Carbon capture, ocean fertilisation and offsets trading (part 1)

The following is based on notes I made during a seminar on carbon capture held at the Royal Society in London on 5 December 2007…

At the beginning of December I attended a very interesting seminar held at the headquarters of the Royal Society in London. At the meeting, a number of scientific experts, introduced by Secretary of State for the Environment Hilary Benn, spoke about various aspects of carbon capture technologies: geology, biology and managing fossil fuel resources.

There follows a report of the seminar, together with some personal comments. The report is lengthy, so I shall break it up into separate posts published over a number of days.

A sample of serpentinite rock, partially made up of chrysotile

After all the political hot air emitted over technical fixes to global warming, it was refreshing to hear scientists talk technics. There were a number of other journalists in attendance, but from what I can see, and what Google tells me, the event was little reported in the media.

For a politician, Benn was both focused and informative, and he outlined both the current situation in general, and government policy in particular. Benn spoke of temperature increases and GDP costs, five year carbon budgets, 2020 and 2050 targets, and whether we could raise our carbon dioxide reduction target to the 80% quoted by various environmental lobby groups.

Carbon Capture and Storage (CCS) is currently the main technology under consideration, said Benn. The minister stressed, however, that we need to prove the whole chain on a commercial scale before implementing the technology in earnest. Benn spoke also about retrofitting devices that filter carbon dioxide from the exhaust of existing power stations, and how this could be mandated once the technologies in question had been proven.

Less clear in Benn’s talk was the reference to China and India, and in particular the near-Zero Emissions Coal Project (nZEC). So far this seems to be a political initiative, with virtually nothing in the way of technical detail and engineering planning.

Of the three scientists presenting at the seminar, geophysicist Professor Peter Styles of Keele University was the first to speak. Styles first noted that we already store hydrocarbons in the ground, and that pumping in carbon dioxide could re-pressurise wells and improve the extraction of remaining reserves. He says that 500 years of UK carbon emissions could be stored in our aquifers, and he made reference to carbon dioxide being pumped into un-mineable coal seams to produce methane by chemical reaction.

Style’s talk focused largely on geochemistry. He identified absorbent minerals such as serpentinite, which can bind carbon dioxide to itself, locking it in permanently. The chemistry here is well understood, but the reaction that occurs in nature takes place over aeons. What we are talking about now is accelerating this by pumping carbon dioxide into the rocks to a depth of 500 metres. At this point the gas becomes supercritical, and hence can diffuse through rocks and dissolve over a relatively short time. It is certainly an interesting idea, but Styles cautioned that ‘chemisorption’ will be limited by suitable geology.

Examples of enhanced oil recovery pilot schemes identified by Styles include BP’s Miller Field, located 240 km offshore from Peterhead in Scotland, and the Shell-Statoil Draugen field in the Norwegian sector of the North Sea.

The Draugen scheme was deemed to be “not commercially defensible”, and the Miller Field project was abandoned after the UK government decided that all carbon capture schemes had to compete for state support in a process that would not reach a decision until 2010. BP was actually looking for a reduced royalty rate rather than direct funding and tax relief, but the end result was the same. The company decided that it could not afford to proceed with the project.

Other technologies referred to by Styles include Enhanced Coal Bed Methane (ECBM) and Underground Coal Gasification (UCG). In ECBM, carbon dioxide is pumped into a coal seam to displace methane gas, which is then extracted and used as a fuel. With UCG, coal seams are ignited in-situ, releasing carbon dioxide and methane gases which are then collected.

There is much interest in these technologies in China and India, and Asian researchers and energy companies are developing them independently of the west.

Styles notes that one barrier to the adoption of these technologies in this part of the world is the lack of a renewables obligation for methane production and extraction from old coal mines. And it could take many years before the technologies are proven and implemented on a large scale.

So where does this fit in with our carbon emissions targets and the the timescales set by climate scientists? From what I can see it doesn’t, hence my continued doubts about carbon capture technologies in general.

Discussions have so far tended to be compartmentalised into science and technology on the one hand, and politics and economics on the other. In that respect the Royal Society seminar was little different, but it was primarily a scientific seminar, and the participants displayed a degree of technological realism and political awareness I have not seen elsewhere.

To be continued… (see part 2; part 3)