HoSt Realises: Biomethane and Organic Fertilizer from Manure in Sint-Oedenrode, Netherlands

In Sint-Oedenrode, province of North Brabant in the Netherlands, 1 million Nm3 (cubic meter) of biomethane per year will soon be produced for supply to the gas network, sufficient for approximately 750 households. For this purpose, 40,000 tons of cattle manure is anaerobic digested from several dairy farms in a HoSt biogas installation. In addition, the digested manure is processed into an organic fertiliser.

The fresh manure originates from both Van Genugten dairy farm in Sint-Oedenrode and several nearby dairy farms. “This project is a great example of regional cooperation resulting in energy production, emission reduction and a closed manure loop,” says Sjaak Klein Gunnewiek, sales manager of biogas projects at HoSt. In addition to sustainable energy production, in this project – GroeneWoudGas – manure is processed into tailor-made products for fertilising the forage crops. Above all, CO2, methane and nitrogen emissions are maximally reduced at company level thanks to 100% manure digestion.

Manure valorisation to organic fertilizer

The recovery of fertiliser concentrate from the digested manure starts with the hygienisation of the digestate, the fertilising product that results from the digestion process. Thanks to hygienisation, any germs are slain and the digestate is made export worthy. This makes it possible to fulfill the duty of manure processing. A centrifuge separates the digestate into a thick fraction and a thin fraction (liquid manure), after which a nitrogen stripper extracts nitrogen from the thin fraction. The thin fraction with valuable potash fertilizers can then be used by the livestock farmers for organic fertilisation.

The remaining product from the stripper is nitrogen-rich ammonium sulfate, which is usable in liquid form or can be crystallised. This product is expected to be recognized by the European Union as a fertiliser substitute from 2021 onwards, but can already be used within the pilot mineral concentrate in which the project is participating. “To close the regional loop, we will use this product on the grassland of our customers, among other things. Knowledge partners supervise use in practice and conduct field trials, “says initiator Van Genugten.

Regional cooperation

The thin fraction returns to the same nearby dairy farms that supply the fresh manure. Both the fresh manure and the thin fraction are transported in a bio-CNG truck from transport company Ton Trans. This is done with an innovative two-compartment trailer for efficient transport.

Emission reduction thanks to manure digestion

100% manure digestion is a proven and feasible innovation for the production of green energy and valuable end-products as well as for emission reduction. The combination of manure digestion and a nitrogen stripper reduces ammonia and methane emissions. Thanks to the supply of fresh manure by several dairy farms, the manure does not remain in the stable and emissions in the barn are greatly reduced.

Clean biomethane production

Anaerobic (anoxic) digestion of manure takes place in the manure digester, producing biogas. In a biogas upgrading system from Bright Biomethane, the biogas is upgraded to green gas (biomethane) with the same properties as natural gas. This produced biomethane goes directly to the Sint-Oedenrode gas network. A very suitable and green alternative for heating, hot water and cooking on the fossil fuel natural gas. Thanks to innovative heat recovery and the use of a heat pump, the digester and processes can be heated with recovered heat from the processes. In addition, the patented insulated double membrane roofs ensure minimal heat loss. The buildings and silos are linked to an odour filter that captures and filters all odours.

The project is stimulated by Top Consortia for Knowledge and Innovation (TKI) that stimulates innovative energy projects. The National Green Fund and Dutch bank Rabobank have made the financing available. Green financing and impact loans were used for this.