Impacts of characteristics of grass silage and cattle slurry feedstocks on the cost of methane production

Abstract

Feedstocks characteristics and their provision cost can have a significant impact on the cost of methane production in an anaerobic digestion (AD) facility. This study investigated the impacts of changing grass silage characteristics, grass silage and cattle slurry provision costs and their binary mixing ratios on the cost of methane production from an on‐farm AD facility. The feedstock provision cost contributed about half of the total cost of methane production when the AD facility solely operated on grass silage. The total cost of methane production from mono‐digestion of cattle slurry, compared to grass silage, was 87% higher when it was supplied free of cost and was 42% higher when a gate fee of €70 t−1 total solids was charged. For co‐digestion of grass silage and cattle slurry, the total cost of methane production progressively increased as the proportion of slurry in the co‐digested feedstocks mixture increased. Antagonistic and synergistic methanogenesis resulted in a corresponding 6% higher and 5% lower total cost of methane production during co‐digestion, at silage:slurry volatile solids ratio of 0.8:0.2, compared to the binary mixture without these effects. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

The Role of Anaerobic Digestion in Reducing Dairy Farm Greenhouse Gas Emissions

“…However, in regions with less favourable weather conditions, growing this crop can cause issues at planting or harvest and there may also be a negative land use change impact from soil carbon losses if converting former grassland into cropland. Grass silage, although of lower energy value than maize, is easier to integrate into a pasture-based farming system and has been shown to be a suitable alternative under Irish conditions [24].…”

Biogas, Biomethane and Digestate Potential of By-Products from Green Biorefinery Systems

“…For example, Xie (2012) reported that maintaining pig manure and grass silage at a ratio of 3:1 yielded 304.2 mL CH 4 /g ml when the two biomass sources were co-digested [16]. In another study, Himanshu et al (2019) reported that maximum synergistic effects for biogas production can be achieved by maintaining a feed ratio of 0.75:0.25 for perennial ryegrass silages with cattle slurry [17]. Both studies observed that increasing the proportion of silage in the feedstock mixture progressively decreased the cost of methane production, increased the methane yield and increased overall plant profitability.…”