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The fuel cell is being considered as an eventual replacement for the internal combustion engine for cars, trucks and buses. Major car manufacturers have teamed up with fuel cell research centers or are doing their own development. There are plans for mass-producing cars running on fuel cells. Because of the low operating cost of the combustion engine, and some unresolved technical challenges of the fuel cell, however, experts predict that a large scale implementation of the fuel cell to power cars will not occur before 2015, or even 2020.

Most fuel cells are still handmade and are used for experimental purposes. Fuel cell promoters remind the public that the cost will come down once the cells are mass-produced and lower cost material are found. While an internal combustion engine requires an investment of $35 to $50 to produce one kilowatt (kW) of power, the equivalent cost in a fuel cells is still a whopping $3,000 to $7,500. The goal is a fuel cell that would cost equal or less than diesel engines.

Most fuel cells designed for use in vehicles produce less than 1.16 volts of electricity—far from enough to power a vehicle. Therefore, multiple cells must be assembled into a fuel cell stack.

Fuel cell system costs have decreased significantly over the past several years but are still nearly twice as high as those for internal combustion engines. Likewise, onboard hydrogen storage costs are currently $15–$18/kWh for high-pressure gaseous storage, while the commercialization target is $2/kWh. There is potential to reduce this cost using lower-cost carbon fiber tanks or materials-based storage technologies, such as metal hydrides.

FCVs will have to offer consumers a viable alternative, especially in terms of performance, durability, and cost, to survive in this ultra-competitive market.

Burning fossil fuels releases carbon dioxide, a heat-trapping gas, into the atmosphere, which is the main reason why the climate is changing.

The Earth is getting warmer because people are adding heat-trapping gases to the atmosphere, mainly by burning fossil fuels. These gases are called greenhouse gases. Warmer temperatures are causing other changes around the world, such as melting glaciers and stronger storms. These changes are happening because the Earth's air, water, and land are all linked to the climate