Carbon capture considerations for combined cycle gas turbine.

Abstract: In the UK, the Committee of Climate Change (CCC) concluded that in order to meet the 80% emission reduction target set for 2050, the power sector would need to be largely decarbonised by 2030. As the emission reduction required by 2030 is substantial, it is likely to require contributions from renewable, nuclear and CCS. By 2030, any plant running for extended periods will probably have to be able to achieve annual average emissions levels of 100 gCO₂/kWh or below vs. the present level of 560 gCO₂/kWh. In this context, the new regulations by Department of Energy and Climate Change (DECC) for making power plants CO₂ capture ready apply to all combustion plants at or above 300 MW output in the UK. As emissions levels for new built CCGT plants without carbon capture are today around 350 kgCO₂/MWh, it is expected that they will not be able to operate without CCS beyond 2030. In order to avoid the deployment of ‘unabated’ gas-fired plants, requirements to fit CCS not only to coal but to gas-fired plants need to be adopted to prevent any inconsistency. Once built, it would be very costly or even infeasible to retrofit the new facilities with CCS, thus “locking-in” many years of CO₂ emissions. Currently in the UK there are no new unabated coal plants under construction, whilst around 4.7 GW of new gas plants are expected to come online over the next few years. As in the UK there are a significant number of CCGT power stations recently permitted or waiting to be granted consent they have been required to be CCR so that CCS can be retrofitted once it is commercially viable. It is therefore of a paramount importance to understand what are the feasible options/issues when CO₂ capture is applied to the CCGT units. This paper is focusing on capture consideration based on post-combustion technology, the most mature option today. When a CCGT plant is designed to be ready for retrofit one of the most important technical consideration is the steam extraction pressure and flow to provide the energy necessary for solvent regeneration as this will have a large impact on the overall plant efficiency. Available options for steam and electricity supply to meet the requirements of the CCS process have been assessed, focusing on two scenarios–integration scenario where the steam is supplied from the main plant and separate generation scenario where steam is supplied from auxiliary boilers with electricity supplied from the grid connection. The findings of this paper are relevant to project developers, power generators and policymakers internationally who have an interest in the potential for CCS to provide an emissions abatement option for the new CCGT assets in the long term. [Copyright &y& Elsevier]