Final answer:
The largest percentage of coal usage in the United States is for electricity production, with 91% of coal consumed for this purpose. Coal-fired power plants have an efficiency of about 42%, meaning that a substantial amount of energy is lost as heat, which in turn contributes to global warming.
Step-by-step explanation:
When considering energy use in the United States that requires the largest percentage of coal, the answer is overwhelmingly the generation of electricity. Currently, coal accounts for 13% of the total energy consumption in the U.S., which has decreased from 23% in 2000. Globally, coal still comprises 25% of primary energy use.
However, it is important to note that of the coal consumed in the U.S., a vast 91% is allocated specifically to electricity production, with the remaining used for industrial processes requiring intense heat. For example, coal is not commonly used for transportation as gasoline is, because gasoline is easier to transport and is the preferred choice for this application.
Coal is a vital source of energy in the U.S., as it has been a reliable fuel for electricity production for many years. Coal-fired power plants are known to have a lower efficiency compared to plants fueled by natural gas or oil, with a large-scale conventional power plant coal efficiency gestimated to be around 42%. This indicates that a significant portion of the energy produced by coal, approximately 59.2%, is lost as waste heat to the environment which contributes to global warming.
The quality of coal used can vary, with anthracite being the most energy-dense but now largely depleted. As coal is combusted in power plants to generate electricity, a considerable amount of CO₂ is released, making coal a less environmentally friendly option compared to other fossil fuels.