Fifth generation of biomass feedstocks to produce cleaner and more efficient energy

The gradual shift from fossil to biomass feedstocks offers hopes for Global Sustainable Development. Biomass is renewable and can be transformed into green energy and chemicals. However, this practice has historically sparked debates, resulting in the development of fourth-generation biomass feedstocks: engineered organisms, which are controversial. This work proposes arid plants as the Fifth Generation Feedstocks for energy transition, food security and water conservation (5Gen Feedstocks). However, the environmental impact and energy efficiency of 5Gen Feedstocks at large scale are unknown. Experiments and analyses of four realistic scenarios were performed with nopal (prickly pear, Opuntia ficus-indica) to propose a cleaner and more energy-efficient system, integrating farming and ethanol production in a plant-wide agrobiorefinery. Life cycle assessment, energy balances, energy efficiency and evolutionary process design principles were applied to design a better agrobiorefinery. Scenario 1 was energy inefficient and environmentally harmful (classic biorefinery). The cleanest and most energy-efficient agrobiorefinery had the lowest environmental impacts in all categories (10); the best energy efficiency (three-fold that of scenario 1) and used the lowest amount of energy per unit of energy produced as ethanol fuel (0.33 MJ MJ-1). 5Gen Feedstocks enable sustainable agrorefineries for renewable energy production, net zero emissions and climate risk mitigation.