Speakers: Boris Lubinski (AGFW), Burkhard Hölzl (Wien Energie), Gerhard Plambeck (Vattenfall Europe Wärme, Berlin), Dr.-Ing. Mathias Safarik (ILK Dresden), Dr. Heinrich Lienkamp (Infraserv, Höchst KG, Frankfurt/Main).
Number of participants: 23 Moderator: Adolf Topp
Adolf Topp opened the workshop with a main question: what are the reasons for a slow deployment path of district cooling technology in Germany? Irrationality of stakeholders, prices, advisors preferring other technologies or in general non-profitability of DC networks? The initial round of introductions revealed that almost half of participants come from the industry sector, the same number of participants from energy utilities, one from the city energy department and one from the research institute.
Boris Lubinski (AGFW) gave a presentation on four kinds of the cooling supply systems: distributed trigeneration with decentralized thermal cooling (DH network, chiller and re-cooling at the building site), district cooling with centralized trigeneration e.g. in Vienna, sub-district cooling with trigeneration e.g. in Berlin and district cooling without trigeneration e.g. partly in Munich. What should be a more desirable asset: trigeneration or high efficient electrical chillers? Preservation of sites of historic interest in Paris prevented Parisians from installing individual cooling devices and gave a green light to district cooling.
Boris Lubinski stressed the biggest advantage of heat and cooling infrastructure systems is their flexibility to use any fuel or energy otherwise wasted and combine it with the most suitable technological solution. District cooling connects local needs with local sources.
Burkhard Hölzl (Wien Energie) enabled participants to gain a deeper understanding of district cooling system in Vienna in technical, economical and marketing aspects. District cooling takes part in the cross-selling initiative of the utility, a customer can be supplied with both products; i.e. district heating and cooling with the temperature difference of 10 K for new customers. Austrian utilities can use the investment financial support at maximum 35 % if at least 50 % of the cooling comes from absorption chillers. In Vienna, absorption technology covers one third of the whole cooling capacity, the rest is covered by compression chillers. Deployment of district cooling is facilitated by the fact that every single spared square meter in central Vienna is an asset for building owners. Wien Energie keeps an eye on new development areas such as heat pumps.
Gerhard Plambeck (Vattenfall Europe) provided a keen insight into the biggest DC system in Germany - in Berlin. Cooling demand depends on various factors such as holidays, office hours, humidity and the system in Berlin achieved the simultaneity factor at 0.6 last year, with the temperature parameters of supply/return at 6/12 °C; new customers are contracted to the bigger temperature difference ΔT. Vattenfall operates cooling devices with a capacity of 44 MW in the energy center Potsdamer Platz. One of the lessons learnt is the recommendation to connect customers indirectly.
Dr. Mathias Safarik (ILK Dresden) introduced participants to vacuum-ice slurry technology. Under constant pressure of 6 mbar and at the freezing temperature at -1°C, large amount of cooling energy can be provided by the phase change to the solid phase and back (the enthalpy of evaporation: hv = 2500 kJ/kg). He highlighted advantages of ice-slurry technology such as the use of water as refrigerant and the high cooling capacity and thus a five times bigger storage density of slurry compared to cold water and expressed the wish of the Institute to find for partners from the industry sector in order to develop joint projects.
Dr. Lienkamp (Infraserv) contributed to the workshop with his presentation on the district cooling supply in the industry field. Within the cooling products portfolio, brine (- 12°C), ammonia - DC, cold water (4-6 °C) and per contracting cold water of temperature 12 °C, binary ice are listed. Ammonia in the range of -15 –20°C is transported to customers by two networks, each at length of 1,5 km, evaporation takes place at their installations. The representative from the city energy department emphasized the transparency for costs of alternative solutions to district cooling. In addition, customers overestimate the amount of cooling they need what results in misconceptions while considering a district cooling option.
The organizer of the event, AGFW, thanks all speakers and participants for their valuable comments on the situation of district cooling in Germany and its economic efficiency. Presentations of speakers were sent to all participants and are available on request (m.grajcar@).
Your RESCUE team from Germany
Photos: Zarmina Temuri (AGFW)