Biomass co-firing in a pressurized fluidized bed combustion (PFBC) combined cycle power plant: A techno-environmental assessment based on computational simulations

The co-utilization of coal with biomass and biomass waste in a pressurized fluidized bed combustion (PFBC) system is a promising power generation option for addressing various areas of concern relating to the anthropogenic sources of harmful emissions, the global reliance on fossil fuel and the overall energy supply issues. In this study, coal with a wide range of biomass and biomass waste types such as straw, willow chips and switch grass as well as miscanthus and olive pits are fired in an advanced PFBC system. The produced gases and the evolved heat energy are employed to run a combined cycle. To understand the behavior of the proposed system, detailed computational simulations are carried out utilizing various feedstock mixtures ranging from 100% coal to 40% biomass. The results of the simulations are used to show the effect of co-firing on the technical and environmental performance of the power plant.The results show that the main parameters affecting the overall power plant efficiency are the co-firing ratios and the specific properties of the chosen biomass/waste types. Furthermore, the investigation indicates that the steam cycle output reacts more sensitive to the fuel configurations than the gas turbine cycle. As expected, the increased fraction of biomass or waste significantly reduces net CO2 emissions, and has a beneficial influence on SOx emissions. NOx emissions tend to rise for all biomass types, except the high moisture content willow chips, with increasing co-firing fraction.