Who Owns Flachau's District Heating System?

Flachau, Austria is home to a district heating system that provides heat and hot water to all of the buildings in the village, about 400 in total. The system is owned by a cooperative and was financed by a local bank. Flachau's district heating system burns locally sourced wood chips to create hot water that is pumped throughout the village. The facility runs two chip-fired boilers, with a maximum output of 8,000 KW. The system includes a backup oil-fired boiler that is used in emergencies.

The cooperative that owns Flachau's district heating system

Flachau's district heating system is owned by a cooperative, or "Genossenschaft". The system is financed by a local bank and was installed by SWH (Strom und Wärme aus Holz, or Power and Heat from Wood), an offshoot of Austria's national forest agency.

The system burns locally sourced wood chips to provide hot water to about 400 buildings in Flachau. The wood chips are sourced from local forests within a 30 to 40-kilometre radius of the village. The use of wood chips is preferred over pellets because they can be easily produced locally from logging waste or low-grade logs.

The heating system consists of two boilers with a combined capacity of 8,000 KW (8 MW). The larger boiler has a capacity of 5,000 KW (5 MW), while the smaller one has a capacity of 3,000 KW (3 MW). The system also includes a backup oil-fired boiler with a capacity of 10 MW, which is only used in emergencies.

The district heating system in Flachau is just one of many such installations in Austria. In the state of Salzburg, where Flachau is located, there are over 100 such installations, and nearly every town has one. The number of installations is even higher in the state of Upper Austria. These systems are popular because they are locally owned, use fuel from nearby forests, and are CO2 neutral.

How the system works

The district heating system in Flachau, Austria, is owned by a cooperative, Genossenschaft. The system is centred around a central plant that burns wood chips from local forests to provide hot water to about 400 buildings in the village. The plant runs two chip-fired boilers, with a combined capacity of 8,000 KW (8 MW). During the winter, both systems are used, but in the summer, only the smaller one is needed. The system also includes a backup oil-fired boiler with a capacity of 10 MW, which is used only in emergencies.

The hot water is pumped through about 24 kilometres of buried pipes to the buildings in Flachau. The pipe diameter varies depending on where the pipe is located in the system and the needs of the particular buildings being served, ranging from 200 mm (about 8 inches) in diameter for pipes leaving the facility to about 25 mm (1 inch) in diameter for the smallest pipes in the system. The pipes are insulated with rigid foam that is about 7 cm (3 inches) thick.

The system consists of two loops: one supply and one return. A single supply pipe of hot water enters each house, where a heat exchanger is used to separate the hot water for heating from the domestic hot water for sinks, showers, etc. A single return pipe exits each house.

The district heating system in Flachau saves the equivalent of 3 million litres (nearly 800,000 gallons) of fuel oil each year and has been well-received by the townspeople, particularly owners of local hotels and guest houses, as it helps protect their businesses against rising energy prices.

The system's environmental impact

Flachau's district heating system is owned by a cooperative, and is fuelled by locally sourced wood chips. The system is designed to burn a wide range of fuels, including low-quality mixtures containing a high percentage of needles and bark. However, spruce is the most common wood species in the area.

The system has a maximum output of 8,000 KW (8 MW), with two chip-fired boilers, one with a capacity of 5,000 KW (5 MW) and the other with a capacity of 3,000 KW (3 MW). The boilers transfer heat from burning chips to water, which is pumped throughout Flachau to provide heat and hot water to residents. The system includes a back-up oil-fired boiler with a capacity of 10 MW, but this is only used in emergencies.

The environmental impact of the district heating system in Flachau is significant. The system is essentially CO2 neutral, saving the equivalent of 3 million litres (nearly 800,000 gallons) of fuel oil each year. This helps to reduce greenhouse gas emissions and combat climate change. The system also protects local businesses against rising energy prices, as monthly bills are significantly less than they would be if buildings used oil, natural gas, or electricity for heat and hot water.

The district heating system in Flachau also has a positive impact on the local economy, as the fuel comes from nearby forests, allowing money to remain in the local economy. In addition, the system helps to ensure jobs in the local forestry industry.

However, there are some potential concerns about the sustainability of the system. While the Austrian government has policies in place to ensure sustainable forestry practices, there is no guarantee that future circumstances won't undermine these policies. Additionally, the use of wood chips for fuel may impact the long-term health of the forest, as trees that would otherwise return to the soil to compost are being harvested for fuel.

The history of the system

The history of Flachau's district heating system began in 2007 when the larger of the two boilers was installed. The smaller boiler came online in 2009. The facility runs two chip-fired boilers, with a maximum output of 8,000 KW (8 MW). The system includes a backup oil-fired boiler with a capacity of 10 MW, which is used only in emergencies.

Flachau's district heating system provides heat and hot water to all the buildings in the village, about 400 total, through 24 kilometres of buried pipes. The system is owned by a cooperative, and the cost was financed by a local bank. Installation was overseen by SWH (Strom und Wärme aus Holz, or Power and Heat from Wood), an offshoot of Austria's national forest agency, with the mission to promote biomass-based energy production.

The system burns locally sourced wood chips from forests within a 30 to 40-kilometre radius. Chips are chosen over pellets because they can be easily produced locally from logging waste or low-grade logs, whereas pellet production is energy-intensive and would require its own plant. The wood species used does not matter as the system is designed to burn a wide range of fuels, but most of the wood is spruce, as that is the most common species in the area.

The system has been working well, and the townspeople have been happy with it. It is technically complex and has many sophisticated components that require monitoring and care, such as the multi-cyclone filter, the electrostatic filter, and the condensation system that recovers heat from flue gases.

The future of the system

The future of Flachau's district heating system, and similar systems across Austria, will likely involve a continued focus on sustainability, efficiency, and the integration of renewable energy sources.

Austria has been making impressive strides in the area of renewable energy, with a particular emphasis on biomass-based energy production. The country's efforts have been characterised by a steady process of continual improvement, with a strong focus on locally produced and used renewable energy.

The Flachau district heating system is owned by a cooperative, with installation overseen by SWH (Strom und Wärme aus Holz), an offshoot of Austria's national forest agency. This local ownership model is common across Austria and is one of the reasons these systems are so popular.

However, one challenge that lies ahead is the decreasing demand for room heating due to the increasing effectiveness of retrofitting measures in the building sector. This, coupled with reducing heat sales and uncertain energy prices, means that historic infrastructures are becoming uneconomic. As a result, heating networks need to be further developed to make them more flexible and intelligent.

To address these challenges, Austria is working on several projects as part of the IEA District Heating and Cooling (DHC) programme. These include:

• InteGradeDH – Large-scale integration of low-grade sources into district heating networks through geothermal seasonal storage and heat pumps
• RE-PEAK – How to cover peak heat loads in DH networks with renewables?
• Flexibility and DH value chain (FlexVal) – advanced analysis and compatible pricing
• HY2HEAT – Using electrolysis waste heat in district heating networks

Additionally, Austria is working towards increasing the share of biomass and renewable energy sources in district heating systems. This is in line with the country's goal to ensure that heat supply contributes to achieving global climate targets while also achieving regional added value.

The future of the Flachau district heating system is thus focused on sustainability, flexibility, and the increased utilisation of renewable energy sources.

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