Techno-Economic Assessment of Four CO2 Storage Sites
Résumé
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.
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.
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