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.
A New Meaning to "Green Roof"
Carbon can be trapped in our roofs as well using another mineral trick that nature has got up its sleeve—namely, olivine.
This literally green mineral, pictured above in its gem form, peridot, is one of the most abundant rocks in Earth’s mantle. It weathers quickly when it is exposed to CO2 in the air, sponging up the offending gas and converting the mixture into silicon dioxide and magnesite, which renders the greenhouse gas chemically inert.
The multinational company Derbigum has devised a roofing system that, when hit by rain, binds with CO2. Olivine in a roof can capture 1.25 times its weight in CO2 during the course of its lifetime. And when the olivine roofing membrane has done its job (it takes about 30 years for the mineral to stop reacting with CO2) then you can roll out a new roof and start all over again.
Separately, the same olivine that captures CO2 in roofs can be used to pave pathways and roads or be added to sandboxes and beaches. It is already being marketed as a soil amendment by the Dutch Company greenSand, which sells it to home gardeners who want to revitalize their soil and raise its pH Level to grow healthier carbon-sequestering trees and flowers.
But the company has even bigger agricultural ambitions. “If this catches on,” says greenSand spokesman Bas Zeën, “large areas of farmland will be turned into CO2 cleaners.”