Green Biz

Capturing Warmth from Hot Asphalt

A Dutch civil engineering company says it is exploiting an abundant source of energy that has been beneath us for many years—or rather, beneath our car tires. It's the heat captured by asphalt baking under the hot sun. Ooms Avenhorn Holding's Road Energy Systems are networks of pipes woven into asphalt, plus storage systems beneath the ground. Water in the pipes is heated, stored, then pumped to nearby buildings. In winter, the same pipes can help keep ice off the roads, reducing the need for salt, Ooms contends. The company has already begun some experimental installations, including a Dutch industrial park that captures heat from pipes in a 36,000-square-foot swath of pavement.

—By Brian Burnsed. Edited by Adam Aston

Taking the Heat off Drywall

When it comes to spewing out carbon dioxide and other agents of global warming, some of the biggest offenders are mundane construction products like drywall. Serious Materials in Sunnyvale, Calif., says that manufacturing it accounts for 1% of all the energy used by U.S. industry, and thus a comparable percentage of all industrial emissions. The company will soon market a product called EcoRock that could drastically shrink drywall's carbon footprint.

In the traditional production process, gypsum and other raw materials are combined in watery slurry that must be rolled flat and dried, guzzling energy. Serious Materials' new recipe combines chemicals that, when mixed, react to create much of their own drying heat. The company was voted the top prospect at a recent green investment forum, and in November, it snared $50 million in venture capital. CEO Kevin Surace argues that industry must find a way to improve on traditional building products.

—By John Carey. Edited by Adam Aston

Of Frugal Drains and Hardy Nukes

When hot water from your shower, washer, or sink drains away, it takes with it nearly all the energy used to heat it. In North America alone, $40 billion worth of energy goes down the drain every year. A device called Power-Pipe, made by RenewAbility Energy, can reclaim much of that. It's essentially a heat exchanger that attaches to a home's drainpipes. The recovered warmth is transferred to incoming freshwater before it's sent to the water heater. RenewAbility, one of several companies developing the technology, claims Power-Pipe can cut water-heating costs by 25% to 40%.

Today, China, the U.S., and other countries are embarking on a binge to build a new generation of nuclear reactors. The trouble is, just one plant in the world (in Japan) can make the huge steel chambers in which the nuclear reaction takes place. But there is a substitute that could clear the bottleneck. Scientists at Clemson University are investigating whether steel could be replaced with the same light, superstrong carbon fibers found in everything from Boeing 787s to high-end bicycle frames. A carbon substitute should be easier to fabricate and lighter to transport, and it might last longer in the reactor's high temperatures. The steel alloys used today liquefy at 2,500F, well below the melting point of carbon-fiber composites.

—Edited by Adam Aston