System integration costs and emission savings of high penetration of intermittent renewable electricity

•System integration cost of spinning reserves, transmission and storage are studied.•Costs increase as the penetration of wind and solar generation increases.•The economic benefits of emissions savings are studied.•Economic benefits increase as wind and solar generation increases.•Economic benefits do not justify system integration cost increases. Integrating intermittent wind and solar generation into the grid has system integration costs of spinning reserves, increased transmission, and storage. As the penetration of wind and solar generation increase, system integration costs need to be considered, but there are also emissions savings. A TIMES model for the Midcontinent Independent System Operator footprint using publicly available data was used to examine system integration costs and emissions savings benefits of high penetration of intermittent renewable electricity. TIMES is a bottom-up optimization model that minimizes the total system cost. The number of time slices was increased to capture wind and solar generation dynamics, to better understand spinning reserves costs, and to allow battery storage. Using candidate sites for solar and wind generation, transmission, investment and production costs were added. Total system costs increased as there were higher transmission and spinning reserve costs. The emissions savings of Carbon Dioxide equivalent, Sulphur Dioxide, and Particulate Matter were converted to economic benefits using the Social Costs of Emissions. As the penetration of wind and solar generation increases, emissions savings and economic benefits increase. The system integration costs are greater than the benefits of emissions savings. The economic benefits do not justify the system integration cost increases.