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’s Beyond Coal campaign.
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. More
