Seeker Blog

I am happy to see a growing number of full life-cyle studies of energy supply alternatives. An outstanding example is this Australian study of the nuclear energy cycle {an input-output-based life-cycle assessment (IO-LCA)} . A just-published study by a Utrecht University team examines the full impact of CCS, i.e., carbon capture and sequestration: Life cycle assessment of a pulverized coal power plant with post-combustion capture, transport and storage of CO2.

For three pulverized coal supply chains, the bottom line is that CO2 emissions are reduced some 71 to 78% while some other emissions like nitrogen oxides and sulfur oxides are higher up to 40% higher. The study is not a “CSS is a bad idea” paper, but demonstrates the environmental tradeoffs involved in most energy policy choices.

Life cycle assessment is a seriously complicated undertaking, so this will not be good bedtime reading — the article is not free. The abstract:

In this study the methodology of life cycle assessment has been used to assess the environmental impacts of three pulverized coal fired electricity supply chains with and without carbon capture and storage (CCS) on a cradle to grave basis. The chain with CCS comprises post-combustion CO2 capture with monoethanolamine, compression, transport by pipeline and storage in a geological reservoir. The two reference chains represent sub-critical and state-of-the-art ultra supercritical pulverized coal fired electricity generation. For the three chains we have constructed a detailed greenhouse gas (GHG) balance, and disclosed environmental trade-offs and co-benefits due to CO2 capture, transport and storage. Results show that, due to CCS, the GHG emissions per kWh are reduced substantially to 243 g/kWh. This is a reduction of 78 and 71% compared to the sub-critical and state-of-the-art power plant, respectively. The removal of CO2 is partially offset by increased GHG emissions in up- and downstream processes, to a small extent (0.7 g/kWh) caused by the CCS infrastructure. An environmental co-benefit is expected following from the deeper reduction of hydrogen fluoride and hydrogen chloride emissions. Most notable environmental trade-offs are the increase in human toxicity, ozone layer depletion and fresh water ecotoxicity potential for which the CCS chain is outperformed by both other chains. The state-of-the-art power plant without CCS also shows a better score for the eutrophication, acidification and photochemical oxidation potential despite the deeper reduction of SOx and NOx in the CCS power plant. These reductions are offset by increased emissions in the life cycle due to the energy penalty and a factor five increase in NH3 emissions.

The MIT Future of Coal study concluded that it is critical to fast-track CCS at industrial scale. We need to know how well it works, and what it really costs. By “we” I really mean those making the new plant investment decisions — notably U.S., Chinese, Indian and Brazilian utility executives. It is those decisions that continue to drive new dirty-coal plant startups every week. And if CCS looks uneconomic we will have to drastically rethink our way to a low-carbon economy — making nuclear even more attractive.