Weighting of environmental trade-offs in CCS—an LCA case study of electricity from a fossil gas power plant with post-combustion CO2 capture, transport and storage

PurposeCarbon capture and storage (CCS) is increasingly acknowledged as a potent global warming abatement option. It is demonstrated that whilst the global warming potential (GWP) decreases, the other environmental impact category potentials often increase in a life cycle perspective. Despite this, only a few studies clearly address this trade-off or use weighting to compare the positive and negative effects of CCS. The present life cycle assessment (LCA) study focuses, therefore, on presenting several environmental indicators and on weighting the inventory results in order to ascertain which of the analysed systems is to be preferred.MethodThe case studied is a projected gas power plant at Tjeldbergodden (Norway), where it is proposed to include post-combustion CCS. Four main scenarios have been analysed, one without and three with CCS. The principal variation between the CCS scenarios is that the steam required for amine regeneration is produced in three different ways: in a separate gas fuelled steam boiler; in a separate biomass fuelled steam boiler; and delivered from the low-pressure steam turbine in the power plant. Design information and technical specifications have been available. The study has used LCA methodology based on the ISO standard 14044, SimaPro 7.3.2.4 software and the Ecoinvent 2.0 database. The functional unit is 1 TWh electricity delivered to the grid. The following environmental impact categories have been included: GWP, acidification potential, eutrophication potential, photochemical ozone creation potential (POCP) and cumulative energy demand (CED). Three weighting methods have been used to ascertain the robustness of the weighting results: ReCiPe, EPS 2000 and IMPACT 2002+.Results and discussionThe characterisation results show that the CCS scenarios have reduced impacts only in the case of GWP. The weighting demonstrates that in the ReCiPe model, climate change is strongly in focus, whilst in EPS 2000, human health and depletion of reserves are dominant. Climate change is also an important factor in IMPACT 2002+, together with effects on human health (respiratory inorganics). The process integration scenario has, however, the best result for all three weighting models. This contrasts with the results from the impact analysis where four of the five analysed impact categories rated the CCS-3 scenario as worse than the reference scenario. One possible option for improving the biofuel boiler scenario is to capture the CO2 from the combustion of biomass in the external steam boiler. This would not, in all probability, affect the acidification, eutrophication, POCP and CED to any significant degree, but the GWP, and hence the ReCiPe and the IMPACT 2002+, weighting results could be expected to improve.ConclusionsThe weighting exercise has identified toxicity as a concern with regard to the biofuel boiler scenarios (CCS-2) and human health issues as having importance for the CCS-3 scenario. It would seem that process integration is a better CCS option than that of CCS providing steam from a separate steam boiler (without CCS), even where this boiler is biomass-fuelled. Any future analysis should focus both on the process integration scenario and the biofuel boiler scenario with CCS of biological CO2.

[1]  B. Metz.  IPCC special report on carbon dioxide capture and storage , 2005 .

[2]  Henrikke Baumann,et al.  The hitch hiker's guide to LCA : an orientation in life cycle assessment methodology and application , 2004 .

[3]  Bart W. Terwel,et al.  Going beyond the properties of CO2 capture and storage (CCS) technology: How trust in stakeholders affects public acceptance of CCS , 2011 .

[4]  Joris Koornneef,et al.  Life cycle assessment of a pulverized coal power plant with post-combustion capture, transport and storage of CO2 , 2008 .

[5]  Rolf Frischknecht.  The ecoinvent Database - Reply to the Letter to the Editor of Schmidt & Jensen [Int J LCA 10 (2) 97] , 2005 .

[6]  Manfred Fischedick,et al.  Comparison of carbon capture and storage with renewable energy technologies regarding structural, economic, and ecological aspects in Germany , 2007 .

[7]  Bert Metz,et al.  Carbon Dioxide Capture and Storage , 2005 .

[8]  R. Frischknecht.  ecoinvent Data v1.1 (2004): From heterogenous databases to unified and transparent LCI data , 2005 .

[9]  Gerald Rebitzer,et al.  IMPACT 2002+: A new life cycle impact assessment methodology , 2003 .

[10]  Andrea Ramírez,et al.  The impact of CO2 capture in the power and heat sector on the emission of SO2, NOx, particulate matter, volatile organic compounds and NH3 in the European Union , 2010 .

[11]  Tim Cockerill,et al.  Life cycle GHG assessment of fossil fuel power plants with carbon capture and storage , 2008 .

[12]  Frédérique Bouvart,et al.  Comparison of life cycle GHG emissions and energy consumption of combined electricity and H2 production pathways with CCS: Selection of technologies with natural gas, coal and lignite as fuel for the European HYPOGEN Programme , 2009 .

[13]  Edgar G. Hertwich,et al.  Life-cycle Assessment of Carbon Dioxide Capture for Enhanced Oil Recovery , 2008 .

[14]  Hans-Jörg Althaus,et al.  The Environmental Relevance of Capital Goods in Life Cycle Assessments of Products and Services , 2007 .

[15]  Edgar G Hertwich,et al.  Human and environmental impact assessment of postcombustion CO2 capture focusing on emissions from amine-based scrubbing solvents to air. , 2010, Environmental science & technology.

[16]  Sevket Durucan,et al.  Life cycle modelling of fossil fuel power generation with post-combustion CO2 capture , 2009 .

[17]  Andrea Ramírez,et al.  The impacts of CO2 capture on transboundary air pollution in the Netherlands , 2009 .

[18]  Pushpam Kumar.  Agriculture (Chapter8) in IPCC, 2007: Climate change 2007: Mitigation of Climate Change. Contribution of Working Group III to the Fourth assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[19]  Bengt Steen,et al.  A Systematic Approach to Environmental Priority Strategies in Product Development (EPS) Version 2000-General System Characteristics , 1999 .

[20]  P. Folger.  Carbon Capture and Sequestration (CCS) , 2009 .

[21]  Aie,et al.  CO2 Capture and Storage: A Key Carbon Abatement Option , 2008 .

[22]  Ola Eiken,et al.  Storage of CO2 in saline aquifers–Lessons learned from 10 years of injection into the Utsira Formation in the Sleipner area , 2009 .