12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaThe figure below is the same as the Fig. 8 added with ared line to help the reader estimate the pumping energyof his own plant. If the pumping energy is above the redline some measures ought to be taken.Specific pumping energy (electrical power / heatsupply)1.7 %1.5 %1.3 %1.1 %0.9 %0.7 %0.5 %0.3 %Specific pumping energy vs. heat density0.1 %0.1 %0 1 2 3 4 5 6 7 8Heat density, GWh/kmFig. 9. Electricity used for pumping in relation to the heatdensity of the district heating network + trend lineFigure 9 shows that on average the electricity neededfor district heating pumping should not be over 0.5 percent of the total energy supply (=sold+losses). If thedensity (supply/length of the network) of the districtheating network is less than 3 GWh/km, the energyneeded for pumping may rise. In any case theproportional pumping energy should be lower than1 percent.1.7 %1.5 %1.3 %1.1 %0.9 %0.7 %0.5 %0.3 %The following figure illustrates an example case inwhich the heat density is over 2.5 GWh/km. The figurecan be utilized when estimating the losses in realmoney if the proportional pumping energy is over theaverage of 0.5 percent.Value of excess pumping energy, 1 000 EUR/a400350300250200150100500Value of "excess" pumping energyHeat density > 2.5 GWh/km, Value of power 60 EUR/MWhProportional share of pumping energy 0.8 %Proportional share of pumping energy 0.7 %Proportional share of pumping energy 0.6 %100 600 1100 1600 2100Heat supply, GWh/aFor example, if the heat supply of the company is 1.1TWh/a and the proportional pumping energy is0.7 percent, the losses of unnecessarily high pumpingenergy is € 130 000 per year.Some of the pumping energy is converted to heat. Thisdecreases the value of the losses.In total, the potential savings in all Finnish districtheating companies are approximately 20 percent of thecurrent pumping energy, i.e. 30 GWh/a. This isequivalent to a yearly saving of approximately€ 2 million.REFERENCES[1] DH statistics 2007, Energiateollisuus ry, 2008287