A primer on carbon capture and storage

Energy and Climate Change Secretary Ed Miliband last week announced that no new coal plants would be built in the  UK without also including technology for carbon capture and storage (CCS). His proposal also called for up to four demonstration CCS plants to be constructed with funding from a new levy mechanism.

Touted as a way to enable continued coal-fired energy production without coal’s massive emissions of carbon dioxide, CCS has been shown to work effectively, although it’s not yet in wide enough use to have an impact on global greenhouse gas levels.

So what do you need to know about CCS? Here’s a rundown:

• It’s already happening: Vattenfall’s Schwarze Pumpe power plant in Germany is one of the first to use carbon capture, though not — technically — storage. It captures nearly 95 per cent of the carbon dioxide produced by the plant, and sells it in compressed liquid form to firms that can use it for making carbonated beverages or to increase production from declining oil wells. Two coal plants in the US have similar operations, selling their captured carbon dioxide to soda companies, or for use as dry ice or a fire extinguisher. Around the world, there are four operations — Sleipner and Snøhvit in Norway, Weyburn-Midale in Canada and Salah in Algeria — that both capture and store carbon dioxide;
• There are various means of doing it: Carbon dioxide emissions from coal plants can be captured in one of three ways: via the oxyfuel process, which involves burning coal first in pure oxygen; via chemical means that extract carbon dioxide from emissions; or via gasification, which converts coal into synthetic natural gas and carbon dioxide;
• It’s not without controversy: FutureGen, a proposed carbon capture and storage project under the Bush administration, was — according to a US congressional report — deliberately killed through inaccurate cost estimates and a focus on schemes known to be unworkable;
• Capture is one thing, storage is another: While the technology for capturing a majority of carbon dioxide emissions from coal plants is proven, making storage effective is a different matter. Unless a suitable underground site is adjacent to a coal plant, the captured carbon must be transported elsewhere — by pipeline, ship or other means — which increases CCS costs. Some environmentalists also worry about the stability of underground carbon dioxide storage: if the gas leaks over time, CCS won’t be able deliver on its promise to cut atmospheric greenhouse gas levels.
• And then there’s the energy issue: A report (PDF) from Greenpeace last year asserts that CCS technology consumes anywhere from 10 to 40 per cent of the energy produced by a power plant, meaning that “wide scale adoption of CCS is expected to erase the efficiency gains of the last 50 years, and increase resource consumption by one third.”