Decarbonising UK industry

Industry is responsible for 24% of global CO₂ emissions, 99.8 Mt of which came from the UK in 2021. Most of these emissions are due to combustion of fossil fuels for energy and heat, or process emissions. These processes must be decarbonised if the UK’s net zero goals are to be realised. A range of decarbonisation solutions are currently available or in development, including fuel switching (renewable electricity, low-carbon H₂, biomass, solar thermal and/or geothermal energy), carbon capture, utilisation & storage (CCUS), and alternative manufacturing pathways (direct-reduced iron, various green chemistry).

Various policies are being designed and implemented to support these decarbonisation options but currently prioritise large, shoreline industrial clusters that benefit from well-connected infrastructure and economies of scale. Dispersed (isolated/inland) emitter sites without access to CO₂ transport & storage (T&S) infrastructure face unique barriers to CC(U)S deployment and have received less support. A 2020 EE/BEIS report explored feasibility of CCUS for large, dispersed emitter sites in certain sectors (cement, iron & steel, oil refining, etc).

Smaller dispersed sites (< 100 ktCO₂/year[1]) receive even less attention. Such sites are often not connected to the gas grid (relying on deliveries of heating oil or LPG) and decarbonisation options are limited. CCUS is deemed unsuitable for these emitters (due to high CAPEX and heat requirements, and lack of T&S options) and fuel switching is usually a more suitable decarbonisation solution. Electrification is often more expensive than fossil fuel combustion, and H­₂ as a fuel has prohibitive transport/storage costs without existing pipeline connections. These issues are complicated by the diversity of processes and energy requirements across the > 1000 small, dispersed sites (spanning multiple sectors) in the UK.

Energy Requirements of Dominant Sectors

Different processes need different grades of heat. High-energy processes (requiring > 1000 °C) are typically iron & steel production, and calcining and processing of minerals (lime, glass, etc.). Medium/high-energy processes (400 – 1000 °C) include metal processing, kilns (ceramics etc.), hydrocarbon cracking and production of certain chemicals (ammonia, olefins, etc.). Lower-energy processes (100 – 400 °C) comprise most chemical and non-metallic material processing, oil refining/distillation, food & drink production, paper manufacture, etc. The lowest heat grades (< 100 °C) are used for heating buildings, and the lower-temperature stages of certain food/drink, chemicals, paper and materials processing. Most of this heat currently comes from fuel combustion (particularly for higher temperatures), or electricity. Heat pumps are a particularly efficient electrical solution for lower grades of heat, but are unsuitable for very high temperatures (currently < 150 °C but possibly up to 300 °C in the near future).

While direct electrification can achieve most of the above, this is expensive for energy consumers and will require significant electrical grid investment & development; a more diverse green energy portfolio is therefore required. Fuel switching commonly requires retrofitting or replacement of existing heating systems; this is more costly for small sites and should ideally be synchronised with equipment end-of-life. The UK government is first focusing on large emitters before developing policy support for smaller sites, who are encouraged to improve energy efficiency where possible, for now, and be ready to decarbonise quickly once support arrives.

Small, Dispersed Emitter Statistics & Decarbonisation Options

Small, dispersed sites are classified here as onshore sites with <100 ktpa CO₂ emissions that are >30 km from any major port or large industrial cluster (from NAEI 2021 Emissions Dataset); lime & cement sectors only offer 3 data points here and have been excluded. Across these 1189 sites, the sectors with the largest cumulative emissions are: “other” minerals (including glass, gypsum & bricks) (2.6 Mtpa); food, drink & tobacco (2.3 Mtpa); public administration (1.9 Mtpa); chemical processing (1.8 Mtpa) and waste collection, treatment and disposal (1.4 Mtpa) (Figure 1a). In terms of individual sites, the sectors with the highest median emissions are still oil & gas exploration & production (19 ktpa), and iron & steel (18 ktpa), followed closely by other metals (16 ktpa), other fuel production (15 ktpa) and paper production & printing (15 ktpa). The sectors with the most individual sites are public administration (208 sites), other minerals (171) and food/drink/tobacco (156), followed next by commercial buildings (110), minor power producers (103) and chemicals (101). The distribution of individual site emissions for each sector is often concentrated towards the low-emission end (< 40 ktpa), coupled with a handful of high-emitting outliers.

Figure 1. (a) CO2 emissions boxplot of small dispersed onshore emitter sites in the UK, separated by sector and sorted by cumulative sector emissions. (b) Locations of small, dispersed emitter sites in the UK with heatmap of absolute emissions (currently for qualitative purposes only). Data points are colour-coded by sector and size-coded by CO2 emissions.

The minerals sector needs high-grade heat from fuel combustion or direct resistive electrification. Heat pumps may be suitable for, e.g., gypsum (requiring < 400 °C), but not for glass or ceramics (400 – 1000°C); a low-carbon combustible fuel may be a good option here. In the absence of H₂ T&S infrastructure, one option could be biofuels, although this comes with supply/demand, food security and deforestation issues. The food & drink and chemical industries are highly emissive with many sites, but mostly require < 400 °C heat. Most of this could be efficiently electrified with next-gen heat pumps, although low-carbon combustible fuels or direct electrification will be required for the higher temperatures. The chemicals sector can/should also decarbonise somewhat via alternative chemical pathways. The emissions of the public admin sector mostly come from building heating, requiring low-grade heat; heat pumps are an obvious choice here. The emissions of the waste disposal sector are mostly from waste-to energy combustion, and decarbonisation options are more related to improvement of waste management & recycling, and minimisation of waste production.

Geothermal heating might be an option for some low-grade heat, and possibly higher-grade geothermal heat potential in areas with granite bedrock (e.g. Scotland and the South West). However, the CAPEX and OPEX for this are both significant. Conversely, solar thermal options come with some CAPEX but relatively little OPEX, although this is an intermittent & seasonal resource suited mainly to the sunnier parts of the UK (i.e. the south east). Neither of these are optimal solutions for most small UK industrial emitters (with highest emission density in the Midlands (Figure 1b)) but could be helpful for the other, smaller emission “hotspots” around Glasgow, the East Anglia coast and Surrey.