The United States currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels are nonrenewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. In contrast, renewable energy resources—such as wind and solar energy—are constantly replenished and will never run out.
Most renewable energy comes either directly or indirectly from the sun. Sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses.
The sun’s heat also drives the winds, whose energy is captured with wind turbines. Then, the winds and the sun’s heat cause water to evaporate. When this water vapor turns into rain or snow and flows downhill into rivers or streams, its energy can be captured using hydropower.
Along with the rain and snow, sunlight causes plants to grow. The organic matter that makes up those plants is known as biomass. Biomass can be used to produce electricity, transportation fuels, or chemicals. The use of biomass for any of these purposes is called biomass energy.
Hydrogen also can be found in many organic compounds, as well as water. It’s the most abundant element on the Earth. But it doesn’t occur naturally as a gas. It’s always combined with other elements, such as with oxygen to make water. Once separated from another element, hydrogen can be burned as a fuel or converted into electricity.
Not all renewable energy resources come from the sun. Geothermal energy taps the Earth’s internal heat for a variety of uses, including electric power production, and the heating and cooling of buildings. And the energy of the ocean’s tides comes from the gravitational pull of the moon and the sun upon the Earth.
In fact, ocean energy comes from a number of sources. In addition to tidal energy, there’s the energy of the ocean’s waves, which are driven by both the tides and the winds. The sun also warms the surface of the ocean more than the ocean depths, creating a temperature difference that can be used as an energy source. All these forms of ocean energy can be used to produce electricity.
Renewable energy provides many important benefits including:
|The U.S. Fish and Wildlife service uses a photovoltaic system to provide clean energy at the Farallon National Wildlife Refuge.|
Renewable energy technologies are a lot friendlier to the environment than conventional energy technologies, which rely on fossil fuels. Fossil fuels contribute significantly to many of the environmental problems we face today—greenhouse gases, air pollution, and water and soil contamination—while renewable energy sources contribute very little or not at all.
Greenhouse gases—carbon dioxide, methane, nitrous oxide, hydrocarbons, and chlorofluorocarbons—surround the Earth’s atmosphere like a clear thermal blanket, allowing the sun’s warming rays in and trapping the heat close to the Earth’s surface. This natural greenhouse effect keeps the Earth’s average surface temperature at about 60°F (33°C). But the increased use of fossil fuels has significantly increased greenhouse gas emissions, particularly carbon dioxide, creating an enhanced greenhouse effect known as global warming. According to the U.S. Environmental Protection Agency (EPA), carbon dioxide is responsible for one-half to two-thirds of our contribution to global warming. Renewable energy technologies, however, can produce heat and electricity with a very low or no amount of carbon dioxide emissions.
Energy use from fossil fuels is also a primary source of air, water, and soil pollution. Pollutants—such as carbon monoxide, sulfur dioxide, nitrogen dioxide, particulate matter, and lead—take a dramatic toll on our environment. On the other hand, most renewable energy technologies produce little or no pollution.
Both pollution and global warming pose major health risks to humans. According to the American Lung Association, air pollution contributes to lung disease — including asthma, lung cancer, and respiratory tract infections — and close to 335,000 people in the United States die from it every year. Meanwhile, the long-term effects associated with global warming may be even more devastating. Deaths due to extreme weather could increase, and diseases could have a greater potential to thrive as temperatures rise.
Ultimately, renewable energy technologies could help us break our conventional pattern of energy use to improve the quality of our environment.
Energy for the Future
|This cornfield can be used to make ethanol—a fuel we won’t run out of as long we grow corn and other comparable plants.|
What will the world’s energy use be like in the future? Well, we can be pretty certain that electricity use will grow worldwide. The International Energy Agency projects that the world’s electrical generating capacity will increase to nearly 5.8 million megawatts by the year 2020, up from about 3.3 million in 2000. However, the world supplies of fossil fuels—our current main source of electricity—will start to run out from the years 2020 to 2060, according to the petroleum industry’s best analysts. How will we meet those electricity needs? Our best answer could be renewable energy.
Shell International predicts that renewable energy will supply 60% of the world’s energy by 2060. The World Bank estimates that the global market for solar electricity will reach $4 trillion in about 30 years. Biomass fuels could also replace gasoline. It is estimated that the United States could produce 190 billion gallons per year of ethanol using available biomass resources in this country.
And unlike fossil fuels, renewable energy sources are sustainable. They will never run out. According to the World Commission on Environment and Development, sustainability is the concept of meeting “the needs of the present without compromising the ability of future generations to meet their own needs.” That means our actions today to use renewable energy technologies will not only benefit us now, but will benefit many generations to come.
Jobs and the Economy
|A certification test engineer, shown here measuring the noise from a wind turbine, is one of many careers available in the renewables industry.|
Many U.S. communities have to import fossil fuels, such as oil and natural gas, to provide electricity, heating, and fuel. The cost of these fossil fuels can add up to billions of dollars. And every dollar spent on energy imports is a dollar that the local economy loses. Renewable energy resources, however, are developed locally. The dollars spent on energy stay at home, creating more jobs and fostering economic growth.
Renewable energy technologies are labor intensive. Jobs evolve directly from the manufacture, design, installation, servicing, and marketing of renewable energy products. Jobs even arise indirectly from businesses that supply renewable energy companies with raw materials, transportation, equipment, and professional services, such as accounting and clerical services.
In turn, the wages and salaries generated from these jobs provide additional income in the local economy. Renewable energy companies also contribute more tax revenue locally than conventional energy sources.
The economic advantages of renewable energy also extend far beyond the local economy. The whole country benefits. In 2001, the United States spent about $103 billion dollars outside the country for oil. But as one of the world’s leading manufacturers of renewable energy systems, we can bring in more money with the increased use of renewable energy sources around the world. Currently, for example, the United States manufactures about two-thirds of the world’s photovoltaic (PV) systems. And it exports about 70% of these PV systems, mostly to developing nations, resulting in annual sales of more than $300 million.
|NREL’s Solar Independence Exhibit featured a 4-kilowatt photovoltaic system that is used for mobile emergency power.|
Our nation’s energy security continues to be threatened by our dependency on fossil fuels. These conventional energy sources are vulnerable to political instabilities, trade disputes, embargoes, and other disruptions.
U.S. domestic oil production has been declining since 1970. In 1973, the United States only imported about 34% of its oil. Today, our country imports more than 53%, and it is estimated that this could increase to 75% by 2010.
Most of the world’s oil reserves are now in the Middle East. We have witnessed this shift in economic influence through the last three sharp increases in the world’s oil prices: the Arab Oil Embargo in 1974, the Iranian Oil Embargo in 1979, and the Persian Gulf War in 1990. It has resulted in periods of negative economic growth and a rising trade deficit.
But with renewable energy, we can decrease our dependency on foreign oil imports. For example, the U.S. Department of Energy (DOE) estimates that if we displace 10% of our petroleum use for transportation with biofuels, which are produced from organic material, we could save about $15 billion over 10 years. A 20% displacement could save us about $50 billion. This would strengthen our energy security, as well as our economic and national security.