Retrofit Solutions to Electric Power Sector Decarbonization in the American Midwest

Abstract

Electric power system decarbonization requires phasing out existing, carbon-emitting power plants and replacing them with new, clean generation and transmission capacity. This transition presents simultaneous challenges in investment and operational costs and system reliability. In hopes of saving costs, ensuring reliability, and preserving the power plant workforce, interest has risen among states and utilities in the potential of power plant retrofits. By reusing existing equipment and infrastructure in aging coal and natural gas power plants, utilities can save costs on new greenfield developments. Several developing technologies well-equipped to reuse all or part of the facilities at these thermal power plants include firm, low-carbon power plants and long-duration storage facilities. These technologies help balance load in a high renewables grid while employing much of the same power plant workforce. A study of retrofit options is particularly important for the American Midwest where coal makes up a large portion of the resource mix and where the potential for intermittent wind deployment is high. This thesis enables retrofit modeling in a multi-stage capacity expansion framework and uses it to evaluate the potential for retrofits to lower system costs and cumulative emissions over three modeled carbon reduction pathways from 2020 to 2040 in the Midwest and surrounding areas. Although resulting reductions in cost and emissions are modest, we observe notable system-level reductions in curtailment of renewable generation, transmission expansion, and new natural gas deployment as well as distributional impacts relating to the costs of transitioning to a low-carbon electric power system.