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Exergy and cost analysis of heating systems with energy storage

Gong, Mei
2017

Conference paper (Refereegranskat)

Abstract:

About three quarters of the total final energy consumption is in the form of electricity and district heat and 49 TWh of district heat was used in Sweden in 2015. The energy supply and user demands vary and do not always match. The electricity production depends on the available energy resource that often is renewable, such as wind, solar and hydro power. The heat demand strongly depends on outdoor temperature and the weather conditions. Electricity and thermal storages are needed in order to reduce the losses from the lack of match between production and consumption. The cost of energy examined by others shows that electricity storage is about 100 times more expensive than thermal storage. However, in this study cost of exergy is only 20 times more for electricity than thermal. This study views electricity and district heat from source to end use and analyze the cost of exergy with storage. With a surplus of electricity the most efficient and cheapest way is to use electricity storage, such as battery or hydro storage on the purpose of electricity usage. The advantage of thermal storage depends strongly on the purpose of use, e.g. if it is for heating purposes. Heat pump is a method to convert electricity to district heat with 56% exergy efficiency. This paper will analyze different cases in order to give a more detailed discussion. Further studies of more cases are needed in the future.

Key words: energy storage; exergy; renewable energy

Cite: Gong, Mei, Exergy and cost analysis of heating systems with energy storage, 2017http://www.4dh.eu/images/4_Mei_4GDH_present.pdf