Compared to first-generation biofuels produced from food crops, production of second-generation biofuels for daily use is an urgent issue. In this study, researchers developed a novel carboxylate-type liquid zwitterion as a solvent of biomass, which could dissolve cellulose with very low toxicity to microorganisms. Use of this novel solvent enables significant reduction of energy cost for ethanol production from non-food biomass. Thus, second-generation biofuel ethanol production is in sight of practical implementation.