Techno-economic evaluation of heat-driven cooling solutions for utilization of district heat in Aalesund, Norway

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Insinööritieteiden korkeakoulu | Master's thesis
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Nordic Master Programme in Innovative and Sustainable Energy Engineering (ISEE)
This study is aimed to evaluate the techno-economic feasibility of implementing heat driven cooling technologies in buildings connected to Tafjord Kraftvarme‚Äôs district heating network in Aalesund, Norway. Heating and cooling demands were found by projecting two 4000 ūĚĎö2 office buildings according to Passive House and Low Energy Building criteria, within the frame of the energy requirements in the TEK17 building regulations (Standard Norge, 2012) (Norwegian Building Authority, 2017). Suitable cooling and heating equipment, both electrical and heat driven, were dimensioned based on the peak cooling load of the projected buildings, and technical and economic information obtained from the distributors of the equipment. LCOE analysis shows that the heat driven cooling solutions could be able to compete economically, in variable extent, with the electrically driven solutions given relatively low heating demand or by applying investment subsidies or price reduction on district heat for cooling purpose. The desiccant cooling solution could even compete with the electrical driven solution even without subsidies or price reduction on DH for cooling. This is mainly because of its enhanced heat recovery reducing the heating demand. The absorption cooler on the other hand, has both a higher consumption and higher power input of district heat while running, and is therefore less competitive without subsidy or price reduction on DH for cooling. In the building cases explored, the absorption cooling solution requires either subsidy or price reduction on DH for cooling to compete with the electric chiller and district heat solution, while it require both to come close to compete economically with the heat pump solutions. With increasing heating demand the heat driven solutions, which use district heat as their heat source, become less competitive compared to the heat pump solutions. This is because, with the mild winters in Aalesund, the heat pumps can run with a COP of 2-3 while the COP of district heat it is considered to be 1. Other important factors that is not covered by the LCOE analysis is the reliability and environmental aspect. None of the heat driven cooling solutions use any environmentally unfriendly refrigerants, and the maintenance of the cooling machines are minor. The lifetimes of the machines are estimated to be 20 years for the desiccant and 40 years for the absorption cooler, compared to 15 years for the heat pumps and electric chiller. The heat driven cooling solutions can therefore be considered more reliable both in terms of regulations on refrigerants and on maintenance and lifetime. An additional important factor is that compared to the heat pump solutions, the heat driven cooling solutions with district heat to cover the heating demand can replace large quantities of electricity consumption with low-grade thermal energy. Considering both the economic, environmental and reliability factors, the heat driven cooling solutions could be a viable option and should be considered when implementing heating and cooling equipment in buildings connected to the district heating network in Aalesund or other locations with similar climate.
Järvinen, Mika
Thesis advisor
Vik, Irene
Chiu, Justin
district heating, heat-driven cooling, Aalesund, techno-economic analysis
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