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A fuel cell converts the chemical energy in hydrogen and oxygen into direct current electrical energy by electrochemical reactions. Fuel cells are devices that convert hydrogen gas directly into low-voltage, direct current electricity. The cell has no moving parts.

The process is essentially the reverse of the electrolytic method of splitting water into hydrogen and oxygen. In the fuel cell, the cathode terminal is positively charged and the anode terminal is negatively charged. These electrodes are separated by a membrane. Hydrogen gas is converted into electrons and protons (positive hydrogen ions) at the anode. The protons pass through the membrane to the cathode, leaving behind negatively charged electrons. This creates a flow of direct current electricity between the terminals when connected with an external circuit. This current can power an electric motor placed in this circuit. The hydrogen ions, electrons, and oxygen combine at the cathode to form water, the only byproduct of the process.

The advantage of AC for distributing power over a distance is due to the ease of changing voltages using a transformer. Available power is the product of current × voltage at the load. For a given amount of powe

The dirty secret of clean energy is that while generating it is getting easier, moving it to market is not.

While the United States today gets barely 1 percent of its electricity from wind turbines, many experts are starting to think that figure could hit 20 percent.

Achieving that would require moving large amounts of power over long distances, from the windy, lightly populated plains in the middle of the country to the coasts where many people live.

Like electricity, hydrogen is a secondary source of energy. It stores and carries energy produced from other resources (fossil fuels, water, and biomass).

ydrogen is the simplest element. Each atom of hydrogen has only one proton. It is also the most plentiful gas in the universe. Stars like the sun are made primarily of hydrogen. The sun is basically a giant ball of hydrogen and helium gases. In the sun's core, hydrogen atoms combine to form helium atoms. This process — called fusion — gives off radiant energy.

Hydrogen gas is so much lighter than air that it rises fast and is quickly ejected from the atmosphere. This is why hydrogen as a gas (H2) is not found by itself on Earth. It is found only in compound form with other elements. Hydrogen combined with oxygen, is water (H2O). Hydrogen combined with carbon forms different compounds, including methane (CH4), coal, and petroleum.

Geothermal Electricity Production This geothermal power plant generates electricity for the Imperial Valley in California. Geothermal power plants use steam produced from reservoirs of hot water found a few miles or more below the Earth's surface to produce electricity. The steam rotates a turbine that activates a generator, which produces electricity.

Advantages Once you've built it, tidal power is free. It produces no greenhouse gases or other waste. It needs no fuel. It produces electricity reliably. Not expensive to maintain. Tides are totally predictable. Offshore turbines and vertical-axis turbines are not ruinously expensive to build and do not have a large environmental impact. Disadvantages A barrage across an estuary is very expensive to build, and affects a very wide area - the environment is changed for many miles upstream and downstream. Many birds rely on the tide uncovering the mud flats so that they can feed. Fish can't migrate, unless "fish ladders" are installed. Only provides power for around 10 hours each day, when the tide is actually moving in or out. There are few suitable sites for tidal barrages Is it renewable? Tidal energy is renewable. The tides will continue to ebb and flow, and the energy is there for the taking.

Geothermal energy has been used for thousands of years in some countries for cooking and heating.

How it works

Hot rocks underground heat water to produce steam. We drill holes down to the hot region, steam comes up, is purified and used to drive turbines, which drive electric generators.

What is wave energy? Waves are generated by the passage of wind across the surface of the sea.  Energy is transferred from the wind to the waves.  Waves travel vast distances across the ocean and at great speed and the energy is concentrated near the water surface.  The energy within a wave is proportional to the square of the wave height.  Therefore a two-meter high wave has four times the power of a one-meter high wave. The longer and stronger the wind blows over the surface of the sea, the higher, longer, faster and more powerful the sea is.

Although wave energy is a form of concentrated wind energy, as it has often travelled over large distances it is regularly out of phase with the local wind conditions.  Wave energy can therefore help to balance output variability from other renewable sources and maximise the efficient use of the electricity networks.   Wave energy is also more predictable than many other forms of renewable energy, such as wind or solar, and can be forecast accurately up to five days in advance.

Wave energy is clean and renewable!  It is one of the last renewable energy forms which mankind has yet to harness, and its potential is huge.

Method Cents/kW-h Limitations and Externalities WindCurrently supplies approximately 1.4% of the global electricity demand. Wind is considered to be about 30% reliable. 4.0 - 6.0 Cents/kW-h Wind is currently the only cost-effective alternative energy method, but has a number of problems. Wind farms are highly subject to lightning strikes, have high mechanical fatigue failure, are limited in size by hub stress, do not function well, if at all, under conditions of heavy rain, icing conditions or very cold climates, and are noisy and cannot be insulated for sound reduction due to their size and subsequent loss of wind velocity and power. GeothermalCurrently supplies approximately 0.23% of the global electricity demand. Geothermal is considered 90-95% reliable. 4.5 - 30 Cents/kW-h New low temperature conversion of heat to electricity is likely to make geothermal substantially more plausible (more shallow drilling possible) and less expensive. Generally, the bigger the plant, the less the cost and cost also depends upon the depth to be drilled and the temperature at the depth. The higher the temperature, the lower the cost per kwh. Cost may also be affect by where the drilling is to take place as concerns distance from the grid and another factor may be the permeability of the rock. HydroCurrently supplies around 19.9% of the global electricity demand. Hydro is considered to be 60% reliable. 5.1 - 11.3 Cents/kW-h Hydro is currently the only source of renewable energy making substantive contributions to global energy demand. Hydro plants, however, can (obviously) only be built in a limited number of places, and can significantly damage aquatic ecosystems. SolarCurrently supplies approximately 0.8% of the global electricity demand. 15 - 30 Cents/kW-h Solar power has been expensive, but soon is expected to drop to as low as 3.5 cents/kW-h. Once the silicon shortage is remedied through alternative materials, a solar energy revolution is expected.

Tide 2 - 5 Cents/kW-h Blue Energy's tidal fence, engineered and ready for implementation, would provide a land bridge (road) while also generating electricity. Environmental impact is low. Tides are highly predictable.

Method Cents/kW-h Limitations and Externalities GasCurrently supplies around 15% of the global electricity demand. 3.9 - 4.4 Cents/kW-h Gas-fired plants and generally quicker and less expensive to build than coal or nuclear, but a relatively high percentage of the cost/KWh is derived from the cost of the fuel. Due to the current (and projected future) upwards trend in gas prices, there is uncertainty around the cost / KWh over the lifetime of plants. Gas burns more cleanly than coal, but the gas itself (largely methane) is a potent greenhouse gas. Some energy conversions to calculate your cost of natural gas per kwh. 100 cubic feet (CCF)~ 1 Therm = 100,000 btu ~ 29.3 kwh. CoalCurrently supplies around 38% of the global electricity demand. 4.8 - 5.5 Cents/kW-h Increasingly difficult to build new coal plants in the developed world, due to environmental requirements governing the plants. Growing concern about coal fired plants in the developing world (China, for instance, imposes less environmental overhead, and has large supplies of high sulphur content coal). The supply of coal is plentiful, but the coal generation method is perceived to make a larger contribution to air pollution than the rest of the methods combined.

Unlike fossil fuel power plants, no smoke is emitted from geothermal power plants, because no burning takes place; only steam is emitted from geothermal facilities. Emissions of nitrous oxide, hydrogen sulfide, sulfur dioxide, particulate matter, and carbon dioxide are extremely low, especially when compared to fossil fuel emissions. The binary geothermal plant, which currently represents around 15% of all geothermal plant capacity, along with the flash/binary plant, produce nearly zero air emissions. Even dry steam plants, which are considered to have the highest levels of air emissions, are considered environmentally benign compared with fossil fuels. For example, Lake County, California, downwind of The Geysers, has met all federal and state ambient air quality standards for almost 25 years. There are 21 power plants at The Geysers, comprising a significant complex of electric generation facilities, yet even despite this, air quality is excellent. At The Geysers, air quality has even improved as a result of geothermal development because hydrogen sulfide, which would ordinarily be released naturally into the atmosphere by hot springs and fumaroles, instead now passes through an abatement system that reduces hydrogen sulfide emissions by 99.9%. (1) See also Myth #2.

Light striking a silicon semiconductor causes electrons to flow, creating electricity. Solar power generating systems take advantage of this property to convert sunlight directly into electrical energy.

If hydrogen extraction is performed using electricity from a coal-driven power plant, it doesn't matter that the fuel cell doesn't pollute because the pollution occurred when the hydrogen was extracted. If hydrogen is to be a true nonpolluting power source, the electricity used to extract the hydrogen will need to be produced by a nonpolluting method such as solar power.

Projects

8: One Megawatt of Wind Energy = 2,600 Fewer Tons of Carbon Dioxide So, with all the noise about clean energy, what kind of improvement are we really talking about with wind? Consider that every year 1MW of wind energy can offset approximately 2,600 tons of carbon dioxide (CO2) [source: NREL], and the interest comes into focus. The simple math is less fossil fuel consumption equals less CO2. And measuring carbon reduction has become a key benchmark for monitoring the progress of alternative energy adoption.

The wind turns the blades, which spin a shaft connected to the generator and produces electricity. Turbine blades are designed in such a way that wind causes them to rotate, which rotates the shaft at low speed, with a gear at the end that itself is connected to small gear on high speed shaft that runs through alternator housing.

he generator produces electricity using the same principle as a generator of your car (depending on the turbine). Magnetic Rotor inside the generator on high speed shaft spins inside loops of copper wire that are wound around an iron core. The rotor creates “electromagnetic induction” as it spins around the inside of the core through the coils, which generates electrical power. The current is regulated and transmission network (or home network system connection), after some changes, so it can use in our homes or sent to a battery bank for storage.

RenewableUK counts 18,465 full-time direct jobs in wind, wave and tidal power and 15,908 indirect jobs

Burning fossil fuels creates carbon dioxide, the number one greenhouse gas contributing to global warming. Combustion of these fossil fuels is considered to be the largest contributing factor to the release of greenhouse gases into the atmosphere. In the 20th century, the average temperature of Earth rose 1 degree Fahrenheit (1°F). This was a period that saw the most prolific population growth and industrial development

Some estimates say our fossil fuel reserves will be depleted within 50 years, while others say it will be 100-120 years.

 The process of converting wind energy to electric energy uses a wind turbine. The wind turbines convert the kinetic energy in the wind into mechanical power. The mechanical power can be used for many things. In the past this meant pumping water, creating ventilation, or grinding food sources. While these things still occur, wind power is also used to generate electricity.      The wind turbine is a tall shaft with several horizontal rectangular blades attached to it. These blades are often covered with stiff material or ratting material. When turned they push against the air, causing pressure, and turning the inner shaft. This shaft connects to a generator which then creates energy.

Somewhat surprisingly, the hot air that carries the heat from the earth at geothermal sites also contains carbon dioxide, CO2, the Greenhouse Gas that sends anti-technologists into a frenzy.  The suite of 20 geothermal sites from which Southern California Electric is obligated to buy electricity produces 730 tonnes of CO2 for every gigawatt-hour (GWh) of electricity produced.  Across the spectrum of all natural-gas power plants in the US, the average CO2 production is 519 tonnes per GWh.  That is, the geothermal power plants, which burn no fossil fuels whatsoever, produce 41% more CO2 than the run-of-the-mill natural gas power plant for the same amount of electrical energy produced.