When the Weatherbird II cruised up the Potomac River and into the nation's capitol in March of last year, spirits were high. The freshly painted 115-foot research vessel was about to set sail for what would be the world's first for-profit effort to "fertilize" the ocean with iron, growing a vast forest of marine plant life that would pull the greenhouse gas carbon dioxide from the atmosphere. The lap through Washington was an effort to drum up support for the voyage to the iron-deficient waters west of the Galápagos Islands.

Sky Serpent
Cost to Develop: $250,000
Time: 9 years
Prototype | | | | | Product
Today’s largest wind farms are the size of small towns, made up of turbines 30 stories tall with blades the size of 747 wings. Those behemoths produce a great deal of power, but manufacturing, transporting, and installing them is both expensive and difficult, and back orders are common as the industry grows by more than 40 percent a year. The solution, says inventor Doug Selsam, is to think smaller: Capture more power with less material by putting 2, 10, someday dozens of smaller rotors on the same shaft linked to the same generator.

From a birds-eye view, the domes of the California Academy of Sciences, set to open in the fall, bulge out of the ground like giant scoops of green ice cream. These undulating hills built into the museums 2.5-acre, flora-covered roof integrate the building into the green space of surrounding Golden Gate Park. They also conserve energy, since the roof insulates and ventilates the 400,000-square-foot museum below.

By this spring, drivers in the U.K. will encounter an unfamiliar, and unprecedented, option at the pump: gasoline blended with a corn-based alcohol called butanol. It's part of a pilot project run by energy company BP, which aims to gauge public reaction to the new fuel. Butanol is easier to store and transport than existing biofuels and has an energy content more comparable to that of gasoline. Now, with more efficient ways to make it on the horizon, an increasing number of experts think butanol is poised to overtake ethanol as the best-selling alternative fuel on the market.