Life cycle analysis of power cycle configurations in bioenergy with carbon capture and storage

Abstract

Bioenergy with carbon capture and storage (BECCS) has been proposed as a promising negative emission technology even though questions remain about the most effective ways to deploy it at large scale. Here, a comparative life cycle analysis of power plant configurations was conducted to understand the effect of three design parameters: (1) centralized versus decentralized siting and size of power plants; (2) steam versus supercritical CO2 (sCO2) working fluids in the turbine; and (3) water versus air cooling of the power cycle. These parameters can be combined to create pathways for delivering BECCS that would leverage the distributed nature of biomass generation in the landscape and the potential to use sCO2 power cycles, which have a higher efficiency, smaller footprint, and greater potential for dry cooling than steam turbines. The performance of the pathways was assessed in terms of energy use, global warming potential, land use, and water use. The results suggest that centralized plants tend to have lower environmental impacts than decentralized plants because the higher efficiencies of larger plants offset the lower environmental burdens of having to transport the biomass. A sCO2 power plant with tower cooling offered the best solution with respect to energy use, land use, and water use. Model results suggest that the least efficient power plant stored the most CO2. To capture the dual benefits of bioenergy with carbon capture and storage, an aggregate metric that combines net energy production and CO2 storage potential is proposed and the results are interpreted using this new metric. A sensitivity analysis reveals the parameters, such as biomass energy density and CO2 capture efficiency that most directly impact the performance of the BECCS life cycle.