Last week our sister organisation, the IEA Greenhouse Gas R&D Programme held the 12th edition of their flagship Greenhouse Gas Technologies conference in Austin, Texas, and I was able to attend on behalf of IEA CCC. This huge event has become the world’s foremost conference on carbon capture and storage, with over 1100 attendees and a four-day-long programme devoted entirely to the subject. Bringing the event to the USA this year seemed like an appropriate choice, given that North America has remained a bastion of CCS development even throughout the recent decline in interest in mainland Europe. The southern states in particular have long been a centre of activity for chemical plant-based capture and enhanced oil recovery, while for power plant capture, Texas itself has recently seen construction start on the WA Parish coal plant, and the nearby Kemper County IGCC capture project is nearing completion. Meanwhile, north of the border in Canada, the start-up of the world’s first CCS power plant at Boundary Dam only the week before the conference added a particular significance to the event.
Status update and policy
Although around 40% of the conference was devoted to geological storage research, my focus was reserved to the sessions on capture technologies, with an eye to a forthcoming CCC report on emerging capture concepts which could dramatically reduce costs. The strong focus of US R&D on such ‘transformational’ technologies was touched on by an opening keynote from the US Department of Energy, highlighting that 30 different technologies have now been brought to the pilot scale. This formed part of a thorough update on the status of CCS worldwide, running through the handful of operating demonstration projects which have now collectively sequestered 100 Mt of CO2. However, this remains a drop in the ocean next to the 40 Gt emitted every year, and the necessary acceleration in CCS adoption could receive much more from the growing profits of the global fossil fuel industry. The following talk focussed on the critical nature of international policy in making such progress, while stressing that policy should follow technology rather than lead it. Theoretically, carbon markets should be most effective, but such schemes have been weak drivers in practice and some government intervention is always needed. The globalised world has also allowed carbon emissions to be easily transferred abroad, so some kind of border tariff could also be required.
An opening technical session on sorbent-based capture featured an update on a 10 MW project in Korea, where there is a strong interest in calcium-based and other dry sorbents. I was also fascinated to be introduced to a new concept of micro-encapsulated sorbents, in which microfluidic devices are used to trap familiar CO2 solvents within hard polymer shells of around half a millimetre in diameter. This provides a much higher surface area to react with CO2, and could also solve many of the problems with the thermodynamically favourable precipitating solvents. However, all sorbent processes share the energetic challenge of achieving good heat integration between a solid and liquid phase, compared to the conventional liquid system.
Boundary Dam and demonstration projects
The second day brought proceedings to the landmark events at the Boundary Dam project, including speakers from the utility Saskpower, and the capture process provider Shell Cansolv. The 110 MW net plant, retrofitted with post combustion capture, will generate 1 Mt of high purity CO2 per year for use in enhanced oil recovery, and has cost 1.4 billion dollars since its inception in 2008. However, Saskpower estimate that optimisation of the design could make future plants up to 30% cheaper, and two more unit conversions are indeed planned by the utility. The technical presentation from Cansolv on the project was a personal highlight, as despite the project being largely too confidential to release much technical detail, all the excitement of the project’s recent success came across from the exuberant speaker. After countering some technical challenges such as preventing amine leakage into effluent, the process appears to have worked better than expected, with an impressive auxiliary power consumption of 21%, or 2.3 GJ/tCO2.
The real possibility of Boundary Dam being joined by a power plant capture project on these shores was raised by a talk from the UK’s own Department of Energy and Climate Change. Recent UK energy reforms are becoming famous as some of the most CCS-friendly policies in the world, due to the technology-neutral decarbonisation plan enabled through ‘contracts for difference’, and the CCS commercialisation programme which should provide capital funding to either one or both of the CCS projects planned for Drax and Peterhead.
Amongst other forthcoming demonstration projects discussed, none involved power generation, but one stood out as nonetheless highly significant. The Decatur project, currently under construction in Illinois, will achieve negative emissions through capturing CO2 from bioethanol production, which has the important advantage of being almost 100% pure and therefore easy to capture. The CO2 is to be stored in the Mt Simon aquifer formation, also earmarked for the still unconfirmed Futuregen oxyfuel project, and the capture process is actually rendered profitable by the increased tax credits offered for aquifer storage in the US. It seems likely that similar projects, providing liquid fuels with negative carbon emissions, will appear in the coming years.
A chemical looping session covered the ongoing activity in this emerging capture technology, including the search for superior oxygen carriers to conventional materials such as nickel. Screening large numbers of materials for their performance has identified some perovskite-type oxides as potential candidates for the advantageous ‘oxygen uncoupling’ mechanism. This variation on chemical looping separates the release of oxygen and its reaction with the fuel into two steps, and dispenses with the need for expensive air separation units. Scaled-up chemical looping units could be closely based on circulating fluidised bed boilers, but despite potential to capture CO2 at 19 euros per tonne, industrial investment has so far been relatively limited.
Besides the existence of large CCS projects in the area, conference hosts the University of Texas are also a world centre for research into post-combustion capture. An opening talk from Professor Gary Rochelle on the third day gave a brilliant overview of the history of post-combustion technology which was invaluable for an oxyfuel devotee such as myself. Although once seen as a more theoretically limited process than oxyfuel or precombustion capture, the much longer history and weight of research behind amine-based systems has enabled a linear reduction in the capture energy penalty from around 4 GJ/tCO2 to approaching 2 GJ, both through new solvent development and more complex process flows. Some of these energy saving measures include using lean solvent and steam condensate heat for solvent regeneration, and compression of the lean vapour. Loss of solvent through degradation and aerosols are now also much more manageable.
Fortunately, the third day also finally brought oxyfuel technologies to the stage, including updates from the largest operating plant at Callide in Australia, and an overview of the gas processing technologies inherent to the process. Some entirely novel capture concepts also come under the oxyfuel banner, such as the gas-based technology from Clean Energy Systems. Gas and oxygen are fired at high temperature in a steam-cooled combustor adapted from rocket engines, producing CO2 and water which are used to drive steam turbines. The day also saw novel concepts in the form of membrane CO2 capture, including Air Liquide’s cold membrane process which has both high permeability and selectivity to CO2 and has been tested at the scale of 0.3 MW on coal flue gases. Both membranes and chemical looping share an intolerance to impurities, so can be more challenging to apply to coal combustion.
As usual, an insight into the generally less-publicised CCS activity in China was another important addition to the third day’s plenary session. The country’s climate change mitigations strategy aims for levels of CO2/GDP in 2020 to be almost half of the 2005 level. Greengen is one high profile CCS project which has completed a 250 MW IGCC and aims to add precombustion capture by 2016. Elsewhere in the power sector, various post-combustion and oxyfuel pilot projects are currently active and demonstration plants designs have been developed for each capture type. However, there is particular interest in implementing CCS with the fast growing coal to chemicals industry in northern China, where over 100 facilities are producing around 430 Mt of relatively high purity CO2.
Social engagement and summing up
The plenary session on the final day featured a presentation on the importance of social engagement in capture projects which is seen as increasingly important after a number of high profile failures. Notably, the concerted public opposition to projects in the Netherlands and Germany were contrasted with the warm welcome received by the Futuregen project in Illinois. Strategies to gain public approval included offering public services rather than being seen as buying people off with money alone.
The closing panel session brought together an eminent team of speakers who all delivered insightful short summaries on each aspect of CCS. In the last decade, capture technologies have been optimised and scaled-up, understanding of CO2 storage has increased immeasurably, and laws addressing CCS have been introduced in many regions. However, it remains difficult for CCS to challenge other forms of low carbon generation while factors such as dispatchability and the need for baseload generation are not sufficiently valued. Questions were then posed to the panel via the hi-tech means of texting messages to the projected screen. While the frivolity of most of these comments and questions was met with some disapproval, my impression was that the anonymity provided gave a rarer insight into the true mood of the CCS community, including a surprising lack of confidence in the technology’s ability to be scaled up sufficiently rapidly while competing with renewables for government attention. As a lost pigeon flapped around the gigantic auditorium during this session, some of this self-doubt within the community was perhaps best expressed by the poignant comment: ‘There is a bird in here. He believes in CCS’.