Underground Thermal Energy Storage of Corn Stover Combustion Heat for Grain Drying and Home Heating

Climate change and the ongoing dependence on fossil fuels present major challenges for global agriculture, with fossil fuel use in the agrifood sector accounting for a substantial and growing share of greenhouse gas (GHG) emissions. Agrifood systems currently contribute approximately one-third of total anthropogenic GHG emissions. Integrating renewable energy solutions for heating and power can help offset a significant fraction of these emissions. In this study, an analytical heat transfer and thermodynamic model is developed to evaluate the performance, energy balance, and thermal losses of the proposed system under realistic operating conditions. The model enables quantitative assessment of heat storage efficiency and long-term thermal retention. Using a representative 800 ha Iowa corn farm as a case study, the analysis shows that combustion of sustainably harvested corn stover (30% removal rate) can provide approximately 9.60 TJ of useful seasonal heat with a plausible range of 6.2 to 18.5 TJ depending on yield, moisture content, and conversion parameters. Thermal analysis of an underground hot water storage for agricultural applications shows that over a storage period of 200 days, the temperature reduction of the stored hot water can be less than 10%. Since the analytical model conservatively neglects container liner and concrete resistances, the actual thermal retention in an engineered system would likely be equal to or better than this estimate. This level of performance is sufficient to meet the seasonal grain-drying and building heating demands on a large Iowa corn farm in a year.