Environmental Problems, Their Causes, and Sustainability 1

Burning natural gas emits CO 2 but at a lower rate perunit of energy than other fossil fuels (Figure 17-16). Forthese reasons, natural gas use is expected to growworldwide (Figure 17-4) and in the United States (Figures17-5 and 17-6).T rade-OffsConventional Natural GasAdvantagesDisadvantagesWho Has the World’s Natural Gas Suppliesand How Long Will the Supplies Last? MoreAbundant than OilRussia and Iran have almost half of the world’sreserves of conventional natural gas, and globalreserves should last 62–125 years.Russia has about 31% of the world’s proven naturalgas reserves, followed by Iran (15%) and Qatar (9%).About 36% of the world’s natural gas reserves are inMiddle Eastern countries. The United States has only3% of the world’s proven reserves. Geologists expectto find more natural gas, especially in unexplored developingcountries.The long-term global outlook for natural gas suppliesis better than for conventional oil. At the currentconsumption rate, geologists estimate that known reservesand undiscovered potential reserves of conventionalnatural gas should last the world for 62–125years and the United States for 55–80 years, dependingon how rapidly it is used.They project that conventional and unconventionalsupplies of natural gas (the latter available at higherprices) should last at least 200 years at the current consumptionrate and 80 years if consumption rates rise2% per year.Figure 17-19 lists the advantages and disadvantagesof natural gas as an energy resource. Energy expertsproject greatly increased global use of natural gasduring this century because of its fairly abundant supply,and lower pollution and CO 2 rates per unit ofenergy compared to other fossil fuels (Figure 17-16).Because of its advantages over oil, coal, and nuclearenergy, some analysts see natural gas as the bestfuel to help make the transition to improved energy efficiencyand greater use of solar energy and hydrogenover the next 50 years.What Is the Future of Natural Gas in theUnited States? Declining Supplies and RisingImportsNatural gas production in the United States is expectedto continue declining, resulting in increaseddependence on imports from Canada, Russia, and theMiddle East.In 2002, natural gas was burned to provide 53% of theheat in U.S. homes and 16% of the country’s electricity.By 2020, the U.S. Department of Energy projects thatnatural gas will be burned to produce about one-thirdAmple supplies(125 years)High net energyyieldLow cost (withhuge subsidies)Less air pollutionthan otherfossil fuelsLower CO 2emissions thanother fossil fuelsModerate environmentalimpactEasily transportedby pipelineLow land useGood fuel forfuel cells andgas turbinesAnode (-)CatalystCathode (+) (+)NonrenewableresourceReleases CO 2when burnedMethane(a greenhousegas) can leakfrom pipelinesDifficult to transferfrom one countryto anotherShipped acrossocean as highlyexplosive LNGSometimesburned off andwasted at wellsbecause of lowpriceRequires pipelinesFigure 17-19 Trade-offs: advantages and disadvantages ofusing conventional natural gas as an energy resource. Pick thesingle advantage and disadvantage that you think are the mostimportant.of the country’s electricity, if the natural gas pipelinedistribution system is greatly expanded.Bad news. U.S. production of natural gas has beendeclining for a long time, and most geologists do notbelieve this situation will be reversed. More naturalgas could be imported from Canada, but this will requirebuilding a major pipeline between the two countries.Also, production in Canada is expected to peakbetween 2020 and 2030. Then the United States and therest of the world would have to rely increasingly onRussia and the Middle East for supplies of natural gas.More liquefied natural gas could be imported byship. But this requires cooling the gas to a very lowtemperature to liquefy it, shipping it in special tankers,and building special LNG receiving terminals. This isquite expensive and reduces the net energy yield fornatural gas. Also, LNG is highly flammable and couldlead to large-scale fires at receiving terminals.http://biology.brookscole.com/miller14363