Assessing Environmental and Economic Sustainability: Valorizing Grape Stems for Animal Feed Production

Area of Science:

• Agricultural Science
• Environmental Science
• Biotechnology

Background:

• Grape stems (GS) are a winery byproduct with underutilized potential.
• Valorizing GS into animal feed offers a sustainable alternative to traditional disposal methods.
• Assessing environmental and economic impacts is crucial for implementing GS valorization.

Purpose of the Study:

• To evaluate the environmental life-cycle and economic feasibility of using grape stems (GS) as an animal feed ingredient.
• To compare hydrolyzed versus nonhydrolyzed GS production processes for animal feed.
• To analyze the overall impact of GS valorization on the animal husbandry sector and circular economy.

Main Methods:

• Life-cycle assessments (LCAs) were conducted using pilot-scale data for GS-based feed and secondary data for conventional feed.
• Economic analyses, including net present value calculations, were performed for GS-based feed ingredient production.
• Environmental impacts were compared across GS valorization, landfilling, composting, and incineration.

Main Results:

• Hydrolyzing GS significantly increases human health impacts (3.8x) due to NaOH and electricity use, though this effect diminishes at the animal feed production stage.
• Incorporating GS-based feed ingredients reduces overall environmental impacts of animal feed, mainly by decreasing reliance on other components.
• Nonhydrolyzed GS-based feed production is more economically viable, with a projected net present value of €-106,766 for a 1000 kg/d plant.

Conclusions:

• GS valorization presents a promising strategy for sustainable animal feed production, contributing to a circular economy.
• Nonhydrolyzed GS processing is recommended for economic feasibility, while hydrolyzed GS requires further optimization to mitigate environmental concerns.
• GS valorization offers environmental benefits over landfilling and composting, though incineration provides greater energy recovery.