Abstract
Abstract
Green biorefineries (GBRs) aim to reduce reliance on imported feed by extracting protein from forage. Their environmental performance depends on co-product utilization, including the pulp which contains up to 70% of the original biomass dry matter. Using a life cycle assessment approach, we compared a conventional dairy system with two GBR-integrated systems differing in land availability for forage production, where pulp fraction replaced forage in cattle diets, adjusted using the Nordic Feed Evaluation System. Both GBR-integrated systems showed higher environmental impacts per kg milk than the conventional, driven by increased concentrate feed inputs or expanded land use for forage production to maintain milk production. Impact increased by up to 7% and 8% for global warming potential and land use, respectively, while other impact categories showed similar or even higher increases. Substituting soybean meal elsewhere with GBR-produced protein concentrate partially offset these impacts but was insufficient to reduce impacts below the conventional system. In a sensitivity analysis, neither a higher feeding value for pulp nor a higher-impact assumption for the avoided soybean meal alone was enough to bring impacts below the conventional system. Only when both were combined did global warming potential and land use fall below conventional, by 5%.