Biomass burning in a fluidized bed with the possibility of obtaining hydrogen with partial CO2 removal

Abstract

An analysis of CO₂ capture and storage technologies resulting from processes in which biomass is converted to energy or used to produce materials (BECCS) was made. It is shown that they will be widely used after 2030. The issues of biomass combustion in a circulating fluidized bed (CFB) are considered, including combustion in an oxygen environment with CO₂ recirculation, which can provide carbon neutrality. The issues of obtaining hydrogen by various methods are considered, their comparison in terms of cost and carbon footprint is given. It is noted that the production of "green" hydrogen by electrolysis from wind and solar energy is hardly justified in the conditions of Russia. Therefore, it is of interest to study the possibility of using electricity from the steam cycle when burning biomass as a renewable energy source. Calculations were made according to our own methods and the results of calculations of a plant with hydrogen production using a CFB boiler with a steam output of 100 t/h are presented. Two variants of biomass are considered - chips and pellets. The boiler was designed for air combustion, oxygen combustion with CO₂ recirculation and variants with the addition of oxygen from the electrolyser at 50% and 100% of the generated electricity supply. The parameters of the boiler and the consumption of hydrogen and oxygen in these options are determined. A Levelized Life Cycle Cost of Hydrogen (LCOH) evaluation has been performed, showing that the proposed carbon neutral plant provides a levelized cost value at the lower end of existing plants with renewable electrolysis. Calculations have shown that when switching to full oxygen combustion with a payment for emissions of 30 USD/t CO₂ LCOH, there will be about 2 USD/kg of hydrogen. Such a BECCS project will be quite promising. It is shown that the indirect carbon footprint for the proposed plant is 0.38 - 0.95 kg/kg and certainly meets the requirements for low-carbon hydrogen (carbon footprint less than 4.4 kg/kg).