Environmental Impact of Wind and Solar Energy
Of the total energy consumed in America, about 39% is used to generate electricity. Therefore, electricity consumption is an important portion of a consumer's environmental footprint.
Non-hydroelectric renewable energy refers to electricity supplied from the following renewable sources of power: solar, geothermal, biomass, landfill gas, and wind. Although installation of these renewable energy resources is growing, non-hydro renewable energy is currently responsible for less than two percent of the electricity generation in the United States.
Air emissions associated with generating electricity from solar and wind technologies are negligible because no fuels are combusted in these processes. The average air emissions rates in the United States from non-hydro renewable energy generation are 1.22lbs/MWh of sulfur dioxide and 0.06 lbs/MWh of nitrogen oxides.
The sources discussed below are considered to be renewable because they are continuously being replenished. They are also considered to be sustainable because nature will replenish these sources into the future and faster than they can be used.
Wind
About This Technology
Wind is created because the sun heats the Earth unevenly, due to the seasons and cloud cover. This uneven heating, in addition to the Earth's rotation, causes warmer air to move toward cooler air. This movement of air is wind.
Wind turbines use two or three long blades to collect the energy in the wind and convert it to electricity. The blades spin when the wind blows over them. The energy of motion contained in the wind is then converted into electricity as the spinning turbine blades turn a generator. To create enough electricity for a town or city, several wind turbine towers need to be placed together in groups or rows to create a "wind farm."
Reserves
The availability of wind power varies across the United States. Areas with the best wind availability include portions of the following states: North Dakota, Texas, Kansas, South Dakota, Montana, Nebraska, Wyoming, Oklahoma, Minnesota, Iowa, Colorado, New Mexico, California, Wisconsin, and Oregon. In general, wind is consistent and strong enough in the Great Plains states and mountain passes in the various mountain ranges throughout the United States to generate electricity using wind turbines. The Rocky Mountain and Great Plains states have sufficient wind resources to meet 10 to 25 percent of the electric power requirements of these states.
Environmental Impacts - Air Emissions
Emissions associated with generating electricity from wind technology are negligible because no fuels are combusted.
Environmental Impacts - Water Resource Use
Wind turbines in areas with little rainfall may require the use of a small amount of water. If rainfall is not sufficient to keep the turbine blades clean, water is used to clean dirt and insects off the blades so that turbine performance is not reduced.
Environmental Impacts - Water Discharges
Wind turbines do not discharge any water while creating electricity.
Environmental Impacts - Solid Waste Generation
Wind technologies do not produce any substantial amount of solid waste while creating electricity.
Environmental Impacts - Land Resource Use
Wind turbines generally require the use of land, although they may also be sited offshore. Land around wind turbines can be used for other purposes, such as the grazing of cattle or farming.
When wind turbines are removed from land, there are no solid wastes or fuel residues left behind. However, large wind farms pose aesthetic concerns and wind turbines that are improperly installed or landscaped may create soil erosion problems. Wind farms can also have noise impacts, depending on the number of wind turbines on the farm. New blade designs are being used to reduce the amount of noise. Bird and bat mortality has been an issue at some wind farms. Improvements to wind turbine technologies and turbine siting have helped mitigate bird mortality. Research on impacts to bats is now underway.
Solar
About This Technology
Solar energy is a renewable resource because it is continuously supplied to the earth by the sun. There are two common ways to convert solar energy into electricity: photovoltaic and solar-thermal technologies. Photovoltaic systems consist of wafers made of silicon or other conductive materials. When sunlight hits the wafers, a chemical reaction occurs, resulting in the release of electricity. Solar-thermal technologies concentrate the sun's rays with mirrors or other reflective devices to heat a liquid to create steam, which is then used to turn a generator and create electricity.
Reserves
Solar resources are available everywhere in the United States, although some areas receive less sunlight than others, depending on the climate and seasons. The greatest solar resources are located in the Southwestern states, where sufficient solar energy falls on an area of 100 miles by 100 miles to provide all of the nation's electricity requirements.
Environmental Impacts - Air Emissions
Emissions associated with generating electricity from solar technologies are negligible because no fuels are combusted.
Environmental Impacts - Water Resource Use
Photovoltaic systems do not require the use of any water to create electricity. Solar-thermal technologies may tap local water resources if the liquid that is being heated to create steam is water. In this case, the water can be re-used after it has been condensed from steam back into water.
Environmental Impacts - Water Discharges
Solar technologies do not discharge any water while creating electricity.
Environmental Impacts - Solid Waste Generation
Solar-thermal technologies do not produce any substantial amount of solid waste while creating electricity. The production of photovoltaic wafers creates very small amounts of hazardous materials that must be handled properly to avert risk to the environment or to people.
Environmental Impacts - Land Resource Use
Photovoltaic systems require a negligible amount of land area because they are typically placed on existing structures. In contrast, solar-thermal technologies may require a significant amount of land, depending upon the specific solar-thermal technology used. Solar energy installations do not usually damage the land they occupy, but they prevent it from being used for other purposes. In addition, photovoltaic systems can negatively affect wildlife habitat because of the amount of land area the technology requires.
