A recent study from Iowa State University, led by mechanical engineering professor Mark Mba-Wright, presents a dual-purpose solution for two pressing environmental issues: agricultural waste and abandoned fossil fuel wells. The research explores the use of bio-oil, derived from plant-based materials like corn stalks and forest debris, as a substance to seal and permanently store carbon in deep, vacant oil and gas well shafts. This innovative approach offers a method to return carbon underground in a stable form, while simultaneously addressing the significant emissions and safety risks posed by hundreds of thousands of orphaned U.S. wells.

The core of the proposed system is fast pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, a process that converts dried biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More into liquid bio-oil using high heat in an oxygen-free environment. According to the study, a network of 200 mobile bio-oil production facilities would be both technically and economically feasible. The research estimates this system could sequester carbon for approximately $152 per ton, making it a competitive option for carbon removal that requires far less initial investment than other technologies.

The study also calculated that each production unit would cost around $1.3 million to build, with the resulting bio-oil needing to sell for at least $175 per ton to be economically viable. The abatement costs can fall even lower, with wood-based feedstocks costing around $100 per ton of carbon removal. The team that modelled the mobile units, estimated that the machines could process 10 tonnes per day, producing 2.5 tonnes of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More and 5.3 tons of bio-oil. However, it is unspecified whether this is estimated at optimal efficiency.

This method also offers a compelling alternative to traditional well-capping, which can cost about $1 million per well. The 2021 bipartisan infrastructure law allocated $4.7 billion to plug around 120,000 abandoned wells, but estimates suggest there could be as many as 300,000 to 800,000 undocumented orphaned wells nationwide. Companies like Charm Industrial, a San Francisco-based startup that helped fund the study, are already using this approach for carbon-removal projects. This technology provides a new market for agricultural residues while contributing to long-term carbon sequestration and addressing a major environmental liability.

SOURCE: Bio-oil made with corn stalks, wood debris could plug orphaned fossil fuel wells