An ecological and economic assessment of absorption-enhanced-reforming (AER) biomass gasification

Highlights: • Analysis of biomass gasification with new absorption enhanced reforming technology. • Energy- and mass balances for three different process configurations to produce heat, SNG and/or hydrogen. • Ecological (based on LCA) and economic (based on production costs) assessment of the technology. • Comparison of results with existing operational plants producing similar products. - Abstract: Biomass gasification with absorption enhanced reforming (AER) is a promising technology to produce a hydrogen-rich product gas that can be used to generate electricity, heat, substitute natural gas (SNG) and hydrogen (5.0 quality). To evaluate the production of the four products from an ecological and economic point of view, three different process configurations are considered. The plant setup involves two coupled fluidized beds: the steam gasifier and the regenerator. Subsequently the product gas can be used to operate a CHP plant (configuration one), be methanised (configuration two) or used to produce high-quality hydrogen (configuration three). Regarding ecological criteria, the global warming potential, the acidification potential and the cumulative energy demand of the processes are calculated, based on a life-cycle assessment approach. The economic analysis is based on the levelized costs of energy generation (LCOE). The AER-based processes are compared to conventional and renewable reference processes, which they might stand to substitute. The results show that the AER processes are beneficial from an ecological point of view as they are less carbon intensive (mitigating up to 800gCO2-eq.kW-1hel-1), require less fossil energy input (only about 0.5kWhfossilkW-1hel-1) and have a comparable acidification potential (300–900mgSO2-eq.kW-1hel-1) to most reference processes. But the results depend heavily on the extent to which excess heat can be used to replace conventional heating processes, and hence on the exact location of the plant. The economic results show that under current German framework conditions, all plant configurations can only be profitable under very favourable site-specific conditions. The main parameters are the investments, accounting for 37–40% of LCOE, the price of the available biomass (27–32% of LCOE) and the revenues generated by selling excess heat. To reflect these dependencies in the economic results, spans between maximum and minimum LCOE-values are given: 19–22 €ct kW−1 hel-1, 10–11 €ct kW−1 hSNG-1 and 14–16 €ct kW−1 hH2-1. While the ecological performance of the considered plant configurations is largely independent of the plant size, the economics of this plant type depend on size and the number of installed plants. Hence future work should consider economies of scale and the learning effects when building multiple plants, and the impact these have on the generation costs