From Grass to Protein: Assessing the Economic Viability of Mechanochemical-Assisted Extraction for Sustainable Food Production

Grasslands represent one of the world's largest yet most underexploited renewable biomass resources. Here, we present a techno-economic framework for transforming grass silage into edible protein and microbial lipids through mechanochemical and biocatalytic processing. Two biorefinery configurations were evaluated using stochastic and spatial modeling: a baseline system producing protein and biogas (Scenario 1) and an integrated design incorporating lipid fermentation (Scenario 2). Both achieve strong economic performance at industrial scale, with median net present values (NPVs) of £528 million and £1.21 billion, respectively, and protein production costs of £2.97-3.40 kg^-1comparable to plant-derived alternatives. Sensitivity analysis reveals that protein extraction efficiency and product price dominate profitability, while scale and coproduct valorisation drive the largest gains in expected NPV. Spatial simulations show that sourcing 33,333 t y^-1 of wet silage (25% DM) is logistically feasible across UK grasslands at delivered costs of £51-58 t^-1, enabling decentralised, regionally integrated deployment. Together, these results establish grass-based biorefineries as a scalable and economically credible route to sustainable protein production, bridging agricultural residues and food technology. The study provides quantitative guidance on how process yield, market development, and spatial logistics can be co-optimized to accelerate the emergence of a circular, pasture-driven bioeconomy.