Carbon Capture and Storage (CCS) sounds simple, but is very complex to put into effect. But it remains a potentially attractive policy option for one key reason: its successful introduction would allow us to burn more gas – and even coal – while reducing carbon dioxide emissions.
It is certainly an attractive concept, but it comes at a cost, and no-one has yet turned it into a successful process that can be built into power stations on a routine basis. The capturing part is quite straightforward. Flue gases from burning fossil fuels are passed through a solution of amines that combine with the carbon dioxide and remove most of it from the waste stream. This can then be stripped from the amines (which are then recycled) and compressed into liquid form.
That is the easy bit. More difficult is finding a way to store the liquid carbon dioxide and keep it from entering the atmosphere. One idea is to pipe it to the ocean floor, where the pressure of the water would keep it in place. Doing this on a large scale is unproven and the option that is used in practice is to pump it into appropriate geological formations.
This has been done for many years by the oil industry, using partly-depleted oil or gas reservoirs as the reservoirs. However, the aim has not been to store CO2, but to extract more oil or gas by increasing the reservoir pressure, and the amounts of carbon dioxide injected have been modest.
There is one successful deep water CCS project run by an oil company (Statoil), the Sleipner CO2 storage project in the North Sea, which has now been operational for 20 years. However, this is something of a one-off, since it strips excess carbon dioxide from gas produced in one part of the field and reinjects it. No combustion is involved and all processing is at the field itself, minimising process and pipeline costs. The project is also economically justified, because the high CO2 content of the natural gas produced makes it otherwise unsuitable for sale.
This is a far cry from capturing carbon dioxide from chimneys at on-shore power stations and transporting it many miles to a suitable rock formation. This is one reason why the UK government decided it would encourage competition between companies to demonstrate the technology and help keeps costs down. In 2012, it made up to a billion pounds of funding available in a bid to get workable large-scale schemes in place by the end of the decade.
The first UK power station to test the technology was Longannet, a large coal-fired plant in south-east Scotland, which started work on this on a small scale in 2009 (carbon capture technology tested). The incentive for companies involved was to show that coal-fired stations could continue to operate by reducing their emissions by about 90%. However, this ended in tears in 2011, apparently because the billion pounds on offer was too little to fund a viable project (carbon uncaptured). In 2015, similar schemes were planned or operational at Peterhead and Drax power stations, but the government announced withdrawal of the funding in November of the same year (UK government carbon capture £1bn grant dropped).
Although this decision is somewhat mired in controversy, it seems clear that the government saw little chance of a return for the taxpayer on this investment. CCS appeared to be the answer to meeting carbon budget targets because it held the promise of reducing emissions at a competitive price. A significant amount of the energy produced by a power station would go into the capture and compression of CO2 – perhaps 20% of the output – but even allowing for the additional capital costs the electricity price would probably be competitive with renewables and power would be despatchable, so avoiding the additional costs of backup.
But it seems that the capital cost was the stumbling block. Another big problem was that each project would be a one-off. Every power station would need to identify an appropriate reservoir and build a bespoke system to pipe the carbon dioxide to it. There is now a proposal for this particular problem to be overcome by building a publicly-funded pipeline network for power stations and factories to pump their captured C02 through (Pump CO2 into rocks, report urges).
The Parliamentary Advisory Group on CCS recommends this in its new report – Lowest cost decarbonisation for the UK: the critical role of CCS. This report is much wider ranging than the headline suggests, proposing also that domestic heating be decarbonised via conversion to electricity, itself generated from new conventional power stations fitted with CCS. The whole massive project would be the responsibility of a CCS Delivery Company, akin to the organisation that planned and ran the London Olympics.
The headline cost of electricity from this low-emission fossil fuel network is projected to be £85 per MWh, far higher than the current wholesale price and close to the much-criticised strike price for Hinkley C, but very competitive with renewables, particularly when backup and transmission costs are properly accounted for.
This proposal certainly does not lack ambition, and the conclusion that CCS must be planned and implemented on a national scale is well argued, but it is difficult to see any government – particularly the present UK government with its new PM, narrow majority and all-pervasive focus on Brexit – make such a bold strategic move in anything like the time scale necessary for CCS to make any real contribution to meeting the fourth and fifth carbon budgets.
Governments everywhere, particularly the UK one with its self-imposed obligations under the Climate Change Act, will sooner or later have big choices to make. They would need to commit large amounts of taxpayers’ money to projects such as this or fail to meet emissions targets. What they can achieve will, ultimately, be decided by those same taxpayers and other voters. There may be interesting times ahead.