Many studies have quantified the cost of Carbon Capture and Storage (CCS) power plants, but
relatively few discuss or appreciate the unique value this technology provides to the electricity system.
CCS is routinely identified as a key factor in least-cost transitions to a low-carbon electricity
system in 2050, one with significant value by providing dispatchable and low-carbon electricity.
This paper investigates production, demand and stability characteristics of the current and future
electricity system. We analyse the Carbon Intensity (CI) of electricity systems composed of unabated
thermal (coal and gas), abated (CCS), and wind power plants for different levels of wind
availability with a view to quantifying the value to the system of different generation mixes. As a
thought experiment we consider the supply side of a UK-sized electricity system and compare the
effect of combining wind and CCS capacity with unabated thermal power plants. The resulting
capacity mix, system cost and CI are used to highlight the importance of differentiating between
intermittent and firm low-carbon power generators. We observe that, in the absence of energy
storage or demand side management, the deployment of intermittent renewable capacity cannot
significantly displace unabated thermal power, and consequently can achieve only moderate
reductions in overall CI. A system deploying sufficient wind capacity to meet peak demand can
reduce CI from 0.78 tCO2
/MWh, a level according to unabated fossil power generation, to 0.38
tCO2
/MWh. The deployment of CCS power plants displaces unabated thermal plants, and whilst
it is more costly than unabated thermal plus wind, this system can achieve an overall CI of 0.1
tCO2
/MWh. The need to evaluate CCS using a systemic perspective in order to appreciate its
unique value is a core conclusion of this study.