Life cycle assessment of heat, CO2 from composting for greenhouse applications

Abstract

Greenhouses play a crucial role in agricultural production, especially in high-latitude regions requiring supplemental heating during winter. This study explores the potential of a Shed-type Greenhouse Composting Device (SGCD) to recover heat and CO₂ from composting agricultural waste (AW) for use in solar greenhouses. A Life Cycle Assessment (LCA) was conducted to evaluate the environmental impacts of the SGCD system, covering its construction, operation, and recycling units. The results show that heat and CO₂ recovery significantly reduce reliance on coal heating and CO₂ cylinders, with heat recovery contributing 30.94 % and CO₂ recovery 17.40 % to impact reduction. Key environmental hotspots include the impacts of construction materials, water, electricity, and diesel use. Sensitivity analysis revealed that the system is most sensitive to freshwater ecotoxicity, toxicity equivalent, and marine ecotoxicity. The impact of AW processing is minimal, contributing only 1.09 % of the total impact. Economically, the SGCD system increases tomato yield by 15.06 %, generating an additional $225.35 in annual revenue, with a payback period of two years and profitability from the third year. Overall, the SGCD system offers both environmental and economic benefits, promoting energy-efficient, low-carbon agricultural practices in high-latitude greenhouses.