Seasonal thermal energy storage

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Seasonal thermal energy storage (or STES) is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season. For example, heat from solar collectors or waste heat from air conditioning equipment can be gathered in hot months for space heating use when needed, including during winter months. Waste heat from industrial process can similarly be stored and be used much later.[1] Or the natural cold of winter air can be stored for summertime air conditioning.[2][3] STES stores can serve district heating systems, as well as single buildings or complexes. Among seasonal storages used for heating, the design peak annual temperatures generally are in the range of 27 to 80 °C (80.6 to 176.0 °F), and the temperature difference occurring in the storage over the course of a year can be several tens of degrees. Some systems use a heat pump to help charge and discharge the storage during part or all of the cycle. For cooling applications, often only circulation pumps are used. A less common term for STES technologies is interseasonal thermal energy storage[4]

An example of one of the several kinds of STES storages illustrates well the capability of interseasonal heat storage. In Alberta, Canada, the homes of the Drake Landing Solar Community (in operation since 2007), get 97% of their year-round heat from a district heat system that is supplied by solar heat from solar-thermal panels on the garage roofs. This feat – a world record – is enabled by interseasonal heat storage in a large mass of native rock that is under a central park. The thermal exchange occurs via a cluster of 144 boreholes, drilled 37 metres (121 ft) into the earth. Each borehole is 155 mm (6.1 in) in diameter and contains a simple heat exchanger made of small diameter plastic pipe, through which water is circulated. No heat pumps are involved.[5][6]

STES technologies[edit]

There are several types of STES technology, covering a range of applications from single small buildings to community district heating networks. Generally, efficiency increases and the specific construction cost decreases with size.

Conferences and organizations[edit]

The International Energy Agency's Energy Conservation through Energy Storage (ECES) Programme[22][23] has held triennial global energy conferences since 1981. The conferences originally focused exclusively on STES, but now that those technologies are mature other topics such as phase change materials (PCM) and electrical energy storage are also being covered. Since 1985 each conference has had "stock" (for storage) at the end of its name; e.g. Ecostock, Thermastock.[24] They are held at various locations around the world. Most recent was Innostock 2012 (the 12th International Conference on Thermal Energy Storage) in Lleida, Spain.[25] Greenstock 2015 will be held in Beijing.[26]

The IEA-ECES programme continues the work of the earlier International Council for Thermal Energy Storage which from 1978 to 1990 had a quarterly newsletter and was initially sponsored by the U.S. Department of Energy. The newsletter was initially called ATES Newsletter, and after BTES became a feasible technology it was changed to STES Newsletter.[27][28]

Use of STES for small, passively heated buildings[edit]

Small passively heated building typically use the soil adjoining the building as a low-temperature seasonal heat store that in the annual cycle reaches a maximum temperature similar to average annual air temperature, with the temperature drawn down for heating in colder months. Such systems are a feature of building design, as some simple but significant differences from 'traditional' buildings are necessary. At a depth of about 20 feet (6.1 m) in the soil, the temperature is naturally stable within a year-round range,[29] if the draw down does not exceed the natural capacity for solar restoration of heat. Such storages operate within a narrow range of storage temperatures over the course of a year, as opposed to the other STES systems described above for which large annual temperature differences are intended.

Two basic passive solar building technologies were developed in the US during the 1970s and 1980s. They utilize direct heat conduction to and from thermally isolated, moisture-protected soil as a seasonal storage medium for space heating, with direct conduction as the heat return method. In one method, “passive annual heat storage” (PAHS),[30] the building’s windows and other exterior surfaces capture solar heat which is transferred by conduction through the floors, walls (and sometimes) the roof into adjoining thermally buffered soil.

When the interior spaces are cooler than the storage medium, heat is conducted back to the living space.[31][32] The other method, “annualized geothermal solar” (AGS) uses a separate solar collector to capture heat.[33] The collected heat is delivered to a storage device (soil, gravel bed or water tank) either passively by the convection of the heat transfer medium (e.g. air or water) or actively by pumping it. This method is usually implemented with a capacity designed for six months of heating.[34]

A number of examples of the use of solar thermal storage from across the world include: Suffolk One a college in East Anglia, England that uses a thermal collector of pipe buried in the bus turning area to collect solar energy that is then stored in 18 100m probes for use in the winter heating. Drake Landing Solar Community in Canada uses solar thermal collectors based on the garage roof of 52 homes, is then stored in an array of 35m deep probes. The ground can reach temperatures in excess of 70°C which is then used heat the houses passively. The scheme has been running successfully since 2007. In Brædstrup, Denmark some 8,000m of solar thermal collectors are used to collect some 4,000,000 kWh/a again stored in an array of 50 50m deep probes.

Small buildings with internal STES water tanks[edit]

A number of homes and small apartment buildings have demonstrated combining a large internal water tank for heat storage with roof-mounted solar-thermal collectors. Storage temperatures of 90 °C (194 °F) are sufficient to supply both domestic hot water and space heating. The first such house was MIT Solar House #1, in 1939. An eight-unit apartment building in Oberburg, Switzerland was built in 1989, with three tanks storing a total of 118 m3 (4,167 cubic feet) that store more heat than the building requires. Since 2011, that design is now being replicated in new buildings.[35]

In Berlin, the “Zero Heating Energy House”, was built in 1997 in as part of the IEA Task 13 low energy housing demonstration project. It stores water at temperatures up to 90 °C (194 °F) inside a 20 m3 (706 cubic feet) tank in the basement,.[36]

A similar example was built in Ireland in 2009, as a prototype. The solar seasonal store[37] consists of a 23 m3 (812 cu ft) tank, filled with water,[38] which was installed in the ground, heavily insulated all around, to store heat from evacuated solar tubes during the year. The system was installed as an experiment to heat the world's first standardized pre-fabricated passive house[39] in Galway, Ireland. The aim was to find out if this heat would be sufficient to eliminate the need for any electricity in the already highly efficient home during the winter months.

Use of STES in Greenhouses[edit]

STES is also used extensively for applications as the heating of greenhouses.[40][41][42] ATES is the kind of storage commonly in use for this application. In summer, the greenhouse is cooled with ground water, pumped from the “cold well” in the aquifer. The water is heated in the process, and is returned to the “warm well” in the aquifer. When the greenhouse needs heat, such as to extend the growing season, water is withdrawn from the warm well, becomes chilled while serving its heating function, and is returned to the cold well. This is a very efficient system of free cooling, which uses only circulation pumps and no heat pumps.

See also[edit]

References[edit]

  1. ^ Andersson, O.; Hägg, M. (2008), "Deliverable 10 - Sweden - Preliminary design of a seasonal heat storage for ITT Flygt, Emmaboda, Sweden", IGEIA – Integration of geothermal energy into industrial applications, pp. 38–56 and 72–76, retrieved 21 April 2013 
  2. ^ a b Paksoy, H.; Stiles, L. (2009), "Aquifer Thermal Energy Cold Storage System at Richard Stockton College", EFFSTOCK 2009 (11th International) - Thermal Energy Storage for Efficiency and Sustainability, Stockholm. 
  3. ^ Gehlin, S.; Nordell, B. (1998), "Thermal Response test-In situ measurements of Thermal Properties in hard rock", Avdelningen för vattenteknik. Luleå, Luleå Tekniska Universitet. 
  4. ^ e.g. Wong B., Snijders A., McClung L. (2006). Recent Inter-seasonal Underground Thermal Energy Storage Applications in Canada. 2006 IEEE EIC Climate Change Technology. pp.1-7.
  5. ^ Wong, Bill (June 28, 2011), "Drake Landing Solar Community", IDEA/CDEA District Energy/CHP 2011 Conference, Toronto, pp. 1–30, retrieved 21 April 2013 
  6. ^ "Canadian Solar Community Sets New World Record for Energy Efficiency and Innovation" (Press release). Natural Resources Canada. 5 October 2012. Retrieved 21 April 2013.  "Drake Landing Solar Community (webpage)". Retrieved 21 April 2013. 
  7. ^ Seibt, P.; Kabus, F. (2003), "Aquifer Thermal Energy Storage in Germany", American Astronomical... 
  8. ^ Snijders, A. (30 July 2008), "ATES Technology Development and Major Applications in Europe", Conservation for the Living Community (Toronto and Region Conservation Authority), Toronto, Canada 
  9. ^ Godschalk, M.S.; Bakema, G. (2009), "20,000 ATES systems in the Netherlands in 2020 - Major step towards a sustainable energy supply", EFFSTOCK 2009 (11th International) - Thermal Energy Storage for Efficiency and Sustainability, Stockholm 
  10. ^ Midttømme, K.; Ramstad, R. (2006), "Status of UTES in Norway", EcoStock 2006 (10th International) - Thermal Energy Storage for Efficiency and Sustainability, Pomona, New Jersey 
  11. ^ Stene, J. (19 May 2008), "Large-Scale Ground-Source Heat Pump Systems in Norway", IEA Heat Pump Annex 29 Workshop, Zurich 
  12. ^ Hellström, G. (19 May 2008), "Large-Scale Applications of Ground-Source Heat Pumps in Sweden", IEA Heat Pump Annex 29 Workshop, Zurich 
  13. ^ Interseasonal Heat Transfer
  14. ^ Thermal Banks
  15. ^ Report on Interseasonal Heat Transfer by the Highways Agency
  16. ^ Chrisopherson, Elizabeth G. (Exec. Producer) (19 April 2009). Green Builders (segment interviewing Lynn Stiles) (Television production). PBS. 
  17. ^ Nussbicker-Lux, J. (2011), "Solar Thermal Combined with District Heating and Seasonal Heat Storage.", OTTI Symposium Thermische Solarenergie, Bad Staffelstein. 
  18. ^ Michel, F.A. (2009), "Utilization of abandoned mine workings for thermal energy storage in Canada", Effstock Conference (11th International) -- Thermal Energy Storage for Efficiency and Sustainability, Stockholm 
  19. ^ Holms, L. (29 September 2011), "Long Therm Experience with Solar District Heating", International SDH Workshop, Ferrara, IT 
  20. ^ Mangold, D. (6 February 2010), "Prospects of Solar Thermal and Heat Storage in DHC", Euroheat and Power + COGEN Europe, Brussels 
  21. ^ Hellström, G. (18 May 2006), and technology in sweden.pdf "Market and Technology in Sweden", 1st Groundhit workshop, pp. see p.23 
  22. ^ IEA ECES Programme (2009). "Homepage". 
  23. ^ Paksoy, S. (2013), International Energy Agency Energy Conservation through Energy Storage Programme since 1978, IEA ECES 
  24. ^ Nordell, Bo; Gehlin, S. (2009), 30 years of thermal energy storage – a review of the IEA ECES stock conferences, IEA ECES 
  25. ^ IEA ECES Programme (2012). "Innostock 2012 webpage". 
  26. ^ IEA ECES Programme (2013), 2015 --13th ECES Conference Introduction 
  27. ^ "ATES Newsletter and STES Newsletter archive". 2012. 
  28. ^ "Index for ATES Newsletter and STES Newsletter". 2012. 
  29. ^ ICAX (webpage, undated). Mean Annual Air Temperature Determines Temperature in the Ground.
  30. ^ EarthShelters (webpage, undated). Improving the Earth Shelter. Chapter 1 in: Passive Annual Heat Storage – Improving the Design of Earth Shelters
  31. ^ Geery, D. 1982. Solar Greenhouses: Underground
  32. ^ Hait, J. 1983. Passive Annual Heat Storage — Improving the Design of Earth Shelters.
  33. ^ Stephens, D. (undated). Capturing Heat While the Sun Shines, to Warm Your Home Next Winter (Annualized Geo-Solar Design).
  34. ^ For a comparison of these methods, see: Stephens, D. (undated). Annualized Geo-Solar.
  35. ^ Sun & Wind Energy (2011). The solar house concept is spreading.
  36. ^ Hestnes, A.; Hastings, R. (eds) (2003). Solar Energy Houses: Strategies, Technologies, Examples. pp.109-114. ISBN 1-902916-43-3.
  37. ^ Scandinavian Homes Ltd, Research - Solar seasonal store
  38. ^ http://www.ukstudentpassivhausconference.org.uk/uploads/4/7/2/1/4721930/shane_colclough_ph_conf_uk.pdf
  39. ^ Construct Ireland Articles - Passive Resistance
  40. ^ Paksoy H., Turgut B., Beyhan B., Dasgan H.Y., Evliya H., Abak K., Bozdag S. (2010). Greener Greenhouses. World Energy Congress. Montreal 2010. https://worldenergy.org/documents/congresspapers/346.pdf
  41. ^ Turgut B., Dasgan H.Y., Abak K., Paksoy H., Evliya H., Bozdag S. (2008). Aquifer thermal energy storage application in greenhouse climatization. International Symposium on Strategies Towards Sustainability of Protected Cultivation in Mild Winter Climate. Also: EcoStock 2006. pp.143-148.
  42. ^ See slide 15 of Snijders (2008), above.

External links[edit]

http://btric.ornl.gov/eere_research_reports/electrically_driven_heat_pumps/ACES_annual_cycle_energy_system/subindex2.html