Decarbonization goals made many sectors rethink the current processes and evaluate potential new solutions that would allow limiting CO2 emissions to the atmosphere. Companies are setting up ambitious goals to become CO2 neutral and starts to measure emissions in different scopes of their processes (direct, indirect, value chain emissions). A big part of such emissions comes from the energy sector like plants producing electricity or heat as well as energy-intensive industries, like producers of fertilizers, steel, cement, and others. For example, when producing electricity from coal - for 1kWh produced, 700-1000g of CO2 is emitted, with gas turbines – 1kWh will emit around 350-500g of CO2. While making products like cement for each 1kg of it 0,9kg of CO2 will be emitted. 1 kg of steel will produce 1,85 kg of CO2. These are rough numbers to understand estimates and the final emission is much dependent on plants' efficiency and internal processes. But when we talk about energy production and reach TWh or million tons of products that means millions of kg of CO2 emitted and for such amounts specific technologies like carbon capture and storage (CCS) can be applied.
While it is difficult to avoid CO2 emissions in many cases for energy production or products of energy-intensive industries, carbon capture is considered a viable mid-term or long-term solution. But for implementing it many aspects must be considered, mainly it is CCS technology itself, capture process implementation, transport, and storage.
As for current CCS, the post-combustion chemical absorption technology is market-ready and utilized on a large scale. Different solvents, liquids, or membranes are currently being tested or piloted, so in the near future, there will be more technologies available for selection in different applications. For the current state-of-the-art technology that uses chemical absorption for catching CO2, the main aspect that must be considered when doing pre-feasibility is the possible integration of CO2 capture infrastructure to existing equipment, together will operational needs such as chemical components, water, steam, and electricity needs. If such technology is applied to existing power and heat production facilities, CO2 capture lowers the total power and heat output. The total investment needs and operational cost really depend on the facility to which the CO2 capture technology is applied. A good example of that is the Gassnova report on the Norwegian full-scale CCS demonstration project, where it clearly estimates the different CAPEX and OPEX values – one for the cement production plant and the other for the waste-to-energy power plant (CAPEX 323 MEUR and 476 MEUR, OPEX 12 MEUR and 24 MEUR respectively). Each plant plans to capture 400,000 tons of CO2 annually.
Transport and storage come to question when there is an answer to how much CO2 can be captured and compressed at the site. Currently, the most viable solution to store captured CO2 is in depleted offshore oil or gas reservoirs. At the moment main potential sites are being explored, and some will start operating as soon as 2024 (for example Northern Lights project in Norway, with a capacity of 1.5 million tons of CO2 per year). For that to become reality, CO2 needs to be prepared at the site and liquified, transported to the shipping port, travel to the storage site, and then using pipelines put deep under the seabed. On the other hand, if the source is close to a storage facility that makes logistics more convenient and less costly. Inland underground storage also has potential, but that depends on the local legislation, site properties, and available capacity. Everything comes down to cost. Since it depends heavily on transport means and distance, such cost can largely vary roughly between 10-50 Eur/ton. If a power plant emits around 200-400 kton of CO2 per year, transport costs become significant.
What are the alternatives for captured CO2 use? The food industry – this is limited use, the capacity here is in a very different scale. Fuel synthesis – it has potential when green hydrogen is produced and by mixing it with CO2 various synthetic fuel types can be produced (like methanol, and synthetic methane), but this comes back to the green hydrogen availability issue.
The final question is - what CO2 price must be or how much it should increase that companies, after evaluating all the investment and operating costs needed, will actually start large-scale CO2 capture plants implementation. And will it be a long-term solution?