The industrial sector is responsible for about 25% of global CO2 emissions – or about 9.3 billion metric tonnes per year and growing. But a team at the University of Leeds says we don’t need to wait for magical new tech to clean most of it up.
In a new study published in the journal Joule, the researchers went through a range of different industrial sectors looking at the available options for decarbonization, their emissions reduction potential, and their technology readiness level (TRL) – a measure of how close a given technology is to being ready for widespread mass adoption.
They found that even if only medium and high-maturity options (TRL 6-9) were used – primarily involving carbon capture and storage (CCS), and/or switching fuel to hydrogen or biomass – most industrial sectors are already in a position to cut an average of 85% of emissions.
Here’s a brief summary of the areas they assessed, the technologies that are ready to roll, and the places where there are still gaps.
Iron and Steel
Most iron and steel production processes involve fossil-fueled blast furnaces and blast oxygen furnaces to achieve high temperatures, as well as coke (baked coal) as a reductant, resulting in about two tons of C02 emissions for every ton of steel produced.
You can replace coke with green hydrogen, and use the same hydrogen to power an electric arc furnace to produce green steel – indeed, there are already green steel plants in operation, one of which has been supplying Volvo.
But even if a steelmaker wants to keep its existing furnace assets, the study finds that CCS can sequester 86% of steelmaking emissions, at the cost of 17% higher energy consumption. There are other options coming down the technological pipeline, such as electrowinning.
The chemicals industry is a bit of a tricky one, since there are so many different products, processes, inputs and reactions involved. But there are some high emissions processes, such as ammonia synthesis, for which there are proven green alternatives.
Steam cracking, for the production of important chemical building blocks like ethylene, propylene, butadiene, acetylene and aromatic compounds, is a little tougher; electric and hydrogen steam crackers, by the team’s estimate, have only reached a TRL of 5, just below the cutoff. But using CCS alone, some 90% of current emissions can be sequestered – albeit requiring somewhere around 25% more energy.
In steam reforming, for the production of methanol and hydrogen, electrolyzers are well established and can totally eliminate carbon emissions – at the cost of a massive amount of electricity, representing a 743% jump in energy consumption over current methods. Here, CCS will be less effective, capturing only 52-88% of emissions from existing production processes and requiring around a 10% increase in energy consumption.
Cement and Lime
Most of the carbon emissions from cement and lime are “process emissions” that appear unavoidable if we’re to continue using these compounds. That means a lot of this sector’s emissions reduction potential will be in CCS, at the cost of “significant” additional energy inputs between 62-166%.
On the other hand, converting lime and cement kilns to run on hydrogen, biomass or electricity could knock out up to 40% of total sector emissions without much effect on energy requirements.
Most of the emissions in aluminum production at the moment – about two thirds – come from the regular, dirty electricity used to power the electrolysis process, so that’s an easy win; use green energy. Some of the remaining emissions are process-based; these can be addressed with a 20% energy consumption penalty by using inert anodes instead of carbon ones in the electrolyzers.
The remaining 13-16% of emissions can be eliminated by moving to electric or hydrogen-fueled boilers and calciners in the alumina refining process, although these still need considerable development.
By far the cleanest and easiest current way to produce aluminum is to recycle it through a well-established secondary production path, which the researchers estimate cuts emissions by about 95%.
Pulp and paper
There aren’t any process emissions to deal with in pulp and paper; decarbonizing the combined heat and power (CHP) systems and boilers is where it’s at here, as well as a number of efficiency measures to bring total power consumption down. The study also highlights some different approaches to paper drying, which are at various stages of development.
As you might imagine, furnace heat is the biggest source of emissions when it comes to glassmaking. Simply switching to an electric or biofuel furnace drops around 80% of total emissions – and in the case of electric, you’re actually reducing energy consumption by 15-25% compared with traditional methods.
Beyond that, using additional cullet and calcined input materials offer a potential extra 5% emissions reduction potential without adding significantly to materials or energy costs.
Food and Drink
While this, like chemical production, is a pretty diverse segment, most of the emissions involved are from the use of steam in heating and drying processes, and from the direct burning of fossil fuels for CHP. There are a variety of electric, biofuel, hydrogen, microwave, ultrasonic, concentrated solar, geothermal and UV processes ready to go.
Industrial barriers to decarbonization
By now, the picture’s fairly clear; the lion’s share of industrial emissions come from heat and power use – the vast majority of which can be electrified or converted to clean fuels – and from process emissions, the vast majority of which can be captured and stored. There are still some technological gaps to absolute zero carbon emissions, particularly in areas like ceramic requiring extremely high heat – but an 85% reduction in industrial emissions is achievable using machines and techniques that are already available.
There are plenty of issues, though. For starters, you can electrify things all you like, but until you decarbonize the power grid, you’re just pushing emissions upstream. The challenge of moving to clean, renewable energy grids the world over is only exacerbated by the fact that everything you electrify places more demand on them. So energy companies don’t just have to replace their existing capacity; they have to make much, much more clean power than they ever made dirty.
Likewise, processes that require hydrogen will necessitate an enormous increase in green hydrogen production worldwide – requiring yet more clean energy, as well as the infrastructure and logistics needed to move it around and store it safely.
And even at the industrial end, with fossil fuels still much cheaper than electricity in many markets, electrifying these low-hanging decarbonization targets can come with a 200-300% operational cost premium. Likewise, carbon capture and storage can get very expensive too, adding between US$10-250 to your costs for each ton dealt with, depending on the technology you’re using and the process you’re decarbonizing. That’s in addition to multi-million dollar upgrades to your electrical infrastructure if you’re using serious amounts of power; electrifying some industrial businesses might require a gigawatt-scale grid connection.
The result, the researchers estimate, might be a 15% increase in steel production costs worldwide, 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, it might not be that bad; one case study focusing on the UK found that “industrial decarbonization consistent with the 2050 net-zero goal could be achieved with an aggregate increase in consumer prices of less than 1%.”
And while clean energy might present a huge challenge at the moment, the economics are strong for solar and wind, which are both highly cost-competitive already – and a couple of critical breakthroughs in ultra-deep drilling could unlock ludicrous amounts of geothermal energy nearly anywhere on the planet, not to mention advanced, modular nuclear power – which could place industrial-scale power generation right there on site.
So while it’s not going to be easy, it’s certainly looking possible. And with the right amount of governmental shepherding, as well as canny commercial thinking and an accelerating pace of technological development, there’s cause for plenty of hope.
The study is open access in the journal Joule.
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