Sep 24, 2007 12:00 PM

4 Technologies on the Brink

| Wind Energy |

Wind Energy Storage wanted

Amajor energy source, wind blows. That's because it doesn't blow all the time, and the electricity produced during blustery periods can't be easily stored. But a possible solution is in the offing: electrochemical double-layer capacitors, or ultracapacitors. Capacitors consist of plate-shaped electrodes that store electricity by creating an electrical field between them. They're much better than batteries, because they don't degrade over time or discharge waste energy as heat. Plus, they're cheaper to make. But the amount of electricity an ultra capacitor can store is limited by the size of its electrodes — the greater the surface area, the more powerful the field. So researchers have been developing electrodes with a jagged nanomolecular texture, allowing them to boost surface area without increasing size. The goal: a box that can hold the power of the wind, whenever it blows. — d Roberts</em

<img Geothermal

thermal Watch for earthquakes

Geothal power has worked the same way for more than a century: Find an underground hot spring and build a generator on top of it. But now engineers are developing a way to create their own springs by injecting cold water into hot bedrock. The steam that billows back out can be used to drive turbines, heat buildings, and power factories. If successful, the approach could unleash 100 gigawatts of generating capacity by 2050 — with 50 times less pollution than power plants running on fossil fuels. And unlike oil or coal, hot bedrock can be found throughout the country, cutting energy-transmission costs. Scientists at MIT are working to adapt equipment and techniques from oil drilling to tap the rock, but two big hurdles remain: how to pump cold water down several thousand feet at 350 pounds per second, keeping it cool as it descends (to maximize efficiency); and, um, how to avoid causing earthquakes along the way. Oops! — PatrDi Justo</p

<src Solar Power Sola

ower Think Thin <p

identisolar has long been limited by the fact that it requires mounting expensive, 40-pound hunks of silicon and glass all over your roof. But flexible "thin-film" photo voltaics — 100 times skinnier than traditional crystalline silicon arrays — may change that. The new materials cost less to produce and are easier to install. Unfortunately, they're also less efficient, requiring up to twice as much space to produce the same amount of electricity. The most promising thin films absorb a much broader range of light than crystalline silicon, thus kicking out more electrons that could be channeled into usable power. But the electrons tend to get lost in the chaotic molecular structures of these new composites, so that potential power is hard to harvest. Still, even the largest solar players are becoming converts: Shell has abandoned its crystalline silicon division in favor of thin-film development. — D.R. <p

="ht Synfuel uel

Ethanol Killer Jay

sling'antra: "Ethanol is for drinking, not driving." Dismissing the current craze for the biofuel, he points out that it produces only 85 percent of the energy of gasoline, requires retrofitting car engines, and is incompatible with existing oil pipelines. That's why Keasling, a chemical engineer at UC Berkeley and Lawrence Berkeley National Laboratory in California, is trying to create a better alternative — his 50-person team is building microbes that can turn cellulosic biomass, not into ethanol but into a fuel molecularly similar to gasoline. The results, he says, will have higher energy content than ethanol and will be easier to extract and distribute. The approach is being explored by several other groups, including companies like Amyris Biotechnologies (which Keasling cofounded) and LS9 of nearby San Carlos; both have claimed success in the lab. The next challenge: producing the fuels in commercial-scale quantities. — E.R. and D.Rm> <em

Pengsathapon FEATU

f="http://uld Cure Our Addiction to Oil</a> <a href="ht/om Grass to Gas</a> <a href="ht/n: Switching to Renewables</a> <a href="ht/Cleans Up: A Wired Fhart<