The use of coal is set to grow over the next decade and, despite concerns over its environmental credentials, the introduction of carbon capture and storage technologies is of utmost importance.
Whilst all key elements of carbon capture and storage (CCS) have been demonstrated in the laboratory or at small scale operation, the key challenge for the industry is to demonstrate the entire chain at commercial scale. This means incorporating CO2 capture from large sources, CO2 compression, and transportation and injection into suitable storage sites or for a use that results in permanent emissions abatement.
Despite misgivings from mainstream media, there was significant progress last year in the number of large-scale integrated projects in operation or under construction, and a clustering of projects in the advanced stages of development planning.
There are eight large-scale projects in operation around the world and six more still under construction, three of which have only recently commenced. Importantly, these include a second power project, Boundary Dam in Canada, and the first project in the US that will store CO2 in a deep saline formation: the Illinois Industrial Carbon Capture and Sequestration (ICCS) project.
The total CO2 storage capacity of all 14 projects in operation or under construction is over 33'million tonnes a year. This is broadly equivalent to preventing the emissions from more than six million cars from entering the atmosphere each year.
As with most industrial projects, building a viable business case for a CCS demonstration project is a complex and time-consuming process that requires both the project economics and the risks to be understood prior to an investment being sanctioned.
All projects in operation use CO2 separation technology as part of an already established industry process. They also use CO2 to generate revenue through enhanced oil recovery (EOR) and/or have access to lower-cost storage sites based on previous resource exploration and existing geologic information sets. Six of the eight operating projects are in natural gas processing, while the other two are in synthetic fuel production and fertiliser production, and five of these projects use EOR.
But it is not all rosy, with 11'CCS projects cancelled last year - eight in the US and three in Europe - due to it being deemed uneconomic in its current form and policy environment. The lack of financial support to continue to the next stage of project development - and uncertainty regarding carbon abatement policies and regulations - were critical factors that led several project proponents to reprioritise their investments, either within their CCS portfolio or to alternative technologies.
Power generation projects have significant additional costs and risks from scale-up and the first-of-a-kind nature of incorporating capture technology. Electricity markets do not currently support these costs and risks, even where climate policies and carbon pricing are already enacted.
One major cost for CCS is the energy penalty or 'parasitic load' involved in applying the technologies. Going forward a major emphasis, in pre-, post- and oxy-fuel combustion capture applied to power stations (and other industrial applications) is on research into reducing cost.
Despite these challenges, construction of a post-combustion capture project (Boundary Dam) and an integrated gasification combined cycle (IGCC) project (Kemper County) is proceeding. This indicates that the technology risk for these applications is considered manageable and the technical barriers are not insurmountable if other conditions, such as allowance for the added cost into the rate base and other incentives, are right.
Pipeline transportation of CO2 is a proven and well-developed technology, but it is the scale of the future CO2 transport requirements that will require strong investment support. While pipelines are expected to be a cost-effective transport solution with increasing distance, in certain circumstances shipping can be cost competitive and offer greater flexibility to serve multiple CO2 sources and sinks.
Significant economies of scale can result from shared transport infrastructure, but establishing a network is a large investment that can add considerable risks to early mover projects. These risks need to be understood, in particular by governments, when providing incentives for demonstration.
CCS in action
One scheme in the UK that is up and running, though only testing carbon capture rather than storage, is at SSE's Ferrybridge Power Station in West Yorkshire. The project is a collaboration between SSE and UK-based Doosan Power Systems and'Vattenfall and is supported by the Technology Strategy Board, DECC and Northern Way. It is the first of its size to be integrated into a live power plant in the UK. As such, this represents a major step forward in proving that carbon capture technology is viable on a commercial scale.
The plant bridges the gap between the various pilot-scale trials that are under way and the commercial-scale demonstration projects envisaged by the UK government, as it captures 100t of CO2 per day from the equivalent 5MW of coal-fired power generating capacity.
SSE chief executive Ian Marchant is keen to stress the significance of Ferrybridge in the broader context of the UK energy industry: "The development of viable carbon capture technology is central to the UK's climate change and energy security objectives. We believe projects such as this will be absolutely crucial in establishing when and how the technology can be developed. What we have at Ferrybridge will provide an invaluable source of reference and learning for the industry as a whole."
"We are capturing CO2 and everything is going as expected," Mark Bryant, director carbon capture at Doosan Power Systems, says. "We are extracting steam as we would on a full-scale plant and we are now in the final stages of the commissioning. We are treating the flue gas and the plant is operating in a very stable position. It's performing well."
Ferrybridge is a two-year test programme and the first phase will be to benchmark the performance using Major Environmental Analysis (MEA). After that, Doosan will spend several months testing some of its formulated solvents.
"At the end of that two-year period we will determine what the next steps are," Bryant adds. "Either to look at further testing or relocating the plant to another site, mothballing it or there is a fourth option to dismantle the plant. I don't think this fourth option would come into play - not at this stage anyway."
The plant is a major step forward in the capture. "It gives us the confidence and certainty to go to those next phases and significantly de-risk the process for when we go to the next scale," Bryant says.
"We have learnt a lot of lessons in the process, both from constructing the plant and working with governing bodies, providing funding and the commercial arrangements as well as the actual technology. It's been good not just for ourselves but for the supply chain as well."
Despite the slow progress in commercialising the technology, Bryant is adamant that its adoption within power generation is vital to the global push to reduce carbon emissions. "There is a pressing need without a doubt," he says. "In a lot of countries you have got indigenous resources of coal and gas that are readily available. We need to face the fact that countries like India and China, that have this massive availability of coal, will be using it."
Ferrybridge is a post-combustion capture technology, but Doosan is keeping its options open and is also developing its oxy-fuel and pre-combustion technology. Bryant says: "As we are traditionally a boiler maker, having a technology which is an intrinsic link to the boiler and the firing systems was a natural fit for the organisation, but the post-combustion is a technology that is certainly closer to a commercial operation."
There are a number of hurdles that still need to be overcome, not least of all making the process economically viable - it is a well reported fact that the loss of efficiency and energy used in the CCS process could increase fuel use from 10 to 40'per cent. "Unless there is legislation or the price of carbon is at such a high level, economically it is not viable," Bryant says. "Developers need some form of financial support or legislation. We certainly need government funding so that we can have the demonstration at the sizes that it needs to. Then there needs to be legislation put in place which limits the omissions of CO2 but does not favour any particular technology."
For Bryant, the next step may prove to be the most difficult: finding the next project. "We need continuity - this is a big issue from a business point of view," he explains.
"We have now finished the Ferrybridge project and are desperately looking for the next project, but there is a gap in terms of other projects.
"We are a business and cannot have our engineers sat on the shelf waiting indefinitely for the next major project to come about. There needs to be continuity and a natural flow." *