Digestion on the farm?
Farm-scale digesters employ an automated process that pumps slurry directly from the manure pit to the digester, significantly simplify to monetize the power of their slurry. By focusing on simpler biological processes, there is also no need to introduce additional energy-rich substrates, thus eliminating the requirement for land dedicated to energy crops and minimizing waste and digestate transportation.
In the foreground, a slurry pump connected to the digester
Moreover, the utilization of fresh manure allows farmers to prevent over 80% of biomethane losses, maximizing both energy output and earning potential. All this possible as of 60 dairy cows (or equivalent). The main two criteria is that manure is collected daily and is pumpable to allow this automation.
Regenerative Agriculture at its finest
Farm-scale digestion exemplifies regenerative principles, converting fresh cow manure directly into electricity, heat, and valuable agricultural inputs. When applying the digestate as fertilizer, the nitrogen is released more gradually into the soil rather than being emitted into the atmosphere. This is much better for the local biodiversity and the nearby bodies of water’s.
Furthermore, applying digestate to soils also enhances biogeochemical cycles which promote carbon retention and by taking the manure out of the stable on a daily basis, it significantly enhances the well-being of the animals.
Proven to be sustainable
Studies conducted by Wageningen University & Research have shown that farm-scale digesters can lead to an impressive 82% reduction in greenhouse gas emissions compared to traditional manure management practices. Additionally, when combined with a Nitrogen stripper, these digesters can achieve up to 65% reduction in nitrogen emissions.
Farmers who embrace this solution can have their CO2 emission reductions certified in the form of carbon credits which can be sold to third parties, further incentivizing sustainable practices and shortening the payback period.
Why choose farm-scale instead of much larger collective digesters?
Choosing to install a digester directly on the farm instead of relying on a larger central biogas plant, offers various benefits which are outlined in below table :
Aspect
Farm-Scale Digester
Large Collective Digester
Size
Smaller than a barn, with a silo below 12 meters high and a volume of 100 – 1500 m³
Multiple silos commonly starting as of a combined 10.000m³ of storage space
Investment
As of 100.000 EUR
As of 1.500.000 EUR
Permit Process
Smoother permit process due to an installation being smaller than stables and no burden for the environment
Complex permitting and regulatory requirements due to larger scale
Workload for farmer
Fully automated, max. 15 minutes of monitoring per day
Intensive : buying waste streams, monitoring biology, managing complex administrative flows, arranging the offtake of digestate
Biology
Simple, harnessing the bacteria already present in rumen animals
Often requires additional energy-rich substrates for optimal performance given manure is never fresh
Land use
No need for land to be used for energy crops
Often requires land for energy crop cultivation
Transport
None, as integrated into the farm
Extensive manure and other waste & digestate transportation
Pathogen risk
No pathogen exchange between different farms
Risk of pathogen exchange among farms because of manure exchange
Greenhouse gas reduction
Prevents up 82% of biomethane losses, through usage of daily fresh manure
As typically it takes at least two weeks before manure is collected, over 50% of biogas into the atmosphere, already escaped prior digestion process
Animal well-fare
Better climate in barn, as this stimulates taking the manure out of the barn on daily basis
Manure often digests couple weeks under animals, resulting in poor barn climate through ammonia gases for feedstock and farmer
Financial benefits
For farmer
Often in the hands of big(ger) industrial players
Offers on the Market
The European micromethanisation market leader is Biolectric, with over 300 manure-only biogas plants and an rapid growth rate. Several other providers offer farm-scale digesters below 100kW, including Ener-G from the UK, Rota Guido from Italy, Biogas Plus from the Netherlands, and Green Service Group from Belgium.
Correlation with European Objectives
Farm-scale anaerobic digestion aligns perfectly with the European Union's commitment to reducing greenhouse gas emissions and achieving carbon neutrality. As the EU progresses with the Renewable Energy Directive (RED III), a 100% manure digesting model is gradually becoming the standard in the next years.
In summary, farm-scale digesters offer a promising and sustainable solution for modern farming. By converting fresh cow manure into renewable energy and quality fertilizer, all while reducing greenhouse gas emissions and nitrogen pollution, these digesters align perfectly with regenerative agricultural principles. As the European Union strives for reduced emissions and greater sustainability, farm-scale anaerobic digestion is primed to play a significant role in the ecological and energy transition.