Naslov
Multi criteria method for evaluation of district heating and cooling with regard to individual systems
(Višekriterijska metoda procjene valjanosti centraliziranih toplinskih i rashladnih sustava u odnosu na individualne)

Autori
Dorotić, Hrvoje

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Mjesto
Zagreb

Datum
09.05

Godina
2022

Stranica
265

Mentor
Duić, Neven

Ključne riječi
District heating ; Energy planning ; Multi-objective optimisation ; Cogeneration ; Exergy ; Natural gas
(Centralizirani toplinski sustavi ; Energetsko planiranje ; Višeciljna optimizacija ; Kogeneracija ; Eksergija ; Prirodni plin)

Sažetak
According to EU climate strategies, district heating and cooling technologies will have an important role in energy transition by contributing to energy efficiency and decarbonisation targets defined for 2030 and reaching climate neutrality by 2050. District heating and cooling systems can integrate renewable energy sources and low-temperature waste heat by utilising heat pumps combined with thermal storage. This makes them a crucial component in future energy systems where power system balancing will have a vital role. Despite these qualities, district heating is still not recognized as the primary heating source in dense urban areas. Due to its relatively low price and the distribution of existing networks in numerous EU member states, a natural gas boiler is usually the preferred heating source. The utilization of natural gas for space heating results in high exergy destruction and represents poor resource management. Due to this, its use in energy transition should be reserved for industrial processes challenging to decarbonise or the production of electrical energy in cogeneration power plants. The main objective of this doctoral thesis is to define the energy market conditions where district systems are superior to individual natural gas solutions by considering economic, environmental and exergetic criteria. It should be mentioned that exergy is usually used for detailed thermodynamic analyses and is rarely considered in energy planning. For this purpose, a novel multi-objective optimisation method was developed based on mixed-integer linear programming capable of finding optimal system capacities and hourly operation for a whole year. Objective functions are defined as minimisation of total cost, minimisation of carbon emissions and maximisation of exergy efficiency. To deal with the multi-objective optimisation, the epsilon constraint method was utilised. Cost and carbon allocation in cogeneration units has been implemented by using a power-loss method. It is based on the reduction of a power output due to heat production. The power-loss is then translated to cost and carbon emissions allocated to heat in cogeneration units. The obtained results have shown the importance of utilising district heating in future energy systems. Firstly, the integration of intermittent renewable energy sources in power markets will have a positive impact on district heating systems, since it will enable larger power-to-heat capacities which are becoming an economically suitable solution. The incorporation of heat prosumers and the deployment of a heat market can provide a price reduction. Secondly, the thesis quantifies the benefits of integrating district heating and cooling systems by using a multiobjective optimisation approach. Thirdly, a district heating model has been developed, which VII considers the exergy destruction of a system. Exergy destruction in heat-only boilers has been calculated as the system cost. The impact of exergy taxing on the displacement of natural gas heat-only boilers has been assessed. Finally, the impact of carbon and cost allocation in cogeneration units has been evaluated. The thesis determines the range of natural gas prices for which district systems are superior to individual heating. It has been shown that cogeneration based district heating is economically, environmentally and exergy-wise better than individual natural-gas boilers, even for low households’ natural gas prices.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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