Comparative environmental and economic performance of solar energy integrated methanol production systems in China

Conventional coal gasification to methanol technology in China results in serious environmental problems. Therefore, a great number of studies focus on the low carbon solutions for methanol production. Our work analyzed and compared the life cycle environmental and economic performance of solar energy integrated methanol production systems in China with the aid of GaBi software. There are three methanol production routes involved in our study: conventional coal to methanol system (Baseline case), solar energy coupled with coal gasification to methanol system (Case-1), solar energy-biomass assisted CO2 hydrogenation to methanol system (Case-2). The results indicate that the environmental impacts of Case-1 and Case-2 are at least 45.7% and 57.5% smaller than the selected impact categories of baseline case, respectively. In Case-2, the utilization of biomass integrated gasification combined cycle (Bio-IGCC) with CO2 capture system leads to negative life cycle greenhouse gas emission (−1092.1 kgCO2eq/ton) of the whole system. However, in economic aspect, the methanol cost of Case-1 and Case-2 is about 3 times and 5 times that of Baseline case (1593.4 RMB/ton). If considering the average carbon tax level (500 RMB/ton CO2eq) in 2030 reported by World Bank, the Case-1 route is expected to be economic feasible in the near future, while the Case-2 is still difficult to have economic advantage compared with the Baseline case. The key to solving the cost problem of Case-2 lies in developing highly efficient photovoltaic electricity generation and biomass integrated gasification combined cycle system, decreasing the capital cost of solar photovoltaic power station, biomass integrated gasification combined cycle station and polymer electrolyte membrane modules for water electrolysis.