Renewable energy can supply a significant proportion of the United States' energy needs, creating many public benefits for the nation and for states and regions, including environmental improvement, increased fuel diversity and national security, and regional economic development benefits.
Using fossil fuels -- coal, oil and natural gas -- to make electricity dirties the nation's air, consumes and pollutes water, hurts plants and animal life, creates toxic wastes, and causes global warming. Using nuclear fuels poses serious safety risks. Renewable energy resources can provide many immediate environmental benefits by avoiding these impacts and risks and can help conserve fossil resources for future generations. Of course, renewable energy also has environmental impacts. For example, biomass plants produce some emissions, and fuel can be harvested at unsustainable rates. Windfarms change the landscape, and some have harmed birds. Hydro projects, if their impacts are not mitigated, can greatly affect wildlife and ecosystems. However, these impacts -- which are discussed in Appendix A -- are generally much smaller and more localized than those of fossil and nuclear fuels. Care must nevertheless be taken to mitigate them.
Clean air is essential to life and good health. Air pollution aggravates asthma, the number one children's health problem. Air pollution also causes disease and even premature death among vulnerable populations, including children, the elderly, and people with lung disease. A 1996 analysis by the Natural Resources Defense Council of studies by the American Cancer Society and Harvard Medical School suggests that small particles in the air may be responsible for as many as 64,000 deaths each year from heart and lung disease. As the figure below shows, air pollution is responsible for more deaths than motor vehicle accidents, and ranks higher than many other serious health threats. A few of the most important pollutants are discussed below.
Electricity production, primarily from burning coal, is the source of most emissions of sulfur oxides (SOx), as the figure shows. These chemicals are the main cause of acid rain, which can make lakes and rivers too acidic for plant and animal life. Acid rain also damages crops and buildings. National reductions in sulfur oxides required by the Clean Air Act Amendments of 1990 may not be sufficient to end damage from acid rain in the northeastern United States. SO2 is also a primary source of fine particles in the air.
Burning fossil fuels either to produce electricity or to power transportation emits nitrogen oxides (NOx) into the air. In the presence of sunlight, nitrogen oxides combine with other chemicals to form ground-level ozone (smog). Both nitrogen oxides and ozone can irritate the lungs, cause bronchitis and pneumonia, and decrease resistance to respiratory infections. In addition, research shows that ozone may be harmful even at levels allowed by federal air standards. The U.S. Environmental Protection Agency (EPA) has published a new rule reducing nitrogen oxide emissions from 0.12 parts per million to 0.08 parts per million. States have until 2003 to submit plans for meeting the new standard and up to 12 years to achieve it.
Carbon dioxide (CO2) is the most important of the greenhouse gases, which contribute to global warming by trapping heat in the earth's atmosphere. Electricity generation is, as the figure shows, the largest industrial source of carbon dioxide emissions and a close second to the transportation sector.
Samples from air bubbles trapped deep in ice from Antarctica show that carbon dioxide and global temperature have been closely linked for 160,000 years. Over the last 150 years, burning fossil fuels has resulted in the highest levels of carbon dioxide ever recorded. In 1995, the Intergovernmental Panel on Climate Change -- an authoritative international scientific body -- concluded that "the balance of evidence suggests that there is a discernible human influence on global climate." All 10 of the warmest years on record have occurred in the last 15 years. The 1990s have already been warmer than the 1980s -- the warmest previous decade on record, according to the Goddard Institute of Space Studies.
Without action, carbon dioxide levels would double in the next 50 to 100 years, increasing global temperatures by 1.8 to 6.3 degrees Fahrenheit. The heat trapped in the atmosphere would cause expansion of the ocean's volume as surface water warms and melt some glaciers. A two-foot rise in sea level could flood 5,000 square miles of dry land in the United States, and another 5,000 square miles of coastal wetlands, as the figure shows. From 17 to 43 percent of coastal wetland-prime fish and bird habitat-could be lost. Building dikes and barriers could reduce flooding of dry land, but would increase wetland loss. Impacts on island nations and low-lying countries, like Egypt and Bangladesh, would be much worse.
Altered weather patterns from changes in climate may result in more extreme weather events. Some areas will suffer more drought and others more flooding, putting crop production under great stress in some regions. The character of our forests could change dramatically. Other expected impacts include an increase in heat-related deaths, increased loss of animal and plant species, and the spread of pests and diseases into new regions with less resistance to them.
In 1997, at a conference in Kyoto, Japan, the developed nations of the world agreed to reduce carbon dioxide emissions. The United States agreed to 7 percent reductions from 1990 levels by the period 2008-2012. Senate ratification of this agreement remains uncertain, however.