The most advanced green buildings don’t just consume fewer resources. Some are made from materials that are taken quite literally out of thin air—forged from carbon dioxide and methane that would otherwise pollute the atmosphere. Everything from walls and furniture to the roofs above our heads can be made from greenhouse gases.
Removing atmospheric CO2 and putting it into something useful or storing it somewhere safely is called carbon sequestration. Carbon can be sequestered by scrubbing CO2 out of the exhaust stream in power plant smokestacks and pumping it deep underground, although this process still remains largely untested and prohibitively expensive. Another promising new technology transforms greenhouse gases into the fuel methanol.
There are even artificial “trees” developed by researchers at Columbia University which use sodium carbonate-impregnated “leaves” to capture carbon in a chemical reaction, producing sodium bicarbonate, also known as baking soda. The baking soda can later be heated to release pure, sequestration-ready CO2. But the problem with these ambitious new technologies is that few consumers have been willing to pay for them.
Trapping carbon in building materials, on the other hand, is a lot cheaper. The products that do this are generally cost-competitive with less sustainable options, and we don’t have to wait for big corporations or governments to act. We can choose to use these green alternatives in our own homes.
Granted, these materials are unlikely to make a big dent in our current climate crisis unless we combine their use with wasting a lot less energy. In 2014, the average U.S. residential utility customer consumed 10,932 kilowatt-hours of electricity, resulting in the emission of over seven tons of carbon into the atmosphere.
We already know some good ways to clean up our act. Insulating better and purchasing the latest energy-efficient appliances are two places to start lowering the carbon footprint of our homes. But to fully earn the Green Housekeeping Seal of Approval, you’ll also need to get smarter about what your house is made of. Fortunately, there is a growing number of cleaner and greener options to choose from.
Follow the Green Brick Road
You may soon be able to slather low-carbon cement onto bricks composed of power plant exhaust. The University of Newcastle in Australia has partnered with the chemical and mining giant Orica and the carbon innovation company GreenMag Group to pioneer a process called mineral carbonation, which turns CO2 from a gas to a solid.
“One of our aims is to use this material in products like brick, pavers and even plasterboard,” says Orica’s senior scientist Geoff Brent.
A metamorphic rock called serpentine is heated to release water and react with compressed CO2 from power plant exhaust to form magnesium carbonate—a powdery substance similar to baking soda—and silica sand, which in turn is molded into assorted building materials.
This carbonation process mimics natural geology, which creates carbonates through the slow weathering of minerals. Geologists believe that over millions of years this process reduced the excessive CO2 in the prehistoric atmosphere to levels that enable life to thrive today.
The world’s first pilot mineral carbonation plant will be opened on the grounds of the University of Newcastle in March. If this venture is successful, Orica hopes eventually to scale up to commercial production.