Solar district heating is attractive business. Not only does this become obvious when looking at the 347 MWth of newly installed SDH capacity in Denmark in 2016, but also when one hears about Big Solar, a 250 MWth collector field – with 1.8 million m² of seasonal storage – planned to cover 20 % of the energy demand in the Austrian city of Graz by 2020. It certainly explains the high interest in international research platform Towards the Integration of Large SHC Systems into DHC Networks, or Task 55 of the IEA Solar Heating and Cooling Programme. “We welcomed 33 participants from eight countries during our second project meeting in Aalborg in mid-March, and even had to limit the number of participants per company because of the huge demand,” explained Sabine Putz, Operating Agent of Task 55 and COO and Head of R&D at S.O.L.I.D.
Photo: AALBORG CSP
Close cooperation between research institutions and turnkey solar thermal suppliers is necessary to realise SDH systems with high solar fractions and low cost per kilowatt-hour. Another key member of the research platform besides S.O.L.I.D. is Arcon-Sunmark, a Danish supplier of large-scale solar thermal systems. Jiao Qingtai, Deputy General Manager of its Chinese-based joint-venture partner Sunrain Solar Energy, heads the subtask on Components Testing, System Monitoring and Quality Assurance.
Drafting a heat delivery contract
Arcon-Sunmark has signed a letter of interest with the regional Austrian energy provider Energie Steiermark in July about intending to set up and operate the above-mentioned Big Solar plant, with S.O.L.I.D. as the junior partner. “A project development business called SWV Solar Wärme Versorgungs GmbH [translates as Solar Heat Supply Company]” had already been founded in Graz, Gerald Moravi, Managing Director of Energie Steiermark, confirmed during his presentation at the Smart Energy Systems Week Austria 2017 in Graz on 17 May. The next steps would be to establish a heat delivery contract between Energie Steiermark Wärme and SWV and acquire the land on which to set up the installation. Moravi said that the project would need 100 hectares, or one-third of the area that the city´s airport had. The project partners had also been advancing the technical design of the plant and prepared the documents for the building permit, which should be available in the second quarter of 2018.
Diagram of hybrid SDH solution with collector field and absorption chiller units
“Big Solar is a great case study for Task 55 because it is one of our major objectives to research and develop SDH solutions connected to absorption heat pumps and seasonal heat storage,” explained Putz. These hybrid SDH solutions are to be evaluated based on static and/or dynamic simulation methods. In addition to the collector field, Big Solar is planned to include six 16 MW absorption heat pumps, which connect the storage tank to the heating grid.
Another interesting case study seems to come from Tibet, where the Chinese government has big plans for extending the district heating network, and solar heat could be an option across an area which enjoys double the irradiation Denmark does.
Websites of organisations and projects mentioned in this article: