Behind the Danish homepage http://www.solvarmecenter.dk, the consultant company PlanEnergi does present a large number of solar heating systems, large as small. The site is very beautiful and ought to get attention by the readers of this blog. Thanks to Jan Erik Nielsen from PlanEnergi Sealand. PS: Why do you not show actively, who’s behind this nice site?

The 14th and 15th of January 2009, there was a workshop at the Technical University of Denmark, Lyngby with aims described by the workshop title “How ambitions can we be in contributing to the worlds energy needs with wind, solar and bio energy. – And what role does energy storage play?”

This was certainly a very interesting place to be and listen to experts, politicians and industries. At the workshop “solar energy” the experts in CSHP, Jan-Olof Dalenbäck, representing amongst other the European platform ESTTP (http://esttp.org), representatives from universities and two major players from industries Sten Beltman Jørgensen, Sunmark A/S (http://www.sunmark.com) and Jes Donneborg Arcon Solvarme A/S (http://www.arcon.dk). Backed up by others the target was to be defined for “solar thermal” including large solar.

Some remarks from the discussion show that even though CSHP have just a share of 1% of the collector area, the production share is at 9%, a Factor 9. This is due to size, efficiency and storage.

According to figures by Jan-Olof there are 30 central plants and 120 block and “small” plants at current times. As you will find in the coming future there are a number of plants under construction and planning.

It was discussed that subsidies schema do not support large-scale solar heating while supporting the small systems. It can be argued that subsidies are not necessary for CSHP due to the cost effectiveness for commercial plants. See the VEKS post below.

It was mentioned that there is a new project founded by the EU “SDH Take-off” probably Solar District Heating (SDH). You will find more on that topic later in this blog. (I could not find any through Cordis or Google – please help).

The method of the workshop was to define an ambitious target, uncover challenges which lead to a number of actions and from here a road map could be drawn. This work, over 2 days let to the following conclusion which was presented at the workshop: (my interpretation)

Pro-solar arguments are that you need 1 hour collection of all solar energy to supply the world with the total energy necessary. This ought to be possible. Solar produces 30-40 times the energy per area as biomass. The ambitious goal was defined at he the COP14 in Poznan, Poland to 50% of all heat demand must be supplied by solar heating in 2050. This target was than distributed over the period, not referred here.

The road map was laying out that all actions ought to start as fast as possible. Politicians ought to adopt the target (which they did i Poland). Next step ought to be public investments into maximum application of solar heating in public buildings, which would result in a) a stable marked condition for the industries and b) a critical mass for the production lines, assuming that marked conditions will lead to price-performance and competitiveness that brings along sustainability for the branch. A very important goal is than to increase the solar fraction of the technologies by improving/increasing the storage technologies. As another effort solar cooling would be investigated.

Please not that the workshop was also working with targets for other solar technology, education, wind and bio energy, plus energy storage.

I hope that other participants will be able to support by their descriptions and comments to this post or we will be able to supply with a proceedings or official summary by Risø. DTU, the organizers. Thanks to them. You may probably find it at http://risoe.dtu.dk

Next step will be COP15 – see http://www.cop15.dk/en

Congratulations to Samsø Green Island pioneer Søren Hermansen. He’s one of the “Heroes of the Environment 2008″ by Times Magazine. Source: http://www.time.com/time/specials/packages/article/0,28804,1841778_1841782_1841789,00.html.

One of the achievements are the central solar heating plan in Nordby. The solar plant of 2,500 m² solar collector supporting a chip wood plant with a 800 m³ thermal storage. You find more information on the plant and all the many other efforts on the Green Island at http://www.energiakademiet.dk/front_uk.asp?id=73.

Congratulation to the whole community of Samsø – well done.

According to the Danish Engineering Newspaper “Ingeniøren”, the Danish consultancy firm behind most of the Danish CSPH, Rambøll, is on it way with a new plant in South Korea. Source: http://ing.dk/artikel/91267?nyhedsbrev.

The plant will support 100 green houses by a panel area of between 200,000 and 500,000 m², reducing the CO₂ emission by approx. 100,000-200,000 tons a year.

The plant will involve heat pumps and heat storage.

By the simple keywords “cshp” and “+solar” you find the most important links to online resources on large-scale solar heating. Her you get the Google query.

The Technical University of Denmark does research in large-scale solar collectors.

Abstract from DTU-homepage regarding the conference publication:

The test method of the standard EN12975-2 (European Committee for Standardization, 2004) is used by European test laboratories to determine the efficiency of solar collectors. In the test methods the mean solar collector fluid temperature in the solar collector, Tm is determined by the approximated equation where Tin is the inlet temperature to the collector and Tout is the outlet temperature from the collector. The specific heat of the solar collector fluid is in the test method as an approximation determined as a constant equal to the specific heat of the solar collector fluid at the temperature Tm. The power produced by the solar collector during a test period is determined by the product of the specific heat, the mass flow rate and the temperature increase of the solar collector fluid. The solar collector efficiency is in the standard determined by measurements at different temperature levels. Based on these efficiencies, an efficiency equation is determined by regression analysis. In the test method, there are no requirements on the ambient air temperature and the sky temperature. The paper will present an evaluation of the test method for a 12.5 m² flat plate solar collector panel from Arcon Solvarme A/S. The solar collector panel investigated has 16 parallel connected horizontal absorber fins. CFD (Computational Fluid Dynamics) simulations, calculations with a solar collector simulation program SOLEFF (Rasmussen and Svendsen, 1996) and thermal experiments are carried out in the investigation. The investigations elucidate: • How the mean solar collector fluid temperature Tm is underestimated by the approximated equation in the test standard and how the collector efficiency equation is influenced by the underestimation of Tm. The dependence of the volume flow rate is shown; • How the use of the approximated specific heat of the solar collector fluid is influencing the collector efficiency expression; • How the temperature levels used is influencing the collector efficiency expression; • How the measured collector efficiency is influenced by the weather conditions such as the ambient air temperature and the sky temperature. Based on the investigations, recommendations for change of the test methods and test conditions are considered. The investigations are carried out within the NEGST (New Generation of Solar Thermal Systems) project financed by EU.

For the first time, a major district heating company is planing to adopt the concept of central solar heating. The company VEKS, distributing heat in the western part of the Copenhagen area is aiming at a CSHP with a solar collector size of 20,000 m2, placed along a main highway. The plant will match the current record of the Marstal plant, also placed in Denmark. The plant will deliver approx. the heat of 5-6,000 single family houses.CEO, Lars Gulev, of the “Vestegnens Kraftvarmeselskab” district heating company estimates the plant to produce 10 GWh heat to the district heating system. The goal is to get the plant into production before the International Climate Conference in Copenhagen, 2009, where the expectations are to replace the Kyoto-protocol with a more ambitious protocol.

It is expected that the application of central solar heating is a factor 4 more cost efficient compare to single family housing solar installations.

Relevant is to mention, that the company is expecting lower production prices for the solar plant compared to the traditional co-generation plants due to the facts that solar prices are reduced as conventional heating prices are increased during the later years.

“In the first place, the solar heating plant is planed due to commercial reasons. Getting reduced CO2 pollution is a environmental side effect.” says Lars Gulev.

We hope others will take this considerations up and CSHP will play a more dominant role in the future of district heating. It would be interesting to see, if surplus heat from the power production will be cooled into the see due to this investment.

You find information on VEKS’s homepage on http://www.veks.dk (in Danish), where you change to English and will be presented for general information on the district heating system of Copenhagen. The solar plant is presented at the location http://www.veks.dk/Artikler/Seneste%20nyt/Solvarme.aspx

Blogging is online. Hence online resources are rather streight forward to point at. However, Googling turns out to show a lack of knowledge within this topic: Central Solar Heating Plants (CSHP) or Large-Scale Solar Heating. As a researcher, library information are traditionally the main source for information. Therefore I tried to search in our library including more than 45,000 journal articles. The hit rate for is 22 hits that matches the full term “Central Solar Heating Plants”; “Central Solar Heating” gives 82 hits, below 10 hits unique and written after 2000, the newest from 2004, most much older.

Can we conclude that Central (large scale) Solar Heating is not relevant?

We can cerainly conclude that the topic is not “hot”. Is this because there is no research going on, is it because the research is not pulished or is not accepted for publishing? This question is keept open.

Is the topic relevant?

Positiv aspects of CSHP: From the experiences from Marstal and most other plants, one can conclude that the efficiency for large-scale systems is much highere, compared to small solar systems. The installation price is appoximatelly 60% of the installation price for small systems. The price-performance is hereby better for both price and performance. Details can be found in the Ph.D. citet earier in the blog by me. Maintenance, effieciency improvements and other aspects do also point at large installations.

Problematic aspects of CSHP: However, heat losses can be relativelly large, if one does not consider it appropriatelly. Modells to do that can be found, among others, in “Heat-load modelling for large systems”, Applied Energy, p. 371-387, 72(1), 2002. Another negative aspect of large scale solar heating comes up, when combining solar heating with co-production power plants, where the “waste” heat is applied in district heating. This is the case for the Copenhagen District Heating, where an area with up to 30 km in wide, supplied with district heating. The problem here is, that the heat exaustion by power production does make the replacement with solar problematic, as long as the overall efficiency of the power production and “waste heat” are related.

So, the question must be answered, that the topic is very relvant for any large-scale heating system. Solar cooling could be combined, improving the efficiency even more. If you are researchers and look for an important research topic, here it is. District Heating & Cooling supported by Solar Energy with and without long-term heat and cool storage. As you find in this blog, there is a lot to work with.

One ought not to forget the main distribution and consumption system for CSHP, the District Heating. Such systems can be used for both heating and cooling. This is certainly obtained by Euroheat, an organisation for the European district heating and cooling industry. They published a nice brochure on district heating and cooling, mentioning a few of the solar plants.

The solar cooling part is of high relevance, due to the fact that cooling demands are closely related to the occurence of the sun. Hence demands and solar availability match perfectly.