The industrial sector is California’s second largest source of greenhouse gases, responsible for roughly 19 percent of statewide emissions. This industry is the backbone of our lives, producing food & beverages, building construction materials, medical and surgical supplies, and much, much more.
However, the industrial sector largely relies on burning natural gas to power an enormous and diverse collection of boilers, kilns, furnaces, combined-heat-and-power systems, and other equipment. Eliminating those emissions will require a giant transformation of how our economy is powered.
Once you’ve decided that industrial decarbonization is important, then you begin thinking how to best reduce those emissions. But unfortunately, industrial decarbonization debates are often framed as a contest between technologies.
Should we electrify industry? Should we use carbon capture? What about hydrogen? Are low-carbon fuels part of the solution?
Those are the wrong questions.
We should not be categorically “for” electrification and “against” carbon capture, or “for” hydrogen and “against” biomass-derived fuels. These are technologies—tools for solving particular emissions problems. Like any tool, each works extremely well in some applications and poorly in others.
Answering that requires understanding the facility before choosing the technology. Asking a series of questions helps lead to more nuanced thinking of the problem:
- How much heat does the process require?
- Are emissions spread across dozens of pieces of equipment or concentrated in one stack?
- Are the emissions caused by combustion or by the manufacturing process itself?
- If carbon capture is considered, how far is the facility from viable geologic storage?
- And what will the technology do to NOx, toxic air contaminants, and other pollution affecting the surrounding community?
Start with those questions, and the appropriate technology becomes clearer.
Temperature matters
Industrial heat encompasses everything from producing hot water and pasteurizing milk to melting metals and manufacturing cement.
A useful way to divide industrial heat demand is into three broad categories:
| Heat requirement | Temperature | Examples | Technologies worth considering |
|---|---|---|---|
| Low-temperature | <180°C | Hot water, food processing, drying, low-pressure steam | Heat pumps, waste-heat recovery, electric boilers, solar thermal, geothermal, thermal storage |
| Medium-temperature | 180–1,000°C | Steam, refining, chemicals, drying, furnaces | Electric boilers, resistance, induction, infrared/RF/microwave, hydrogen, low-carbon fuels, CCS |
| High-temperature | >1,000°C | Cement, glass, metals | Electric arc, resistance/induction, plasma, hydrogen/low-carbon fuels, CCS, process changes |
85%+
of California industrial heat demand occurs below 1,000°C, creating a substantial opportunity for electrification.
But even that fact doesn’t mean the answer is simply “electrify everything.”
It means electrification should be evaluated where its characteristics match the application.
Use efficient electrification where it fits
For many lower-temperature applications, electrification has compelling advantages.
Industrial heat pumps are a good example. Instead of simply converting electricity into heat, they move thermal energy from one place to another. Depending on operating conditions, one unit of electricity can provide multiple units of useful heat.
If a food-processing plant is burning natural gas to produce 100°C hot water while simultaneously rejecting waste heat elsewhere in the facility, a heat pump may be an extraordinarily efficient solution.
In that application, many other technologies would be less efficient and overly expensive. It is less efficient to convert electricity into hydrogen, transport the hydrogen, and then burn it to produce the same low-temperature heat. There may also be little reason to install an elaborate carbon-capture system on numerous small boilers.
The solution should use the simplest, most efficient technology that solves the problem.
But a different industrial process may require a different solution.
Higher temperatures require a broader toolbox
As temperatures increase, the choice becomes more process-specific.
A number of electric heating technologies are already commercially established:
- Resistance heating is widely used in industrial furnaces, ovens, melting and heat-treatment applications.
- Induction is a mature technology for metals and other conductive materials.
- Infrared heating is also commercially established for applications such as drying, curing and surface heating.
- Electromagnetic technologies, including microwave and radio-frequency heating, are commercially used in more specialized applications but remain less mature for replacing large-scale, high-temperature combustion processes.
The question is therefore not simply whether electricity can reach the required temperature. In many cases, it can. The more important questions are whether an electric technology is commercially proven for the specific industrial process, whether it can operate at the necessary scale and production rate, whether sufficient grid capacity is available, and whether its operating costs are competitive.
There are applications where direct electrification may require extremely large electrical loads, expensive grid upgrades, major process modifications, or equipment that is not yet commercially appropriate for the particular operation.
Hydrogen or other low-carbon fuels may be worth considering in some of those applications, particularly when a fuel or molecule plays a role beyond simply providing heat.
The point isn’t that hydrogen is “good” or “bad.” It is that using hydrogen to make low-temperature hot water is a very different proposition from using hydrogen in an industrial process that actually requires hydrogen as a feedstock or reducing agent.
Technology should follow the application.
Some emissions cannot be eliminated just by changing the heat source
Cement provides perhaps the clearest example of why a technology-first approach breaks down.
A cement kiln requires extremely high temperatures. Those temperatures could potentially be supplied through several technologies.
But heating the kiln isn’t the entire emissions problem.
When limestone is converted into clinker, the chemical reaction itself releases CO₂ (approximately 60 percent of the overall emissions). Even a hypothetical cement plant running entirely on zero-carbon electricity would continue producing these process emissions.
~60%
of a cement plant’s overall emissions are released by the chemical reaction itself, when limestone is converted into clinker.
Electrification alone therefore cannot fully decarbonize conventional cement production.
Alternative materials, like supplementary cementitious materials or SCMs can reduce the amount of clinker required and prevent some emissions from occurring in the first place. Fuel changes can reduce others. Carbon capture can capture much of the concentrated CO₂ that remains.
The most efficient answer may therefore be a combination rather than choosing one technology over another.
Whether emissions are distributed or concentrated matters
Looking at the MDI map, you can explore how different facilities across California contain wildly different facility profiles. A cement plant in the Kern air basin has 35 devices producing almost 1 million tons of CO2e while a mineral mining facility in the Mojave air basin has 158 devices producing a total of 1.3M CO2e emissions. This physical configuration of a facility can be just as important as temperature.
Imagine two hypothetical industrial facilities that each emit 500,000 tons of CO₂ annually.
Facility A
California Paper Products
Emissions come from 30 smaller boilers, heaters, dryers, and furnaces scattered across a large site.
Likely starting point
Electrify individual pieces of combustion equipment
Facility B
Western Cement
Most of the CO₂ exits through one or two large exhaust streams.
Likely starting point
Give carbon capture much closer consideration
It would make little sense to assume that both facilities should use the same technology simply because they emit the same amount of CO₂.
At California Paper Products, electrifying individual pieces of combustion equipment may be relatively straightforward. Capturing CO₂ from dozens of small sources could require extensive ductwork and collection infrastructure.
At Western Cement, carbon capture may deserve much closer consideration. Hundreds of thousands of tons of CO₂ may already be flowing through a limited number of locations.
CO₂ concentration matters as well. Separating CO₂ from a highly concentrated stream generally requires less energy than separating it from dilute flue gas.
So before declaring that a facility “should electrify” or “should use CCS,” ask:
Where are the emissions actually coming from?
CCS also depends on geography and scale
Even a perfect candidate for carbon capture has another practical question to answer:
Where will the CO₂ go?
Captured CO₂ must be transported to suitable permanent geologic storage, typically using Class VI injection wells. These are marked with the black diamonds on the MDI map.
A large, concentrated source located near suitable storage starts with an economic advantage. A smaller facility hundreds of miles from storage may face a very different calculation.
But distance shouldn’t become an arbitrary cutoff.
A facility capturing one million tons annually may be able to support pipeline infrastructure anywhere between 50-100 miles. But that makes little sense for a source capturing 50,000 tons. Several facilities may also be able to share a CO₂ transportation network.
The economics therefore move along a spectrum:
The economics move along a spectrum
- Small distributed sources
- Distant storage
- Dedicated infrastructure
- Large concentrated source
- Nearby storage
- Shared infrastructure
The point, again, isn’t to be “for” or “against” carbon capture. It is to use carbon capture where its characteristics match the emissions source and where it can deliver reductions efficiently.
Community impacts belong in the equation
The same principle applies to local air pollution.
Industrial decarbonization shouldn’t be evaluated solely by counting tons of CO₂. Already industrial sources are principally located in our most disadvantaged communities. But California should further prioritize opportunities to reduce emissions at facilities located in the state’s most disadvantaged and pollution-burdened communities, where investments can produce both climate and immediate local health benefits.
Technology choice matters here too.
Electrifying combustion equipment can eliminate onsite combustion and therefore eliminate the NOx and other combustion-related pollutants produced by that equipment.
Combustion-based alternatives require closer examination. Hydrogen, biomass-derived fuels, and other alternative fuels may reduce lifecycle greenhouse gas emissions, but depending on the technology choices, NOx, particulate matter, toxic air contaminants, or other pollutants could remain or even increase.
That doesn’t mean those technologies should be rejected. It means pollution controls should be part of the technology package.
A decarbonization project should demonstrate that reducing CO₂ will not result in an increase in harmful local pollution. And when two approaches offer similar climate benefits and costs, the approach that produces larger reductions in NOx, toxic air contaminants, and other pollutants—particularly in a disadvantaged community—should have a clear advantage.
Ask the questions in the right order
Instead of starting with a preferred technology, start with the industrial source.
The checklist
Seven questions to ask — in this order
What temperature is required?
Low-temperature heat may strongly favor heat pumps and other efficient electric technologies. Higher-temperature applications require a broader set of options.
Are the emissions distributed or concentrated?
Distributed combustion can favor electrification. Large, centralized emissions streams can improve the case for CCS.
Are the emissions from combustion or from the industrial process itself?
Changing the heat source doesn’t eliminate process emissions. Alternative materials, process changes, or CCS may also be necessary.
How concentrated is the CO₂?
Higher-concentration streams generally improve capture economics.
If CCS is an option, where is permanent storage?
Distance, capture volume, pipeline utilization, storage quality, and opportunities for shared infrastructure all affect economics.
What happens to local air pollution?
Prioritize reductions in disadvantaged communities and make sure the replacement technology and its pollution controls prevent increases in NOx, particulate matter, toxic air contaminants, and other harmful pollutants.
What does each alternative actually cost?
Compare capital expenditures, energy costs, infrastructure, maintenance, useful life, emissions reductions, and time to deployment.
Only after answering those questions should we decide which technology is appropriate.
The answer will often be a portfolio
A cement plant might…
- Reduce clinker use
- Electrify smaller distributed equipment
- Utilize a lower-CO₂ feedstock
- Capture the concentrated process emissions remaining at the kiln
A food processor might…
- Recover waste heat
- Install heat pumps
- Electrify boilers
- Add thermal storage
A refinery might…
- Electrify appropriate distributed combustion sources
- Use low-carbon hydrogen where hydrogen is actually needed
- Improve heat integration
- Capture CO₂ from suitable concentrated streams
Those aren’t compromises between competing decarbonization philosophies.
They are what efficient industrial decarbonization looks like.
Don’t pick a team. Solve the problem.
Technologies are the tools. The true objective is to reach net-zero greenhouse gases. We must also reduce air pollution and toxics along the way.
The most effective industrial climate policy should therefore be technology-neutral but performance-driven: identify the emissions source, understand the engineering constraints, compare the feasible alternatives, account for community impacts, and select the technology—or combination of technologies—that achieves deep emissions reductions most efficiently.
Sometimes that will overwhelmingly favor electrification. Sometimes carbon capture will be the obvious answer. In other applications, alternative materials, low-carbon fuels, hydrogen, or process redesign may win.
The important thing is not to decide which technology we like before doing the analysis.
Start with the problem. Match the technology to the application. And pursue the combination that delivers the greatest practical emissions reductions while protecting the communities surrounding industrial facilities.
