What is a hard to abate sector?
While the term “hard to abate” is widely used in various policy documents, scientific literature, media, and corporate roadmaps, there is currently no single formally agreed upon definition of this term. In general, it can be understood as sectors that emit substantial volumes of greenhouse gases (GHGs) but are “harder to decarbonise due to their physical, technological, or market particularities” [1, 3, 7].
There are a number of sub-sectors that are commonly identified as energy-intensive and hard-to-abate. However, these lists vary and remain non-exhaustive. Industry sectors such as metals, cement, and chemicals are often included. Transport — notably shipping, aviation, and road freight — is also often included as its operations require fuels [1, 2, 3, 6, 7].
These sectors represent a substantial share of global emissions. In 2024, these sectors were collectively estimated to have accounted for around 40 to 60% of global GHG emissions [5, 7].
Decarbonization pathways
Different decarbonization solutions and technologies for hard to abate sectors exist or are in the process of being developed.
The technology readiness level (TRL) of these technologies varies. The TRL indicates the maturity of a solution and can be assessed on a 9-level scale: 1) basic principle observed, 2) technology concept formulated, 3) first assessment feasibility concept and technologies, 4) validation of integrated prototype in test environment, 5) testing prototype in user environment, 6) pre-production product, 7) low scale pilot production demonstrated, 8) manufacturing fully tested, validated and qualified, 9) production and product fully operational [9].
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Improved efficiency, circularity, and demand reduction
Improved energy or material efficiency focuses on using less energy and less GHG-intensive materials. Efficiency can be improved through better equipment and infrastructure or optimized processes. Such improvements are applicable across a wide range of sectors, but their scope and impact depend on specific contexts.
These improvements can be readily implementable and cost-effective options, and could provide emissions reductions and economic benefits for companies [1, 5]. In addition, circularity and demand reduction can contribute to overall GHG emissions reduction [1, 5].
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Direct electrification
Direct electrification replaces the use of fossil fuels with electricity from renewable sources such as wind or solar power. Examples of direct electrification include the use of electric arc furnaces for steelmaking, battery electric trucks, and heat pumps for low- to medium-temperature heating in industry [1, 4, 5, 7]. These technologies are already mature or close to maturity.
Other applications of direct electrification, such as electric crackers to produce primary chemicals or electrolysis of iron ores, have potential but require further development. Overall, most projects and facilities involving direct electrification currently have a TRL of 6-7 [1, 11].
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Alternative / renewable fuels
Where direct electrification is not yet feasible, alternative / renewable fuels can come into play. They include sustainable biofuels produced using biomass and synthetic fuels produced using clean electricity and sustainable carbon sources. These fuels play a complementary role to electrification and are particularly important for industrial processes that require high energy consumption [1, 4, 5, 7].
The TRL varies depending on the specific type of alternative fuel and the supply chain stages across the lifetime of the fuel (from raw materials to end use). According to the Lloyd’s Register Zero-Carbon Fuel Monitor, certain types of biofuels (e.g., biodiesel) have reached a TRL of 8-9 across most of their supply chain stages. Other fuels, such as e-methanol or e-ammonia, have a TRL of 4-7 [9, 10].
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Carbon capture, utilisation, and storage (CCUS)
CCUS addresses emissions that cannot be fully eliminated. It involves capturing the CO2 before it enters the atmosphere and either storing it permanently or using it in ways that do not lead to future emissions [3, 4, 5].
CCUS technologies are at different stages of maturity depending on the application and process. While several capture technologies have reached commercial deployment (TRL 9), their integration across all industrial sectors remains uneven. Transport and storage components are generally considered technologically mature (TRL 9) [8].
Challenges
These decarbonization pathways can reduce GHG emissions, especially when used in combination with one another. There is no single most effective solution, as the effectiveness of each solution varies across industries and regional contexts. Yet despite progress to decarbonize hard to abate sectors, key challenges persist: technology maturity, costs, and infrastructure.
Many promising solutions are not yet fully ready for larger-scale use and their deployment remains limited. While some technologies have reached advanced TRLs, this does not necessarily reflect their readiness for commercial deployment. TRLs primarily assess technical maturity and do not always capture challenges related to scalability or market uptake. As a result, a significant gap (known as the “valley of death”) remains between successful pilot and deployment at industrial scale [1, 7, 13].
Economic barriers can also slow progress as many of these newer technologies require high upfront investments. Other challenges include permitting delays, long timelines, and supply chain volatility [1, 7]. In the case of CCUS, projects can be delayed when transport and storage infrastructure is not yet available, despite progress in capture technologies [12]. As such, decarbonizing hard to abate sectors will require not only deploying available technologies faster, but also overcoming economic and infrastructure challenges.
