Techno-Economic Assessment of Four CO2 Storage Sites

Abstract

Carbon Capture and Storage (CCS) should be a key technology in order to achieve a decline in the CO2 emissions intensity of the power sector and other intensive industry, but this potential deployment could be restricted by cost issues as the International Energy Agency (IEA) in their last projections (World Energy Outlook 2013) has considered only around 1% of global fossil fuel-fired power plants could be equipped with CCS by 2035. The SiteChar project funded by 7th Framework Programme of European Commission gives the opportunity to evaluate the most influential parameters of techno-economic evaluations of four feasible European projects for CO2 geological storage located onshore and offshore and related to aquifer storage or oil and gas reservoirs, at different stages of characterization. Four potential CO2 storage sites have been assessed in terms of storage costs per tonne of CO2 permanently stored (equivalent cost based). They are located offshore UK, onshore Denmark, offshore Norway and offshore Italy. The four SiteChar techno-economic evaluations confirm it is not possible to derive any meaningful average cost for a CO2 storage site. The results demonstrate that the structure of costs for a project is heterogeneous and the storage cost is consequently site dependent. The strategy of the site development is fundamental, the technical choices such as the timing, rate and duration of injection are also important. The way monitoring is managed, using observation wells and logging has a strong impact on the estimated monitoring costs. Options to lower monitoring costs, such as permanent surveys, exist and should be further investigated. Table 1 below summarizes the cost range in Euro per tonne (Discount Rate (DR) at 8%) for the different sites, which illustrates the various orders of magnitude due to the specificities of each site. These figures have how to be considered with care. In particular the Italian and Norwegian sites present very specific features that explain the high estimated costs. For the Italian site, the short duration of CO2 injection associated with a low injection rate makes the CO2 project comparable to a demo project. The Norwegian site is an offshore site located in a virgin area with high infrastructure costs and a combination of injection duration and injection rate that makes the derived costs very sensitive to the discount rate. Table 1. Summary of the cost range in Euro per tonne (discount rate at 8%) €/t CO2 Equivalent storage cost at 8% DR Injectivity (Mt CO2/year) Injection duration (year) Base case Base case Base case UK 11.4 5 20 Denmark 3.2 1.5 40 Norway 26.6 1 40 Italy 29 1 10 The results for both UK and Danish sites confirm therefore the value range calculated by the European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP). The main uncertainties in the costs are linked both to the choice of economic parameters (e.g. injected quantities, contingencies) and to the technical choice of operations. This has been studied by sensitivity analyses: for example, if an injection rate is halved and the injection duration is doubled, the Equivalent Storage Cost (ESC) increases by 23% (UK case at 8% DR). Introducing a water production well and water treatment facilities also increases the ESC by 23%, at least on an onshore site. Techno-economic assessments were basically carried out using an 8% discount rate. For projects of long lifetime such a rate severely discounts the late cash flow, especially after 40 years, so that a discount rate of around 4% more in logic of public investment. Compared to other studies, it has to be noted that the scope of the SiteChar analysis does not consider compression and pumping cost, nor transportation cost. This simplifies the techno-economic evaluation but it may not adequately reflect the specific conditions of the individual developments and, hence, distort the comparison between different cases. Lastly, techno-economic evaluation poses questions to policy makers about the real lifetime of a CO2 storage project: what should be the abandon phase and the associated cost and what is the real value of the liability transfer after 20 years of storage? This issue is still an open question, which has been addressed in SiteChar assuming the same approach as ZEP (2011). To counterbalance these CO2 storage costs, policy makers have to set up incentives, either through ETS (Emission Trading System) credits, tax credits or public funding. To improve the commerciality of CCS, Enhanced Oil Recovery (EOR) should be taken into account in the regulation of CCS, as it is one of the rare sources for revenue from a commodity with a real market value. CO2 storage in a saline aquifer close to oil and gas fields could also be considered as a source for CO2 EOR.