Carbon capture and storage – magic bullet or white elephant?

Tony Alderson

In any discussion of CO2 emissions reduction, it does not take long before the topic of carbon capture and storage, or CCS, is raised. Is CCS the magic bullet, allowing ‘business as usual’ to continue, or a white elephant, draining cash and research, development and demonstration effort that could be better spent on other emission reduction technologies?

The answer to this is not straightforward; CCS potentially has a significant role to play in emissions reduction, but is not without challenges, and the path to large-scale deployment is less than straightforward.

"Fitting CO2 capture to four coal-fired plants means that you would need to build a fifth plant to make up for the lost output."

At the front end of the CCS process chain is carbon (or more correctly CO2) capture, in simple terms intercepting and diverting to storage CO2 that would otherwise be emitted into the atmosphere. While attention has to date mainly focussed on applying carbon capture to the power generation sector, it can also be applied to a range of CO2-intensive industries including iron & steel, cement manufacture, oil refining and petrochemicals production.

Indeed, while the power sector has a greater range of options for decarbonisation such as switching from fossil fuel generation to renewables and nuclear, for many industry sectors CO2 emissions are an integral part of their processes, and capture may be the only viable option for significant decarbonisation.

The most obvious way to perform CO2 capture is to take the flue gas from a fossil-fuelled power plant or other industrial process, and extract the CO2 before it is sent up the chimney – a process referred to as post-combustion capture. However, the flue gas will be at near-atmospheric pressure, so the volumes of gas will be large, resulting in a need for massive ductwork and process units.

 It also needs high-volume, high-power CO2 compressors, and requires significant heat input – so much so that if post-combustion capture is applied to a coal-fired power plant it reduces the net power output of the plant by around 20%. So fitting CO2 capture to four coal-fired plants means that you would need to build a fifth plant to make up for the lost output.

Post-combustion capture is not the only option for CO2 capture. Two other leading technologies, oxy-combustion and pre-combustion capture, are also being developed. Each has its own features, advantages and disadvantages, but overall the costs and efficiency are comparable with those of post-combustion capture. Other advanced technologies are also under development, but are some way from commercial implementation, and the potential advantages of these processes are not certain to be materialised.

So if carbon capture reduces efficiency and increases costs, why would power generators and other industry players implement it?

There needs to be either a carrot or a stick. The stick approach, in terms of CO2 emissions limits or high emissions taxes, is unlikely to result in the implementation of CO2 capture. Power generators can switch to other technologies or fuels, shut down existing assets or not commit to new-build capacity in a country or region that imposes such measures.

Industrial emitters can move their production to other parts of the world that do not have the emissions limits or taxes, thereby reducing their costs, taking jobs and investment out of the country (along with the associated CO2) but, on a global level, making no reduction in their CO2 emissions – so-called Carbon Leakage.

This leaves the carrot: normally a financial mechanism that creates a revenue stream for a company implementing CO2 capture that, as a minimum, compensates for the additional costs associated with implementing capture. This can take the form of capital subsidies and/or the provision of a price premium for the low-carbon or ‘green’ product coming from the capture-fitted facility.

"Industrial emitters can move their production to other parts of the world that do not have the emissions limits or taxes"

 In the power sector, schemes such as the UK’s Contract for Difference Feed in Tariff (FiT) provide this price premium. However, in industrial sectors, as yet no such mechanisms exist. Will we see a FiT for green steel or green cement, or will a market develop that regards these green products as more desirable, and enjoying a higher price, analogous to organic food perhaps? Without local or regional incentive schemes, or global agreement to prevent carbon leakage, the implementation of CO2 capture within the industrial sector will be a major challenge.

In summary, CO2 capture can make a significant impact on CO2 emissions from power generation and industrial sources. It could typically reduce CO2 emissions from a site by 90%. However, the cost and performance impact will be significant.

For power generation, other decarbonisation options may be more attractive to generators, but mechanisms such as Feed in Tariffs can incentivise investment in CO2 capture-fitted generation. For industry, a pathway to CO2 capture implementation is less clear; carbon leakage is a risk without global agreements, and creating a market for price-premium green products presents major challenges.

So, how great an impact will CCS have on global CO2 emissions – only time will tell – but we’ll certainly know by 2050!

Tony Alderson is CCS lead at Parsons Brinckerhoff

Parsons Brinckerhoff was technical adviser to both the European Commission and the UK government CCS competitions and has supported similar programmes in Australia and through the Global CCS Institute