Assessing the environmental performance of hydrogen-oxidising bacteria as feed alternative at pilot and commercial scale, using a combination of intermittent and baseload renewable energy sources

Abstract

Aquacultures are rapidly increasing worldwide to meet the rising protein demand caused by population growth. However, commonly used fish feed products are known to harm the environment while depleting natural species. Various microbial protein forms are thus being investigated, such as those using hydrogen-oxidising bacteria, referred to as MP. This study investigates MP’s environmental performance over conventional feed products as overall
advantages and disadvantages remained unclear based on previous publications.

A four-phase explorative scenario framework for assessing novel technologies was used, further developed from recent studies. Based on a literature review of MP’s environmental performance, the ammonia and heat source used needed further evaluation. At the same time, previous studies displayed limitations related to CO2 allocation, continuous energy and nutrient supply, energy
grid stability, the readiness of the assessed technologies, the cost of production, and other influencing socio-economic factors. An attributional cradle-to-gate life cycle assessment (LCA) was conducted to determine an optimal system performance at a pilot-scale rooted in the literature findings. Subsequently, technical and socio-economic parameters were evaluated to influence MP’s progressive environmental performance.

Consequently, an ex-ante LCA compared MP production scenarios over time, differing in energy sources and production scales, against soybean meal (SBM). Even at high technical development, comparative results closely aligned, yet MP using geothermal energy showed a slight overall advantage over SBM after normalisation, in contrast to hydro and bioenergy displaying no real benefit. When oxygen (O2) was recycled, the former showed an overall
advantage over the incumbent at high production capacity. A total disadvantage would be expected for the latter, considering continuous H2 and NH3 supply. Further research should focus on integrating recycled phosphate, green H2 in the steel industry, differences in databases regarding water use for hydropower plants, and scenario analysis of the incumbent system. Besides these findings, the developed framework contributes toward the comparative assessment
of novel technologies against established ones.