The great energy transition from fossil fuels to renewable sources of energy is under way. As fossil fuel prices rise, as oil insecurity deepens and as concerns about pollution and climate instability cast a shadow over the future of coal, a new world energy economy is emerging. The old energy economy, fueled by oil, coal and natural gas, is being replaced with an economy powered by wind, solar, and geothermal 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.
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 U.S., 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.
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.