To report our July cover story on solutions to the energy crisis, PopSci consulted dozens of energy experts, from leaders of renewable-energy nonprofits, to industry engineers, to laboratory scientists. Our conclusion: Assuming political and bureaucratic hurdles could be overcome, the U.S. is capable of eliminating use of fossil fuels for electricity generation by 2025. We were not quite as optimistic about our ability to wean ourselves from fossil fuels for our transport needs, predicting that we could realistically eliminate half of our transport-related fossil-fuel use by 2025 (although we think we could do it all by 2050).

Our projections do not arise out of a strict methodology or mathematical equation. Rather, we polled the experts, examined our country´s natural resources, looked at our own technological successes and those of other nations, talked it all over, and assigned what we believe is an optimistic but realistic number to the potential of each alternative power source.

Here´s what we´re thinking in each area:


First, some context. Here´s how current U.S. electricity use breaks down, by source:

Coal 50%

Natural gas 18%

Petroleum 3%

Hydroelectric 7%

Nuclear 20%

Other, including wind and biomass 3%

According to U.S. Energy Information Administration [] projections, by 2025, our country´s electricity use will be 5,208 billion kilowatt-hours (kWh) a year. Assuming that we maintain our current rate of use of hydroelectric and nuclear power, our power equation, described below, will actually create more electricity than our projected needs by 2025 (allowing for a couple technological faceplants along the way).

The PopSci 2025 Projection Wind supplies 20 percent of electricity (1,040 billion kWh; 960 million metric tons [MMT] of CO2 displaced).

Our Justification Wind is the world´s fastest-growing renewable energy source, with several European countries already close to getting 20 percent of their electricity from wind. A 2005 Stanford University study found that the U.S. has more sites appropriate for placing wind farms than any other country. The middle of the country has the strongest potential, although near-shore or offshore wind farms on the East and West coasts would also be an efficient source of clean energy. In many ways, this 20 percent recommendation is conservative. If the political will exists, wind could actually supply a much greater proportion of our electricity, with no new technological breakthroughs required.

The PopSci 2025 Projection Solar supplies 10 percent of electricity (520 billion kWh; 500 MMT of CO2 displaced).

Our Justification Solar is poised to benefit from breakthroughs in thin-film technology and nanotechnology that will significantly improve the efficiency with which our current panels can convert the sun´s energy to electricity. A combination of increased home- and business-based solar-energy generation and construction of large-scale solar farms, like the one under construction in the Mojave Desert, could lead to a 10 percent dependence on solar by 2025. After 2025, solar technology is expected to gain even more momentum; by 2050 it will probably meet far more than 10 percent of our electrical needs.

The PopSci 2025 Projection Ocean power supplies 2 percent of electricity (105 billion kWh; 95 MMT of CO2 displaced).

Our Justification The power is there to be tapped (more than 10 times as much as we need to create 105 billion kWh). By employing new wave technology emerging from Europe and expanding our nascent use of underwater turbines, we could easily use current power to make 2 percent of electricity by 2025. Cities with substantial tidal and wave resources, such as San Francisco, could get up to 10 percent of their power from such sources.

The PopSci 2025 Projection Geothermal supplies 5 percent of electricity (290 billion kWh; 290 MMT of CO2 displaced).

Our Justification With the help of federal and state support, geothermal is already expanding. At its current rate of growth, it could provide 5 percent of the country´s electricity by 2025.

The PopSci 2025 Projection Biopower supplies 17 percent of electricity (800 billion kWh; 960 MMT of CO2 displaced).

Our Justification Biopower is already the U.S.´s largest source of non-hydro renewable energy. As more municipalities search for efficient ways to rid themselves of garbage and agricultural waste, the most efficient of biopower technologies will grow in popularity.

The PopSci 2025 Projection Grid savings supply 10 percent of electricity (520 billion kWh; 495 MMT of CO2 displaced).

Our Justification Energy experts believe that grid enhancements could cut the growth of electricity use in half, providing efficiencies that would equal 10 percent of our 2025 projected electricity use.

The PopSci 2025 Projection Efficiency savings supply 36 percent of electricity (1,885 billion kWh; 1,800 MMT of CO2 displaced).

Our Justification Efficiency could be the single largest contributor to reducing energy use. With a 2 percent economy-wide improvement per year, overall demand could be reduced by .6 percent a year. By 2025, efficiency measures could meet 1,185 billion kWh of demand under a business-as-usual scenario.

A note about the CO2 displaced These numbers are based on the assumption that the given alternative energy source replaces the use of coal-generated electricity.


The U.S. Energy Information Administration´s 2025 projection for American vehicle-related oil use is 26.05 million barrels of oil per day. (The U.S. now uses 21 million barrels a day.)

The PopSci Projection Vehicle efficiency accounts for 19 percent of fuel savings (5 million barrels of oil a day saved; 890 MMT of CO2 displaced).

Our Justification A combination of significantly increased use of new hybrid technologies and other efficiency-upping measures such as lower vehicle size and weight could seriously reduce the amount of fuel consumed. It´s not realistic, however, to think that we´ll completely turn over our vehicle fleet within 20 years.

The PopSci Projection Alternative fuels account for 30 percent of fuel savings (8 million barrels of oil a day saved; 500 MMT of CO2 displaced).

Our Justification A report by Oak Ridge National Laboratory and the U.S. Department of Agriculture determined that adequate land resources are available in the U.S. to sustainably produce a biomass capable of displacing 30 percent of our current use of petroleum by the year 2030. Other energy experts believe that estimate is conservative. The real promise of alternative fuels, though, is in developing them from cellulosic materials, which would drastically increase the energy efficiency of shifting to ethanol. Significant progress is being made on that front.

A note about the CO2 displaced These numbers are based on the saved emissions from standard oil-based gasoline.