Capturing carbon dioxide in China
Preliminary geological surveys suggest there may be potential for ‘significant [onshore] storage in Chinese basins for carbon dioxide’, says Dr Mike Stephenson, Head of Science for Energy at the British Geological Survey (BGS).
His comments follow a conference held in Nottingham, UK, from 10-12 February, presenting the first technical assessments as part of the COACH (Cooperation Action within Carbon Capture and Storage China-EU) project, as well as the Near Zero Emissions from Coal (NZEC) initiative, established in 2007. The BGS is a key European partner in both programmes, collaborating with geologists from Chinese universities.
Stephenson says, ‘In parts of northeast China, coal power generation capacity is increasing at an amazing rate. China is now the largest carbon dioxide emitter. It does not matter what we in the developed world do [to reduce emissions] if we do not help the big emitters – China, Brazil, India and Russia – do the same’.
The BGS is lending its expertise in estimating the carbon dioxide storage volume of different geological formations in China. The aim is to produce an ‘inventory’ of space available in old or depleting oil fields, naturally occurring underground brine, and unmineable coal, where most basins comprise sandstone. Accurate calculations of the porosity between the particles of sand is vital.
‘You need to take into account that there might be other minerals that reduce the volume, and also the permeability. If the pores are not connected, they will not take the carbon dioxide,’ explains Stephenson.
One of the main conclusions of the research so far in China is that the reservoirs of porous rocks are compartmentalised, containing numerous faults in them. This may pose technical difficulties. ‘We are used to dealing with them in the North Sea, but in those days we were sucking oil and gas out, now we are putting gas in,’ says Stephenson.
Furthermore, he adds, that ‘the big scientific question in carbon capture and storage (CCS)’ is what will happen to carbon dioxide in brine aquifers – will it leak or rise to the surface, and how will this be detected?
The conundrum, says Stephenson, is that ‘brine aquifers are enormous, but they are not as well known as depleted oil and gas fields’, where capacity is not as large.
The conference in Nottingham enabled geologists from China and Europe to exchange ideas about the potential for CCS in China.
The next stages will involve obtaining more detailed estimates about storage capacity, with the eventual view, as part of NZEC, of establishing a demonstration CCS plant in China by 2014.
Having identified storage options, there is a long series of site-specific surveys ahead to ensure investor confidence in what is an expensive technology. Site studies will explore where to drill wells, how to handle and inject of carbon dioxide, as well as how to monitor the rock surface.
Furthermore, the appropriate legal, financial and societal frameworks in China need to be examined so that a large-scale demonstrator has public acceptance.
‘It’s early days,’ notes Stephenson.
Further information: COACH and NZEC