Power-to-Protein: pilot (phase 2)

The supply of sufficient food, energy and water present huge challenges worldwide – among the causes are global population growth and the impact of climate change on crops. There is no obvious universal solution. Rather, what will be needed are local, situation-oriented tailored solutions, based in part on creative, cross-sectoral thinking. The available options depend on the relevant raw material streams in a geographically defined area. One contribution involves closing the hydrogen loop through the direct conversion of hydrogen into protein.

Technology

The Power-to-Protein concept involves the production of high-value proteins via biosynthesis from hydrogen, oxygen, carbon dioxide and ammonium-nitrogen. Ammonium, carbon dioxide and energy are released, in the form of residuals or energy sources, during wastewater treatment processes. With Power-to-Protein, a valuable product – a protein – is created from these residuals and/or energy. This means that energy is indirectly saved for the production of artificial fertiliser in the early part of the chain, and for the destruction of ammonium in water treatment via nitrification/denitrification. In this manner a link is forged in the water-food-energy nexus.

Challenge

The conversion of the above-mentioned residuals into a single-cell protein has been successfully demonstrated on a lab scale. In the present project the production of protein is being scaled up to about 1 kg per day and, in pilot-scale research at different locations, a direct connection is being established with the wastewater cycle. The quality of the protein produced is then being evaluated on the basis of analyses and application tests, including a determination of the protein’s digestibility through in vitro and in vivo tests. An assessment is also to be made of the economic feasibility of the large-scale production of the protein – partly with an eye to future food supply – and of the costs and timeline for the introduction of the new food product. In addition, Life Cycle Assessment is to be used to compare the concept’s environmental impact with that of existing plant and animal proteins.

Solution

The project aims at the further development of an integrated application of the concept at different wastewater treatment sites. This will produce the following outcomes:

A more developed design of the pilot installation’s reactor.
Insight into the required quality and reprocessing methods for the raw materials.
Insight into the feasibility of producing 1 kg of protein per day at different pilot, onsite experiments.
Evaluation of the quality of the protein produced.
Determination of the overall environmental yield and economic feasibility.

In 2016 the reactor’s design was completed and a patent request submitted. Construction of the installation was then begun. In January 2017, the pilot was delivered and sent to the first research site at the Enschede WWTP. In May 2017 it was then taken to Avecom in Ghent for technical adjustments, after which it was restarted using ammonium sulphate from the Enschede WWTP. The ammonium sulphate was produced by the Nijhuis Ammonia Recovery (NAR) pilot, which was in operation at the Enschede WWTP in June and July 2017. During this period spike tests were also carried out in the NAR using indicator organisms, to research which pathogens could still be found in the ammonium sulphate. In September 2017, the harvesting of the first proteins from the power-to-protein reactor began. In the period ahead, the harvested protein powder will be further characterised.