Environmental impacts of a novel biorefinery platform integrated with power-to-protein technology to decrease dependencies on soybean imports.

The consistent population growth is directly tied to the annual rise in livestock production, placing a substantial burden on the crop sector that supplies animal feed. The Danish government has been relying on importing soybeans and soybean meal to be used as animal feed. However, this sparked environmental concerns that require more environmentally friendly solutions, such as self-sufficiency in animal feed production. The rise of green biorefineries allows new avenues of animal proteinaceous feed production using green biomass to produce leaf protein concentrate (LPC) and utilize side-stream products, such as brown juice and press cake, for feed-quality products. This study evaluated the combination of grass-clover biorefinery and the power-to-X concept, including power-to-protein technology, for its environmental sustainability through a consequential life cycle assessment (CLCA). The production of protein concentrate from organic grass clover exhibits optimal environmental performance when press cake and brown juice are used for bioenergy recovery. The findings indicate that combining a green biorefinery with power-to-protein to fully valorize the carbon and nitrogen content of brown juice and press cake into feed-grade protein can increase the environmental benefits. Such an integration resulted in an avoided impact of -995.9 kg CO2-eq/tonne of protein concentrate. The avoided impacts of climate change could be higher within the first 20 years due to a higher carbon sequestration rate. However, even after 20 years when a new carbon balance in the soil is reached, the environmental gain could be big enough to encourage the production and use of organic grass-clover protein concentrate.

Going beyond conventional wastewater treatment plants within circular bioeconomy concept - a sustainability assessment study.

Wastewater treatment plants (WWTP) have extensive energy processes that undermine their economic and environmental performance. In this context, the integration of wastewater treatment with other biochemical processes such as co-digestion of sludge with organic wastes, and production of value-added products at their downstream processes will shift conventional WWTPs into biorefinery platforms with better sustainability performance. The sustainability of such a biorefinery platform has been investigated herein using an economic and life cycle assessment approach. This WWTP-based biorefinery treats wastewater from Copenhagen municipality, co-digests the source-sorted organic fraction of municipal solid waste and sludge, and upgrades biogas into biomethane using a hydrogen-assisted upgrading method. Apart from bioenergy, this biorefinery also produces microbial protein (MP) using recovered nutrients from WWTP's reject water. The net environmental savings achieved in two damage categories, i.e., -1.07 × 10-2 species.yr/FU in ecosystem quality and -1.68 × 106 USD/FU in resource scarcity damage categories along with high potential windows for the further environmental profile improvements make this biorefinery platform so encouraging. Despite being promising in terms of environmental performance, the high capital expenditure and low gross profit have undermined the economic performance of the proposed biorefinery. Technological improvements, process optimization, and encouraging incentives/subsidies are still needed to make this platform economically feasible.