Last week the GHGT conference on carbon capture and storage returned for its 13th edition, hosted by the Ecole Polytechnique Federale de Lausanne on the shores of Lake Geneva. Despite the continuing sluggish uptake and uncertain outlook for CCS since the last event, the conference managed to strike a much more positive note for the future of the nascent CO2 mitigation technology – thanks largely to a strong emphasis on the global climate agreement reached last year at COP21 in Paris, which set CO2 mitigation goals that will be difficult to meet without CCS. As starkly laid out by a keynote from the IPCC, average global temperatures have risen sharply over the past three years, and the world is well on course to see warming of up to 9ºC by 2100 – equivalent to the difference between an ice age and modern temperatures, and far from the 1.5ºC target encouraged by COP21.
With a challenge this great (some may say impossible), everything is on the table, and the unique ability of CCS to remove CO2 from the atmosphere – even from non-power sector emitters such as the cement industry – is receiving increasing recognition. The IEA presented one of their familiar ‘wedge’ projections, showing a 12% contribution from CCS is needed to meet 2050 decarbonisation targets at a reasonable cost to society. Some cynical murmurs in the crowd noted that this is down from previous projections of 17%, and this is likely due to CCS deployment repeatedly missing its targets over the last decade. Some of the reasons behind these struggles are explored in a recent retrospective ‘20 years of CCS’, which the IEA launched on the conference’s first day to mark the anniversary of Norway’s pioneering Sleipner project. Early political support in the 2000s was dealt a blow by the global financial crisis and the resulting decline of interest in climate change, but now seems to be picking up again. Helped by favourable policy and a market for CO2 in enhanced oil recovery, large-scale CCS demonstrations are continuing to appear in North America, and the delegates saw keynotes from Shell’s recently commissioned Quest project at a hydrogen plant in Canada, and the soon-to-be-operational Kemper County coal plant in the USA. Always a leader in CCS, Norway has regrouped and is now giving clear support to developing full-scale CCS at three industrial sites, including a cement plant and waste-to-energy facility. Yet there is still a shortage of new projects in the pipeline – particularly in coal power or in Asia, where it’s needed most. What can be done to revive a technology which seems so necessary to battling climate change?
Many of the policy talks brought up the same issues highlighted by the failure of the UK CCS competition, and tackled in Lord Oxburgh’s subsequent report to the government. Calls for a ‘level policy playing field’ with other low carbon technologies such as renewables seem to have been replaced with recognition that CCS actually needs quite specific support, able to separate parts of the process chain (capture, transport, and storage) and better deal with the unique risks associated with the transport infrastructure and storage site. As proposed by Lord Oxburgh and many others at GHGT, this may require setting up a public enterprise to manage the infrastructure. Variations on this were put forward by the UK’s Crown Estate, which suggested a form of public-private partnership, but all with the ultimate aim of taking risk away from the private sector and encouraging independent competition at each stage of the CO2 chain.
Although the focus of the CCS community has decidedly shifted away from technological issues to these kinds of barriers to deployment, new research in improving the existing technology was still very much in evidence. CO2 capture with amine solvents is a fully commercial technology which seems to have kept improving even when many thought it had reached its limits, as new solvent formulations and process designs are developed with reduced energy consumption. Significantly reducing its capital cost, however, is much more challenging, and many radical alternatives continue to be proposed and scaled up. For instance, the much-vaunted Allam Cycle promises essentially zero cost capture, and the inventor of this revolutionary oxyfuel gas turbine-based process provided an update on the 50 MWt pilot which is expected to be commissioned early next year. Other entirely reimagined power generation concepts, such as chemical looping combustion, can also offer big energy and cost gains, but post-combustion technologies are still needed for retrofit to existing power plants and other emitters.
There was an interesting panel discussion which pitted representatives from all the major post-combustion capture concepts (amines, non-aqueous solvents, sorbents, calcium looping, and membranes) against each other. It is perhaps surprising that research into all these avenues has continued without any clear winners or losers emerging, but some clear niches are emerging for some technologies, such as sorbents for pressurised gas streams of calcium looping in cement. Although much has been made of the need to look at the benefits of membranes and sorbents for partial CO2 capture rather than the 90% targets set by most research programmes, current thinking seems to be going in the other direction, as nearly 100% clean plants will be needed if we are to meet our strict climate targets. To achieve these rates on low pressure coal flue gas, it is challenging to beat amines, but alternative solvents which can be regenerated using low value, waste heat (rather than steam) may offer a promising solution. Canadian company CO2 Solutions use an engineered enzyme to allow regeneration of their capture solvent with hot water, and have funding for a number of pilot projects around Canada. Other low energy solvents include a non-aqueous liquid from RTI International, and an offering from ION Engineering which is currently being tested at the large TCM facility in Norway. While using solid sorbents tends to suffer from long process times, work presented by EPRI has looked at embedding CO2 sorbent particles in a hydrophobic polymer, allowing for fast mass transfer and very rapid regeneration with direct steam heating.
Another interesting panel discussion dealt with the concept of CO2 utilisation, or the idea of converting the gas into useful chemicals such as hydrocarbon fuels, which has seen an explosion of interest and ‘grand prizes’ to innovators who can come up with a viable process. Unfortunately, opinion among the speakers was almost unanimous that such initiatives represent a dangerous distraction from properly sequestering CO2 underground, as most of the processes developed do nothing to reduce emissions and can often make them worse. Most criticism was reserved for the popular idea of using surplus, low-carbon energy from renewables to convert CO2 into transport fuels such as methanol, effectively using CO2 as an energy storage vector before it is eventually released to the atmosphere. This conversion essentially uses significant amounts of electricity and hydrogen to avoid the CO2 emissions associated with conventional methanol production, and begs the question: why not just use hydrogen as the energy storage vector? Although a representative of the European Commission defended certain cases of CCU, largely based on regional electricity surpluses, a conference-closing speech from pro-CCS NGO Bellona even made an impassioned call for delegates to work to oppose a recent EU policy brief aiming to further reward CCU projects.
A closing panel session discussed what the CCS community can do to better argue its case and improve political support. Having looked at public outreach initiatives for CCS myself over the last few months, ideas such as using professional ‘communicators’ and not presenting the technology as an alternative to renewables were very familiar. In this charm offensive there is a growing focus on targeting key political figures as much as the public, although ultimately support from both will surely be necessary. I was surprised by speakers relating the relative success of renewable energy to more vigorous lobbying, as CCS clearly has a bigger mountain to climb in losing its image as an unsustainable quick fix to carry on ‘business as usual’. As the cost of renewables falls while CCS will stay relatively costly without the benefit of more deployment, this case is getting even harder to make; yet the need for the technology remains. One of the problems highlighted is that the ‘deep decarbonisation’ provided by CCS will only become clear later on, when other options are exhausted, but long-term vision is needed to develop the technology now. Perhaps the best way of spurring political leaders to action is simply by effectively communicating the true severity of the global warming problem. Once this is realised, it should be very clear that no CO2 mitigation technology can be discounted lightly.