By all means, swap out your regular light bulbs for compact fluorescents, take the bus, weatherize your home and install solar panels on your roof. Oh, heck, go crazy: tell your senators to give the nuclear industry everything it wants so it starts building reactors again. But while you're doing all that to reduce the world's energy use and cut emissions of greenhouse gases, keep this in mind: even if we scale up existing technologies to mind-bending levels, such as finishing one nuclear plant every other day for the next 40 years, we'll still fall short of how much low-carbon energy will be needed to keep atmospheric levels of carbon dioxide below what scientists now recognize as the point of no return.

As the world gets closer to a consensus that we need to slash CO2 emissions, a debate is raging over whether we can achieve the required cuts by scaling up existing technologies or whether we need "transformational" scientific breakthroughs. The Intergovernmental Panel on Climate Change, which assesses the causes, magnitude and impacts of global warming, said in 2007 that "currently available" technologies and those on the cusp of commercialization can bring enough zero-carbon energy online to avoid catastrophic climate change. And I regularly get reports from renewable-energy and environmental groups arguing that off-the-shelf technologies, fully deployed, can get us there. In the opposite corner is the Department of Energy, which in December concluded that we need breakthroughs in physics and chemistry that are "beyond our present reach" to, for instance, triple the efficiency of solar panels; DOE secretary Steven Chu has said we need Nobel caliber breakthroughs.

That is also the view of energy chemist Nate Lewis of the California Institute of Technology. "It's not true that all the technologies are available and we just need the political will to deploy them," he says. "My concern, and that of most scientists working on energy, is that we are not anywhere close to where we need to be. We are too focused on cutting emissions 20 percent by 2020—but you can always shave 20 percent off" through, say, efficiency and conservation. By focusing on easy, near-term cuts, we may miss the boat on what's needed by 2050, when CO2 emissions will have to be 80 percent below today's to keep atmospheric levels no higher than 450 parts per million. (We're now at 386 ppm, compared with 280 before the Industrial Revolution.) That's 80 percent less emissions from much greater use of energy.

Lewis's numbers show the enormous challenge we face. The world used 14 trillion watts (14 terawatts) of power in 2006. Assuming minimal population growth (to 9 billion people), slow economic growth (1.6 percent a year, practically recession level) and—this is key—unprecedented energy efficiency (improvements of 500 percent relative to current U.S. levels, worldwide), it will use 28 terawatts in 2050. (In a business-as-usual scenario, we would need 45 terawatts.) Simple physics shows that in order to keep CO2 to 450 ppm, 26.5 of those terawatts must be zero-carbon. That's a lot of solar, wind, hydro, biofuels and nuclear, especially since renewables kicked in a measly 0.2 terawatts in 2006 and nuclear provided 0.9 terawatts. Are you a fan of nuclear? To get 10 terawatts, less than half of what we'll need in 2050, Lewis calculates, we'd have to build 10,000 reactors, or one every other day starting now. Do you like wind? If you use every single breeze that blows on land, you'll get 10 or 15 terawatts. Since it's impossible to capture all the wind, a more realistic number is 3 terawatts, or 1 million state-of-the art turbines, and even that requires storing the energy—something we don't know how to do—for when the wind doesn't blow. Solar? To get 10 terawatts by 2050, Lewis calculates, we'd need to cover 1 million roofs with panels every day from now until then. "It would take an army," he says. Obama promised green jobs, but still.

Hence the need for Nobel-caliber discoveries. Lewis's research is on artificial photosynthesis, in which a material (to be determined, thus the research) absorbs sunlight and water and produces hydrogen for fuel but zero CO2. "If we could figure out how to make and deploy such a system, the capacity would be essentially infinite," he says. Another need is for transmission lines that don't leak 80 percent of what they carry, says physicist David Pines of the University of California, Davis. "The technology is not remotely there," he says. "We're going to have to discover yet another family of superconductors [which do not lose current] that are easily made into wires" and that work at the temperature of liquid nitrogen, a coolant.

Prospects stink for discovering what we need to discover, especially when you consider that to get the right energy mix in 2050, given how long it takes to capitalize and deploy new technologies, we need breakthroughs soon, not in 2049. Yet despite the pressing need, DOE spent a pitiful $2 billion to $3 billion on nondefense, basic energy R&D last year, less than one fifth what we spent in the 1970s and 1980s. A new report from the Brookings Institution calls for $20 billion to $30 billion a year and—to improve the odds of success—revamping the nation's energy labs, which today are "too far removed from the marketplace to produce the kind of transformational research we need for new energy technologies," says Brookings's Mark Muro. The clock is ticking.

© 2009