Imagine energy sources that use no oil, produce no pollution, cannot be affected by political events and cartels, create no radioactive waste, and yet are economical. Although it sounds impossible, some experts claim that technological advances could make wide use of renewable energy sources possible within a few decades. Renewable energy is energy that is naturally regenerated and is, therefore, …
Before the eighteenth century, most energy came from renewable sources. People burned wood for heat, used sails to harness the wind and propel boats, and installed water wheels on streams to grind grain. The large-scale shift to nonrenewable energy sources began in the 1700s with the Industrial Revolution, a period marked by the rise of factories, first in Europe and then in North America. As dema…
Renewable energy contributes only a small portion of the nation's energy supply. In 2003 the United States consumed approximately 6.2 quadrillion Btu of renewable energy, about 6% of the nation's total energy consumption. (See Table 6.1.) Biomass sources (wood, waste, and alcohol) contributed 2.9 quadrillion Btu, while hydroelectric power provided 2.8 quadrillion Btu. Together, bioma…
Biomass refers to organic material such as plant and animal waste, wood, seaweed and algae, and garbage. The use of biomass is not without environmental problems. Deforestation can occur from widespread wood use if forests are clear-cut, resulting in the possibility of soil erosion and mudslides. Burning wood, like burning fossil fuels, also pollutes the environment. Biomass can be burned directly…
Hydropower, the energy that comes from the natural flow of water, is the world's largest renewable energy source. The energy of falling water or flowing water is converted into mechanical energy and then to electrical energy. In the past, flowing water turned waterwheels to grind grain or turn saws, but today flowing water is used to turn modern turbines. Hydropower is a renewable, nonpollu…
Since ancient times, humans have exploited the earth's natural hot water sources. Although bubbling hot springs became public baths as early as ancient Rome, using hot water and underground steam to produce power is a relatively recent development. Electricity was first generated from natural steam in Italy in 1904. The world's first steam power plant was built in 1958 in a volcanic …
Winds are created by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and the rotation of the earth. Winds are strongly influenced by local terrain, water bodies, weather patterns, vegetation, and other factors. Wind flow, when "harvested" by wind turbines, can be used to generate electricity. Early windmills produced mechanical energ…
Ancient Greek and Chinese civilizations used glass and mirrors to direct the sun's rays to start fires. Solar energy (energy from the sun) is a renewable, widely available energy source that does not generate greenhouse gases or radioactive waste. Solar-powered cars have competed in long-distance races, and solar energy has been used routinely for many years to power spacecraft. Although ma…
The potential power of the world's oceans is unknown. Because the ocean is not as easily controlled as a river or water that is directed through canals into turbines, unlocking that potential power is far more challenging. Three ideas being considered are tidal plants, wave power, and ocean thermal energy conversion (OTEC). The tidal plant uses the power generated by the tidal flow of water…
Hydrogen, the lightest and most abundant chemical element, is the ideal fuel from the environmental point of view. Its combustion produces only water vapor, and it is entirely carbon-free. Three-quarters of the mass of the universe is hydrogen, so in theory the supply is ample. However, the combustible form of hydrogen is a gas and is not found in nature. The many compounds containing hydrogen…
In Annual Energy Outlook 2004, the EIA forecasted that total renewable fuel consumption, including ethanol for transportation, will increase by 1.9% per year from 2002 to 2025. About 60% of the projected demand for renewable fuel in 2025 will be for electricity generation. In 2002 renewable energy provided 5.8 quadrillion Btu, which is projected to increase to 9 quadrillion Btu in 2025. Renewable …
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