The effects of renewables portfolio standards on renewable energy generation

Renewable energy as a share of total electricity generated has been increasing in recent years. According to The Energy Information Administration (EIA), half the installed capacity for electricity generation in 2017 came from renewable energy. Thirty-eight states have enacted policies to encourage or require some of their generated electricity to come from renewable sources. Renewables Portfolio Standards (RPS) have varying requirements and objectives among the states, but the overall objective is to diversify the ways electricity is generated and reduce emissions of greenhouse gases. A state fixed-effects panel data model is used to estimate the effects of an RPS policy on renewable electricity generation. Results show that states which enacted mandatory RPS policies experienced an increase in the share of total renewable energy generation of about 1.08 percentage points. States which enacted voluntary policies experienced a larger increase in renewable energy generation relative to those with mandatory polices, about 1.9 percentage points. States implementing voluntary polices also see larger effects on the share of wind generation.