In cooperation with EU project SmartReFlex, solarthermalworld.org will soon hold the webinar Think big – Design rules and monitoring results of solar district heating systems. We invite every stakeholder to join the event scheduled online for 1.5 hours on Tuesday, 6 December 2016, from 2 p.m. to 3:30 p.m. Central European Time (time zone includes Berlin, Brussels, and Copenhagen). The webinar will be free of charge and will be open to anyone interested in the topic. You can register for it online.
Seasonal storage is a key component in the transformation of today’s energy industry. Besides storing energy in summer for heating in winter, it can also be used to save waste heat from the industry and to increase the electricity production from biomass CHP plants. Experiences gathered with the technology during case studies were summarised as part of the study Seasonal thermal energy storage – Report on state of the art and necessary further R+D, which was published by Task 45, Large Scale Solar Heating and Cooling Systems, of the IEA SHC programme. Together with the Guidelines for Materials & Construction on the two most common storage types, borehole (see the chart) and water pit, it provides a good overview of the current advancements in this field (all three documents attached). Additional research into the design of seasonal storage will be carried out in follow-up Task 55, Towards the Integration of Large SHC Systems into District Heating and Cooling (DHC) Network. Interested stakeholders have been invited to join the kick-off meeting of Task 55 in Graz, Austria, between 19 and 21 October (see contact details below).
The global solar thermal market went into another year of notable decline in 2015. With 37.2 GWth, the newly installed glazed and unglazed collector capacity in the 18 largest countries was 14 % lower than in 2014 (43.4 GWth). Between 2013 and 2014, the decrease in these 18 major countries – which represent 95-97 % of the world market – had been 15 %. The further slowdown last year was the result of diminishing collector area figures in China (-17 %), and in Europe (nine biggest nations down by -5 %). The countries with the highest growth rates last year were Denmark (+55 %), Turkey (+10 %), Israel (+9 %) and Mexico (+8 %). The chart shows both 2015’s newly installed collector area, broken down by collector type – flat plate, vacuum tube and unglazed collector area, and the 2014-2015 growth rate (excluding China, whose 2015 market volume was 21-times larger than Turkey, which ranked second). China added 30.5 GWth in 2015 of which 12.6 % were flat plate collectors (5.5 million m2).
As in previous years, Denmark remained the country dominating Europe’s solar district heating market. Twenty of the 23 new and upgraded district heating plants in Europe above 350 kWth (500 m²) from the statistics compiled by Jan-Olof Dalenbäck from the Chalmers University of Technology, Sweden, went into operation in Denmark – whereas Austria, Italy and Sweden had only one each to show for. Dalenbäck’s database shows 211 large-scale district heating plants currently in operation, with combined output at 708 MW (1.01 million m²). This means that only every fourth district heating plant in Europe uses solar energy compared to the 5,400 district heating systems a database from Swedish Halmstad University lists from across the EU-27. The map shows 2,188 cities with 2,445 larger district heating systems. The highest plant densities can be found in Denmark, Poland, the Czech Republic and Slovakia.
Source: Heat Roadmap Europe 2050 - Second pre-study for the EU27 (see the attached document)
The IEA’s solar heating and cooling programme has begun its research activities on solar thermal systems of gigawatt size. Scientists, industry representatives and utilities have been invited to participate in a definition workshop for a new task in the Austrian city of Graz on 5 November 2015. Sabine Putz, COO and R&D Manager at S.O.L.I.D., an Austrian large-scale turnkey system supplier, has proposed a four-year research programme entitled Large Scale Solar District Heating and Cooling Systems, which aims at studying economic, engineering and quality factors influencing solar district heating and cooling systems above 3.5 MW and up to GW size.
In Denmark, there are currently around 576,000 m² of solar collectors providing 403 MW of thermal power to 61 district heating systems. Another 28 plants with 395 MW and 564,000 m² of collector area are in the pipeline, according to a presentation held by Danish consultant Per Kristensen at the SDH conference in Toulouse in June 2015. Widely replicable plant concepts are part of the success story.
The interactive map on www.solvarmedata.dk, a website operated by agency Easynet, shows yield information entered by more than 40 solar district heating companies. The data also includes the irradiation figures and for most plants, even the hourly results of past years. The website was the brainchild of Per Kristensen, who came up with the idea when he was director of Braedstrup Fjernvarme. The screenshot shows the website’s first page.
The new seasonal pit heat storage Sunstore 4 is at the heart of Marstal´s extended solar district heating network. The town on the Danish island of Aeroe receives 55 % of its heat from the 33,000 m² of solar collectors. The pit heat storage installation, the first of its kind, was a difficult undertaking - the team had to cope with heavy rainfalls in the summer and a thick layer of ice in the winter of 2012, when the underground storage was still not covered. June 2014 was the official end of EU project Sunstore4, which contributed EUR 6.1 million to the extension and the monitoring of Marstal´s district heating plant, but work will go on. Marstal Fjernvarme now hopes to receive support from the Danish government.
The calculation of solar heat prices very much depends on the frame conditions. The chart on the left shows heat prices for a solar district heating system, with costs differing between 37 and 88 EUR/MWh. The best-case scenario - with a 3 % low-interest loan and a 40 % investment subsidy – allows a heat price of 37 EUR/MWh, whereas the worst case without a subsidy and with an 8 % interest rate forces the heat price to levels as high as 88 EUR/MWh. The calculation, which uses the newly developed online tool by German research institute Solites, is based on a 3,000 m² collector field and a 600 m³ storage tank. The tank feeds directly into a district heating network, which covers 9 % of the annual heat demand.
On 15 March, the excavators began their work for Denmark’s largest solar district heating project so far. The collector field in the town of Dronninglund, about 30 km northeast of Aalborg, will have an area of 35,000 m², but installing the collectors will only be the last step. First, there is the seasonal pit heat storage - a hole in the ground filled with 60,000 m³ of water. In combination with the seasonal heat storage, the solar plant is said to achieve a yield of 15,000 MWh per year and to provide 40 % of the heat for the local district heating network with its 1,350 customers. In the long run, the collectively owned district heating company Dronninglund Fjernvarme plans to provide all of its heat through renewable energies to keep heat prices stable, albeit there have not yet been any details on how to accomplish this task. Currently, the heating network’s supply is based on four combined gas-based heating plants (7 MWel and 12 MWth total) and two biofuel boilers (15.1 MW total).
Photo: ARCON Solar