Optimisation of lean vapour compression (LVC) as an option for post-combustion CO2 capture: Net present value maximisation

Many process schemes have been proposed in literature to decrease the energy demand of amine based carbon dioxide processes. These process schemes are generally analysed in terms of energy demand savings and compared to a common baseline based on the solvent monoethanolamine (MEA). In this work, the application of one of these process schemes (lean vapour compression or LVC) has been evaluated and optimised based on maximising the net present value (NPV) of the process scheme savings (including capital investment), rather than minimising energy demand in the form of equivalent work. Two scenarios have been analysed. In the first scenario, the capture plant was fully adapted to the effect of LVC. In the second scenario, LVC is retrofitted to a basic capture plant design. For both scenarios the net present value (expressed in M€) of the process scheme over the whole plant life was calculated as a function of the LVC operating conditions. It was found that the NPV of the LVC process scheme is always positive and attractive from a financial point of view. The first scenario has been identified as the most attractive scenario for LVC application. Although the extent of the savings depends on design conditions and financial assumptions, this approach shows that the optimisation based on minimising equivalent work does not necessarily match the optimisation based on maximising net present value.

► Evaluation of lean vapour compression for a 250 MWe equivalent capture plant.
► Lean vapour compression maximises capture plant's net present value.
► Adapting capture plant design to LVC operation is a better option than retrofitting.