Bio-oil from agricultural and forest waste could help seal abandoned oil wells and store carbon

Bio-oil from agricultural and forest waste could help seal abandoned oil wells and store carbon
by Clarence Oxford
Los Angeles CA (SPX) Sep 07, 2025

Filling abandoned oil and gas wells with bio-oil derived from corn stover, switchgrass, wood debris, and other organic byproducts may offer a cost-effective way to trap carbon dioxide underground. Researchers at Iowa State University, led by mechanical engineering professor Mark Mba-Wright, analyzed the economics and feasibility of this approach in a new study.

The technique relies on fast pyrolysis, which exposes dried biomass to intense heat in an oxygen-free chamber, producing carbon-rich liquid bio-oil, along with biochar and reusable gas. The oil can be injected into idle fossil fuel wells, locking in carbon that plants originally absorbed from the atmosphere.

Mba-Wright said, "On the one hand, you have these underutilized waste products. On the other hand, you have abandoned oil wells that need to be plugged. It's an abundant resource meeting an urgent demand."

The team found that a network of 200 mobile pyrolysis units, each processing about 10 tons of biomass daily, could sequester carbon at about $152 per ton - competitive with other carbon removal methods but requiring far lower upfront investment. Units would cost about $1.3 million to build, with projected bio-oil selling prices starting around $175 per ton.

The approach also leverages billions in federal funding for capping orphaned wells, which otherwise cost about $1 million each to seal. With more than 120,000 identified abandoned wells and potentially up to 800,000 undocumented sites, the opportunity is vast. Filling one oil well requires more than 216,000 gallons of liquid.

Biochar byproducts can be sold to farmers as soil enhancers, while bio-oil offers carbon storage benefits beyond potential energy uses. Cost estimates vary by feedstock, with wood-based materials projected at $100 per ton of carbon removal, dropping further when factoring in efficiency gains over time.

San Francisco-based startup Charm Industrial, which has piloted bio-oil sequestration, partially funded the study. "We hear it time and again: after taking a close look among their options, leading carbon-removal buyers find that bio-oil sequestration represents one of the highest-quality and most cost-effective approaches," said Peter Reinhardt, Charm's CEO.

The Iowa State team concluded that bio-oil sequestration compares favorably with direct air capture, the leading atmospheric carbon removal method, because it avoids high infrastructure costs while creating rural economic benefits. Mba-Wright emphasized, "What we're trying to show here is that carbon removal doesn't need to be either/or. There are a lot of opportunities."

Research Report:Enhancing carbon removal via scalable on-site pyrolysis and well-plugging systems