CCS is the only available means to tackle emissions that are integral to many important industrial processes. Energy-intensive industries such as steel mills, cement factories, chemical plants and refineries are reaching theoretical efficiency limits and CCS is the only technology that can substantially reduce their emissions – renewables or efficiency measures will not be able to tackle these emissions and CCS is needed for deep decarbonisation of industry.
Almost 45% of worldwide CO2 emissions are attributed to industrial activities, mostly related to the large primary material industries, such as chemicals and petrochemicals, iron and steel, cement, pulp and paper, and aluminium. Although their energy intensity has lessened significantly in most sectors as a result of improvements in energy efficiency and material flow management, the demand for industrial products is expected to double or triple over the next 40 years.
Furthermore, some of these industries’ CO2 emissions are integral to the production process. Cement production results in CO2 emissions from calcination, which contributes more than half of total emissions. In many industry sectors CCS is therefore the only available technology that allows for deep reductions in CO2 emissions. In the iron and steel sector, the main sources of CO2 emissions are power production, iron ore reduction in either a blast furnace or a DRI plant, and coke and sinter plants.
In a number of cases, capturing industrial CO2 emissions will require the reengineering of certain established and reliable production techniques. It should however be clear that in order to reduce global CO2 emissions on the necessary scale by 2050, large-scale demonstration of CO2 capture technologies in industry should be undertaken in parallel with projects planned for the power sector.
The application of CCS in industry, as in any other sector, depends on transporting the CO2 from source(s) to a suitable storage site. With industry often concentrated in certain areas, this provides significant potential for clustering and hubs development, which can afford economies of scale and integrated solutions to CO2 transport and storage development.
Special requirements for CCS in industry
The heterogeneity of industrial processes poses challenges but also gives major opportunities for CCS development. High purity CO2 streams (i.e. CO2 emissions that rise from processes other than the combustion of fossil fuels and result in highly-concentrated CO2 off-gases) can be identified in a number of industrial processes, whereby the CO2 needs minor treatment prior to compression, transport and storage. This is the case in for instance bioethanol production, which with sustainable biomass sourcing provides potential for carbon negative emissions through Bio-CCS. High-purity CO2 streams with revenue-generating storage options such as Enhanced Oil Recovery (EOR) could offer early opportunities.
There are three possible capture technologies for CCS in industry:
Removal from diluted streams, similar to post-combustion capture in power generation applications: The low-pressure flue gases exiting an oxidation process are treated using chemical or physical sorbents to remove CO2 selectively from the gas mixture. The sorbents are then regenerated – using steam, for example – to produce a concentrated CO2 stream from a stripping column.
Removal from oxy-fired streams, similar to oxyfuel combustion in power generation applications: Combustion or oxidation in a relatively pure oxygen or CO2 environment results in streams with high concentrations of CO2, which are suitable for transport and storage after particulate and contaminant removal, optional flue gas desulphurisation and water removal.
Pre-process removal, similar to pre-combustion CO2 capture in power generation applications: Carbon-containing fossil fuels or biomass can be gasified with partial oxidation to produce high-pressure synthetic gas mixtures (syngas), which are then typically subjected to a water-gas shift reaction and gas separation to produce hydrogen and CO2. The CO2 is thus available at a higher concentration and pressure which simplifies the CO2 separation process prior to transport and storage.