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Major changes will be needed to grow, handle, transport and store the immense quantities of biomass -- mostly lignocellulosic feedstocks such as switchgrass, crop residues and forest wastes -- necessary to continually feed electric power generation stations and produce biofuels for transportation,

converting to a system in which biomass provides much of the country's energy will require new ways of thinking about agriculture, energy infrastructure and rural economic development.

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.

Photovoltaic cells are made of at least two layers of semiconducting material. The first layer has a positive charge; the next layer has a negative charge. When sunlight strikes the cell, the semiconducting material absorbs photons from the light. This process frees electrons from the negative layer, which move to the positive layer. This flow of electrons constitutes an electric current, which can be captured in a circuit connecting the two layers. The electricity generated by a photovoltaic cell can be used directly, stored in batteries or sold back to a utility company.

The heat from the earth's own molten core can be converted into electricity. This core consists primarily of extremely high temperature liquid rock known as magma. This "geothermal" heat circulates within the rock or is transferred to underground reservoirs of water, which also circulate under the earth's crust. Because of the near limitless ability of the earth to produce magma, and the continuous transfer of heat between subsurface rock and water, geothermal energy is considered a renewable resource.

bounadaries and faults are cracks in the Earth’s crust where magma rises near or to the surface. Geothermal plants take advantage of this fact using water heated by this volcanic activity to produce electric power.

The best part is that it is clean energy. There is no way it can produce pollution that can harm the environment

Each year we release millions of tonnes of carbon dioxide by burning fossil fuels (oil, coal and gas). In 2010, on average, every single EU citizen emitted 9.4 tonnes of CO2 – that’s enough to fill ten three-storey buildings. For every kWh of wind energy that you use, you will save approximately 696g of CO2. EWEA estimates that wind energy avoided the emission of 140 million tonnes of CO2 in 2011 in the EU, equivalent to taking 33% of cars in the EU – 71 million vehicles – off the road. This avoided CO2 costs of around €3.5 billion (assuming a price of €25/t CO2). Choosing how your electricity is produced plays an important role in protecting the climate: it’s easy to switch to a green power provider; you request the change and your current and future providers will organise it themselves.

It depends what you mean by "solar energy." Humans have always used solar energy in some sense: to warm themselves, to grow food, etc. However, I'm assuming that's not really what you mean (although it is important to realize that all energy on earth, with the exception of nuclear fission and geothermal, is ultimately driven by the sun's energy -- even fossil fuels, which after all were plants that grew with sunlight millions of years ago). Solar power has been used directly in various forms for over 100 years.

Advantages: Geothermal energy cost is extremely low compared to many other energy sources. It has low pollution compared to fossil fuels and nuclear energy. Geothermal energy is a renewable energy source. Almost no environmental impact when using geothermal heat from nuclear decay. Geothermal heat pump systems can reduce your energy use storing heat from the summer/sun and makes use of it in the night and winter. Low maintenance systems.

Disadvantages: The most important disadvantage is absolutely the geological problem.  The heat source is mostly close to volcanic activity of some sort. Chemicals are byproducts of the production electricity with hot ground water. Some geothermal plants use a lot of water and it needs to go somewhere its after use. Some of the poluting chemicals in that water and steam are sulfur, mercury, hydrogen sulfide, arsenic, ammonia. Earth is a changing creature.  A drilled hole in the ground could supply thousands of homes heat and one earthquake could change that in a second.  It can also change gradually over time. Location, location, location.  That is certainly true of geothermal energy.  It cannot be transported over vast distances.  If used to heat up houses or for hot tap water it is only the quality of the pipe that delivers the water that determines how far it can go and if it will be of any use when it arrives. If the heat is used for electrical production it helps to have plants close so the energy loss is not too great. 

Corrosion is a big problem.  Composition of the chemicals can vary but it is always a problem.  It is among other the reason they need to heat up clean water to use and do not use it directly in to heating of houses.  In cases it has been used directly it causes pipes to corrode. In nuclear heating rock the rock cools down over few decades and hundreds of years are needed to get initial heating back.  Power stations of that sort are therefore not considered as profitable. Geothermal Heat pump systems do have high installation cost. Some areas run out of water or run low on ground water during seasonal dry spells. Less water means less heat and less energy to produce. Some drilling sites are too hot to handle.  Yea. Drillers have actually tried and tried some holes and they just can’t get the needed equipment in because the holes shoot it out like guns.   With workers running to stay alive while steel rains down on them. 

Biofuels are made with biomass (biological material from living or recently living organisms) there are many kinds, for example biodiesel involves growing crops that contain large amounts of natural oil, these plants then go through a refining process and subsequently are mixed in with regular diesel to power cars. Bio petrol is made in a similar way; plants are refined to make a natural ethanol.

Table 1: Levelized cost of capital electricityInitial Capital InvestmentCost of Power (cents/kWh)*$2400 per KW3.99 - 5.76$2900 per KW4.40 – 6.54$3400 per KW4.81 – 7.33 

A price on carbon, such as that which would exist under a GHG cap-and-trade program, would raise the cost of electricity produced from fossil fuels relative to the cost of electricity from renewable sources, such as geothermal energy, and other lower-carbon technologies.

Carbon dioxide contributes to global warming by absorbing heat energy from the earth, trapping it and preventing its release into space.

Burning one gallon of gas creates 20 pounds of carbon dioxide, and the average car emits about six tons of carbon dioxide every year

So... let's accept that global warming is caused by greenhouse gasses, chief among them carbon dioxide. Cars emit carbon dioxide as part of their emissions...

The major challenge to using wind as a source of power is that it is intermittent and does not always blow when electricity is needed. Wind cannot be stored (although wind-generated electricity can be stored, if batteries are used), and not all winds can be harnessed to meet the timing of electricity demands. Further, good wind sites are often located in remote locations far from areas of electric power demand (such as cities).

Although wind power plants have relatively little impact on the environment compared to fossil fuel power plants, there is some concern over the noise produced by the rotor blades, aesthetic (visual) impacts, and birds and bats having been killed (avian/bat mortality) by flying into the rotors. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants.

The Benefits "Geothermal energy has the potential to generate and deliver sustainable supplies of clean, renewable base load power. Depending on the nature of the resource and the reservoir, individual production wells have the potential to generate consistent supplies of base load power for decades."

Geothermal energy has the potential to generate and deliver sustainable supplies of clean, renewable base load power.

individual production wells have the potential to generate consistent supplies of base load power for decades.