Final answer:
Coal and natural gas are the primary sources of electricity generation in the U.S., with coal being a larger contributor to global warming due to its higher CO2 emissions. Solar power and nuclear power are alternative sources that diversify the electricity generation mix. Coal also plays a role in metal refining, beyond just power generation.
Step-by-step explanation:
Coal and natural gas are primary sources of electricity generation in the United States, contributing 44% and 23% respectively. Coal, with its origins in powering early 20th-century steam engines due to its abundance and high energy density, is known for its higher carbon dioxide emissions compared to natural gas, making it a larger contributor to global warming. Natural gas became a significant component post-World War II and expanded rapidly after 1990. Despite this, the demand for electricity constitutes only 38% of energy usage in the U.S., indicating that other energy demands, such as transportation and industrial processing, rely less on electricity and more on direct fuel use. Solar power is an alternative source, converting sunlight into electricity through solar cells, which is then used for the same applications as coal-generated electricity.Nuclear power is another significant source of electricity, accounting for 19% of electricity production and utilizing the heat from nuclear reactions to generate steam that turns turbines to create electricity. Renewable energy sources contribute the remaining 13% of the electricity mix, signaling a diversification of energy sources beyond fossil fuels.Lastly, coal's role extends beyond electricity generation; it is also a reducing agent in metal refining, emphasizing its broader impact on industrial processes.