Techno-economic assessment of the CO2 value chain with CCUS applied to a waste-to-energy Italian plant

Abstract

Recently, post-combustion CO2 removal has been considered also for the CO2 separation from the flue gases of Waste-to-Energy (WtE) plants, that manage high amounts of Municipal Solid Waste (MSW) by combusting it and generating power and heat. Moreover, because of the presence in MSW of an organic waste fraction, net negative CO2 emissions are feasible when integrating CCUS systems into WtE plants. Currently, to the best of the authors’ knowledge, there are only few incineration plants around the world that are successfully coupled with a carbon capture system, resulting in near-zero (or even negative) CO2 emission power generation.This work focuses on the evaluation of the whole value chain of the non-biogenic CO2 that is emitted in a power plant located in Northern Italy and on its possible utilization, from the CO2 source in the flue gas to the market-ready product.The design of the process for the CO2 removal from the flue gas has been carried out specifically for the considered flue gas to be treated with an aqueous solution of MonoEthanolAmine 30% wt., the benchmark solvent used in other types of power plants (fuelled by coal and natural gas). The main process parameters (e.g., lean loading, absorber packing height, regenerator packing height, regenerator pressure, gas inlet temperature, solvent inlet temperature) have been selected in order to optimize the reboiler duty and the water requirement, the latter being usually not considered in literature works dealing with this type of analysis. Then, the CO2 utilization has been evaluated, considering the options of both sequestration in the Adriatic Sea and utilization of CO2 for production of sodium bicarbonate, on the basis of the information available in the literature.In compliance with Directive 2003/87/EC and with the Italian legislation, Waste-to-Energy plants that treat municipal solid waste are currently exempt from the application of the CO2 Emissions Trading System (ETS). This article speculates about the application of the ETS to an urban WtE plant, located in Northern Italy, and evaluates its economic implications by comparing the purchase of emission quotas with the construction of a CCS or CCU plant.A business plan, detailing the obtained revenues from the utilization and from the avoided cost of purchasing emission allowances and the expenses related to the operation of the carbon capture plant, taking into account the taxes and the inflation, has been created and used for comparing the two considered CO2 value chains. For the option of CO2 sequestration, sensitivity analyses on the variation of investment costs (+10 %), operating costs (+10 %) and revenues (−10 %) have been performed and the breakeven value of the ETS certificate that can make the Net Present Value (NPV) non-negative has been determined. For the option of CO2 utilization, the revenue from sodium bicarbonate that can make its production profitable has been evaluated.