Biochar has long been hailed in the environmental community as a potent solution for mitigating certain aspects of climate change, from fixing soil erosion to upping water absorption and pulling carbon out of the atmosphere. Now, there is a growing list of industries that might improve their environmental impact from adding it to their processes.

It’s a technique that indigenous Amazonians have been using to fertilize soils for thousands of years, creating “Terra preta” or “black soil” to boost production in otherwise infertile ground. Unbeknownst to those ancient farmers, this practice has a lasting impact on the soil. Thanks to biochar’s uniquely porous and absorbent qualities, “terra preta” soils are worth five times as much as others, even today.

What is biochar? 

Biochar is an ancient process that uses agricultural waste and burns it at high temperatures with low oxygen — a process known as pyrolysis that creates a fine-grained highly porous charcoal.  It enhances soil like a powerful fertilizer, and its remarkably stable structure makes it a tremendous carbon sink that can lock up carbon for thousands of years.

As a soil additive, some studies have shown that by adding biochar to the soil on agricultural land, atmospheric carbon might be reduced by 12% annually. However, the process has not yet been adopted at scale due to a relatively high cost and low profit margins in farming.

As reported in the Daily Beast, Kathleen Draper, the board chair of the International Biochar Initiative explains, “In the beginning of an industry, the price point is usually quite expensive, and expecting farmers to be the ones to adopt an expensive product was maybe the wrong first step. We need to find markets that can afford biochar.”

Where can biochar make a difference? 

While the biochar industry is still very young, and too costly for large scale agriculture, there are some industries where biochar might make all the difference in terms of mitigation and adaptation to climate change:

• Organic Waste Management

Biochar is made by burning things like wood, husks, stalks, and other agricultural by-products. One issue related to extreme wildfires is the abundance of dead trees and other materials due to drought, pests, and other climate change effects. Harvesting the dead trees to feed the growing biochar industry would be a win-win. There’s also abundant leftover material from agriculture that often gets burned on site which could instead become biochar feedstock!

• Dairy Farming

In addition to milk, dairy cows also create massive amounts of manure. The slurry ponds that contain this waste are hotbeds of methane-producing bacteria, adding to our global warming problems. When researchers at the University of California, Merced added biochar to composted manure, they found that it reduced the methane emissions by up to 80 percent.

• Stormwater filtration

Cities are bastions of pavement and concrete, and in heavy rainfalls flood drainage systems that may or may not be able to handle it. Even the green areas that line highways are usually hard packed and contain mostly dead soils, making them the equivalent of concrete in terms of water absorption. Like rain gardens that help filter pollution from runoff in urban areas, adding biochar to urban green spaces, even these “dead” zones, transforms the dirt into living soil that also helps filter stormwater through the porous carbon in the biochar.

• Building materials

Biochar can displace sand and other additions that go into making concrete, asphalt, and other composite materials, offsetting some of the concrete’s large carbon footprint. There is also a movement to replace the gypsum that’s used in drywall with biochar. This is in an effort to cut down on gypsum’s mining, or the need to source it from coal stacks, especially as we move away from burning coal.

• Remediating abandoned oil fields

We’ve written about the problem of abandoned oil wells quite a bit on The Optimist Daily.  Well, adding biochar to the areas around the wells can help offset the carbon emitted when that oil was burned. It also helps to absorb the continued emission of methane after the well has run dry by adding a layer of biochar on top of the well and underneath concrete that’s used to cap it off. This might be a great use for biochar created from contaminated feedstocks like agricultural waste that’s laced with pesticides or sludge from wastewater treatment that contain heavy metals.