India's coal-fired generating capacity doubled between 1990 and 2010 and currently accounts for 70 percent of electricity produced. Despite this, thermal efficiency at state-owned coal-fired power plants in India is significantly lower than at plants in the United States. When matched on age and capacity, heat input per kWh was 8 percent higher at Indian plants between 1997 and 2009. This can only partly be explained by the lower heat content of Indian coal.