The Clinton Administration views renewable energy as the key part of its energy supply policy, both for environmental and technology competitiveness reasons. The Congressional Research Service Issue Brief, Renewable Energy: Key to Sustainable Energy Supply (May 27, 1999) addresses the funding and direction of renewable energy programs being discussed in the 106th Congress. Focus includes restructuring the electricity industry, worldwide emphasis on environmental problems of air and water pollution and global climate change and the related development of clean energy technologies.
Renewable energy is broadly defined as power derived from resources that are constantly replaced and are usually less polluting, such as the sun and wind and water movement. These resources, requiring different technologies to harness them, are then converted into heat, electricity and mechanical energy.
Solar energy technologies use sunlight to warm and light homes, heat water, and generate electricity. This energy comes from processes called solar heating, solar water heating, photovoltaic energy (converting sunlight directly into electricity), and solar thermal electric power (when the sun's energy is concentrated to heat water and produce steam, which is used to produce electricity).
Wind energy systems convert moving air to mechanical power or electricity through the use of wind turbines. This moving air is actually a form of solar energy because wind is driven mainly by temperature differences on the surface of the earth that are caused by sunlight. Wind turbines usually have just two or three blades that turn when the wind blows. The blades drive a generator that produces electricity, much like steam turbines.
Bioenergy is the use of biomass or organic matter to produce electricity, transportation fuels, or chemicals. There are three ways to use biomass. It can be burned to produce heat and electricity, changed to a gas-like fuel such as methane, or changed to a liquid fuel, also called biofuel. Although wood is the largest source of biomass energy, corn, sugarcane wastes, and other farming byproducts are commonly used.
Geothermal energy technologies get energy directly from the heat in the earth. Under the right geological conditions, the Earth's heat collects in large underground reservoirs of steam or hot water. This energy is tapped by drilling wells into the reservoirs and piping the steam or hot water to power plants, which convert the heat to electricity.
Hydropower systems tap the energy in flowing water to generate electricity. The most common form of hydropower uses dams on rivers to create large reservoirs of water. Water released from the reservoir flows through turbines, causing them to spin. The turbines are connected to generators that produce electricity.
Current Status (CRS Issue brief RL30307, Department of Energy: Programs and Reorganization Proposals)
The largest R&D efforts from the Department of Energy are focused on "clean" solar, wind and biomass power sources, to combat air pollution, climate change and other environmental problems, and on biofuels as a clean vehicle fuel to reduce oil import vulnerability and air pollution problems. Wind energy is expanding in global markets and recent progress in fuel cells for vehicles has rekindled interest in hydrogen as a fuel. There is also expectation that hydrogen can serve as an energy carrier and storage medium that allows renewable energy power production to support vehicle fuel needs.