Author: Ali Hasanbeigi, Ph.D.
The U.S. industrial sector accounts for about a quarter of energy use and greenhouse gas (GHG) emissions in the U.S. The majority of the energy used in U.S. industry is fossil fuels (Figure 1).
Figure 1. U.S. industrial sector energy use by fuel type, 1950-2019 (US DOE/EIA, 2020)
The top five U.S. manufacturing sectors in terms of energy use are bulk chemicals, petroleum refining, pulp and paper, primary metals, and the food and beverage industry
Thermal processes account for 74% of total manufacturing energy use in the U.S.; process heating accounted for 35%; combined heat and power/cogeneration for 26%; conventional boilers for 13% (US DOE, 2019) (Figure 2).
Figure 2. U.S. manufacturing energy use by end uses- values in Trillion Btu (US DOE, 2019)
Five industries account for more than 80% of all U.S. manufacturing thermal process energy consumption: petroleum refining, chemicals, pulp and paper, iron and steel, and food and beverage (US DOE/EIA, 2017).
Industrial process heating operations include drying, heat treating, curing and forming, calcining, smelting, and other operations (Figure 3).
Figure 3. Energy use for process heating in the U.S. industry by type of process heat (US DOE, 2015)
Process heating technologies can be grouped into four general categories based on the type of energy consumed: direct fuel-firing, steam-based, electric-based, and hybrid systems (which use a combination of energy types). In process heating, material is heated by heat transfer from a heat source such as a flame, steam, hot gas, or an electrical heating element by conduction, convection, or radiation—or some combination of these. In practice, lower-temperature processes tend to use conduction or convection, whereas high-temperature processes rely primarily on radiative heat transfer. Energy use and heat losses from the system depend on process heating process parameters, system design, operating practices, and other factors (ORNL, 2017).
Around 30% of the total U.S. industrial heat demand is required at temperatures below 100°C. Two-thirds of process heat used in U.S. industry are for applications below 300°C (572°F) (Figure 4) (McMillan, 2019). In the food, beverage, and tobacco, transport equipment, machinery, textile, and pulp and paper industries, the share of heat demand at low and medium temperatures is about, or even above, 60% of the total heat demand. With a few exceptions, it is generally easier to electrify low-temperature processes than high-temperature processes. Therefore, there is significant potential for electrification of industrial processes for low or medium heating applications. Figure 5 shows the share of industrial head demand by temperature in selected industries.
Figure 4. Cumulative process heat demand by temperature in 2014 (McMillan, 2019).
Figure 5. Share of industrial head demand by temperature in selected industries (Caludia et al., 2008)
Industry uses a wide variety of processes employing different types and designs of heating equipment. Process heating methods used in manufacturing operations largely depend on the industry, and many companies use multiple operations. For example, steelmaking facilities often employ a combination of smelting, metal melting, and heat-treating processes. Chemical manufacturing facilities may use fluid heating to distill a petroleum feedstock and a curing process to create a final polymer product (ORNL 2017). Table 1 shows the industrial process heating temperature profile for various subsectors. As can be seen from this table, a variety of thermal processing is conducted in each industry under different temperature profiles.
Table 1. Industrial process heating temperature profile for various subsectors (DGA, 2018)
As can be seen, there is a significant opportunity to decarbonize the industrial sector by shifting heat production away from carbon-intensive fossil fuels to electrified technologies where low- or zero-carbon electricity is used.
On January 27, 2021, Global Efficiency Intelligence and David Gardiner and Associates (DGA) released a report on industrial electrification titled “Electrifying U.S. Industry: A Technology and Process-Based Approach to Decarbonization”. The report’s Technical Assessment provides an analysis of the current state of industrial electrification needs, the technologies available, and the potential for electrification in thirteen industrial subsectors. The report also analyzes a separate scenario for electrification of all conventional boilers in the U.S. industrial sector. Besides, the report reviews the major technical, economic, market, institutional, and policy barriers to scaled development and deployment of industrial electrification technologies, as well as proposals that could help to overcome these barriers.
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Reference:
Hasanbeigi, Ali, et al. 2021. Electrifying U.S. Industry: A Technology and Process-Based Approach to Decarbonization.
U.S. Department of Energy (US DOE). (2019). Manufacturing Energy and Carbon Footprint.
U.S. DOE/ Energy Information Administration (US DOE/EIA). (2017). Manufacturing energy consumption survey, 2014.
U.S. Department of Energy (US DOE). (2015). Technology Assessments: Chapter 6: Innovating Clean Energy Technologies in Advanced Manufacturing. Quadrennial Technology Review 2015.
McMillan. C. 2019. Solar for Industrial Process Heat Analysis. Available at: https://www.nrel.gov/analysis/solar-industrial-process-heat.html
Caludia, V., Battisti, R., & Drigo, S. 2008. Potential for solar heat in industrial processes.
David Gardiner and Associates (DGA). (2018). A Landscape Review of the Global Renewable Heating and Cooling Market.
Oakridge national laboratory (ORNL). 2017. Application of Electrotechnologies in Process Heating Systems—Scoping Document.