Optimal Design of Integrated Power Generation and CO2 Capture Systems

There have been extensive efforts to date related to the design and optimisation of CO₂ capture processes in isolation. However, very little work has been performed on the evaluation of CCS from integrated power plants and CO₂ capture processes. To improve the overall efficiency, increased process integration of the power generation process and capture process is required. Furthermore, it is well known that CCS from gas-fired power-plants presents a very different challenge to CCS from coal-fired power-plants.

Insights regarding the integrated plant operation can be provided through dynamic modelling and simulation. In this study, we present novel dynamic models of both decarbonised coal- and gas-fired power plants which account for the various transients associated in the power generation process. Sub-critical plants are considered as the dynamics of their operation are of more interest than those of the super-critical plants. Owing to its technological maturity, the decarbonisation technology of choice is post-combustion CO₂ capture using amine-based chemisorption. Detailed mass and energy balances were performed for each of the sub-models. All sub-models and their integration are implemented in gPROMS, and finally a generic system modelling framework is developed to study the performance and cost implications.

Based on a rigorous whole system analysis, the interaction of CO₂ capture level and power plant output control are investigated. The cost-optimal degree of CO₂ capture from both kinds of power station are also determined. In solving this optimisation problem, we account for the time-varying value of electricity as well as market prices associated with CO₂ emissions. Moreover, an objective function is proposed which maximises the revenue stream associated with energy production whilst simultaneously minimising the CO₂ emitted to atmosphere.