National Geographic : 2009 Sep
2 3 4 6 KILOWATT-HOURS PER SQUARE METER PER DAY SOLAR RADIATION HITTING THE EARTH'S SURFACE ANNUAL AVERAGE, 1983--2005 565 UNITED STATES 21 CANADA 10 MEXICO ELECTRICITY GENERATED FROM SOLAR ENERGY DURING 2006, IN GIGAWATT-HOURS ENERGY EQUAL TO 6,000 TIMES the world's elec- tricity use constantly shines on Earth. Even with current technology, we could harvest enough to supply dozens of times our demand for electricity--- but building the infrastructure needed to switch to solar would cost much more at current prices than continuing to burn fossil fuels. As data from NASA satellites show (map, right), the world's solar leaders, notably Germany, are not the sunniest countries but the ones that can afford to pay extra for solar power. Solar costs are falling steadily, however. Developing nations in the subtropics may benefit from that trend; steady sunshine there means investment in solar infrastructure could pay off fast. Most of the world's best solar potential remains unexploited. ENDLESS POTENTIAL Electricity generated worldwide in 2006 Electricity that could be generated worldwide from renewable sources 470,278 TWh SOLAR PHOTOVOLTAIC 275,556 TWh CONCENTRATING SOLAR 6,111 TWh WIND (OFFSHORE) 13,889 TWh HYDRO 91,398 TWh OCEAN (TIDAL AND WAVE) 105,278 TWh WIND (LAND BASED) 12,500 TWh GEOTHERMAL 19,015 TERAWATT-HOURS 975,010 TERAWATT-HOURS NONRENEWABLE RESOURCES 81.51% OTHER RENEWABLE 1.37% SOLAR 0.02% WIND 0.68% HYDRO 16.41% RANKING THE RENEWABLES The sun's potential for power generation eclipses that of all other renewable energy sources. But for now solar power barely registers in the world's energy portfolio (inset graph). It accounts for only a small fraction of a percent of total electrical output--- much less than hydropower or wind energy, which are cheaper to produce. SEAN MCNAUGHTON, NG STAFF GRAPHIC BY 5W INFOGRAPHICS SOURCES: NASA WORLD MAP ; WORLD ENERGY STATISTICS AND BALANCES © OECD/IEA, 2008; NATIONAL RENEWABLE ENERGY LABORATORY SOUTHWEST MAP ; ECOFYS POTENTIAL GENERATION NOTE: ONE TERAWATT HOUR = 1,000 GIGAWATT HOURS = 1 BILLION KILOWATT HOURS. ONE KILOWATT HOUR WILL POWER A 100 WATT LIGHTBULB FOR TEN HOURS.