Sources of Greenhouse Gas Emissions
Industry Sector Emissions
Total U.S. Greenhouse Gas Emissions by Economic Sector in 2013
The Industry sector produces the goods and raw materials we use every day. The greenhouse gases emitted during industrial production are split into two categories: direct emissions that are produced at the facility, and indirect emissions that occur off site, but are associated with the facility's use of energy.
Direct emissions are produced by burning fuel for power or heat, through chemical reactions, and from leaks from industrial processes or equipment. Most direct emissions come from the consumption of fossil fuels for energy. A smaller amount, roughly a third, come from leaks from natural gas and petroleum systems, the use of fuels in production (e.g., petroleum products used to make plastics), and chemical reactions during the production of chemicals, iron and steel, and cement.
Indirect emissions are produced by burning fossil fuel at a power plant to make electricity, which is then used by an industrial facility to power industrial buildings and machinery.
More information about facility-level emissions from large industrial sources is available through EPA's Greenhouse Gas Reporting Program's data publication tool. National-level information about emissions from industry as a whole can be found in the sections on Fossil Fuel Combustion and the Industrial Processes chapter in the Inventory of U.S. Greenhouse Gas Emissions and Sinks.
Emissions and Trends
In 2013, direct industrial greenhouse gas emissions accounted for approximately 21% of total U.S. greenhouse gas emissions, making it the third largest contributor to U.S. greenhouse gas emissions, after the Electricity and Transportation sectors. If both direct and indirect emissions associated with electricity use are included, industry's share of total U.S. greenhouse gas emissions in 2013 was 29%, making it the largest contributor of greenhouse gases of any sector. Greenhouse gas emissions from industry have declined by almost 12% since 1990, while emissions from most other sectors have increased.
To learn about projected greenhouse gas emissions to 2020, visit the U.S. Climate Action Report 2014 (PDF) (310 pp., 23.1 MB).
Greenhouse Gas Emissions from Industry
Reducing Emissions from Industry
There are a wide variety of industrial activities that cause GHG emissions, and many opportunities to reduce them. The table shown below provides some examples of opportunities for industry to reduce emissions. For a more comprehensive list, see Chapter 7 of the Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.
|Type||How Emissions are Reduced||Examples|
|Energy Efficiency||Upgrading to more efficient industrial technology.
EPA's ENERGY STAR® program helps industries become more energy efficient.
|Identifying the ways that manufacturers can use less energy to light and heat factories or to run equipment.|
|Fuel Switching||Switching to fuels that result in less CO2 emissions but the same amount of energy, when combusted.||Using natural gas instead of coal to run machinery.|
|Recycling||Producing industrial products from materials that are recycled or renewable, rather than producing new products from raw materials.||Using scrap steel and scrap aluminum as opposed to smelting new aluminum or forging new steel.|
|Training and Awareness||Making companies and workers aware of the steps to reduce or prevent emissions leaks from equipment.||Instituting handling policies and procedures for perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF6) that reduce occurrences accidental releases and leaks from containers and equipment.
EPA has a variety of voluntary programs that provide resources for training and other steps for reducing greenhouse gas emissions:
6,822 million metric tons of CO2 equivalent--what does that mean?
An Explanation of Units
A million metric tons is equal to about 2.2 billion pounds, or 1 trillion grams. For comparison, a small car is likely to weigh a little more than 1 metric ton. Thus, a million metric tons is roughly the same mass as 1 million small cars!
The U.S. Inventory uses metric units for consistency and comparability with other countries. For reference, a metric ton is a little bit larger (about 10%) than a U.S. "short" ton.
GHG emissions are often measured in carbon dioxide (CO2) equivalent. To convert emissions of a gas into CO2 equivalent, its emissions are multiplied by the gas's Global Warming Potential (GWP). The GWP takes into account the fact that many gases are more effective at warming Earth than CO2, per unit mass.
The GWP values appearing in the Emissions webpages reflect the values used in the U.S. Inventory, which are drawn from the IPCC's Second Assessment Report (SAR). For further discussion of GWPs and an estimate of GHG emissions using updated GWPs, see Annex 6 of the U.S. Inventory and the IPCC's discussion on GWPs.