The largest contributor to building sector emissions (49% of total) is the production of electricity for use in buildings. To decarbonize the building sector, the production of electrical energy will need to reduce its dependence on fossil fuels such as coal and natural gas, and instead shift to carbon-free alternatives like solar, wind, and nuclear. Currently many countries are heavily dependent on fossil fuels for electricity generation. In 2018, 61% of US electricity generation was produced by fossil fuel power plants (23% by coal and 38% by natural gas).