Biochar for carbon-negative hydrogen production from fossil fuel reservoirs

Biochar is an abundant and inexpensive material derived from biomass, renowned for its exceptional physicochemical properties such as high surface area and superior dielectric parameter. In this perspective, we first propose and evaluate a carbon-negative approach that utilizes biochar for in-situ hydrogen (H₂) production from natural gas reservoirs through electromagnetic (EM) heating. By critically reviewing synthesized parameters, properties, and applications of biochar, it becomes clear that biochar can boost natural gas conversion to hydrogen when used as a catalyst. Additionally, the subsurface use of biochar improves EM-heating efficiency, enhances economic viability, aids in agricultural waste management, and captures substantial amounts of carbon underground. These advantages make biochar a perfect material for optimizing in-situ hydrogen production from gas reservoirs via EM heating. In this paper, we highlight the fundamentals, prospects, and knowledge gaps of this new technology. Key factors such as catalytic performance, engineering feasibility, economic viability, and industrial synergies are thoroughly evaluated. The challenges in biochar synthesis, hydrogen production efficiency, well safety, and downhole technologies are also discussed. By leveraging multidisciplinary industry resources, renewable energies, and public support, it is anticipated that the hydrogen cost of this approach could fall below $1/kg H₂, thus enabling a transformative, affordable, and carbon-negative hydrogen production from fossil fuel reservoirs.