The 100-percent project

The idyllic community of Waldkirch is located at the edge of the Black Forest. The road in and out of town leads to the Sozialwerk am Bruckwald. 300 people live at the site, and there are 250 jobs for adults with special needs in a large number of workshops that produce high quality food, do gardening work and devote their energy to crafts and manual work. “The site was built just under 25 years ago. Back then, our wood chip-fired system made us pioneers in the area of renewables,” says Michael Danner-von Wilpert, business manager at the facility. “Even then, it was important to us to ensure that our energy supply was sustainable and our carbon footprint small.”

The Sozialwerk has continued to grow over the years, which ultimately necessitated an expansion. The old system just didn’t have the capacity anymore and a new solution was required to supply newly constructed buildings and the adjacent site with a decentralized heating network. Infrastructure was built that allowed five new buildings to be connected to the existing community heating network. “It was clear that we wanted to continue using wood as a fuel. The existing wood chip-fired system was unable to supply the new buildings with both heat and warm water,” recalls Felix Böttcher from Bosch Energy and Building Solutions. As a planning engineer, he managed the project throughout the consultancy, planning and final implementation stage before handing the project over to the Bosch Operations Team. The on-site work was something special for him. “The Sozialwerk is a wonderful thing. We felt like we really belonged to the community right from the beginning.” As Michael Danner-von Wilpert adds: “People who come here are part of our community, whether they’re a visitor, craftsperson or, as on this project, an energy expert. That means, for instance, that we all sit down to lunch together – everyone talks to everyone. This allows us all to get to know each other. And once the Bosch Team got down to work, our residents found it exciting and interesting.”

The new solution is based around a 500 kW wood chip-fired boiler system. “Right from the moment we first contacted the engineers at Bosch up to the inventory analysis, everything proceeded quickly, and we soon had the foundations for a grant proposal. In the future, we’ll have the means to supply the social campus, which is currently being developed at the periphery our site, with energy. That’s in keeping with our philosophy of opening up spaces for development within the community,” explains Michael Danner-von Wilpert. These ideas and goals remained front and center during the planning phase. “This is how the site will develop and change. How will people live and work here in the future? Factoring in these considerations allowed us to extrapolate our power requirements and adapt our supply of heat to our future needs,” says Böttcher, describing the planning phase. “The required capacity will continue to grow, but the building where the heating system is located won’t. This meant we had to get creative.” Böttcher and his team planned a new heat distribution system. Three pipelines supply heat to the different building clusters that have gone up over the years. One line, sections of which were newly laid, supplies the new buildings on the other side of the road. Each of these lines is supplied by a new, high-efficiency pump of its own. When modernizing the central power station, the control and regulation systems were updated, and an energy management system from Bosch was installed. Since then, the central heating station and the substations of the individual buildings have also been equipped with heat flowmeters. These are all measures that are critical to increased efficiency and a reliable monitoring system.

“Using our energy management system , we receive data from all users, providing us with a comprehensive overview. If anything should go wrong because, for instance, a valve is defective, we’ll see it and pass that information along to the facilities managers,” explains Böttcher. The energy management system allows energy data from several sources to be recorded and analyzed. For the Bruckwald site, for example, the system gives us a picture of the wood-fired boiler and measures the fill level of the bunker and the heat storage units on the heat generation side, as well as key parameters on the consumer side. “Our employees have remote access to the building control system and the energy management system. Even the on-site facilities managers can use their computers for direct access to information about whether everything is running smoothly,” says Böttcher. In the background, the energy management system is supplying even more information to the Operations Team from Bosch. Over the long term, data can be evaluated that could point to potential new approaches to energy efficiency. This will allow the energy and resource requirements to be monitored precisely and managed to ensure optimal use. The Bosch Operation Team monitors the system parameters, optimizes the system during operation, manages maintenance, thereby ensuring that the energy supply is 100% reliable.

The untreated wood chips are transported short distances by truck from regional sources and dumped directly into the underground bunker. “Our team has years of experience in planning and operating biomass facilities. Using wood chips as fuel remained the obvious solution here in the Sozialwerk Breisgau,” Böttcher explains. A push floor is used to transport the wood chips onto a screw conveyor, which carries the material into the central heating system and, from there, into the combustion chamber of the furnace. The ash produced is collected in special containers and later added to lime as fertilizer for the forest. A high-efficiency electric filter is used to reduce the particulate matter which the flue gas contains.