CCS has not yet been implemented on a scale needed to make a substantial difference to climate change. However it continues to look necessary for the longer term, with more projects necessary to get costs down.
A decade or so ago many people expected rapid development of Carbon Capture and Storage (CCS) as a major contributor to reducing global emissions. I was one of them – at the time I was working on developing CCS projects. However, the hoped-for growth has not yet happened on the scale needed to make a material difference to global emissions.
The chart below shows total quantities captured from large CCS projects, including 17 that are already operational and a further 5 under construction. The quantity of emissions avoided are somewhat lower than the captured volumes shown here due to the CO2 created by the process itself.[i]
Between 2005 and 2020 capture will have grown by only around 25 million tonnes p.a.. This is only 0.07% of annual global CO2 emissions from energy and industry. In contrast the increase in wind generation in 2017 alone reduced emissions by around 60 million tonnes[ii], so wind power reduce annual emission more from about 5 months’ growth than CCS will from 15 years’ growth – though it took wind power several decades to get to this scale.
Chart 1: Growth of large CCS projects over timeThe picture gets even less promising looking at the types of projects that have been built. The chart below shows the proportion of projects, measured by capture volume, in various categories. The largest component by some distance is natural gas processing – removing the CO2 from natural gas before combustion – which accounts for over 60% of volumes. This makes sense, as it is often a relatively low cost form of capture, and is often necessary to make natural gas suitable for use.
However, it will clearly not be a major component of a low carbon energy system. Much of the rest is chemicals production, including ethanol and fertiliser production. These are helpful but inevitably small. There are just two moderate size power generation projects and two projects for hydrogen production, which is often considered important for decarbonising heat.
Furthermore, most of the projects separate out CO2 at relatively high concentrations or pressures. This tends to be easier and cheaper than separating more dilute, lower pressure streams of CO2. However it will not be typical of most applications if CCS is to become more widespread.
Chart 2: Large CCS projects by type (including those under construction)
This slow growth of CCS has been accompanied by at least one spectacular failure, the Kemper County power generation project, which was abandoned after expenditure of several billion dollars. Neither the circumstances of the development or the technology used on that particular plant were typical. For example, the Saskpower’s project at Boundary Dam and Petra Nova’s Texas project have both successfully installed post combustion capture at power plants, rather than the gasification technologies used at Kemper County. Nevertheless, the Kemper project’s failure is likely to act as a further deterrent to wider deployment of CCS in power generation.
There have been several reasons for the slow deployment of CCS. Costs per tonne abated have remained high for most projects compared with prevailing carbon prices. These high unit costs have combined with the large scale of projects to make the total costs of projects correspondingly large, with a single project typically having a cost in the billions of dollars. This has in turn made it difficult to secure from governments the amount of financial support necessary to get more early projects to happen. Meanwhile the costs of other low carbon technologies, notably renewables, have fallen, making CCS appear relatively less attractive, especially in the power sector.
The difficulties of establishing CCS have led many to propose carbon capture and utilisation (CCU) as a way forward. The idea is that if captured CO2 can be a useful product, this will give it a value and so improve project economics. Already 80% by volume of CCS is CCU as it includes use of the CO2 for Enhanced Oil Recovery (EOR), with project economics supported by increased oil production.
Various other uses for CO2 have been suggested. Construction materials are a leading candidate with a number of research projects and start-up ventures in this area. These are potentially substantial markets. However the markets for CO2 in construction materials, while large in absolute terms, are small relative to global CO2 emissions, and there will be tough competition from other low carbon materials.
For example, one study identified a market potential for CCU of less than two billion tonnes p.a. (excluding synthetic fuels) even on a highly optimistic scenario[iv], or around 5% of total CO2 emissions. It is therefore difficult to be confident that CCU can make a substantial contribution to reducing global emissions, although it may play some role in getting more early carbon capture projects going, as it has done to date through EOR.
Despite their slow growth, CCS and CCU continue to look likely to have a necessary role in reducing some industrial emissions which are otherwise difficult to eliminate. The development of CCS and CCU should be encouraged, including through higher carbon prices and dedicated support for early stage technological development. As part of this it remains important that more projects CCS and CCU projects are built to achieve learning and cost reduction, and so support the beginnings of more rapid growth. However in view of the lead times involved the scale of CCS looks likely to continue to be modest over the next couple of decades at least.
[i] CO2 will generally be produced in making the energy necessary to run the capture process, compression of the CO2 for transport, and the rest of the transport and storage process. This CO2 will be either emitted, which reduces the net gain from capture, or captured, in which case it is part of the total. In either case the net savings compared with what would have been emitted to the atmosphere with no CCS are lower than the total captured.
[ii] Wind generation increased by a little over 100 TWh between 2016 and 2017 (Source: Enerdata). Assuming this displaced fossil capacity with an average emissions intensity of 0.6 t/MWh (roughly half each coal and gas) total avoided emissions would be 60 million tonnes.