The basic supply of B. Braun Melsungen AG with wood energy at its headquarters – a practical example.

In the decision-making process on transitioning from fossil to regenerative fuel and its practical implementation, typically the same questions arise – particularly from a management perspective: What about price security and price planning? After all, the transition should not, at best never, be more expensive than the current fossil fuel use (usually natural gas). Currently, this financial aspect of the decision-making process also includes questions about possible CO2 pricing. Especially when it comes to the use of industrial process steam, any negative process can lead to immense costs and thus, the requirements for supply security and availability are extremely high. Another desirable corporate goal for many entrepreneurs today is achieving a higher degree of independence from international and geopolitical energy markets. “The selection of the right partner is also a key criterion to which our customers attach great importance,” says Tobias Mayinger, adding to the list of customer expectations and wishes. The founding shareholder and board member of the Prolignis group based in Ingolstadt, Germany, knows the wishes of his contacts, who primarily want to concentrate on their core competencies. “We keep our customers’ backs clear in regard to any aspect related to wood energy.” This also includes a Prolignis biomass supply concept specifically developed for each project location, as questions about long-term and sustainable security of supply with wood fuels are essential success factors for the application of wood energy. The supply concept forms the basis for any transition project and ensures the long-term supply of the locations with wood fuels. Within the frameworks of this supply concept, regional aspects are examined and taken into account. Moreover, the suitability of suppliers is checked and long-term supply contracts with them are made. In practice, sustainability and circular economy thinking round off the material flow management. For example, the grate and boiler ashes produced during the incineration process are awarded the RAL 252-1 quality mark as a raw material for fertilizers. This means that the nutrient-rich bottom ash and boiler ash can be reintroduced into the natural cycles, for example in the production of compost and soil or as an additive in forest lime.

The detailed technical explanations then always revolve around very specific issues: Which thermal energy (heat, process steam, cold) is required in which quantities and at what times and in which places? Together with the customer, Prolignis then develops possible technical implementation concepts which, following a positive customer decision, lead to the design of a new wood-energy plant.

A practical example

The first contacts between the Prolignis Group and B. Braun Melsungen AG were established in 2011. Since its founding in 2006, Prolignis had already implemented seven wood-energy plants in Germany in the performance class relevant to B. Braun Melsungen AG, with a rated thermal output of around 20 megawatts, thus providing a solid background of experience.

At the Melsungen site, a wood energy plant with a furnace thermal capacity of 21.6 megawatts, a so-called natural circulation water-steam system with combined heat and power generation, was built. The electricity generated is fed into the public grid in accordance with EEG regulations and can supply more than 8,000 households there with green electricity. Around 10 % of the thermal energy produced is used for heating purposes. The vast majority is supplied as process steam and used for sterilisation in the production chain. In medical technology in particular, these are highly sophisticated, continuously certified and externally monitored processes to which no “external” supply unit was allowed to be connected. In order not to interfere technically with the existing supply system, a so-called steam-steam heat exchanger was installed, which on the one hand separates the systems and on the other hand reliably provides both the required reaction speed and the required steam quality. “This convinced our energy colleagues at B. Braun that we were technically clearly competitive in comparison to the fossil solution,” notes Florian Schechinger, technical operations manager at Prolignis.

Thanks to this positive experience since commissioning at the end of 2014, among others, B. Braun and Prolignis are jointly preparing to further expand their share of renewable energy supplies. “We will build a second wood energy plant at the Melsungen site to supply heating water to B. Braun. It will also supply large parts of the required cooling energy in the future on the basis of wood energy,” says project manager Ulf Junger. A plant with a furnace thermal capacity of 15.5 MW is planned. “With the supply of process steam, heating and cooling, the Melsungen site is a shining example of the possible uses of wood energy in industrial environments,” Tobias Mayinger sums up, expecting a corresponding signalling effect.



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