Actually, We CAN Put It Back in the Ground

One of the most demoralizing things about climate change is that it’s generally a one-way process: it’s easy for us to put more greenhouse gases into the atmosphere, but not so much for us to take them back out–at least, that’s what I thought until recently.

True, there has been some research into carbon sequestration (putting carbon dioxide directly into underground spaces or at the bottom of the sea), but these processes aren’t very far advanced or very affordable, and some of the plan for them is just to capture CO2 being produced by fossil fuel plants and sequester that. The fossil fuel industry likes to hold this very theoretical idea out as though it’s an available technology, so as to get a free pass to burn more fossil fuels.

But I mentioned that there was some hope, and there is: biochar.

What is biochar? It’s basically charcoal, an extremely carbon-rich material made at high temperatures, from 200 to 700 degrees Fahrenheit, which consumes pretty much everything in the fuel except the carbon. Biochar can be made from practically any burnable material–wood, seed pods, husks, brush, paper, manure, etc.–even trash.

biochar pellets

What’s so great about that? A few things, actually! First, using the right process to make it, biochar produces energy without producing much in the way of greenhouse gas emissions. Second, the process that makes biochar can alternatively make liquid fuels from renewable sources. Third, and most intriguingly, biochar is very stable: you can bury it in the ground, and the carbon won’t go anywhere for hundreds to thousands of years. Fourth, when you do bury it in the ground, it increases the fertility of the soil by making necessary chemicals more available to plants and by helping retain and regulate water in the soil. Fifth, the process is simple enough that it can be used for everything from massive plants to cookstoves.

So the cycle can go something like this: plants grow, absorbing and using carbon from the atmosphere. The plants are harvested, and some or all of the resulting plant matter is made into biochar, producing up to about six times as much energy as it consumes in the process. The biochar is then buried in the ground, accelerating plant growth. Even without this acceleration, the new plants that grow where the old ones were harvested absorb more carbon from the atmosphere, and the process continues.

If we’re willing to commission a lot of large biochar plants and to make biochar a standard part of preparing agricultural lands–including reclaiming currently unproductive lands, such as former farmland that is tapped out or turning to desert–then we can actually pull a huge amount of the carbon dioxide we’ve generated over the past couple of centuries back out of the atmosphere, and reverse the process we’ve been causing that is currently wrecking our climate with no relief in sight.

Photo by Lou Gold