Branch Line

'Deep Branch' is an £8m UK startup claiming to turn carbon dioxide into protein. Its postulated intention, is to use the generated protein for animal feed (https://www.theguardian.com/environment/2021/mar/22/uk-startup-raises-8m-funding-convert-co2-animal-feed). The 'Deep Branch' technology involves 'feeding' carbon and hydrogen to cultures of a particular microbe in fermentation vats. Fermentation, in this case, generates protein rather than alcohol. This protein can then be dried and converted into pellets of animal feed. Part of the 'sale's pitch' is that the Deep Branch's protein would reduce the use of soya and fishmeal in animal feed. Soya has been implicated in deforestation (areas are cleared to grow the crop) and fishmeal in over-fishing (and losses of fish-eating birds). The company plan to open a first plant in Norway (a country with the world's largest salmon farms). The Deep Branch process is not, however, quite as 'green' as it appears. The generated protein would have to be blended with other biomass, to meet the nutrient requirements of the cattle and fish receiving the pellets. The process is also not a form of carbon capture. Carbon dioxide going into the process is counter-balanced by carbon dioxide generation. Indeed, the provision of carbon and hydrogen to the vats, both have intrinsic carbon 'footprints'. The process might well be useful but appears far from a solution for climate change.