The industrial sector accounts for approximately 25% of global emissions, or approximately 9.3 billion tons per year, and is growing. But a research team from the University of Leeds says we don't need to wait for magical new technologies to remove most of the carbon dioxide. Tools exist to decarbonize industry by 85%.
In a new study published in the journal Joule, researchers looked at a range of different industrial sectors, looking at existing decarbonization options, their potential to reduce emissions, and technology readiness levels (TRL), a measure of how close a given technology is to widespread adoption.
They found that even with only medium- and high-maturity scenarios (TRL6-9) – which mainly involve carbon capture and storage (CCS) and/or switching fuels to hydrogen or biomass – most industrial sectors have been able to reduce emissions by an average of 85%.
Below is a brief summary of the areas they assessed, the technologies that are ready, and where gaps remain.
steel
Most steel production processes require fossil-fueled blast furnaces and forced oxygen furnaces to achieve high temperatures and use coke (roasted coal) as a reducing agent, thus emitting approximately two tons of carbon dioxide for every ton of steel produced.
You could replace coke with green hydrogen and use the same hydrogen to power an electric arc furnace to produce green steel - in fact, there are already green steel plants operating, one of which is already supplying Volvo.
But the study found that even if steelmakers wanted to retain existing furnace assets, CCS could sequester 86% of steelmaking emissions at the cost of a 17% increase in energy consumption. Additionally, there are other technological options such as electrolysis.
chemical production
The chemical industry is a tricky one because there are so many different products, processes, inputs and reactions involved. But some high-emission processes, such as ammonia synthesis, already have mature green alternatives.
Steam cracking, used to produce important chemical components such as ethylene, propylene, butadiene, acetylene and aromatic compounds, is slightly more difficult; the research team estimates that the TRL of electric and hydrogen steam cracking units is only 5, just below the critical value. However, using carbon dioxide capture and storage technology alone, it is possible to store about 90% of current emissions, although it would require about 25% more energy.
Electrolysers are already widely used in the steam reforming process used to produce methanol and hydrogen and can completely eliminate carbon emissions - but this requires a large amount of electricity, increasing energy consumption by 743% compared with existing methods. Here, carbon capture and storage is less effective, capturing only 52-88% of emissions from existing production processes and requiring about 10% more energy consumption.
cement and lime
Most of the carbon emissions from cement and lime are "process emissions" that appear to be inevitable if we are to continue using these compounds. This means that much of the industry's emissions reduction potential will come from carbon dioxide capture and storage (CCS), at the expense of "substantial" increases in energy inputs of 62-166%.
On the other hand, converting lime and cement kilns to ones that use hydrogen, biomass or electricity could reduce the industry's total emissions by up to 40% without having a big impact on energy demand.
aluminum production
Currently, most of the emissions from aluminum production - about two-thirds - come from ordinary dirty electricity used in the electrolysis process, so success with green energy sources is easy. Some of the remaining emissions come from the production process; by using inert anodes instead of carbon anodes in the electrolyzer, these problems can be solved by reducing energy consumption by just 20%.
The remaining 13-16% of emissions could be eliminated by switching to electric or hydrogen-fueled boilers and calciners in the alumina refining process, although these equipment still require significant development.
By far the cleanest and simplest way to produce aluminum is to recycle it through well-established secondary production routes, which researchers estimate can reduce emissions by around 95%.
pulp and paper
Pulp and paper do not have any process emissions issues; decarbonization of combined heat and power (CHP) systems and boilers is key, along with a range of efficiency measures to reduce overall electricity consumption. The research also highlights a number of different paper drying methods, which are in various stages of development.
Glass
As you can imagine, kiln heat is the largest source of emissions in the glass manufacturing process. Simply switching to an electric or biofuel stove can reduce your overall emissions by around 80% - in the case of electric stoves, you actually use 15-25% less energy than traditional methods.
On top of this, the use of additional roasted straw and calcined input materials can reduce emissions by an additional 5% without significantly increasing material or energy costs.
food and drink
While this, like chemical production, is a fairly diverse sector, most of the emissions involved come from the use of steam in heating and drying processes, and the direct combustion of fossil fuels in combined heat and power processes. A variety of electric, biofuel, hydrogen, microwave, ultrasonic, solar, geothermal and UV processes are available.
Industrial barriers to decarbonization
The picture is now fairly clear: the vast majority of industrial emissions come from heat and electricity use (the vast majority of which can be electrified or converted to cleaner fuels), and process emissions (the vast majority of which can be captured and stored). There are still some technological gaps to achieve absolutely zero carbon emissions, especially in areas such as ceramics that require extremely high heat, but using existing machinery and technology, reducing industrial emissions by 85% is achievable.
However, there are many problems. First, we can electrify all we want, but until the grid is decarbonized we are just pumping emissions upstream. Globally, the challenge of transitioning to clean, renewable energy grids will be even greater as all electrification creates more demand on the grid. As a result, energy companies must not only replace existing generation capacity, but also produce more clean electricity than the dirty electricity they have produced in the past.
Likewise, processes that require hydrogen will require a massive increase in the production of green hydrogen around the world - which will require more clean energy, as well as the infrastructure and logistics needed to safely transport and store the hydrogen.
Even in the industrial sector, with fossil fuels still much cheaper than electricity in many markets, electrification to achieve these low-carbon targets could result in operating cost premiums of 200% to 300%. Likewise, carbon capture and storage is expensive, adding $10-$250 per ton of carbon processed, depending on the technology used and the decarbonization process. In addition, if power usage is high, millions of dollars in upgrades to the power infrastructure will be required; the electrification of some industrial enterprises may require gigawatt-scale grid connections.
The researchers estimate that the result could be a 15% increase in the cost of global steel production, a 50-220% increase in the cost of olefins and aromatics, and a 30% increase in the cost of concrete.
On the other hand, if these additional costs are passed on to consumers through price increases, the situation may not be so bad; a UK-focused case study found that "industrial decarbonization consistent with the 2050 net zero target can be achieved with a total increase in consumer prices of less than 1%".
While clean energy may currently face huge challenges, the economics of solar and wind are strong and both are already extremely cost-competitive, while some key breakthroughs in ultra-deep drilling could unleash staggering amounts of geothermal energy almost anywhere on Earth, not to mention advanced modular nuclear power that can generate electricity on an industrial scale on site.
So while it's not easy, it's certainly possible. With proper guidance from the government, coupled with smart business thinking and the accelerating pace of technological development, hope is still high.
The research has been published publicly in the journal Joule.