SolarThe solar irradiation in the South-Western United States is exceptional, equivalent to that of Africa and Australia, which contain the best solar resources in the world. Much of the United States has solar irradiation as good or better than Spain, considered the best in Europe, and much higher than Germany. The variation in irradiation over the United States is about a factor two, quite homogeneous compared to other renewable resources. The size of the United States adds to its resource, making it a prime opportunity for solar development.GeothermalGeothermal energy is present throughout the entire country, with most of the highest-quality geothermal resources generally located in the western United States, Alaska, and Hawaii. However, all states may have geothermal electricity generation potential through the use of enhanced, or engineered, geothermal systems (EGS) technologyWind EnergyWind is the fastest growing renewable source, but contributes only 1% of total energy used in the U.S. The country's onshore wind resources have the potential to generate almost 10,500 GW of electricity, 175 times more than the current installed capacity of 60 GW. Based on the average U.S. electricity fuel mix, a one MW wind turbine can displace 1,800 tons of CO2 emissions per year. With a wind power capacity of 300 GW, 825 million metric tons of CO2 emissions could be avoided annually.BiomassU.S. biomass electricity generation potential is highly dependent on how much biomass is available and how much biomass material is dedicated for this specific use. In 2009 an estimated 54,493 GWh of electricity was generated from biomass, which represented approximately 1.2% of total U.S. net electricity generation. According to DOE, approximately 190 million tons of biomass are consumed each year, with roughly 25% to 35% of current biomass consumption being used for electricity generation. DOE analysis and reports indicate that the potential may exist to produce about 1.3 billion tons of biomass annuallyBiogasCorn-based ethanol is the largest source of biofuel in the United States and the world, but the environmental and food supply problems caused by expanding corn cultivation to produce fuel make it ineffective as a strategy to reduce global warming emissions or create additional oil savings.Advanced biofuels made from non-food sources such as perennial grasses, garbage, and waste materials from agriculture and forestry (known as cellulosic biofuels) offer the greatest potential for oil savings and significant global warming emissions reductions with minimal environmental impacts.The United States has the potential to dramatically expand the production of these better biofuels and take a significant step toward cutting U.S. oil consumption in half over the next 20 years. By 2030, the United States could sustainably produce enough non-food biomass resources to generate as much as 54 billion gallons of ethanol each year—four times as much corn ethanol as the United States produced in 2010.HydroHydropower is currently the largest source of renewable electricity production in the United States. In 2010, approximately 257,000 GWh was generated from hydropower resources, equal to roughly 7% of total U.S. electricity generation. A 2007 report by the Electric Power Research Institute (EPRI) estimated that additional hydropower capacity potential was equal to 62.3 GW.