Things are happening at Grignon experimental farm!
November 09 2022Grignon farm has 400 hectares of crops, a herd of 200 dairy cattle, 600 dairy sheep, a dairy, and soon to come, a biogas plant. After setting up a system for recovering methane with the start-up Nénufar in 2014 (a project developed by Farm’InnLab), the farm is taking things further with its Grignon Positive Energy program by building a biogas plant and, at the end of this year, installing photovoltaic panels. This will halve the farm’s carbon footprint!
For a number of years, Grignon farm has been committed to recovering waste and eight years ago acquired a “Nénufar cover” (nénufar meaning water lily) which, floating on top of the slurry, consists of a floating cover and ballast system to recover and store the biogas. Today, the approach is evolving further still with the construction of a biogas production unit (composed of a digester and a purifier) operating in a more “traditional” way: incoming matter (waste such as manure, for example) is mixed and ferments, with bacteria transforming the matter to produce biogas. The work required to set up this unit will take several months to complete: “We will inject our first kilowatt hour of green gas into the GRDF network (the French gas distribution network) in July 2023, producing 50m3 of biomethane per hour. This will be distributed in Grignon, of course, as well as in Plaisir, the neighboring town. To give you an idea, our production will be able to heat the equivalent of 400 homes (1,200 people) with gas heating, which is significant," says Dominique Tristant, farm director.
The photovoltaic panels are also an important step. A frame is currently being built (scheduled for completion early December 2022, see photo above), onto which the panels will be installed. The idea is not only to benefit from electricity produced by and for the farm, but also to be consistent in this “ecoresponsible” approach by installing, in the photovoltaic building, an automated system for producing specific feed for cattle and sheep, powered by this electrical system. This is also a no-brainer, according to Dominique Tristant, as “electricity represents one third of the farm’s current consumption, so producing our own power is obviously a good idea. In summer, we will produce more and consume less, which means we can also sell part of the electricity produced.”
Next year, the roof of the farm’s 50-year-old sheep pen will be renovated, providing the opportunity to continue in this direction with the installation of a photovoltaic roof.
What are the advantages of biogas production?
The twofold recovery of organic matter and energy, plus the reduction of waste, of course, which helps reduce the farm’s carbon footprint and limit odors on the premises (as the process takes place in an “anaerobic” environment, i.e. without oxygen). According to Dominique Tristant, the result is simple: “We halve the farm’s carbon footprint by avoiding greenhouse gas emissions, because by producing biogas directly after production there is no manure storage, and we also save on energy and nitrogen fertilizer (manufacturing fertilizer produces a lot of CO₂). With everything taken into account, we obtain this result.”