Environmental Problems, Their Causes, and Sustainability 1

Nuclear power6%Hydropower, geothermal,solar, wind6%Nuclear power8%Hydropowergeothermal,,solar, wind3%NONRENEWABLE 84%Coal23%Naturalgas22%Oil33%Biomass10%RENEWABLE 16%Coal23%NONRENEWABLE 94%Naturalgas24%Oil39%6%RENEWABLEBiomass3%WorldUnited StatesFigure 17-3 Commercial energy use by source for the world (left) and the United States (right) in 2002.Commercial energy amounts to only 1% of the energy used in the world; the other 99% is direct solar energyreceived from the sun and is not sold in the marketplace. (U.S. Department of Energy, British Petroleum,Worldwatch Institute, and International Energy Agency)Figure 17-4 shows the global consumption of energyby fuel type between 1970 and 2003, with projectionsto 2020. Note that oil predominates, followed bynatural gas.Roughly half the world’s people in developingcountries burn wood and charcoal to heat theirdwellings and cook their food. This biomass energy isrenewable as long as wood supplies are not harvestedfaster than they are replenished. Most of this biomassis collected by users and not sold in the marketplace.Energy consumption (quadrillion Btus)25020015010050019701980History1990YearProjections200320102020OilNatural gasCoalNuclearNonhydrorenewableRenewablehydroFigure 17-4 Global energy consumption by fuel type,1970–2003, with projections to 2020. (A Btu is a British thermalunit, a standard measure of heat for value comparison of variousfuels.) (Data from U.S. Department of Energy, AnnualEnergy Review, 2003 and 2004)Thus the actual percentage of renewable biomass energyused in the world is higher than the 10% figureshown in Figure 17-3 (left).Bad news. Many people in developing countriesface a fuelwood shortage that is expected to get worsebecause of unsustainable harvesting of fuelwood.Also, people die prematurely from breathing particlesemitted by burning wood indoors in open fires andpoorly designed primitive stoves.What Is the Energy Future of the United States?Searching for Fossil Fuel SubstitutesThere is debate over whether U.S. energy policy forthis century should continue its dependence on oiland coal or depend more on natural gas, hydrogen,and solar cells.The United States is the world’s largest energy user,with the average American consuming as much energyin one day as a person in the poorest countriesconsumes in a year. In 2004, with only 4.6% of the population,the United States used 24% of the world’scommercial energy. In contrast, India, with 16% of theworld’s people, used about 3% of the world’s commercialenergy.About 94% of the commercial energy used in theUnited States comes from nonrenewable energy resources(86% from fossil fuels and 8% from nuclearpower; Figure 17-3, right). The remaining 6% comesmostly from renewable biomass and hydropower.352 CHAPTER 17 Nonrenewable Energy Resources