The single-cell protein (SCP) production occurs in 120 fermentation tanks (each 200 m 3 ) by CO 2 assimilation of H 2 -oxidising chemoautotrophic microorganisms at 30 C. The process requires carbon dioxide (CO 2 ), oxygen (O 2 ), hydrogen (H 2 ), ammonia (NH 3 ) solution, and water, as well as minerals 39 supplied through filter sterilisation. H 2 and O 2 are supplied by water electrolysers, and the required CO 2 is captured by direct air capture (DAC) units. Ammonia is produced onsite via a small-scale Power-to-Ammonia plant. The fermentation process is exothermic and the temperature of the solution in the fermentation tanks is stabilised by a water chiller system. The broth (a liquid medium containing water, unused minerals, and microbial cells referred to as cell dry weight (CDW)) is then pasteurised with low pressure steam and guided to the cell separation units where 97.5% of CDW is separated in the form of concentrated broth with 200 g CDW L -1 density. Of the remaining supernatant, mainly water, half is recycled to the media preparation unit and the other half is discarded as wastewater. Then, the concentrated broth is sent to the drum dryer units where most of the remaining water is evaporated via high pressure steam, provided by electric steam boilers. The product SCP is 95% dry matter and 5% moisture. The moisture content is over 96% water and less than 4% non-volatile salts from unreacted minerals in the medium. The dry matter is 65% protein. The waste heat from the electrolysers and the evaporated water from the dryer units are partly retrieved and used as heat sources for heat pumps to provide heat at the desired temperature for the DAC units. The rest of water vapour escapes the system. Additional power is required for agitation in fermentation tanks and auxiliary use in the chain. RE renewable electricity, PU process unit, comp compressor.
