HOT | COOL NO. 4/2012 - Interface, Users and Utilities

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THE NEED FOR LOW TEMPERATURE DISTRICT ENERGY Another aspect of Smart Cities which was discussed on the symposium was low temperature district energy. The subject of low temperature district energy is mostly raised as a part of the discussion of zero energy buildings. But it is also very relevant for the Smart Cities discussion. If we are to develop a variety of different heat sources, we will have to develop the ability to use lower supply temperature. Among the many articles were the presentation of two concrete cases of low temperature district energy to low energy housing; one case from Aarhus, DK and one case from Slough, Great Britain. The two cases illuminated two very crucial aspects of the problem. The case in Slough demonstrated how low temperature district heating could be delivered, using only renewable energy, whereas the case in Lystrup, Aarhus demonstrated how low temperature district energy can be delivered from a medium temperature district heating plant and the ordinary transmission net. The overall conclusion of the demonstration projects was that low temperature district energy is possible and feasible. Furthermore, the study from Denmark shows that the space heating demand in the low energy building was up to 70% higher than the building regulation design value. This was caused by the fact that consumers wanted an indoor temperature 2-4 degrees higher than design specifications had estimated. Also the heating season was prolonged, as floor heating led consumers to keep the heat on in their bathroom. These results show that district heating is a definite possibility, and hence the technology to allow better integration of different heat sources exists. WHAT’S NEXT? The problem of mapping heat resources and designing networks able to use low supply temperature is, however, only part of the Smart Cities problem. Some issues that were not discussed in the symposium were for instance: control of return temperature and IT-solutions for the district energy systems. What is positive is that it gives our brilliant young minds something to do in the next two years leading up to the DHC14, which will be held in Sweden. In the mean time I will recommend that anybody with an interest in – for instance – fault detection, ultra-low supply temperature or the possibility of using CO2 as medium for district energy: go to the DHC13 website – - and download the publication containing all 43 articles from the symposium.

By Astrid Møller Fjernvarmens Udviklingscenter

THE DISTRICT ENERGY SYSTEM OF TOMORROW 100 of the world’s leading experts on district energy were gathered in Copenhagen this September for the DHC13 symposium. The purpose was to meet and to share the latest research on district energy. There were many different topics on the symposium - among them: pipe laying, design of DHC systems challenges and opportunities on different markets and one very interesting article on how to finance DHC system by selling the CO2 quotas one saves by using district energy. It has been difficult to write cohesively on the symposium without feeling that something extremely important would be neglected. There was however one topic that seemed to dominate the symposium – whether discussed in part or as a whole. And that was the concept of integrated energy systems: Smart Cities. WHAT IS SMART CITIES? The concept of Smart Cities was presented in the article “Smart Cities: Challenges and Opportunities for Thermal Networks” by Ralf Roman Schmidt of the AIT. The Smart City is - in short - a city which utilizes every available energy source and ensures that the maximum amount of the produced energy is consumed by the end-user while at the same time ensuring low cost and high comfort for the end-user. This kind of energy system, of course, requires district energy. But in order to meet the demand of the Smart City, many single elements of district energy technology must change. If the district energy sector is to play its part, it must – among other things - use a larger variety of heat sources, integrate with other parts of the energy system and it must use IT-technologies to control heat supply and heat demand in detail. Many of the papers presented on the symposium focused on the enabling technologies, which must be developed in order to create Smart Cities. One example is the article”Small-scale district energy. Demand side management”, which discussed intelligent control of district energy supply. The most discussed topic, however, was the mapping and utilization of heat sources. Eight articles on the subject were presented, among them “GIS based analysis of future district heating potential in Denmark”, “Green energy systems in low carbon economies, a geothermal district heating case study” and “Analysis of diversification of fuel in DH sources. Potential of reducing GHG”. These articles give a great insight into challenges and opportunities in different district energy markets.

For further information please contact:

Fjernvarmens Udviklingscenter Att.: Astrid Møller Borggade 6 DK-8000 Aarhus C

Phone: +45 4122 7148


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