Imagine an energy source that uses no oil, produces no pollution, cannot be affected by political events and cartels, creates no radioactive waste, and yet is economical. Although that might sound impossible, some experts claim that technological advances could make a renewable energy-based economy achievable by the mid-twenty-first century. Renewable energy is a term used to describe energy from …
Before the nineteenth century most energy used 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 1800s with the Industrial Revolution, a period marked by the rise of factories—first in Europe and then in North Americ…
The term bioenergy refers to energy that is generated using biomass—organic material such as wood, agricultural waste from plants and animals, seaweed and algae, and municipal solid waste (MSW) or garbage. These raw materials can be converted into liquid or gaseous biofuels or used directly to provide heat, electricity, or combined heat and power. Figure 10.5 shows common materials used to …
Hydropower is the energy that comes from the natural flow of water. Usually, the power is harnessed by taking advantage of gravity when water falls from one level to another. The energy of falling water is converted into mechanical energy. In the past, water's energy was harnessed by waterwheels to grind grain or turn saws. Modern technology uses water's energy to turn turbines that …
Since ancient times humans have exploited the earth's natural hot water sources. Although bubbling hot springs became public baths in ancient Rome, using naturally occurring hot water and underground steams to produce power is a relatively modern development. The first electricity to be generated from natural steam was in Italy in 1904. The world's first natural steam power plant was…
Wind energy is really a form of solar energy. 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. As a result, winds are strongly influenced by local terrain, water bodies, weather patterns, vegetation, and other factors. This wind flow, when "harvested" by wind turbines, can be used to…
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 FIGURE 10.12 Solar house types energy source that generates neither pollution nor hazardous waste. Solar-powered cars have already competed in long-distance races, and solar energy has been used routinely for many y…
Hydrogen is the lightest and most abundant chemical element. It contains only one proton and one electron. From an environmental point of view it is also the ideal fuel. Its combustion as a fuel or conversion to electricity produces only water vapor—it is entirely carbon-free. The National Aeronautics and Space Administration (NASA) has used liquid hydrogen for decades to power rockets into…
Renewable energy accounted for 8 percent of the total world energy production in 2001. (See Figure 10.15.) Global energy consumption is expected to increase by 60 percent through the next two decades, reaching 600 quadrillion Btu by 2020. Most of the growth will be in developing countries, particularly in Asia. In 2003 renewable energy contributed only 6 percent of the total energy consumed by the…
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