Life-Cycle Environmental and Economic Assessments of the Oxy-coal Combustion System Combined with a Pressurized Circulating Fluidized Bed and the Supercritical CO₂ Brayton Cycle

Abstract

Oxy-coal combustion with circulating fluidized bed (OCFB) is a promising technology for CO 2 capture and sequestration. However, its development is highly hindered by the high price of electricity and CO 2 capture. In this work, a comprehensive life-cycle environmental and economic assessment of OCFB power plants with a pressurized combustor (POCFB) and a supercritical CO 2 Brayton cycle is conducted using a specific life-cycle assessment (LCA) method. There are four processes evaluated in this work, including construction material production, transport, raw material mining, and power plant operation. Both environmental midpoint and endpoint impacts are derived and compared. The results show that compared to the oxy-coal combustion power plant, systems with a pressurized combustor and a S-CO 2 Brayton cycle have less damage (6−12%) to the human health and the environment. Meanwhile, compared to the OCFB power plant, POCFB has relatively lower costs of electricity, CO 2 capture, and CO 2 avoidance, which are 58.1 USD/MWh, 15.5 USD/t, and 33.4 USD/t, respectively. The results from the Analytic Hierarchy Process-Technique for Order Preference by Similarity to Ideal Solution methodology show that comprehensively considering the economy, resource, and environment, the POCFB power plant is the best option among the cases from the perspective of residents and the government. The influence of several parameters including net electricity efficiency, CO 2 capture rate, boiler investment, coal price, and CO 2 tax on the economic indicators is also discussed.