Friday, November 13, 2009

Bricks Made From Waste Fly Ash

Amid buzz about algae biofuel and electric cars, some start-ups hope to use "green" technology to reinvent more mundane products like bricks and cement.

CalStar Products Inc. plans to open a factory next month to make bricks from fly ash, a byproduct of coal burning. It claims to use roughly 85% less energy than traditional clay brick manufacturing, with an equivalent reduction in carbon-dioxide emissions.

Cari Tuna for The Wall Street Journal

Workers at CalStar's Newark, Calif., facility press the fly ash into a test mold.

"Innovation is not necessarily discovering new things, but discovering how to use old things in a new way," says Amitabha Kumar, CalStar's director of research and development.

The process for making clay bricks—mining clay, forming it into bricks and firing in kilns using coal or natural gas—has remained largely unchanged for decades, though manufacturers have made improvements to reduce environmental impacts.

CalStar forms its bricks from fly ash—a gray, chalky byproduct of burning coal— and a proprietary stew of chemicals. During eight hours of steam baths, the calcium in the fly ash hardens, making bricks that look, feel and act like their clay counterparts, Mr. Kumar says.

CalStar says the bricks are designed to meet standards set by ASTM International, a standards-setting organization, for things like strength, durability and water absorption—and will be installed in buildings for the first time early next year. CalStar says the bricks will be priced competitively with commercial clay bricks. In Chicago, for instance, its bricks will sell for 53 cents apiece on average, compared with 55 cents on average per commercial clay brick, Calstar says.

Cari Tuna for The Wall Street Journal

CalStar makes bricks using fly ash, a byproduct of coal burning.

Executives at the Brick Industry Association argue that CalStar's fly-ash products aren't bricks by definition, and question whether they'll last as long as clay bricks. "No one knows how the fly-ash unit will really perform," says Dick Jennison, the trade group's president.

Richard Klingner, a civil engineering professor at the University of Texas at Austin who sits on the ASTM's panel for brick standards, says the ASTM's standards don't apply to fly-ash bricks. That doesn't mean they are unsuitable for buildings, he says, "it just means that there isn't a standard for them yet."

The Environmental Protection Agency says fly ash is not hazardous and has advocated its reuse in building materials, though an EPA spokeswoman says the agency is reconsidering the classification this year. Most fly ash is mixed into concrete or disposed of in landfills.

CalStar's Caledonia, Wis., factory will recycle fly ash from a neighboring Wisconsin EnergyCorp. coal plant, making 40 million bricks annually and shipping only to nearby cities, to minimize carbon-dioxide emissions.

Cement maker Calera aims to capture carbon-dioxide emissions before they are released into the atmosphere. The start-up, is backed by nearly $50 million from Khosla Ventures.

In Moss Landing, Calif., Calera will pipe exhaust fumes from Dynegy Inc.'s natural-gas-burning power plant to its pilot facility, set to open this year, where it will flush the gas through seawater or brackish water. That will produce chalky substances it can use to make cement.

Producing one ton of traditional cement releases roughly one ton of carbon dioxide, says Calera founder Brent Constantz. But making one ton of Calera cement captures half a ton of the greenhouse gas. And like CalStar's bricks, Calera's cement is less expensive to produce than traditional cement, he says.


Fly Ash bricks made by CalStar

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1 comment:

archaalto said...

cool! the color selection is pretty nice.