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, EstoniaIt was also shown that if all plants in the system arereplaced with BCHP plants, with an electricity-to-heatoutput ratio 0.46, up to 10TWh electricity can beproduced and the potential for decrease of GECO 2 ofthe system would be 3 tons CO 2 annually. If all plantsin the system are replaced with NGCHP plants, with anelectricity-to-heat output ratio 1.2, the electricitygeneration in the system can increase to 11TWh andthe potential for decrease of the GECO 2 of the systemwould be about 5 tons CO 2 annually. However, sincethese two studies were done, a new connectivitybetween networks has been built and the total installedelectricity capacity in the system has increased by 20%[5]. Furthermore, new CHP technologies are constantlybeing developed, which enable greater electricityefficiency and consequently greater benefits fromeconomic, energy and environmental viewpoints.Regarding interconnection and cooperation of DHsystems, some studies have been conducted in aSwedish context. However, none of them have focusedon cooperation between energy companies. They haveinstead focused on cooperation between energycompanies and industry.Thollander et al. [15] found that technical aspects areseldom barriers to cooperation. The barriers are ratherrisk, different aspects of information duringnegotiations, and other social factors such as inertiaamong personnel. Driving forces have been economicfactors such as an aim for lower costs and means ofcontrol, as well as environmental values. In a study witha similar aim, Fors [16] found the same results, thattechnical aspects are seldom barriers. Informationduring negotiations, stable contracts and theimportance of involving the personnel at the plants inthe process are important factors. It is also importantthat the cooperation benefits both parties. Grönkvistet al.[17] reached a similar conclusion in a study thatemphasises the importance of the willingness of peopleon both sides to cooperate. The main advantages ofthe cooperation are lower costs and benefits for theenvironment, while the main disadvantages are lessflexibility as both parties work under contracts.Historically, interconnection of technical systems hasbeen seen in the theory of Large Technical Systems asone way for systems to grow. Systems start in a localcontext, but when the technology is transferred to othergeographic areas, the systems grow and can then beinterconnected as they often have grown into eachother. Interconnection of systems can also beexplained through the fact that larger systems have ahigher load factor and better economic mix [18], [19],[20].4. RESULTS OF THE SCENARIOSThe results from the scenarios are presented inTable VI and Table VII.According to the optimisation results, if betterconnectivity is introduced, some economic benefitsexist. In both cases the case with only existing plants inthe system and the case where the new plants areintroduced in the model (scenarios 2 and 5) thedecrease in system costs would be about 10 million €annually. The potential for decrease of theenvironmental impact of the system is more notable. Ifbetter connectivity were introduced in the systemtoday, the biomass share in total fuel use would be 8%higher and consequently both the local emissions ofCO2 (LECO2) and GECO2 of the system would beabout 0.25 million tons lower annually. The potential fordecrease of GECO2 of the system if better connectivityis introduced after the building of new CHP plants(scenarios 4 and 5) is 0.4 million tons annually.Table VI. – Results for the scenarios – economic aspects.Sc.AnnualsystemcostsCHP heatproductionshareElectricityAnnualproductionTheincomefromelectricitymillion € % TWh Million €1 258 47 2.30 1222 245 47 2.31 1253 243 48 2.35 1504 204 58 2.96 1645 192 62 3.15 1766 403 4247 344 100 6.39 4828 546 2819 504 100 17.66 777As the electricity price increases, the system wouldearn extra income from the electricity sold, and thus theheat production cost would decrease (scenarios 1, 3).This gives an even bigger advantage to CHPgeneration compared with pure heat production.291