CCS has long been recognised as a key component of an effective mitigation strategy to decarbonise the power and industrial sectors. Commercial deployment of the technology, however, has been slow and must accelerate if it is to achieve its potential and contribute effectively to mitigating climate change. Accordingly, much effort has been focused on improving its techno-economic performance, not least the performance of fossil-fired power plants with CO2 capture.
In this study, the techno-economic impacts of recent developments and improvements made to core components and system designs for both ultra-supercritical pulverised coal (USC PC) and natural gas combined cycle (NGCC) power plants with CO2 capture were examined. Techno-economic benchmarks were updated and, in line with latest findings, the impact of markedly increasing the capture rates to achieve near-zero CO2 emissions was investigated. Post combustion capture based on solvent scrubbing, currently the commercially leading option for capture on both pulverised coal and natural gas-fired power plants, was the technology of choice. The study also looked at improvements to the flexible operation of plants, the impact of efficiency improvements in USC PC and NGCC power plants, and the benefits of flue (or exhaust) gas recirculation in natural gas-fired plants.
Most previous techno-economic studies, including those commissioned by IEAGHG, have capped the CO2 capture rate at 90%. However, a recent IEAGHG study has established that the 90% cap in capture rate ubiquitously adopted by most in the energy community is, in fact, an artificial cap. There are no technology barriers to prevent operation at capture rates consistent with net zero CO2 emissions. This is important because, in the longer term, residual emissions from a 90% capture rate will not be compatible with the level of reductions needed to achieve the aims of the Paris Agreement. This is because, in a net-zero world, the residual emissions will also have to be mitigated.
It is essential that the broader energy and financial communities understand this potential in an environment where yet more stringent demands will be made on technologies to meet the challenge of climate change. Findings from this study show that, for both NGCC and USC PC plants, increasing the CO2 recovery from 90% to much higher capture rates yields but modest increases in both LCOE and CAC. Reducing CO2 emissions by a factor of 10 or thereabouts increases the LCOEs, relative to the 90% cases by just 5% (NGCC) and 8% (USC PC), and the CACs by 5% (NGCC) and 4.3% (USC PC). While these results are very promising, it is now important that these findings are tested in practice, i.e. in CCS plants at scale.
Further findings from the study show, for example, that flue gas recirculation leads to substantial savings in the CAPEX and OPEX of the capture unit, revealing it to be an effective option to reduce costs associated with CO2 capture on NGCC plants.