从化石燃料到可再生能源的巨大能源转型正在进行中。随着化石燃料价格的上涨,石油不安全性的加深,以及对污染和气候不稳定的担忧给煤炭的未来蒙上了阴影,一个新的世界能源经济正在出现。
The old energy economy, fueled by oil, coal, and natural gas, is being replaced with an economy powered bywind,solar, andgeothermal energy. The Earth’s renewable energy resources are vast and available to be tapped through visionary initiatives. Our civilization needs to embrace renewable energy on a scale and at a pace we’ve never seen before.
Our Fossil Fuel Heritage
We inherited our current fossil fuel based world energy economy from another era. The 19th century was the century of coal, and oil took the lead during the 20th century. Today, global emissions of carbon dioxide (CO2)—the principal climate-altering greenhouse gas—come largely from burning coal, oil, and natural gas.
Coal, mainly used for electricity generation, accounts for 44 percent of global fossil-fuel CO2 emissions. Oil, used primarily for transportation, accounts for 36 percent. Natural gas, used for electricity and heating, accounts for the remaining 20 percent. It is time to design a carbon- and pollution-free energy economy for the 21st century.
Some trends are already moving in the right direction. The burning of coal, for example, is declining in many countries. In the United States, the number two coal consumer after China, coal use dropped 14 percent from 2007 to 2011 as dozens of coal plants were closed. This trend is expected to continue, due in part to widespread opposition to coal now being organized by the Sierra Club’sBeyond Coalcampaign.
Oil is used to produce just 5 percent of the world’s electricity generation and is becoming ever more costly. Because oil is used mainly for transport, we can phase it out by electrifying the transport system. Plug-in hybrid and all-electric cars can run largely on clean electricity. Wind-generated electricity to operate cars could cost the equivalent of 80-cent-per gallon gasoline.
As oil reserves are being depleted, the world has been turning its attention to plant-based energy sources. Their potential use is limited, though, because plants typically convert less than 1 percent of solar energy into biomass.
Crops can be used to produce automotive fuels, such as ethanol and biodiesel. Investments in U.S. corn-based ethanol distilleries became hugely profitable when oil prices jumped above $60 a barrel following Hurricane Katrina in 2005. The investment frenzy that followed was also fueled by government mandates and subsidies. In 2011, the world produced 23 billion gallons of fuel ethanol and nearly 6 billion gallons of biodiesel.
But the more research that’s done on liquid biofuels, the less attractive they become. Every acre planted in corn for ethanol means pressure for another acre to be cleared elsewhere for crop production. Clearing land in the tropics for biofuel crops can increase greenhouse gas emissions instead of reducing them. Energy crops cannot compete with land-efficient wind power.
The scientific community is challenging the natural gas industry’s claim that its product is fairly climate-benign. Natural gas produced by hydraulic fracturing, or fracking (a much-touted key to expanding production) is even more climate-disruptive than coal because of methane gas leakage. (Methane is a potent contributor to climate change.)
The last half of the twentieth century brought us nuclear power, once widely touted as the electricity source of the future. Although nuclear reactors supply 13 percent of the world’s electricity, nuclear power’s limited role in our future has been clear for some time. It is simply too expensive.
The Shift to Renewable Sources of Power
Countries around the world are richly endowed with renewable energy, in some cases enough to easily double their current electrical generating capacities. A revamped clean energy economy will harness more energy from the wind and sun, and from within the Earth itself. Climate-disrupting fossil fuels will fade into the past as countries turn to clean, climate-stabilizing, nondepletable sources of energy.
将阳光转化为电能的太阳能电池的使用增长只能用爆发性来形容,2011年增长了74%。早期的光伏发电装置都是小规模的,大多安装在住宅屋顶上。随着更多公用事业规模的光伏项目的推出,这种情况正在改变。例如,美国正在建设和开发100多个公用事业规模的项目。太阳能发电在美国西南部等沙漠地区特别有吸引力,因为高峰发电与高峰空调使用非常吻合。
The world’s current 70,000 megawatts of photovoltaic installations can, when operating at peak power, match the output of 70 nuclear power plants. With PV installations climbing and with costs continuing to fall, cumulative PV generating capacity could surpass 1 million megawatts in 2020. (Current world electricity generating capacity from all sources is 5 million megawatts.) Installing solar panels for individual homes in the villages of developing countries is now often cheaper than it is to supply them with electricity by building a central power plant and a grid.
来自地球内部的热量——地热能——可以用来加热或转化为蒸汽发电。许多国家有足够的可利用地热能来满足他们所有的电力需求。尽管地热能储量丰富,但截至2012年,地热能装机容量仅够为全球约1000万户家庭提供电力。
Roughly half of the world’s 11,000 megawatts of installed geothermal generating capacity is concentrated in the United States and the Philippines. Altogether, 24 countries now convert geothermal energy into electricity. The United States, with 130 confirmed geothermal plants under construction or in development, will be bringing at least 1,000 megawatts of generating capacity online in the near term. Worldwide, this accelerating pace could yield 200,000 megawatts of generating capacity by 2020.
Each alternative energy source—whether solar, geothermal, or wind—has a major role to play, but it is wind that is on its way to becoming the foundation of the new energy economy.
Stay tuned for more discussion of the advantages and potential of wind energy in Part II.
Adapted from “Exciting News About Renewable Energy,” by Lester R. Brown, in the October/November 2012 issue ofMother Earth News.
Lester R. Brown is President of Earth Policy Institute and author ofFull Planet, Empty Plates: The New Geopolitics of Food Scarcity.
Data and additional resources atwww.earth-policy.org
Delmar Jacksonsays
Why haven’t we heard about the safety and low cost of thorium reactors?
http://www.youtube.com/watch?v=RDzDk44bzyU
Jeff McIntire-Strasburgsays
As I understand it, thorium isn’t the panacea many claim. I’m no expert, but I do trust Zach at Cleantechnica:http://cleantechnica.com/2012/09/11/why-thorium-nuclear-isnt-featured-on-cleantechnica/