Austrian Town’s Dual-Fuel District System Gives It Secure Heat, Renewably Fueled
Town of Gleinstätten
Woodchip District Heating System
Heating Capacity (output): 2.5 MW (8.5 MMBtu/hr)
Emissions Reduction and Combustion Control Equipment: Multi-cyclone, condensation plant, moving grates
Year Installed: 2006
Thermal Output: Hot water
District Heating Network Length: 5.7 km (3.5 miles)
Number of Customers: 75
Town of Gleinstätten PDF
Many Austrians feel a double impetus to move toward renewable energy systems. Along with weaning their country and communities from imported oil, they tend to see the supply of natural gas, imported mainly from Russia, as uncertain—especially after Russia cut off supplies during a quarrel with Ukraine in the winter of 2008.
This small country’s response has been striking. More than 300 biomass district energy systems are now operating within the south-central state of Styria alone. These range from tiny systems that serve a few buildings to one that heats Graz, the state’s capital city. Many district systems have been developed by local entrepreneurs who partnered with an energy company—as happened in Gleinstätten, a small market town of about 1,500 people.
“We always partner with local people for establishing district heating systems,” says Evelyn Schweinzger, marketing director for Nahwärme, the company that worked with local resident Wolfgang Waltl to develop Gleinstätten’s wood-and-solar district system. Nahwärme, a developer of community district-energy systems, is a spinoff and partner of S.O.L.I.D., a larger firm that designs and installs central solar energy systems.
Gleinstätten’s district heating system uses both biomass and solar technologies to produce hot water. The water is distributed through 5.7 kilometers (3.5 miles) of in-ground piping to heat the town’s municipal buildings, schools, a number of commercial buildings, some houses within the compact village, and Gleinstätten’s historic, Renaissance-era castle and church.
“We often integrate solar into our biomass heating projects—we look for the right mix for each project,” says Schweinzger. “We do small community projects, so we do not do any electricity production.”
The Gleinstätten wood boiler provides 2.5 MW of thermal energy (8.5 MMBtu/hour), along with heat generated by 1,315 square meters (14,000 square feet) of solar hot water panels on the plant’s roof. Additionally, up to 300 kW (one MMBtu/hour) of heat can be provided by the condensation plant, which recovers heat from the flue gases. The system required a total investment of €3.2 million ($4 million US). It sells heat to its customers for 6.5-8 Euro cents per kWh ($24-$30 US per MMBtu).
A Flexible System, Simple to Maintain
Wolfgang Waltl had grown tired of commuting about 35 kilometers (20 miles) to his job in Graz, and wanted to start a local business in his hometown. He started the project, and Nahwärme—which now has 29 similar projects, all over Austria—came in as his partner. The other partners in the Gleinstätten company are three townspeople and the local farmers’ wood supply co-op.
“Here in Gleinstätten, the first idea was to get the town off Mideastern oil—but people in Austria also want to get free of Russian natural gas,” says Schweinzger of Nahwärme. “We’ve seen our gas supply cut off in midwinter when there were pipeline disputes between Russia and Ukraine.
“Last winter, Russia turned off gas supplies to Ukraine in a dispute over prices, which left large parts of Eastern Europe without supplies during a bitterly cold spell,” explained a July 2009 article in the Wall Street Journal. “Europe gets a quarter of its gas supplied from Russia, mostly via pipelines through Ukraine. Several southeastern European countries almost totally depend on that gas.”
The Gleinstätten district system has been working very well.
“Hot water district heating is very flexible,” says Harald Blazek, project manager for S.O.L.I.D. “You can use both biomass and solar hot water to provide the thermal input, and you can use it for both heating and cooling. The equipment for turning hot water into cool water has almost no moving parts, and is very easy for maintenance.”
Gleinstätten’s system is small, but has a very effective emissions control mechanism—a typical multi-cyclone particulate removal device, together with a condensation system to increase efficiency and add a much higher level of emissions reduction.
The plant can burn high-moisture green wood, and generally uses fuel that is a mix of ground-up wood and bark. The woodchips are fed into a rotating sorter drum, whose various-sized holes allow the chips to sort out into bins for rough, fine, and finer grades. As a secondary revenue source for the district heating business, some of the finer chips are sold on the residential fuel market—Austria has a robust market for various grades of chips. The plant itself uses about 10,000 cubic meters (3,500 US tons) of chips per year.
The system produces two waste products: solids, such as wet ash from the boiler, are taken to a local landfill, while liquid wastes from the condensation system go into the municipal sewage treatment system. In summer, the plant continues to produce heat, some of which it uses to dry its chips for winter use and for sale. A nearby window manufacturer also buys hot water in summer to heat its drying kilns.
Staffing the district system requires two hours of one person’s time each day in winter, one hour in summer.
Summing up his project, Waltl speaks of both tradition and innovation.
“This area has a strong solar tradition—a lot of solar collectors were installed in the state of Styria starting years ago,” he says. “The idea of integrating solar hot water into our wood-heating plant was quite natural.”