Abstract: This paper presents EleMod, an annual recursive-dynamic regional electric power capacity expansion and hourly operation model, which has been formulated to assess the evolution over time of the energy mix of a power system, in terms of capacity and generation, with increasing penetration of intermittent generation such as wind or solar photovoltaic.

The model includes interregional transmission. It also includes low carbon technologies such as utility-scale storage, carbon capture and sequestration for fossil-based plants, and nuclear technologies. By ether minimizing the total cost of producing electricity or maximizing the total system welfare, the model is designed to calculate marginal prices for the wholesale supply of energy in the short-term, and also the prices for the provision of guaranteeing of supply and operating reserves. The EleMod model considers the hourly variability of intermittent resources (wind and solar) and hydro resources, and also an hourly variability of regional electricity demand as well.

This simulation tool can be used to understand the long-term adaptation of a power system to the penetration of intermittent generation and to the evolving climate and energy policies in the U.S. It also can be used to assess the short-term operational decisions of the system in response to the long-term planning. The model can also serve to estimate CO₂ prices and regional hourly marginal prices, and more general generation and emissions pathways under various costs and policy scenarios.