Polytechnik

Use of Wood to Generate (Process) Heat

Lighthouse Projects in Biomass Energy Use

The use of solid biomass for energy has been a controversial topic in the EU for some years. However, when specific criteria are considered, this energy source offers numerous advantages for achieving the desired energy transition. In recent years, the Polytechnik Group, based in Weissenbach an der Triesting (Austria), has built numerous biomass heating plants and combined heat and power (CHP) plants that set standards for sustainability, resource and energy efficiency, and emissions.

Wood Processing Industry

Historically, and to some extent still today, the heat required in the wood processing industry was provided by fossil fuels, while the resulting production waste often went unused. Initially driven by cost pressures, and now also by climate protection concerns, more companies are using their waste to heat drying plants, steaming pits, veneer dryers, and similar facilities. Polytechnik has designed and installed numerous biomass plants for the wood industry in recent years. Selected examples include:

Erdenwerk Ziegler, Plößberg: Polytechnik supplied the wood-firing system and thermal oil system for an ORC CHP plant. The boiler has a nominal output of 14 MW and heats an indirect steam generator in addition to the ORC module. The waste heat from the ORC process is used to dry chips from the neighboring sawmill for subsequent pellet production.

Bühler Spankorbfabrik: Located on the edge of the Black Forest, this veneer manufacturer generates hot water at 180°C by burning its production waste in an adiabatic combustion chamber. The plant’s nominal heat output is 4.5 MW, and the process heat is used for veneer dryers and steaming pits.

Industry and Trade

Polytechnik has planned and installed a steam boiler system to heat a powder coating plant for an automotive supplier in Hesse. The system provides process steam at approximately 35 bar and 240°C year-round. Numerous other industrial and commercial enterprises, as well as municipal facilities, generate district and process heat using biomass firing systems from Polytechnik. These include AIRBUS, STOROPACK, Tirol Milch (Austria), Migros (Switzerland), Klärschlammverwertung Albstadt, and various municipal utilities and energy supply companies.

Carbonization Plants

Polytechnik has advanced climate protection with the development of a pyrolysis process. The pilot plant in Mecklenburg-Western Pomerania converts forest residues, wooden green waste, and other solid biomass into biochar. This process separates the carbon-rich fraction of the biomass from the hydrogen-rich fraction, the pyrolysis gas. The carbon-rich fraction, known as biochar, can be sustainably used in agriculture, the construction industry, and other applications. Additionally, the pyrolysis gas can be used for heating, process heat and power generation.

The pilot plant has an annual production capacity of 3,000 tons of biochar. The biomass required for this has removed around 10,000 tons of CO2 from the atmosphere during its growth stage, with more than half of this amount being sequestered long-term as biochar. The process thus serves as a CO2 sink.

Selected Projects in Neighboring Countries

Spain: Polytechnik built a biomass CHP plant for the cosmetics giant L’Oréal, providing up to four types of energy simultaneously via the thermal oil plant, an ORC process, and an absorption refrigeration plant: saturated steam, electricity, hot water, and brine for air conditioning. This optimizes the use of wood for a complex industrial production process.

Denmark: Polytechnik constructed a biomass CHP plant with flue gas condensation and a downstream heat pump. The plant has a thermal output of 28 MW and a gross electrical output of 5.6 MW. It uses only residual forest wood as fuel. With a flue gas temperature at the end of the process below 50°C, the plant achieves an efficiency of over 110% relative to the lower calorific value of the fuel, showcasing exceptional energy and resource efficiency.

All Polytechnik systems can be remotely monitored using sophisticated control software, enabling support for system operators in locations as far-flung as China or New Zealand without the need for on-site service visits.

Solid Biomass – A Renewable Raw Material

The projects highlighted here exclusively utilize forest and sawmill waste wood, solid biomass char, and landscape conservation wood—biomass that cannot be used otherwise and would otherwise decompose unused. Biomass plants can be operated based on current heat demand and provide heating and process heat in various forms (warm water, hot water, steam, hot air, thermal oil), process cooling, and electricity. As a renewable raw material, the sustainable use of biomass ensures a largely CO2-neutral energy supply for municipalities, trade, and industry.

Hans Sanzenbacher

Managing Director, Polytechnik Deutschland GmbH

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