Electricity and Heat Production
The generation of electricity for commercial and industrial use, directly coupled with heat production, is an economic sector that releases global emissions of GHG and other volatile gases into the environment. At its source is the burning of coal, natural gas and oil to generate electricity and heat. The United States EPA estimates its contribution at 25% of all global GHG emissions, the largest single contributor. The most prominent GHG due to energy production is CO2, combined with smaller amounts of CH4, N2O and a fraction of sulfur hexafluoride (SF6) also emitted during the burning process. The Inventory of US Greenhouse Gas Emissions and Sinks (1990-2014) shows an increase in CO2 emissions from electricity production between 1990 and 2007 from 1900 million metric tons to just below 2500 million metric tons, specifically in the United States. Since 2007 and up to the availability of data given in 2014, there has been a decline in CO2 GHG emissions from its peak in 2007, to just above 2000 million metric tons. A similar trend is evident in Europe, where the Eurostat database in March 2016 showed that the 28 European Union (EU) member states (EU-28) exhibited a decline of 11.8% of CO2 emitted between 2008 and 2013. GHG emissions from the supply of electricity, gas, steam and air conditioning also declined by approximately 12.6% over the same period. Although the total GHG emissions globally are still high, these statistics show a significant improvement in leading nations. Several developments, including urban planning, are responsible for the decrease in carbon emissions. The most substantial contribution is from the manufacturing sector, with a 20.1% reduction in GHG emissions. Electricity and heat generation demands determine the production and emissions profile of fossil-fuel burning.