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Clean energy has a long way to go. Only 2.2% of the world's energy comes from "new" renewables such as small hydroelectric dams, wind, solar and geothermal. (Traditional renewable energy from large dams provides another 2.2%.) How to boost that share--and at what pace--is debated in industrialized nations--from Japan, which imports 99.7% of its oil, to Germany, where the nearby Chernobyl accident turned the public against nuclear plants, to the U.S., where the Bush Administration has strong ties to the oil industry. But the momentum toward clean renewables is undeniable. Globally, solar- and wind-energy output is growing more than 30% annually--far faster than conventional fuels--and their cost is plummeting. "We are on the cusp of an energy revolution," says Christopher Flavin, president of the Worldwatch Institute, a Washington nonprofit. "It will be as profound as the one that ushered in the age of oil a century ago."
Even oil companies are trying to cash in on the decarbonization trend. The world has gradually moved toward cleaner fuels--from wood to coal, from coal to oil and from oil to natural gas. Renewables are the next step. Royal Dutch/Shell has pledged to spend up to $1 billion on renewables through the next five years. Japanese manufacturers, led by Sharp and Kyocera, have moved aggressively into photovoltaic cells, which turn sunlight into electricity. And in April General Electric snapped up Enron Wind from the bankrupt energy giant. "We are on a journey to a lower-carbon world," says Graham Baxter, an executive at Britain's BP, which is building a $100 million solar plant in Spain.
How soon we reach an era of clean, inexhaustible energy depends on technology. Solar and wind energies are intermittent: when the sky is cloudy or the breeze dies down, fossil fuel or nuclear plants must kick in to compensate. But scientists are working on better ways to store electricity from renewable sources. Current from wind, solar or geothermal energy can be used to extract hydrogen from water molecules. In the future, hydrogen could be stored in tanks, and when energy is needed, the gas could be run through a fuel cell, a device that combines hydrogen with oxygen. The result: pollution-free electricity, with water as the only by-product. Already fuel-cell buses, cars and small generators are being tested. Eventually, some visionaries say, fuel cells placed in individual buildings could replace many of today's giant electric plants. But that will not happen unless the technology is refined and the cost drops. "A hydrogen economy," says Alan Nogee of the Union of Concerned Scientists, a U.S. environmental group, "is the Holy Grail."