A 10-week project by Shaw Renewables to replace legacy diesel boilers with carbon-friendly biogas alternatives is delivering cost and carbon savings for leading AD operator BioteCH₄. Since the two 1.5MW Viessman dual fuel boilers and associated equipment were installed at the R100 Energy plant in Goole, Yorkshire, the financial benefit to BioteCH₄ is £150,000 per year. In addition to the cost savings, the company is now generating 3,000 MW/h of heat from renewable sources as opposed to fossil fuels, and has reported ZERO faults and downtime.

Seeking increased efficiencies

Commissioned in 2020, the R100 Energy AD plant generates 11MW_th of renewable biogas each year from 90,000 tonnes of organic waste. 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 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 3MW, the team at Shaw Renewables recommended a solution which incorporated two separate 1.5MW boilers. Andrew Shaw, Managing Director, explains why: “While we could have met the customer’s request with a single boiler, the use of two brings a number of additional benefits. 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 3MW boiler the maximum turndown would only be around 1.2MW, 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 1.5MW 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 1.5MW Viessmann 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

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

“Being able to leave the installation and pre-commissioning to Andrew was a real bonus,” says Adam Carter. “Everything ran entirely to plan – it was one of the smoothest projects I’ve ever been involved with.”

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. “The benefits were clear from day one,” enthuses Adam. “We’re coming up to our first service and I’m delighted to report that we’ve had no downtime at all. 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. “We are now generating approximately 3,000MW/h of heat from renewable sources, as opposed to fossil fuels,” adds Adam. “That’s the equivalent of around 240,000kg of kerosene.”

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. This has been backed up by after-care from Shaw Renewables in the form of free 60-day support post-commissioning, followed by options including a service package to deliver six-monthly boiler servicing, retained labour, discounts for parts and a 24-hour dedicated helpline.

“I wouldn’t hesitate to recommend Shaw Renewables to other AD operators; in fact, we’ve already used them for a further two boiler projects at our other plants,” concludes Adam Carter. “They’re reliable, knowledgeable and delivered exactly what they promised us, resulting in real carbon and cost savings for our plant.”