Global potential of integrated biorefineries for leaf protein and sugar: Producing sustainable food and preventing starvation in catastrophes

To accommodate population growth and shifting diets, the global protein supply must increase. Simultaneously, rising climate variability increases agricultural yield shocks, disrupting conventional crops. Worse, global catastrophes such as nuclear war or pandemics could collapse the global food system. Here, we turn to the potential of grasslands and plentiful legume biomass (e.g., alfalfa, clover) to address these challenges. We demonstrate the potential and cost of integrated biorefineries for food production from biomass to obtain leaf protein concentrate (LPC), lignocellulosic sugar, and/or single-cell protein (SCP). These sustainable alternatives to conventional protein and sugar sources show remarkable global production potential: LPC+sugar could fulfill ~5% of the caloric requirements in one year, while LPC factories alone could fulfill global protein needs within 2 years. Combining LPC and SCP production enables food protein per hectare yields higher than any conventional food crop. Our crop modeling shows that LPC from grasslands could be more than enough to cover global calorie requirements. Even in extreme nuclear winter scenarios, grasslands could meet global protein requirements. However, this would require a large effort to multiply global legume biomass production several times over. The product is affordable for global catastrophe response, at ~$1/kg (dry) of food, or a retail cost of ~$1-2/person/day to fulfill energy needs. Locations with long growing seasons, low biomass cost, and repurposable infrastructure minimize production costs. Future work should model tradeoffs with competing uses of land (food crops, grazing, etc.) to improve policy recommendations for crisis response.