Abstract
The sense of urgency in achieving large reductions in anthropogenic CO2 emissions has increased the interest in carbon dioxide capture and storage (CCS). CCS can be defined as the separation and capture of CO2 produced at large stationary sources, followed by transport and storage in geological reservoirs, the ocean or
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minerals in order to prevent its emission to the atmosphere.
The objective of this thesis is to assess the technical possibilities, costs and risks of CCS systems to allow comparison, identify promising options and determine how and to what extent CCS could be deployed over time in the Netherlands.
In the short term, electricity can be produced with strongly reduced CO2 emissions by means of pulverised coal-fired power plants and natural gas-fired combined cycles equipped with chemical absorption units, or integrated coal gasification combined cycles integrated with a shift reactor and a physical absorption unit. Electricity production costs and CO2 mitigation costs versus an identical plant without capture are calculated at 5-7 €ct/kWh and 15-50 €/t CO2. CO2 transport and storage in depleted gas fields or aquifers typically add another 0.1-1 /ct/kWh. In the longer term, the efficiencies could be improved with 30-40%, and mitigation costs could eventually be reduced to 10-40 €/t CO2.
Hydrogen can be produced by means of large-scale steam methane reforming or coal gasification with CO2 capture from the shifted syngas, or by means of decentralised membrane reformers. The latter technology, which has been studied using Aspenplus, promises economic small-scale hydrogen production and inexpensive CO2 separation. The additional costs to induce CCS at hydrogen plants is relatively low (5-20 €/t CO2). Nevertheless, electricity production with CCS generally deserves preference as CO2 mitigation option, as the costs to replace natural gas or gasoline for hydrogen are relatively high.
CCS may play a significant role in decarbonising the Dutch energy and industrial sector, which currently emit nearly 100 Mt CO2/yr. We found that 15 Mt CO2 could be avoided annually by 2020, mainly by capturing CO2 from new coal-fired power plants. Halfway this century, the mitigation potential of CCS is estimated at 80-110 Mt CO2/yr, of which 60-80 Mt CO2/yr may be avoided at costs between 10 and 40 €/t CO2. The mitigation potential in the power sector has been estimated at 60-84 Mt CO2/yr by 2050, assuming electricity supply is doubled. Industrial sources add another 16 Mt CO2/yr. The development of a market for alternative fuels produced via syngas production with CCS creates an opportunity to decarbonise the transport sector. The reduction potential by 2050 has been estimated very roughly at 10 Mt CO2/yr for F-T diesel or H2 production with CCS.
However, truly realising these potentials will require long-term climate policy and a clear and internationally oriented vision on the organisation of CCS deployment in the coming decades. In the Netherlands, gas fields seem the most appropriate reservoirs for CO2 storage given their large storage capacity. As many reservoirs will be abandoned before 2025, a strategy must be developed to assure sufficient storage capacity will be available in the spring of a potential CCS era. Not all reservoirs will be suited for CO2 storage due to an array of geological constraints, in particular the risk of CO2 leakage through abandoned wells, faults and fractures. Although the mechanisms of CO2 leakage are fairly well understood, quantifying leakage rates is still a challenge. In addition, underground gas storage may become a serious 'competitor' with underground CO2 storage, especially when the Netherlands becomes an international gas hub. When large CO2 reductions are required, we may have to rely on the Groningen gas field, or the mega reservoirs in the British or Norwegian part of the North Sea.
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