Life cycle assessment of co-firing coal and wood waste for bio-energy with carbon capture and storage – New South Wales study

Abstract

Bio-Energy with Carbon Capture and Storage (BECCS) is an emerging energy conversion technology with the potential to deliver ‘negative emissions’, a net removal of CO2 from the atmosphere that may be necessary to achieve the net-zero targets adopted in the Glasgow Climate Pact at COP26. This paper uses Life Cycle Assessment (LCA) to investigate the environmental impacts of co-firing dry waste biomass (wood and paper waste) while implementing CCS technology (i.e., BECCS) in a conventional black coal-fired power plant. The LCA covers CO2 emissions and trace contaminants, determined via combustion modelling coupled with chemical-equilibrium-based ash-forming element and trace element calculations. As a case study, the context of New South Wales, Australia, is analysed to assesses the viability and discuss policy implications of waste co-firing BECCS as a future energy source for coal-reliant regions. An increase in co-firing ratio is found to decrease emission intensity. At current typical efficiencies, BECCS with a 10 % co-firing ratio can reduce emission intensity from 938 to 181kgCO2/MWh. At 20 % to 25 % co-firing, the emission intensity of BECCS is comparable with other renewable technologies, and negative emissions are achievable above 30 %, although waste availability in NSW is insufficient to achieve these levels. Moreover, BECCS increases environmental impact in all categories except for global warming potential (GWP), land use, and terrestrial acidification. Nonetheless, when aggregating all impacts, the large reduction in GWP drives an endpoint score reduction, indicating that co-fired BECCS may be preferred over sub-critical black (bituminous) coal-fired power without or with CCS, or other higher emission intensity coal-fired power generation. Therefore, policy makers should consider incentivising waste co-firing BECCS as part of future energy policies towards achieving the net-zero targets, weighing its benefits against other environmental impacts, waste availability and competition with recycling initiatives.