Energy issues are beginning to have an impact on recreation as well as daily lives. Recent federal legislation mandates an increase in energy from renewable sources.

Geothermal, solar, and wind are the primary sources of renewable energy being reviewed. The brief descriptions below are from the U.S. Department of Energy:

Geothermal

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

The Department of Energy’s Geothermal Technologies Program supports the U.S. geothermal industry in providing diversity, and therefore security, in domestic energy supply options. This support also helps the industry maintain its technical edge in world energy markets, thereby enhancing exports of U.S. goods and services and U.S. job growth. Energy works in partnership with U.S. industry to establish geothermal energy as an economically competitive contributor to the U.S. energy supply.

The Office of Scientific and Technical Information maintains technical reports related to geothermal energy on its Geothermal Energy Technology (GET) subject portal.

Wind

Wind energy uses the energy in the wind for practical purposes like generating electricity, charging batteries, pumping water, or grinding grain. Wind turbines convert the kinetic energy of the wind into other forms of energy. Large, modern wind turbines operate together in wind farms to produce electricity for utilities. Small turbines are used by homeowners and remote villages to help meet energy needs.

The Department of Energy's Wind & Hydropower Technologies Program is managed in accordance with national energy policy. Wind energy diversifies the nation's energy supply, takes advantage of a domestic resource, and helps the nation meet its commitments to curb emissions of greenhouse gases, which threaten the stability of global climates. The DOE Wind & Hydropower Technologies Program works with industry to keep U.S. wind energy technology competitive in global markets, thus strengthening the economy. The program includes a comprehensive wind energy research program, wind turbine research and development, and support for utilities, industry, and international wind energy projects.

The Office of Scientific and Technical Information maintains technical reports and other information about Wind Energy Technology.

Solar

The Department of Energy’s Solar Energy Technology Program, managed by the Office of Energy Efficiency and Renewable Energy accelerates the development of solar technologies as energy sources for the nation and world. The solar program also educates the public about the value of solar as a secure, reliable, and clean energy choice.

Developing technologies that take advantage of the clean abundant energy of the sun is important to reducing greenhouse gasses and helps stimulate the economy. Examples of solar technologies being developed by the Department of Energy and Industry are Photovoltaic cells, concentrating solar power technologies and low temperature solar collectors.

Photovoltaic cells convert sunlight directly into electricity and are made of semiconductors such as crystalline silicon or various thin-film materials. Photovoltaics can provide tiny amounts of power for watches, large amounts for the electric grid, and everything in between.

Concentrating solar power technologies use reflective materials to concentrate the sun's heat energy, which ultimately drives a generator to produce electricity. These technologies include dish/engine systems, parabolic troughs, and central power towers.

Low-temperature solar collectors also absorb the sun's heat energy, but the heat is used directly for hot water or space heating for residential, commercial, and industrial facilities.

You can also find statistical information relating to the use of solar thermal and solar photovoltaic energy through the Energy Information Administration.