(226d) Nuclear Power-Driven Utilization of Coal As a Raw Material for Chemical Products, Including CO2 Byproduct Utilization

Coal is a globally abundant resource, but its utilization range is limited. More than 90% of the coal produced in the United States is utilized for electric power generation as a fuel through pulverized coal combustion and integrated gasification combined cycle plants. While some plants are fitted with carbon dioxide (CO₂) capture and storage, the sequestration of carbon has associated costs and environmental concerns. Alternatively, CO₂ can be combined with hydrogen to make many high-value chemical products such as formaldehyde, carboxylic acids, and fertilizers. Utilizing coal and CO₂ as carbon feedstocks beyond electric power generation can broaden coal industries while limiting carbon emissions. Besides being utilized as or reprocessed into fuels for power generation, coal can also be converted into chemical products. As most carbon will be captured and stored in the product material, this process has less concern of CO₂ emissions than that of coal for energy. This study presents the possibility of the utilizing high-quality coal as a carbon source to produce valuable chemical products via methanol pathways with aid of nuclear power. All heat, steam, and electricity power required to produce chemicals from coal can be supplied from carbon-free nuclear power instead of coal combustion. Multiple pathways for CO₂ utilization, including urea and formic acid, are considered to target and supply local agricultural markets.

The “carbon refinery” design converts coal to solid char and syngas using pyrolysis and hydrothermal gasification and incorporates methanol synthesis. The Rectisol process controls the amount of CO₂ and removes sulfur. Nuclear-driven hydrogen production from high-temperature steam electrolysis (HTSE) replenishes hydrogen to obtain the proper syngas composition for methanol production, avoiding the addition of a water-gas shift reactor. The design follows a “self-sustaining” approach to minimize waste streams and utilize coproducts throughout the refinery, such as converting char to an activated carbon product for flue gas mercury removal and using chilled methanol for CO₂ removal in the Rectisol process. Nuclear-driven hydrogen production from high-temperature steam electrolysis facilitates various chemical reactions within the refinery as well as CO₂ hydrogenation to produce carbon utilization products. This cost and material sharing approach can improve the economics of hydrogen production and de-carbonization compared to the traditional methods of producing these chemicals. This study will consider the integration of the carbon refinery with advanced light-water reactor (LWR) and high-temperature gas reactor (HTGR) technologies. Even with heat from a high-temperature gas reactor, nuclear-driven energy cannot reach the high temperatures obtained from coal combustion. We modeled chemical processes in Aspen Plus with consideration of the lower temperature heat source, with nuclear heat introduced at the highest temperature in the hydrothermal gasification process (up to 750°C) and recovered by the pyrolysis process (500°C) and coal drying (250°C).

This study investigates the technical feasibility of this process and through an performs economic evaluation using Aspen Plus and Aspen HYSYS along with Aspen Process Economic Analyzer and the Framework for the Optimization of ResourCes and Economics (FORCE). The refinery feedstock demands, product outputs, and equipment costs will be scaled based on the increase in coal input, but the chemical process operations are steady state. Optimization studies using FORCE will provide descriptive economics of the entire design, including the cost of the nuclear reactor. Figures of merit for these models include the total net present value of the refinery and the cost of carbon avoided compared to the incumbent production methods of each refinery product.

This project will provide an illustration of the technical and economic feasibility of nuclear-driven chemical production using coal as a feedstock with either CO₂ sequestration or CO₂ utilization. An analysis of will inform opportunities for CO₂ utilization at operating coal plants. The resulting economic estimates at both a product subsystem and refinery level will guide decisions for the optimal processing of coal to produce chemical products.