This study demonstrates that nuclear energy must remain a leading source of electricity in the Northeastern United States for decades to come if efforts under the Regional Greenhouse Gas Initiative (RGGI) to reduce CO₂ emissions in the electricity sector are to prove successful without major upheaval for industry and consumers. Nuclear energy produces 31.6 percent of the Northeast’s electricity, making it the single-largest electricity source in the region. The prominence of nuclear power plants means that Northeastern states already enjoy some of the lowest carbon dioxide emission rates in the country.