Case Study

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One of the World’s First High-Availability Wood Gasification Plants

Erwin Schiefer benefits from a coherent, CompactLogix based package that meets its needs... all from a single source

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  • An efficient wood gasification plant that currently produces 440kW of electrical energy (the company is planning output of up to 900kW in the second phase) as well as 1570kW of thermal energy
  • High plant availability of at least 7,800 operating hours per year; from Feb. 2010 to Feb. 2011 it was operational for 8,300 hours or 95 per cent of its capacity
  • Increased safety and reliability with constant fine-tuning as well as remote diagnostics and maintenance capability
  • Having built a successful wood gasification plant on his farm, Erwin Schiefer has achieved international recognition and now sells plants to other companies


With the extensive range of products and solutions from Rockwell Automation, customers in the gas production industry benefit from a coherent package that meets their needs... all from a single source. This has been invaluable to Austria's Erwin Schiefer for his wood gasification project. He started out building a plant for his farm's use and now sells plants to other companies too.

This has been invaluable to Austria’s Erwin Schiefer for his wood gasification project. He started out building a plant for his farm’s use and now sells plants to other companies too.


The production of gas from wood burning is a complex process with a number of potential pitfalls. It places heavy demands on the plant control system, which needs to detect and counterbalance any process related deviations right at the outset. A high level of built-in intelligence is also required in the other components deployed in the system. A huge electricity bill prompted Austrian farmer Erwin Schiefer to think about becoming his own energy supplier. Schiefer knew that some natural energy sources were slowly but surely coming to an end, whereas there is still a lot of untapped potential in other sources – such as wood.

Although power generation by wood gasification was discovered some 200 years ago, it never really took off as there were always easier or more cost-effective alternatives available. Schiefer says: “Wood gasification technology is difficult to get right and many companies have failed at it. Although it's relatively easy to produce the gas, ensuring the stability of the system is where the real challenge comes in.”


Together with Rockwell Automation, Schiefer built a wood gasification plant which – along with producing energy – has attracted a lot of attention abroad. And with 8,300 productive hours of operation per year it's hardly surprising – that's an unusually high level of availability. It's almost 95 per cent of the plant's total capacity and a performance most other wood gasification operators can only dream of. This success prompted Schiefer to think about diversifying his farming business by developing wood gasification plants for other companies.

“We developed the entire system ourselves, from the reactor down to the last filter for gas cleaning,” says Schiefer, visibly proud of a system that produces up to 200 kilowatts electrical and up to 400 kilowatts thermal energy per hour. The farmer can more or less leave the combined heat and power plant to get on with its job, thanks to the Allen-Bradley® CompactLogix™ system that manages the automation, including the heating technology, wood and maize drying and energy supply to the grid.

According to Schiefer, the key to achieving high availability in a wood gasification plant is accurate zone control within the reactor. “The reactor's ventilation is located in the oxidation zone,” he explains. “That's where CompactLogix makes sure that the zone, which is the hottest, does not rise due to variations in materials or humidity. It does that by adjusting the ventilation levels accordingly.”

He believes that as long as the ventilation is right and there's perfect coordination between the four reactor zones – drying, pyrolysis (carbonisation), oxidation and reduction – the stability issue can solve itself.

Fine-Tuning Makes All the Difference

The system requires precise fine-tuning, which is handled by the Allen-Bradley control system and by the Walking Floor based drying technique, which was developed by Schiefer. “The higher the humidity of the chopped wood, the more water will evaporate from it, so the dryer is adjusted to move forward more slowly.” This procedure contributes to better safety and reliability and is so effective that it's being talked about throughout Europe.

In the meantime, more modular wood gasification power plants in Germany, Italy and Slovakia have been installed. Also, there were very high expectations placed on the technology and with the brand Xylogas® found. The advice, support and expertise of Mr. Schiefer is another important aspect for customers, who can rely on his experience and thus save a lot of time and money.

Meanwhile, the Xylogas brand has established itself in the market and is especially known for quality and performance far beyond the borders of Austria. Additional product lines are developed and adapted to the new segment requirements. As there are still millions of people worldwide who have no access to electric power. Xylogas want to develop technology for these areas and so become a global player in the alternate segment.


A plant in Sterzing/South Tyrol is delivering on its promises: After overall completion 900kW electrical power shall be supplied to the official power grid in Italy. 1570kW of thermal energy to the local grid.

Within this plant, the order of command is clear – the Allen-Bradley components call the shots. They're headed up by a CompactLogix controller from the 1768 series with a L43 CPU. This manages the flow of material from the silo to the reactor as well as the particle filtering and the drying systems. It also monitors the critical gas cleaning and production processes and fine-tunes all the action based on data provided by 1734 Point I/O™.

Erwin Schiefer is particularly impressed with the Allen-Bradley PowerFlex® 40 and 70 AC drives that manage a variety of pumps, drives and compressors, and with the Factory Talk View Studio visualisation system. He and his team can take a closer look at the system via a secure VPN connection whenever necessary, carrying out remote diagnostics and maintenance via EtherNet/IP. But that's something that is rarely needed, thanks to sophisticated automation technology from Rockwell Automation.


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