CASE STUDY | HORNSYLD HEAT NETWORK hours per year. Heat production is calculated to give a system coefficient of performance (COP) of 6.75. Two boilers at Hornsyld Kbmandsgrd will be used to supplement the reclaimed heat from Triple A. One is a 1.8MW unit fuelled by biomass which is primarily waste material from grain products and the heat is mainly used for process heating for Triple A. When production is under way at Triple A, only 0.9MW of capacity will be available from the biomass boiler. The boiler is also used to produce heat for Hornsyld School, Hornsyld Kbmandsgrd, and a few other nearby buildings, all of which are expected to be included in the district heating system, so this element of boiler capacity will be available to the network (see map on page 37). The other Hornsyld Kbmandsgrd boiler is a 4MW oil-fired boiler. This will be converted to run on natural gas, and will serve as a back-up to the biomass boiler. It is assumed that 3.5MW of capacity will be available for the district heating supply. The operational and maintenance costs of both boilers will be covered under the scheme. To provide a buffer between the heat demand, production at Triple A, and the operation of the boilers, the system will incorporate a 1,000m3 thermal store. The addition of a storage tank will allow greater use of the available waste heat and the biomass boiler. There is currently no heat network in Hornsyld, so a new plantroom will be constructed. Heat will be distributed via a pre-insulated, twin-pipe system. Planenergi, the consulting engineers responsible for the project, are continuously updating the project as certainty increases around customers numbers, and energy costs rise. SAV Systems are PlanEnergis design partner in the UK. heat demand of more than 100MWh. Together, they could amount to a heat demand of more than 9,000MWh annually, which will provide sufficient anchor loads for the heat network. The council hopes that a high connection rate can be achieved by signing up these large consumers so that the project is less dependent on getting a high take-up from large numbers of domestic customers. The heat network is designed to supply 100% of Hornsylds heat demand. However, the project has assumed a total connection rate corresponding to 60% of the heating demand, and it is expected to be converted at the rate indicated in Figure 1. A total annual heat loss of 15.2% has also been calculated for the network, corresponding to 2,942MWh/year. This gives a total heat requirement of 19,395MWh/year. Anchor loads Cost savings Of the 471 buildings supplied by natural gas in Hornsyld, there are 29 large heat consumers, with an annual The project is expected to provide an annual cost saving of 6,300 Danish kroner (DKK about 700) for a typical dwelling currently heated by natural gas, and DKK 5,400 (about 600) for one heated by an air-to-water heat pump. The savings are well above the minimum set by the Danish Project Evaluation Act, which requires a cost saving of 170 per household for a project to be approved. An estimated socio-economic surplus of 4.1m has been identified for the project over 20 years, largely because of the reduction in natural gas consumption, which more than offsets the investment cost. CJ 25.000 Waste grain products will provide fuel for a 1.8MW biomass boiler 1,6 15.000 1,2 1 0,8 10.000 5.000 0,6 0,4 0,2 0 0 ply ion ate on r vers l sup ersi etime) con dua v i e n v t i o e C on lif pl Ind Com ed (bas Individual heat pumps Individual gas Individual oil Large-scale gas boilers Large-scale biomass boilers Heat pump using waste heat from industry Gas consumption Figure 1: Spread of heat production in Hornsyld 36 August 2022 www.cibsejournal.com Gas consumption / (mil Nm3/yr) Heat production (MWh/yr) 1,4 20.000 HEAT PLAN DENMARK 2021: KEY MESSAGES The heating sector can be transformed quickly using available technologies the four key messages are: 1. Energy savings of between 36-40% are required in the current building stock to cost-effectively minimise the demand for heat. 2. District heating should be expanded to supply up to 70% of building heat demand, to enable individual buildings gas- and oil-fired boilers to be taken out of commission. 3. Existing third-generation heat networks should be transitioned to lower-temperature, fourth-generation networks, to enable low-grade waste and geothermal heat to be used efficiently. 4. Waste heat and geothermal heat should be exploited to provide up to half of the heat demand from district heating systems in the energy system of the future.