POTENTIAL FACTORS INFLUENCING THE FEASIBILITY OF UNDERGROUND HYDROGEN STORAGE IN THE ILLINOIS BASIN

The interest in renewable energy has grown recently with technological advancements, financial incentives, and renewable energy policies. The transportation sector could move faster towards decarbonization by using hydrogen fuel cells instead of internal combustion engines that use fossil fuels to generate power. Hydrogen as an energy source also provides the opportunity for the energy sector to move towards large-scale grid decarbonization because some hydrogen technologies emit zero greenhouse gases to generate electricity, hence, could be referred to as “green hydrogen.” When coupled with other renewable energy sources such as wind and solar, hydrogen storage can serve as a battery analogue through power-to-gas technology, where surplus electricity from these renewable sources is converted into hydrogen via electrolysis.

Hydrogen has been successfully stored in solution-mined salt caverns in the United States since the 1980s, but the feasibility of storing hydrogen in siliciclastic formations (e.g., sandstones) is under assessment. Through modeling and batch reaction experiments, recent studies demonstrate that injecting hydrogen into a siliciclastic reservoir might trigger geochemical reactions and/or microbial activity that could lead to hydrogen consumption. Identifying the reactions that might consume hydrogen is critical to determining optimum storage conditions.

The Illinois Basin has been producing hydrocarbons for more than a century. Records show that formations within the basin have also been storing natural gas since the 1950s. The target formations range from Late Cambrian (e.g., Mt. Simon) to Carboniferous (e.g., Cypress) and have been proven to trap natural gas or carbon dioxide. Storing hydrogen underground can be more challenging than other gases due to the physicochemical properties of hydrogen. Therefore, before pumping hydrogen into a depleted reservoir or saline aquifer, it is important to determine optimum reservoir conditions to avoid commodity loss. Research is underway to determine the geochemical reactions that could trigger hydrogen degradation, and to determine the potential of indigenous microbial communities to convert hydrogen into other gases such as methane.