Sources of Industrial Greenhouse Emissions

The industrial sector is the third largest source of direct greenhouse gas (GHG) emissions in the United States. When emissions associated with electricity purchases are accounted for, the industrial sector contributes 30% of total U.S. GHG emissions.⁽¹⁾

Roughly 75% of industrial GHG emissions is carbon dioxide (CO₂) linked to energy use from on-site combustion of fossil fuels (Scope 1/direct) and emissions associated with purchased electricity (Scope 2/indirect). Other emissions include CO₂ released from chemical reactions (process emissions) and from non-CO₂ gases, such as refrigerants or methane.

Highest Emitting Sectors

Within the broader manufacturing sector, a handful of industries with high temperature processes and large thermal energy loads produce the largest share of industrial CO₂ emissions. Many of these sectors have both fuel- and process-related emissions. These sectors include:

Chemicals
Petroleum Refining
Cement (Non-metallic mineral products)
Iron and Steel
Glass (Non-metallic mineral products)
Iron and Steel
Pulp & Paper
Food Processing
Aluminum

Facilities with high GHG emissions are required to report direct emissions annually to the U.S. EPA’s Greenhouse Gas Reporting Program.

Pie chart of Industrial GHG emissions by NAICS

Industrial Fuel Use

Direct emissions from on-site fossil fuel use are the largest source of all energy-related CO₂ emissions in manufacturing, typically contributing 60% to 70% of total emissions depending on the sector.

Energy-intensive sectors with high temperature processes have historically relied on carbon-intensive fuels such as coal and coke. In less energy-intensive industrial sectors, natural gas is the primary fuel for thermal processes.

Reducing fuel use through greater efficiency and switching to less carbon-intensive fuels are first steps toward reducing direct emissions. Redesigning industrial processes to use less energy or to run on low- and no-carbon energy sources will cut emissions further.

Electrification of thermal process can reduce emissions when renewable electricity is used. Less energy-intensive sectors are well-suited for electrification, as these sectors typically have lower temperature processes (<400^o F). However, in sectors with high temperature processes, electrification will be challenging.

More information

Reference:

1. U.S. EPA, Sources of Greenhouse Gas Emissions https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions