Not even ten years ago, most engineers would not have been familiar with the term “decarbonization.” Over the past two years, searches for the term on Google increased by approximately 300% in the U.S. Today, you commonly hear about decarbonization at industry events and in news coverage; the term gets mentioned by CEOs when discussing high-level sustainability strategies; and we hear about its importance as an integral piece of future regulatory frameworks.
More than just a phasing out of atmospheric greenhouse gas (GHG) emissions from industrial processes, decarbonization can be thought of as a movement — one in which processes that have traditionally relied on fossil-based energy will be made more efficient, electrified, or modified to rely on lower-carbon fuels and energy sources, like solar power. Some scientists believe that the decarbonization movement will also require the deployment of direct air capture technologies to halt the temperature rise of the earth. The Special Section on Accelerating Decarbonization (pp. 20–47) in this issue of CEP discusses the regulations and frameworks that are being implemented to decarbonize industry in the U.S., as well as the technologies that will be critical to these frameworks.
As chemical engineers, when we hear the term decarbonization, we tend to think about the industrial sector, e.g., decarbonizing process heating and cooling, re-imagining the processes that rely on fossil fuels as raw material inputs, etc. Although the industrial sector accounts for 30% of all domestic GHG emissions, the residential sector is not far behind — accounting for 19% of GHG emissions in the U.S. Arguably, great strides could be made in emissions reductions by establishing decarbonization pathways for the residential sector. Strategies might include installing efficient electric heat pumps; greening the grid by ensuring that electricity is generated by carbon-free sources; and electrifying ovens and water heaters that previously relied on fossil fuels. In 2019, for example, Berkeley, CA, banned natural gas hookups in new buildings in an effort to limit GHG emissions. Although many states and cities are blocking such measures, home chefs that prefer cooking over a gas flame may be in for a rude awakening when they decide to move into a new home.
Refrigerators will be another appliance affected by decarbonization measures. In the 1980s, the most common type of refrigerants found in air conditioners and refrigerators were chlorofluorocarbons (CFCs). After CFCs were found to be responsible for the thinning of the ozone layer, these refrigerants were phased out in favor of hydrofluorocarbons (HFCs), which break down ozone far less. However, HFCs are extremely potent GHGs; in fact, their global warming potential is thousands of times greater than carbon dioxide. When not recycled properly, HFCs leak into the atmosphere at the end of an appliance’s working life. To mitigate this source of GHG emissions, manufacturers are investigating other refrigerants — such as ammonia and propane — although these are not without their own problems and risks.
Meeting the primary goal of the Paris Agreement (i.e., keeping global temperature rise below 2°C) will require decarbonization on many scales in all sectors. Even though it’s a relatively new movement, decarbonization will have sweeping changes on our lives over the next 25 years — from the industrial systems we design to the cars we drive.
Emily Petruzzelli, Editor-in-Chief
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