The prospective impacts of 2019 state energy policies on the U.S. electricity system

Over the past several years state energy policies have been evolving rapidly, and are more frequently including higher targets, including 100% clean energy targets. This study assesses the aggregate impacts of state clean energy standards and emissions policies on national electricity generation, power sector carbon dioxide (CO2) emissions, and electricity prices and system costs. To do so, we apply the Regional Energy Deployment System (ReEDS) model, which is a detailed electric sector capacity expansion model, to evaluate scenarios with and without state policies and using a range of renewable energy technology cost projections. Across the scenarios analyzed, we find that the state policies drive 1.9%–10.7% of total nationwide clean energy and reduce cumulative power sector CO2 emissions by 2.6%–5.4% over the 2020–2050 study period. This incremental generation is predominantly, but not exclusively, from renewable energy technologies. In most cases, the state policies result in increases to electricity prices and electricity system costs, and policy costs are sensitive to the future cost of clean energy technologies. Across all scenarios, the levelized cost of incremental policy-driven clean energy generation is estimated to be $17–38/MWh and the average cost of CO2 abatement from the state-level policies is estimated to be $29–74/metric ton. •State energy policies increase clean energy generation during 2020–2050 by 1.8%–10.7%.•State policy-driven demand for clean energy is supplied primarily by renewable energy technologies.•The levelized costs of incremental clean energy generation is estimated to be $17–38/MWh.•The average cost of CO2 abatement from the state-level policies is estimated to range from $29/MT to $74/MT.•The additionality of state policies is highly sensitive to future technology costs.