Last Updated: October 14, 2014 In recent years, there have been changes in the mix of fuels used to generate electricity in the United States. Natural gas and renewable energy sources have increased their role in producing the U.S. electricity supply, while coal has generally declined. In its Annual Energy Outlook, the U.S. Energy Information Administration (EIA) projects the share of electricity generated from natural gas and nonhydro renewable energy sources, such as wind and solar, will grow through 2040, while the share of other fuels, such as coal and petroleum, will decline. The mix of fuels used to generate electricity in the United States has changed since 1990 Since 1990, the mix of fuels that are used to generate electricity in the United States has changed. For example, in 1990 coal-fired power plants accounted for about 42% of U.S. electricity generation capacity, but produced more than half of the total...

Last Updated: October 2, 2014 The United States leads all other countries in the amount of electricity generated by wind, a title it has held since 2008. U.S. wind power totaled nearly 168 million megawatthours during 2013, about three times more than the wind power generated in the United States in 2008. The top five global producers of electricity from wind also include China, Spain, Germany, and India. Why wind power has increased A major contributor to increasing U.S. wind power in recent years has been the federal production tax credit. This tax credit pays producers 2.3 cents for every kilowatthour of electricity they generate from wind during the first 10 years a turbine is in operation. The current version of the tax credit allows producers to earn the credit as long as they began construction of their wind power projects during 2013 and, in general, as long as the turbines...

Last Updated: September 30, 2014 The world oil market is complex. Governments as well as private companies play roles in moving oil from producers to consumers. Government-owned national oil companies (NOCs) control most of the world’s proved oil reserves (78% in 2012) and oil production (58% in 2012). International oil companies (IOCs), which are often stockholder-owned corporations, make up the balance of global oil reserves and production. Proved reserves are the amount of oil in a given area, known with reasonable certainty, that today's technology can recover cost-effectively. Worldwide proved oil reserves are about 1.6 trillion barrels and global oil production averages roughly 90 million barrels a day. There are different types of oil companies There are three types of companies that supply crude oil to the global market. Each type has different operational strategies and production-related goals: International oil companies (IOCs): Includes companies like ExxonMobil, BP, and Royal Dutch Shell....

Last Updated: September 16, 2014 The U.S. power grid is the electrical system that connects electricity producers and consumers by transmission and distribution lines and related facilities. It has evolved into three large interconnected systems that move electricity around the country. Mandatory reliability standards have been developed by the electric power industry and approved by the Federal Energy Regulatory Commission (FERC) to ensure coordinated electric system operations. FERC is an independent federal agency that regulates the interstate transmission of natural gas, oil, and electricity. The process of transporting electricity Getting electricity from power generating stations to our homes and workplaces is a challenging process. To ensure the stability of the entire power grid, electricity must be produced at the same time it is used as large quantities of electrical power cannot be stored effectively. High-voltage transmission lines, which are often seen hanging between tall metal towers along the highway, are used...

Last Updated: September 4, 2014 Over the past decade, the combination of horizontal drilling and hydraulic fracturing has provided access to large volumes of oil and natural gas that were previously uneconomic to produce from low permeability geological formations composed of shale, sandstone, and carbonate (e.g., limestone). Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles. Black shale contains organic material that can generate oil and natural gas, and that can also trap the generated oil and natural gas within its pores. Where are shale gas and oil resources found? Shale oil and natural gas resources are found in shale formations that contain significant accumulations of natural gas and/or oil. The Barnett Shale in Texas has been producing natural gas for more than a decade. Information gained from developing the Barnett Shale provided the initial technology template for developing other shale plays in...

Last Updated: August 7, 2014 Greenhouse gases trap heat from the sun and warm the planet's surface. Of all U.S. greenhouse gas emissions the majority are related to energy production and consumption; specifically most of those are carbon dioxide (CO2) from the burning of fossil fuels. From 1990 to 2013, energy-related carbon dioxide emissions in the United States increased on average by about 0.3% per year. Because greenhouse gases trap radiation (heat) from the sun and warm the planet's surface, a certain amount of these gases are beneficial (see "Did you know?"). But as concentrations of these gases increase as a result of human activity, more warming occurs than would happen naturally. What specific kinds of greenhouse gases does the United States emit? The major greenhouse gases the United States emits as a result of human activity and that are included in U.S. and international emissions estimates are: Carbon dioxide (CO2)...

Last Updated: June 2, 2014 The United States holds the world's largest estimated recoverable reserves of coal and is a net exporter of coal. In 2013, U.S. coal mines produced just under one billion short tons of coal, the lowest output level since 1993. More than 90% of this coal was used by U.S. power plants to generate electricity. While coal has been the largest source of electricity generation in the United States for over 60 years, its annual share of total net generation declined from nearly 50% in 2007 to 39% in 2013 as some power producers switched to more competitively priced natural gas. At the same time, new environmental regulations also made it more costly to operate some coal plants. Coal is an abundant U.S. resource The United States is home to the largest estimated recoverable reserves of coal in the world. In fact, we have enough estimated recoverable...

Last Updated: May 30, 2014 The major energy sources consumed in the United States are petroleum (oil), natural gas, coal, nuclear, and renewable energy. The major users are residential and commercial buildings, industry, transportation, and electric power generators. The pattern of fuel use varies widely by sector. For example, oil provides 92% of the energy used for transportation, but only about 1% of the energy used to generate electric power. Understanding the relationships between the different energy sources and their uses provides insights into many important energy issues. How can we compare different fuels? Primary energy includes petroleum, natural gas, coal, nuclear fuel, and renewable energy. Electricity is a secondary energy source that is generated from these primary forms of energy. Primary energy sources are commonly measured in different units: one barrel (equals 42 gallons) of oil, cubic feet of natural gas, tons of coal. To compare across fuels a common...

Last Updated: April 14, 2014 U.S. power plants used renewable energy sources, including water (hydroelectric), wind, biomass wood and waste, geothermal, and solar, to generate about 13% of electricity produced in the United States during 2013. Most renewable-generated electricity is from hydropower The largest share of electricity generated by renewable sources in 2013 came from hydroelectric power (52%), followed by wind (32%), biomass wood (8%), biomass waste (4%), geothermal (3%), and solar (2%). Electricity generation from renewable resources is primarily a function of generation capacity and the availability of the resource. The history of electricity generation has been different for each renewable energy source. Nearly all hydroelectric capacity was built before the mid-1970s, and much of it is at dams that are operated by federal agencies. Biomass waste is mostly municipal solid waste that is burned in waste-to-energy power plants. Most electricity generation from wood biomass occurs at lumber and paper...