Central solar heating

Central solar heating is the provision of central heating and hot water from solar energy by a system in which the water is heated centrally by arrays of solar thermal collectors (central solar heating plants - CSHPs) and distributed through district heating pipe networks (or 'block heating' systems in the case of smaller installations).

For block systems, the solar collectors are typically mounted on the building roof tops. For district heating systems the collectors may instead be installed on the ground.

Central solar heating can involve large-scale thermal storage, scaling from diurnal storage to seasonal thermal energy storage (STES). Thermal storage increase the solar fraction - the ratio between solar energy gain to the total energy demand in the system - for solar thermal systems. Ideally, the aim for applying seasonal storage is to store solar energy collected in the summer time to the winter month.

Compared to small solar heating systems (solar combisystems), central solar heating systems have better price-performance ratios due to the lower installation price, the higher thermal efficiency and less maintenance.

Central solar systems can also be used for solar cooling in the form of district cooling. In this case, the overall efficiency is high due to the high correlation between the energy demand and the solar radiation.

Marstal central solar heating, have an area of 18,365 m². It covers a third of Marstal's heat consumption.
District heating accumulation tower from Theiss near Krems an der Donau in Lower Austria with a thermal capacity of 2 GWh.

Largest CSHPs

Name Country Owner Size Thermal
Power		 Annual
production		 Installation
year		 Storage
volume		 Storage type
Facilities		 Collector manufacturer
m² MWth GWh m³
Vojens DK Vojens Fjernvarme 70,000 50 35 2012-2015 203,000 Insulated water pond
Water tank		 ARCON (DK)[1][2][3]
Dronninglund DK 37,573 27 18 2014 ArCon (DK)[4]
Ringkøbing DK 30,000 22.6 14 2010-2014 ArCon[5]
Vildbjerg DK 21,234 14.5 9.5 2014 ArCon[6]
Helsinge DK Helsinge Fjernvarme 19,588 14 9.4 2012-2014 [7]
Gråsten DK 19,024 13 9.7 2012 ARCON (DK)[8]
Brædstrup DK Brædstrup Fjernvarme 18,612 14 8.9 2007/2012 ARCON (DK)[9]
Tarm DK 18,585 13.1 9 2013 ARCON (DK)[10]
Marstal DK Marstal Fjernvarme 17,943 13.5 8.5 1996–2002 2,100
3,500
10,000		 Water tank
Sand/water ground pit
Insulated water pond		 Sunmark / ARCON (DK)[11]
Jetsmark DK 15,183 10.6 7.6 2015 Arcon/Sunmark (DK)[12]
Oksbøl DK 14,745 9.9 7.7 2010/2013 Sunmark (DK)[13]
Jægerspris DK 13,405 8.6 6 2010 Sunmark (DK)[14]
SydLangeland DK 12,500 7.5 7.5 2013 Sunmark (DK)[15]
Grenaa DK 12,096 8.4 5.8 2014 Arcon (DK)[16]
SydFalster DK 12,094 8.5 6 2011 Arcon (DK)[17]
Hvidebæk DK 12,038 8.6 5.7 2013 Arcon (DK)[18]
Sæby DK Sæby Fjernvarme 11,866 8 6.3 2011 Sunmark (DK)[19]
Toftlund DK 11,000 7.4 5.4 2013 Sunmark (DK)[20]
Gram (Denmark) 10,073 7 4.8 2009 122,000 Insulated water pond.
10MW electric boiler
900 kW heat pump		 [21][22]
Kungälv SE Kungälv Energi AB 10,048 7.0 4.5 2000 1,000 Water tank ARCON (DK)
Svebølle-Viskinge 10,000 5.3 5 2011/2014 [23]
Karup DK 8,063 5.4 3.7 2013 ARCON (DK)[24]
Strandby DK Strandby Varmeværk 8,000 5.6 3.6 2007 ARCON (DK)[25]
Nykvärn SE Telge Energi AB 7,500 5.3 3.4 1985 1,500 Water tank Teknoterm (SE)
ARCON (DK)
Ærøskøbing DK Ærøskøping Fjernvarme 7,050 3.4 3 1998/2010 1,200 Water tank ARCON/Sunmark (DK)[26]
Falkenberg SE Falkenberg Energi AB 5,500 3.9 2.5 1989 1,100 Water tank Teknoterm (SE)
ARCON (DK)
Neckarsulm DE Stadtwerke Neckarsulm 5,044 3.5 2.3 1997 25,000 Soil duct heat exchanger Sonnenkraft (DE)
ARCON (DK)
Ulsted DK Ulsted Fjernvarme 5,000 3.5 2.2 2006 1,000 Water tank ARCON (DK)
Friederichshafen DE Technische Werke Fried. 4,250 3.0 1.9 1996 12,000 Concrete tank in ground ARCON (DK)

Source: Jan Erik Nielsen, PlanEnergi, DK.

Hereafter you find a plant in Rise (DK) with a new collector producer, Marstal VVS (DK), a plant in Ry (DK), one of the oldest in Europe, a plant in Hamburg and a number of plants below 3,000 m². It may be relevant mentioning, that the island of Ærø in Denmark has three of the major CSHP, Marstal, Ærøskøping and Rise.

History of central solar heating plants

The history of CSHP given here is mainly a Nordic-European perspective on the topic.

Sweden has played a major role in the development of large-scale solar heating. According to (Dalenbäck, J-O., 1993), the first steps were taken in the early seventies in Linköping, Sweden, followed by a mature revision in 1983 in Lyckebo, Sweden. Inspired by this work, Finland developed its first plant in Kerava, and the Netherlands built a first plant in Groningen. These plants are reported under the International Energy Agency by (Dalenbäck, J-O., 1990). Note that these plants did already combine CSHPs with large-scale thermal storage.

The first large-scale solar collector fields were made on-site in Torvalle, Sweden, 1982, 2000 m² and Malung, Sweden, 640 m². Prefabricated collector arrays were introduced in Nykvarn, Sweden, 4000 m² in 1985. There was from the beginning a strong international perspective and cooperation within this research field, through investigation with the European Communities (Dalenbäck, J-O., 1995) and the International Energy Agency (Dalenbäck, J-O., 1990). Denmark did enter this research area parallel to the Swedish activities with a plant in Vester Nebel in 1987, one plant in Saltum in 1988 and one in Ry in 1989, taking over the know-how for prefabricated solar collectors of large size by the Swedish company Teknoterm by the dominating company ARCON, Denmark. In the later 1990s Germany and Switzerland were active among others with plants in Stuttgart and Chemnitz.

Due to cheap land prices, in the Nordic countries new collector arrays are ground-mounted (concrete foundations or pile-driven steel) in suitable areas (low-yield agricultural, industry etc.). Countries with high ground prices tend to place solar collectors on building roofs, following the 'block plant' variant of CSHPs. In Northern Europe, 20% solar heat of annual heating requirement is the economic optimum in a district heating plant when using above-ground storage tanks. If pond storage is used, the solar contribution can reach 50%.[27]

By 1999 40 CSHPs were in operation in Europe generating about 30 MW of thermal power .

Related systems

Central solar heating is a sub-class of 'large-scale solar heating' systems - a term applied to systems with solar collector areas greater than 500 m².

In Alberta, Canada the Drake Landing Solar Community has achieved a world record 97% annual solar fraction for heating needs, using solar-thermal panels on the garage roofs and thermal storage in a borehole cluster.[28][29][30]

See also

References

  1. ↑ Wittrup, Sanne (14 June 2015). "Verdens største damvarmelager indviet i Vojens". Ingeniøren.
  2. ↑ http://xqw.dk/work/FG22/okt/Projektforslag_for_udvidelse_af_Vojens_solvarme_med_bilag.pdf
  3. ↑ Current data on Danish solar heat plants (click Vojens in South-West Denmark, then "About the plant")
  4. ↑ Current data on Danish solar heat plants (click Dronninglund in North Denmark, then "About the plant")
  5. ↑ Current data on Danish solar heat plants (click Ringkøbing in West Denmark, then "About the plant")
  6. ↑ Current data on Danish solar heat plants (click Vildbjerg in West Denmark, then "About the plant")
  7. ↑ Current data on Danish solar heat plants (click Helsinge in East Denmark, then "About the plant")
  8. ↑ Current data on Danish solar heat plants (click Gråsten in South Denmark, then "About the plant")
  9. ↑ Current data on Danish solar heat plants (click Brædstrup in Central Denmark, then "About the plant")
  10. ↑ Current data on Danish solar heat plants (click Tarm in West Denmark, then "About the plant")
  11. ↑ Current data on Danish solar heat plants (click Marstal in South Denmark, then "About the plant")
  12. ↑ Current data on Danish solar heat plants (click Jetsmark in North Denmark, then "About the plant")
  13. ↑ Current data on Danish solar heat plants (click Oksbøl in West Denmark, then "About the plant")
  14. ↑ Current data on Danish solar heat plants (click Jægerspris in East Denmark, then "About the plant")
  15. ↑ Current data on Danish solar heat plants (click Langeland in South Denmark, then "About the plant")
  16. ↑ Current data on Danish solar heat plants (click Grenaa in North Denmark, then "About the plant")
  17. ↑ Current data on Danish solar heat plants (click Falster in South-East Denmark, then "About the plant")
  18. ↑ Current data on Danish solar heat plants (click Hvidebæk in East Denmark, then "About the plant")
  19. ↑ Current data on Danish solar heat plants (click Sæby in North Denmark, then "About the plant")
  20. ↑ Current data on Danish solar heat plants (click Toftlund in South Denmark, then "About the plant")
  21. ↑ Inspirationskatalog for store varmepumpeprojekter i fjernvarmesystemet page 59. November 2014
  22. ↑ Current data on Danish solar heat plants (click Gram in South-West Denmark, then "About the plant")
  23. ↑ Current data on Danish solar heat plants (click Svebølle-Viskinge in East Denmark, then "About the plant")
  24. ↑ Current data on Danish solar heat plants (click Karup in North Denmark, then "About the plant")
  25. ↑ Current data on Danish solar heat plants (click Strandby in North Denmark, then "About the plant")
  26. ↑ Current data on Danish solar heat plants (click Ærøskøping in South Denmark, then "About the plant")
  27. ↑ Wittrup, Sanne. "https://ing.dk/artikel/dansk-solteknologi-mod-nye-verdensrekorder-179658 Dansk solteknologi mod nye verdensrekorder]" Ingeniøren, 23 October 2015. Accessed: 16 July 2016.
  28. ↑ Wong B., Thornton J. (2013). Integrating Solar & Heat Pumps. Renewable Heat Workshop. (Powerpoint)
  29. ↑ Natural Resources Canada, 2012. Canadian Solar Community Sets New World Record for Energy Efficiency and Innovation. 5 Oct. 2012.
  30. ↑ Drake Landing

External links

Further reading

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