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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.

According to the government, geothermal has the potential to supply the United States with 20% of our electricity needs.

The capital cost of geothermal development is expensive, however; 2/3rds are drilling costs. Yet as we overcome some of these technology challenges and make the process more standardized it is believed that geothermal can supply up to 20% of the United States electricity needs by 2050. But innovation and investment in initial steps need to happen now.

"But if we could harness 0.1 percent of the energy in the ocean, we could support the energy needs of 15 billion people.

Geothermal Energy produces no pollution. There are virtually no greenhouse gases given off. There is no pollution.

3. You cannot transport geothermal energy. I used to live in the coal region of Pennsylvania. For years coal trucks used to drive by our front door hauling Anthracite coal to home and industries.

4. There may be geothermal gases. Geothermal steam and hot water do contain naturally occurring traces of hydrogen sulfide (a gas that smells like rotten eggs) and other gases and chemicals that can be harmful in high concentrations.

Solar Cells or photovoltaic cells convert sunlight directly into electricity. When energy from the sun comes in contact with the cell, electrons in the two different semiconductors absorb the energy and use it to move around, creating an electrical current.

The cost of producing ethanol varies with the cost of the feedstock used and the scale of production. Approximately 85 percent of ethanol production capacity in the United States relies on corn feedstock. The cost of producing ethanol from corn is estimated to be about $1.10 per gallon.

Because a gallon of ethanol contains less energy than a gallon of gasoline, the production cost of ethanol must be multiplied by a factor of 1.5 to make an energy-cost comparison with gasoline. This means that if ethanol costs $1.10 per gallon to produce, then the effective cost per gallon to equal the energy contained in a gallon of gasoline is $1.65. In contrast, the current wholesale price of gasoline is about 90 cents per gallon.

A major hurdle facing commercial biodiesel production is the cost of producing the fuel. Vegetable oil seed procurement, transport, storage and oil extraction accounts for at least 75 percent of the cost of producing biodiesel. The cost varies depending on the feedstock used. For example, based on the market price for industrial rapeseed grown in Washington and Idaho, the estimated cost of producing biodiesel is $2.56 per gallon of rapeseed methyl ester. Recent estimates put the cost of production in the range of $1.30 per gallon (using waste grease feedstock) to $2.00 or more per gallon using soybean oil.

"Our study found that any biofuel that causes clearing of natural ecosystems will increase global warming," Joe Fargione, a scientist for The Nature Conservancy, told CTV.ca.

He said converting natural areas into croplands results in tons of carbon being emitted into the atmosphere -- a carbon 'debt' that outweighs any benefits.

The first tidal power station was the Rance tidal power plant built over a period of 6 years from 1960 to 1966 at La Rance, France.[8] It has 240 MW installed capacity.

Historically, tide mills have been used, both in Europe and on the Atlantic coast of North America. The incoming water was contained in large storage ponds, and as the tide went out, it turned waterwheels that used the mechanical power it produced to mill grain. [1] The earliest occurrences date from the Middle Ages, or even from Roman times.[2][3] It was only in the 19th century that the process of using falling water and spinning turbines to create electricity was introduced in the U.S. and Europe.[

Tidal energy use harnesses the water flow created primarily by the moon orbiting the Earth. As water is pulled toward the gravity of the moon, currents are created that can turn generator turbines.

Tidal energy use involving dams creates many of the same environmental concerns as damming rivers. Tidal dams restrict fish migration and cause silt build up which affects tidal basin ecosystems in negative ways. Systems that take advantage of natural narrow channels with high tidal flow rates have less negative environmental impact than dammed systems. But they are not without environmental problems. Both systems use turbines that can cause fish kills. But these are being replaced by new, more fish friendly turbines. The art and science of environmentally friendly hydro engineering is well advanced and will certainly be applied to any tidal energy project.

Because of intermittency and variable flow problems of tidal energy, it is a very limited resource. The DOE Tidal Energy link, above, states that there are only about 40 really good sites on Earth with high enough flows to be considered economically practical

Where Does Tidal Energy Come From? The gravitational force of the Earth stops the ocean from floating off into space, just like everything else. The Moon also has a very weak gravitational effect on the Earth, which is not normally noticable as far as falling teacups are concerned, but the ocean, which can flow around the globe to even out differences, is noticably affected.

The elimination of pollution caused by fossil fuels - When hydrogen is used in a fuel cell to create power, it is a completely clean technology. The only byproduct is water. There are also no environmental dangers like oil spills to worry about with hydrogen. The elimination of greenhouse gases - If the hydrogen comes from the electrolysis of water, then hydrogen adds no greenhouse gases to the environment. There is a perfect cycle -- electrolysis produces hydrogen from water, and the hydrogen recombines with oxygen to create water and power in a fuel cell. The elimination of economic dependence - The elimination of oil means no dependence on the Middle East and its oil reserves. Distributed production - Hydrogen can be produced anywhere that you have electricity and water. People can even produce it in their homes with relatively simple technology.

Energy Is the Ability To Do Work Energy comes in different forms: Heat (thermal) Light (radiant) Motion (kinetic) Electrical Chemical Nuclear energy Gravitational

Renewable Energy Renewable energy sources include: Solar energy from the sun, which can be turned into electricity and heat Wind Geothermal energy from heat inside the Earth Biomass from plants, which includes firewood from trees, ethanol from corn, and biodiesel from vegetable oil Hydropower from hydroturbines at a dam

CostChief among the problems associated with fuel cells is how expensive they are. Many of the component pieces of a fuel cell are costly.

InfrastructureIn order for PEMFC vehicles to become a viable alternative for consumers, there must be a hydrogen generation and delivery infrastructure. This infrastructure might include pipelines, truck transport, fueling stations and hydrogen generation plants

The best known early fuel cell experiments were performed in 1842 by the British physicist and lawyer, Sir William R. Grove (1811-1896)

Due to easily accessible and large amounts of oil and the invention of the combustion engine (Carl Friedrich Benz and Gottlieb Daimler), fuel cells were forgotten until the middle of the 20th century. In the US Apollo space programme, fuel cells exhibited their first renaissance in the 1960’s. 

Fuel cell development has been slowed down by a fear of hydrogen as a fuel. It is commonly believed that hydrogen is an extremely explosive and dangerous gas. Most of this belief was founded in 1937, when the hydrogen-filled zeppelin “Hindenburg” caught fire and crashed in Lakehurst, USA.

Fuel Cell Principle A fuel cell is an electrochemical energy converter. It converts chemical energy into electrical energy by two separated electrochemical reactions. In a hydrogen-fuelled polymer electrolyte membrane fuel cell (PEMFC), hydrogen is oxidised to protons and electrons at the anode. Protons migrate through the membrane electrolyte to the cathode. As the membrane is an electric insulator, electrons are forced to flow in an external electric circuit. At the cathode, oxygen reacts with protons to produce water, which is the only waste product

"Biofuels" are transportation fuels like ethanol and biodiesel that are made from biomass materials.

Ethanol and biodiesel are usually more expensive than the fossil fuels that they replace, but they are also cleaner-burning fuels, producing fewer air pollutants.

What Is Ethanol? Ethanol is an alcohol fuel made from the sugars found in grains, such as:

In scientific terms, wind energy is the "force" of winds blowing across the earth’s surface ("Wind Energy"). Wind is caused by uneven heating on the earth’s surface. The equator region receives more heat than say, Antarctica.

That heat tries to move from hotter to colder regions. Wind energy was first harvested centuries ago, when early windmills were used to power millstones, pumps, and forges

The amount of kinetic energy within Earth's atmosphere is equal to about 10,000 trillion kilowatt-hours.