CO2 capture from syngas generated by a biomass gasification power plant with chemical absorption process

Abstract

In the context of the climate changes and to improve people's life, solutions for reducing the amount of CO2 emissions into the atmosphere from the energy sector are being sought after. One of the solutions is to produce a greater part of the global energy requirement from renewable energy sources. Nowadays, biomass is one of the most easily available renewable energy sources. The biomass gasification is a technology which presents several important advantages of the bioenergy in terms of producing heat, power and biofuels for useful applications. In this article, the biomass gasification with the CO2 capture technology (BIGCC + CAP) by using an aqueous monoethanolamine solution was studied for converting the treated syngas into electricity in a combined cycle power plant. The biomass gasification can be done using either air or oxygen in order to improve the quality of the syngas produced. However, only the gasification with air was studied in this research due to the large energy consumption in the ASU (air separation unit) unit for oxygen separation. Thus, the CO2 post-combustion capture by the chemical absorption technology was studied to determine its effects on the performances of a gas turbine power plant with an HRSG (Heat Recovery Steam Generator) with a total installed power of 10 MW. In order to increase the performances of the combined cycle, the exhaust gases are supplementary used in an HRSG unit in order to produce steam for the steam turbine, with an installed power of 4 MW. The chemical solvent used for the CO2 capture separation was monoethanolamine with a concentration of 30 wt. %, considering a CO2 capture efficiency of 90%. The thermal heat required for the solvent regeneration is provided by the steam extracted from the low pressure steam turbine. To reduce the thermal energy requirement for the chemical solvent regeneration, an HRSG unit was used to recover the heat from the syngas. Thus, the overall efficiency was reduced from 50.9% to 45.8% in the case without the HRSG unit and to 47.03% in the case with the HRSG unit. By comparing the BIGCC + CAP with and without the HRSG unit, the lowest value of the LCOE was obtained for the BIGCC + CAP + HRSG, and was found to be 77.56 €/MWh.