Leading Biomass Producer Achieves Efficiency Milestone with STELA’s Innovative Low-Temperature Drying Solution

by | Nov 11, 2023

Efficient Drying Solution for Wood Pellet Production for Ziegler Group, Pressath, Germany


This project is a Greenfield initiative, focused on establishing an environmentally sustainable and economically viable wood pellet production facility at Ziegler Group’s Pressath location in Germany. The goal was to achieve the highest efficiency at the lowest operational expenditure (OPEX), strictly adhering to the European Best Available Techniques (BAT) and German Technical Guidance on Air Emissions (TA-Luft) standards.

At the Pressath facility, the primary challenge was drying sawmill residue from an initial moisture content of 40% to a targeted 10%, processing an annual tonnage of more than 650,000 pounds (approx. 300,000mt). The facility aimed for peak production efficiency with minimal energy consumption, employing a hot water boiler operating at 266°F/194°F (130°C/90°C) using hog fuel. This process was constrained by stringent environmental permits aligned with the highest European and national standards.

  • Material to Process: Sawmill residue, screened and homogenized using a hammer mill
  • Initial Moisture Level: 40%
  • Target Moisture Level: 10%
  • Drying Requirement: Approximately 650,000 pounds (approx. 300,000mt) per year

STELA Solution: 

To address the drying and energy efficiency challenges while complying with rigorous environmental standards, STELA’s BTU RecuDry system was implemented. This system is renowned for its exceptional efficiency and flexibility, dynamically adjusting thermal usage based on varying ambient temperatures and fluctuating product supply. It is designed to regulate heat demands effectively between winter and summer, ensuring consistent drying quality year-round.


Final Moisture Level: Successfully reached the targeted 10% moisture content.

Outcome: The integration of the BTU RecuDry system by STELA was swift and efficient, allowing the client to begin their drying operations just 8 months into the project timeline.

Measurements indicated an efficiency between 0.68 to 0.75 MW per short ton (0.68 to 0.75 MW per 0.907 metric tons) of evaporation. This equates to 2.1 to 2.3 MMBtu per short ton or 1050 to 1160 Btu per pound of evaporation.

Conclusion: After implementing the STELA BTU RecuDry solution, Ziegler Group’s facility in Pressath not only reached their moisture target but also achieved exceptional drying efficiency. This success underscores STELA’s capability to provide efficient drying solutions that comply with the most stringent environmental standards, fulfilling both the project’s ecological and economic objectives.

The Role of Sawmill Residue in Biomass Energy

Definition: Sawmill residue refers to the by-products from lumber processing, including sawdust, shavings, and wood chips.

Importance in Biomass Pellets:

  • Sustainability: Repurposing sawmill residue as biomass pellets contributes to waste reduction and taps into a ready energy source.
  • Calorific Value: Sawdust, which makes up a significant part of residue, is prized for its high calorific potential for energy production.

Moisture Level Significance:

  • Quality and Efficiency: Managing moisture content is crucial for the structural integrity of pellets and optimal combustion efficiency. Precise moisture control is key to producing durable pellets and enhancing energy output, which results in a more optimized and efficient biomass energy process.

About Ziegler Group

Ziegler Group, based in Bavaria, Germany, is a diversified company primarily focused on the forestry and wood processing sectors. Established in 1948, it has grown into one of Europe’s largest family-owned wood processing companies. Its operations span timber processing and trading, wood pellet production, sawmill operations, energy production with a focus on renewable sources, and logistics and transportation to support its core operations. The Group is also known for its commitment to sustainability and environmental stewardship, particularly in forestry and wood processing. More information about Ziegler Group.