Marstal heating network

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Solar thermal system of the Marstal district heating system

The Marstal heating network (Danish: Marstal Fjernvarme ) is a heating network supplied with renewable energies in the Danish town of Marstal . The system, referred to in the literature as both local and district heating networks, is fed with solar district heating , biomass and a large heat pump . The system was at times the largest local solar heating project in Europe. In 2013, 32 GWh of renewable heat was delivered to customers, the solar coverage is given as around 55%.

History and technology

Solar thermal systems of the heating network, in the background the steel tank district heating storage

The city of Marstal has had a district heating network since 1962. This was converted to renewable energies in several steps. In 1996, the first open-space solar thermal system with 8,000 m² of collector area was built and, in parallel, a district heating storage system in steel tank design with a capacity of 2,100 m³ was installed. In 2003 the solar collector area was increased to 18,300 m² and an underground water storage tank with 10,000 m³ was built. This meant that around 30% of the 28 million kWh of heat required at that time could be covered by the solar systems. In 2012, the solar system was expanded again to a total of 33,300 m², which gave the system a nominal thermal output of 23.4 MW. In addition, another underground storage tank with 75,000 m³ was built. In total, the two underground storage facilities have a storage capacity of 638 and 6960 MWh respectively; they cost the equivalent of around 400 euros / MWh. The installation costs of the last solar thermal systems were 175 euros / m². The heat generation costs are 3–4 ct / kWh, making the system economically competitive without subsidies.

Parallel one in was cogeneration powered cogeneration plant installed, the thermal via boiler 4 MW has. An Organic Rankine Cycle process generates 750 kW of electrical power, and the remaining heat is fed into the local heating network. Another new addition was a compression heat pump with 500 kW electrical power and 1.5 MW heat output. A vegetable oil- operated peak load boiler with 18.3 MW is also available as a safeguard .

business

In summer the solar thermal systems cover the entire heat demand in the network. At the same time, the solar heat surpluses that occur are stored in the geothermal heat storage for autumn and winter. The heat pump can be operated variably as a power-to-heat system and is used particularly when electricity prices are low. In winter, it is also used to use residual heat from the geothermal storage systems when their temperature has fallen below the network temperature. The biomass boiler is also used in winter to provide electricity and heat. If required, it can also be used to reheat the seasonally stored solar heat.

Web links

Commons : Marstal Fjernvarme  - collection of images, videos and audio files

Individual evidence

  1. a b Volker Quaschning , Regenerative Energy Systems. Technology - calculation - simulation . 8th updated edition. Munich 2013, p. 101f.
  2. a b Viktor Wesselak , Thomas Schabbach , Thomas Link, Joachim Fischer: Handbuch Regenerative Energietechnik , Berlin / Heidelberg 2017, p. 419f.
  3. a b c d Thomas Pauschinger, Thomas Schmidt: Solar assisted combined heat and power with seasonal heat storage . In: Euroheat & Power , May 2013.
  4. Henrik Lund : Renewable heating strategies and their consequences for storage and grid infrastructures comparing a smart grid to a smart energy systems approach . In: Energy . tape 151 , 2018, p. 94-102 , doi : 10.1016 / j.energy.2018.03.010 .