Life cycle sustainability assessment of lysine products in China: Integrating environmental and economic perspectives

Lysine is a crucial human nutrient and animal feed additive. Despite China being the world's largest producer and exporter, there is a notable lack of comprehensive evaluation regarding the life cycle environmental impact and economic benefits of its various lysine salt products. This study employs LCA and LCC to develop a "cradle-to-gate" model evaluating the environmental and economic impacts of two lysine salt products—98.5 % lysine hydrochloride (98LH) and 70 % lysine sulfate (70LS)—across their full life cycle from maize cultivation to final product delivery, and proposes improvement strategies. Five environmental impact indicators were quantified using LCA: primary energy demand (PED), global warming potential (GWP), water use (WU), acidification potential (AP), and eutrophication potential (EP), with integrated net economic benefit analysis. Results show that to produce 1 t of effective L -lysine, the PED (117,000 MJ/t), GWP (7138.26 kg CO₂ eq/t), WU (640,000 kg/t), AP (43.79 kg SO₂ eq/t), and EP (6.82 kg PO₄³⁻ eq/t) of 98LH are significantly higher than those of 70LS (93,100 MJ/t, 4094.71 kg CO₂ eq/t, 737,000 kg/t, 42.61 kg SO₂ eq/t, and 6.74 kg PO₄³⁻ eq/t, respectively). Economic analysis indicates that the net economic benefit of 98LH (5037.8 CNY/t) is 2.15 times that of 70LS. Process optimization studies suggest that co-production technologies of 98LH and 70LS can effectively reduce environmental burdens. Major contributors include energy consumption, liquid ammonia and ammonium sulfate usage during lysine salt production, and irrigation water and nitrogen fertilizer application in maize cultivation. We propose balancing environmental and economic goals through measures such as promoting co-production technologies and enhancing resource recycling in maize cropping systems. This study fills the research gap in integrated life cycle assessment of key products in the bio-fermentation industry. The results directly support the transformation of China's maize deep-processing industry under the "Dual Carbon" goals, providing scientific basis for establishing clean production standards and green subsidy policies. • 98LH exhibits significantly higher environmental burdens compared to 70LS. • Co-production technologies can effectively reduce overall environmental impacts. • Key contributors to environmental impacts and economic costs include energy consumption, liquid ammonia, and fertilizers. • Fertilizer substitution, recycling of maize stalks and cobs, and bio-based ammonia production can effectively reduce environmental impacts.