Viessmann Biogas boilers save Yorkshire energy plant £150k per year

Seeking increased efficiencies

Commissioned in 2020, the R100 Energy AD plant generates 11 MWth of renewable biogas each year from 90,000 tonnes of organic waste. UK Anaerobic Digestion (AD) operator, BioteCH4, processes organic waste from supermarkets, local authorities and manufacturing facilities, which comprises a mix of liquids, solids, wastewater, oils and fats.

In order to pasteurise this Category 3 food waste and heat the digesters to the required temperature for the anaerobic digestion process, BioteCH4 has a need for heat on-site. Initially, the team employed diesel boilers as an interim measure while they waited for the installation of their combined heat and power engines (CHPs). But a need for cheaper, more reliable and more environmentally friendly CHP back-ups soon transpired, and the company contacted bioenergy specialists, Shaw Renewables, for support.

“We had worked with Shaw Renewables before at some of our other sites and were impressed with their knowledge of biogas boilers and their level of service,” states Adam Carter, Group Project Lead for BioteCH4. “So when we began looking for an alternative on-site heat solution for our R100 Energy plant, they were the obvious choice.”

Twice as nice

Although BioteCH4’s heat requirement was for 3 MW, Shaw Renewables recommended a solution which incorporated two separate Vitomax M60-A 1.5 MW boilers. 

“While we could have met the customer’s request with a single boiler, the use of two brings a number of additional benefits,” explains Andrew Shaw, Managing Director. 

“The first is modulation. Our fully modulating burners provide excellent turndown ratio, between 5-10 step depending on the fuel quality. But there’s a limit to how low you can go – with a 3 MW boiler the maximum turndown would only be around 1.2 MW, meaning that at off peak or low demand times in the plant’s cycle we are generating more than is required, which will lead to short cycling of the boilers. This is obviously less efficient than with two 1.5 MW boilers, when one could be left idle and the other used at just 800kW, for example.

“The second benefit of using a two-boiler configuration is back-up. If one boiler goes down or needs servicing, a spare is then available to keep the heat generating as required. 

“And finally, there’s the benefit of duty sharing. Alternating between two boilers means they share the wear and tear associated with operation, prolonging the lifespan of not just the boilers but also the pumps and associated equipment.”

Containerised solution

Shaw Renewables created a two-boiler cascade solution for the R100 site, incorporating a modulating gas booster to deliver the required pressure. In just 10 weeks, Andrew Shaw and his team of engineers built a 40ft-long plant room fully fitted with lighting, combustion air ventilation, small power for service equipment, and a gas safety system with gas interlock.

The plant room houses two 1.5 MW Viessmann Vitomax M60-A low-temperature hot water boilers with a steel shell, with fully modulating dual fuel (biogas and LNG) Riello gas burners. It also includes a variable speed Utile gas booster with pressure transducers to provide fully modulating gas pressure, as well as Grundfos TPE pumps. Gas safety has been addressed with a multi-sensor alarm which monitors lower explosive limits, carbon monoxide, hydrogen sulphide, smoke and fire.

Superior project management

A crane was hired to position the plant room in place. The works were then followed by fabrication, installation and insulation of the heating pipework, biogas pipework and gas booster pipework. Testing and commissioning checks came next, before the containerised biogas boiler solution was handed over to BioteCH4’s in-house engineers and operators.

Reaping the benefits

The project was completed in early 2024 and the team at R100 Energy have now used the solution for a full year. 

“We’re coming up to our first service and I’m delighted to report that we’ve had no downtime at all,” says Adam Carter. “The new boilers are super-efficient, work exactly as we intended them to, and have given us no issues whatsoever.”

Compared to the previous diesel boilers that were in use, they’ve also delivered considerable cost savings. “Before, we had to pay for the fuel we used,” confirms Adam. “But now, we can use the biogas that we’re generating on site, meaning the fuel is effectively ‘free’ (barring nominal parasitic load and feedstock costs). Overall, the benefit of the new biogas boilers over the previous diesel alternatives equates to around £150,000 per year. ”

The carbon savings are impressive, too. Adam Carter reports that approximately 3,000 MWh of heat is now being generated from renewable sources (biogas), which releases approximately 600 kg CO2eq emissions. Generating the same amount of heat through diesel or kerosene would have resulted in CO2-equivalent emissions of approximately 720,000 kg, according to DEFRA GHG reporting: Conversion Factors 2025.

Remote monitoring

A further benefit of the new biogas boilers is the fact that they come with remote monitoring as standard. 

“BioteCH4 had no visualisation over the old boilers,” explains Andrew Shaw. “If a boiler went down, they may not have known until the temperature dropped in one of the digesters. Heat recovery can take a few days, during which time the gas yield can start to drop off. And if the pasteuriser isn’t operating at the required temperature, they may have to stop feeding the plant altogether.”

The new boilers and associated equipment are interfaced with the plant-wide Scada system, issuing alerts for any immediate problems and early warning fault messages for performance deterioration. The team has remote access, enabling the boilers to be monitored 24/7, stopped and started in seconds, and even the fuel type to be changed.