What Are Low-Carbon Feedstocks and Why Are they Important?
Feedstocks are materials used directly in manufacturing processes and transformed into an intermediate or finished material. For example, the chemicals industry uses a large amount of fossil-fuel-derived feedstocks, like natural gas, to manufacture a range of building block chemicals, such as ethylene and propylene, which are then used to produce everything from plastics to fertilizer.
These building block chemicals, however, can be energy- and carbon-intensive to create. For example, propylene and ethylene are critical to America’s manufacturing sector and used in nearly all plastic products. Conventionally, these are produced by refining petroleum and natural gas liquids in high temperature reactors, releasing CO2 through combustion and from the chemical reactions that create the feedstock chemicals. Fossil fuels are both transformed into chemical feedstocks and burned to provide the energy the reactions require.
How Do We Use Low-Carbon Feedstocks?
Finding zero-carbon pathways to produce key industrial feedstocks and integrating these pathways into manufacturing processes are key to industrial decarbonization. Incorporating low-carbon feedstocks into industrial processes involves:
- Identifying sustainable sources of new feedstocks.
- Developing processes and equipment to effectively utilize the feedstock, such as pre-treatment, conversion processes, or entirely new methods for production.
- Validating quality and quantity of production to de-risk alternative feedstock usage.
In some cases, new industrial processes will need to be developed to decarbonize the production of key feedstocks. For example, to create iron suitable for steelmaking, coal is often used for two purposes: 1) as a source of carbon that chemically binds with the oxygen in iron ore and escapes into the atmosphere as carbon dioxide, as well as 2) a source of carbon atoms that are incorporated into the final steel alloy products to generate its unique material properties. To eliminate these emissions, other molecules, such as green hydrogen, in conjunction with non-coal based sources of carbon feedstock, can be used to “reduce” iron ore into feedstock iron. Producing green hydrogen and integrating it into iron reduction requires developing alternative processes and equipment to replace traditional, carbon-intensive methods.
In industrial processes where carbon is an essential component of the feedstock, there is an opportunity to integrate alternative sources of carbon that do not lead to a net increase in atmospheric GHGs. This can be sustainably provided through captured carbon or sustainably produced biofuels. Sustainable carbon can then be synthesized with green hydrogen to create the building block chemicals propylene (C3H6) and ethylene (C2H4). Under the Clean Fuels and Products Energy Earthshot™, the U.S. Department of Energy is developing alternative fuels and feedstocks which can achieve an 85% net reduction in CO2 versus fossil-based sources.