From Colorado’s high desert to the wooded hills of Pennsylvania, millions of oil and gas wells sit deserted, plunging thousands of feet into the earth. Many haven’t been plugged, some leak greenhouse gases.
In Colorado, lawmakers are considering a solution that would give these wells a new, redemptive purpose: deep receptacles to trap carbon for millennia.
The idea is to keep carbon locked away in a special type of charcoal known as biochar, which is made by burning organic matter at high heat and low oxygen. The substance could be used to fill defunct oil and gas wells. Proponents say biochar would not only filter dangerous gas leaks but also stop that carbon from forming carbon dioxide, a greenhouse gas.
Colorado lawmakers gave initial approval on 16 February for a study to assess whether biochar would work to plug defunct wells.
If successful, experts say that sinking biochar into a portion of the over 3 million abandoned oil wells nationwide could help tackle climate change—estimates range from keeping millions to billions of tons of carbon dioxide out of the atmosphere.
Still, the idea is relatively new and a number of feasibility questions remain. The study would direct Colorado State University to review research and run new tests to determine, in part, the efficacy of biochar in filtering gases and sequestering carbon as well as the technical feasibility of using it to plug oil and gas wells.
Carbon naturally cycles through Earth’s ecosystems, floating in the atmosphere as carbon dioxide before being snatched up by little bluestem grasses, ingested by grazing bison on the prairie, and when the animal keels over and begins decomposing, returning to the atmosphere as carbon dioxide.
But extracting fossil fuels has unearthed carbon—formed out of ancient plant matter over eons—that’s been stored underground largely since the Mesozoic Era, the age of dinosaurs over 65 million years ago.
“Where we need to focus is: How do we not only stop putting excess carbon into the cycle but can we take measures to take carbon out of the cycle permanently?” said Rep. Karen McCormick, a Democrat and one of the bill’s sponsors. “That’s where I see biochar having a great benefit.”