Evaluation of the economic feasibility of a two-stage gasification system for hydrogen, liquid fuels and energy production from residues

Abstract

Although two-stage gasifier design offers a number of advantages i.e., producing high-quality gas (high H2 content, low CO2 and other impurities) and tolerating high degree of heterogeneity of feedstock, its economic feasibility is yet to be evaluated. In this study, a techno-economic assessment is fully conducted to assess the economic feasibility of a two-stage gasification system for three routes: hydrogen production, liquid fuels via Fischer-Tropsch synthesis, and electricity production from biomass. For a two-stage gasification of 20 years at a plant size of 1000 dry t/d, the total capital investment for hydrogen, FT-liquid and electricity production are US $214.8 million, US $345.5 million and US $307 million with operating costs of US $35.6 million/y, US $62.2 million/y and US $48.6 million/y, respectively. The minimum selling price for hydrogen (at a pressure of 70 bar) and liquid fuel from biomass is comparable to that from fossil fuels (US $1.59/kg for H2 and US $1,109/m3 for liquid fuel) whereas for electricity (US $ 0.09/kWh), it is around half of the current electricity price from the grid in the UK. Comparing to conventional fluidised bed gasification for the same feedstock, around 25% cost reduction can be achieved for either hydrogen or liquid fuel production but only around 10% reduction for electricity. The results also show that the economics of the system can be improved further by 35–40% if the cost of feedstock is reduced by 30–50% at large-scale production facility (≥2000 dry t/d).