Integrated economic and life cycle assessment of thermochemical production of bioethanol to reduce production cost by exploiting excess of greenhouse gas savings

In this work, two options are investigated to enhance the economics of the catalytic production of bioethanol from biomass gasification by exploiting the excess of CO2 emission saving: (i) to import fossil energy, in the form of natural gas and electricity or (ii) to trade CO2 emissions. To this end, an integrated life cycle and economic assessment is carried out for four process configurations, each using a different light hydrocarbon reforming technology: partial oxidation, steam methane reforming, tar reforming and autothermal reforming. The results show that for all process configurations the production of bioethanol and other alcohols significantly increases when natural gas displaces biomass, maintaining the total energy content of the feedstock. The economic advantage of the partial substitution of biomass by natural gas depends on their prices and this is explored by carrying out a sensitivity analysis, taking historical prices into account. It is also concluded that the trade of CO2 emissions is not cost-competitive compared to the import of natural gas if the CO2 emission price remains within historical European prices. The CO2 emission price would have to double or even quadruple the highest CO2 historical price for CO2 emission trading to be a cost-competitive option.