As reported on this page a number of weeks ago, Ireland’s approach to developing anaerobic digestion (AD) on farms needs a major rethink. So far, the focus has been on large-scale, agribusiness-style AD plants producing biomethane from waste and agricultural feedstocks.
While these offer farmers a chance to diversify into new markets, manage slurry or access digestate, very few will be in a position to build or own such a facility.
Meanwhile, farm-scale AD projects have been largely overlooked by Government policy, despite strong farmer interest in systems that integrate with existing farm operations. In response, Lely Center Mullingar recently organised a visit to Belgium with small-scale AD manufacturer Biolectric to see these systems in action.
All components are housed in a steel container.
Design
The Biolectric model has been designed to run on fresh slurry produced on the farm. It’s a single-tank system, with all of the equipment housed in a single steel container.
The models we viewed on the first day of the trip used combined heat and power plants. That means the biogas is collected from the slurry and combusted through an engine to produce electricity and heat.
The plant is sized to closely match the demand of the farm, with import displacement being prioritised over exporting to the grid. The company, which is 15 years old, has systems in 25 countries.
The system works best on farms with regular amounts of fresh slurry and a high energy demand. So, indoor dairy farmers, those using robotic milking and feeding systems, pig farms, and finishing yards which are using high-energy feed, are best placed to make the investment stack up.
François Hubert at the Van Eyck Farm.
Van Eyck Farm
The first visit was to François Hubert at Van Eyck Farm in Gembloux, Wallonia, where he milks around 130 Holstein Friesian cows and grows cereals, seed potatoes and oilseed on his 170-acre farm. Each cow produces 35–38 litres of milk daily and is milked indoors year-round using two Lely A4 robots.
In 2022, François installed a 22kW Biolectric AD plant. It receives approximately 9.5 cubic meters of fresh slurry daily, pumped directly from the cattle shed. As slurry enters, digestate is simultaneously pumped into a separate storage tank. The slurry remains in the digester for around 35 days at 42°C. Biolectric claims up to 90% of the gas is extracted during this period, provided the slurry is fresh.
The AD plant generates about 300 cubic meters of biogas daily, converting to roughly 150,000 kWh of electricity annually via a four-cylinder Kubota engine.
Most of the electricity powers the farm, with 25% exported to the grid. François still imports around 45,000 kWh of electricity. Heat from the CHP engine is used to warm the plant and his house.
He earns about €200 per year from electricity exports but benefits significantly from a government scheme, receiving around €25,000 annually for the green electricity used on-farm. Additionally, the AD plant reduces energy costs by about €13,000 per year.
At the year of instillation, François’s plant cost €150,000, with a further €100,000 spent on civil works. He has a 20-year maintenance and monitoring contract costing €15,000 per year. Digestate from the plant is used to fertilise crops and is pumped to nearby fields via an umbilical system. The entire system is expected to pay for itself in about five years.
Bart Vanderstraeten at Koeweidehof.
Vanderstraeten Farm
The second visit was to Bart Vanderstraeten at Koeweidehof, a fourth-generation, highly innovative farm. In addition to milking 175 cows, Bart runs a tillage enterprise growing maize, clover, potatoes, sugar beet, onions and peas. He also bottles milk, sells directly to shops and cafés and hosts corporate events on-site.
Half of his milk is sold directly to customers, with the other half going to a processor.
His cows are housed year-round and produce around two million litres of milk annually, using two Lely robots and an Orbiter feeder.
When building a new shed in 2012, Bart planned for biogas integration, making it easier to install an AD plant. He began with a 9.7kW system, upgrading to a 22kW plant in 2019.
Slurry is scraped by a Lely collector, pumped four times daily into a small tank, and then into the digester. The digestate is returned to storage, where it is separated – the solids reused as bio-bedding for the cows.
His system yields 25–30 cubic meters of biogas per tonne of slurry, with fresher slurry delivering better output. The AD plant generates around 155,000kWh of electricity annually, most of which is used on-farm. Only 20,000kWh is imported during peak times, and a similar amount is occasionally exported.
At the time, the plant cost €190,000 fully installed along with civils, with annual monitoring and maintenance costing around €15,000. Bart receives 10c/kWh plus a green electricity premium, totalling around €15,000 annually. Combined with energy savings (valued at 23c/kWh), he expects to recoup the investment within five years.
Digestate is also used to fertilise crops. Bart compares the AD system to “a large extra cow on the farm” and monitors it remotely via his phone, just like his robotic milkers and other smart farm equipment.
Can this system work in Ireland?
The answer to if this system can work in Ireland is yes – but how widely it can be adopted depends on the support available and the type of feedstocks the technology can handle.
For high-energy, indoor pig or dairy herds, the system may be financially viable without support, though payback within 5–7 years remains challenging.
The gas is combusted in a a four-cylinder Kubota engine.
If the technology – or its components – became eligible under a separate TAMS ceiling, it could significantly improve the economics however.
A €40 million capital grant was recently introduced for large-scale AD plants; similar support for small-scale units could transform its viability. Grants covering 50–60% of capital costs would be a game changer.
AD is also eligible under the SBCI Growth and Sustainability Loan Scheme, which could bridge funding alongside Department of Agriculture grants. However, banks must become less risk-averse toward small-scale AD.
Grants and loans are the easier part. The rest – planning, tariffs and feedstock flexibility – requires more effort but is achievable with the right will.
Planning rules also need review. If an AD plant manages existing slurry more sustainably – without increasing herd size – there’s a strong case for an exemption for small scale installations. The slurry already exists; the system just changes how it’s used.
The Small-Scale Renewable Electricity Support Scheme (SRESS) has underdelivered so far, but could be reshaped. Including AD with higher tariffs could make a real difference. Current thresholds – 50kW minimum size and export-only rules – must also change. If we’re serious about green energy on every farm, rigid schemes like this must be made flexible and farmer-friendly.
The group examine the AD plant.
Finally, to make small-scale AD truly viable, we must go beyond slurry. The seasonal nature of slurry supply is a major concern for the viability of small systems in Ireland. For year-round use, systems need to handle other feedstocks – like farmyard manure or surplus silage – when cows are grazing. That’s what it will take to make on-farm AD work in Ireland.
Next week
Next week, we have an Irish Farmers Journal exclusive looking at a small-scale biomethane plant that could put biomethane production directly into farmers’ hands.
As reported on this page a number of weeks ago, Ireland’s approach to developing anaerobic digestion (AD) on farms needs a major rethink. So far, the focus has been on large-scale, agribusiness-style AD plants producing biomethane from waste and agricultural feedstocks.
While these offer farmers a chance to diversify into new markets, manage slurry or access digestate, very few will be in a position to build or own such a facility.
Meanwhile, farm-scale AD projects have been largely overlooked by Government policy, despite strong farmer interest in systems that integrate with existing farm operations. In response, Lely Center Mullingar recently organised a visit to Belgium with small-scale AD manufacturer Biolectric to see these systems in action.
All components are housed in a steel container.
Design
The Biolectric model has been designed to run on fresh slurry produced on the farm. It’s a single-tank system, with all of the equipment housed in a single steel container.
The models we viewed on the first day of the trip used combined heat and power plants. That means the biogas is collected from the slurry and combusted through an engine to produce electricity and heat.
The plant is sized to closely match the demand of the farm, with import displacement being prioritised over exporting to the grid. The company, which is 15 years old, has systems in 25 countries.
The system works best on farms with regular amounts of fresh slurry and a high energy demand. So, indoor dairy farmers, those using robotic milking and feeding systems, pig farms, and finishing yards which are using high-energy feed, are best placed to make the investment stack up.
François Hubert at the Van Eyck Farm.
Van Eyck Farm
The first visit was to François Hubert at Van Eyck Farm in Gembloux, Wallonia, where he milks around 130 Holstein Friesian cows and grows cereals, seed potatoes and oilseed on his 170-acre farm. Each cow produces 35–38 litres of milk daily and is milked indoors year-round using two Lely A4 robots.
In 2022, François installed a 22kW Biolectric AD plant. It receives approximately 9.5 cubic meters of fresh slurry daily, pumped directly from the cattle shed. As slurry enters, digestate is simultaneously pumped into a separate storage tank. The slurry remains in the digester for around 35 days at 42°C. Biolectric claims up to 90% of the gas is extracted during this period, provided the slurry is fresh.
The AD plant generates about 300 cubic meters of biogas daily, converting to roughly 150,000 kWh of electricity annually via a four-cylinder Kubota engine.
Most of the electricity powers the farm, with 25% exported to the grid. François still imports around 45,000 kWh of electricity. Heat from the CHP engine is used to warm the plant and his house.
He earns about €200 per year from electricity exports but benefits significantly from a government scheme, receiving around €25,000 annually for the green electricity used on-farm. Additionally, the AD plant reduces energy costs by about €13,000 per year.
At the year of instillation, François’s plant cost €150,000, with a further €100,000 spent on civil works. He has a 20-year maintenance and monitoring contract costing €15,000 per year. Digestate from the plant is used to fertilise crops and is pumped to nearby fields via an umbilical system. The entire system is expected to pay for itself in about five years.
Bart Vanderstraeten at Koeweidehof.
Vanderstraeten Farm
The second visit was to Bart Vanderstraeten at Koeweidehof, a fourth-generation, highly innovative farm. In addition to milking 175 cows, Bart runs a tillage enterprise growing maize, clover, potatoes, sugar beet, onions and peas. He also bottles milk, sells directly to shops and cafés and hosts corporate events on-site.
Half of his milk is sold directly to customers, with the other half going to a processor.
His cows are housed year-round and produce around two million litres of milk annually, using two Lely robots and an Orbiter feeder.
When building a new shed in 2012, Bart planned for biogas integration, making it easier to install an AD plant. He began with a 9.7kW system, upgrading to a 22kW plant in 2019.
Slurry is scraped by a Lely collector, pumped four times daily into a small tank, and then into the digester. The digestate is returned to storage, where it is separated – the solids reused as bio-bedding for the cows.
His system yields 25–30 cubic meters of biogas per tonne of slurry, with fresher slurry delivering better output. The AD plant generates around 155,000kWh of electricity annually, most of which is used on-farm. Only 20,000kWh is imported during peak times, and a similar amount is occasionally exported.
At the time, the plant cost €190,000 fully installed along with civils, with annual monitoring and maintenance costing around €15,000. Bart receives 10c/kWh plus a green electricity premium, totalling around €15,000 annually. Combined with energy savings (valued at 23c/kWh), he expects to recoup the investment within five years.
Digestate is also used to fertilise crops. Bart compares the AD system to “a large extra cow on the farm” and monitors it remotely via his phone, just like his robotic milkers and other smart farm equipment.
Can this system work in Ireland?
The answer to if this system can work in Ireland is yes – but how widely it can be adopted depends on the support available and the type of feedstocks the technology can handle.
For high-energy, indoor pig or dairy herds, the system may be financially viable without support, though payback within 5–7 years remains challenging.
The gas is combusted in a a four-cylinder Kubota engine.
If the technology – or its components – became eligible under a separate TAMS ceiling, it could significantly improve the economics however.
A €40 million capital grant was recently introduced for large-scale AD plants; similar support for small-scale units could transform its viability. Grants covering 50–60% of capital costs would be a game changer.
AD is also eligible under the SBCI Growth and Sustainability Loan Scheme, which could bridge funding alongside Department of Agriculture grants. However, banks must become less risk-averse toward small-scale AD.
Grants and loans are the easier part. The rest – planning, tariffs and feedstock flexibility – requires more effort but is achievable with the right will.
Planning rules also need review. If an AD plant manages existing slurry more sustainably – without increasing herd size – there’s a strong case for an exemption for small scale installations. The slurry already exists; the system just changes how it’s used.
The Small-Scale Renewable Electricity Support Scheme (SRESS) has underdelivered so far, but could be reshaped. Including AD with higher tariffs could make a real difference. Current thresholds – 50kW minimum size and export-only rules – must also change. If we’re serious about green energy on every farm, rigid schemes like this must be made flexible and farmer-friendly.
The group examine the AD plant.
Finally, to make small-scale AD truly viable, we must go beyond slurry. The seasonal nature of slurry supply is a major concern for the viability of small systems in Ireland. For year-round use, systems need to handle other feedstocks – like farmyard manure or surplus silage – when cows are grazing. That’s what it will take to make on-farm AD work in Ireland.
Next week
Next week, we have an Irish Farmers Journal exclusive looking at a small-scale biomethane plant that could put biomethane production directly into farmers’ hands.
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