Sector coupling of the electricity and district heating system of Gothenburg - Integrating electric boilers in a multi-zone district heating model
Typ
Examensarbete för masterexamen
Program
Sustainable energy systems (MPSES), MSc
Publicerad
2022
Författare
Haagensen Thornström, Tim
Larsson, Viktor
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
To lower emissions of green house gases, Göteborg Energi AB plans to retire their
fossil-fueled heat generation. To replace this generation, one possibility can be to
utilise the existing electricity grid via power to heat generation. This master’s thesis
investigates the possibility for electrical boliers (EB)s to support the district heating
system (DHS) by evaluating economical viability, geographical placements and the
role EBs can take in heat generation.
A techno-economical model of the DHS in Gothenburg was developed using linear
programming in the software, General Algebraic Modeling System (GAMS).
The modeled DHS of Gothenburg was divided into seven zones to account for bottlenecks
within the DHS and the availability in the electricity system. Data was
gathered from Göteborg Energi AB and Göteborg Energi Nät AB to depict the
DHS during the period 2020-09-01 to 2021-04-30. The objective function was set to
minimize the cost of heat generation while fulfilling the heat demand. With the possibility
to invest in EBs, the model evaluated their competitiveness. Different cases
and scenarios were studied, such as the implementation of possible future plants,
reducing the energy tax on electricity, increasing fuel prices and the availability of
electricity.
The results indicate that the operational cost are an important factor for the competitiveness
of EBs which can be seen when looking at scenarios with lowered energy
tax. For cases and scenarios that don’t change the variable costs for the investigated
period, the model only invests in EBs to fulfill the heat demand if no other option
are available. When in use the EBs mostly contribute to heat generation during
peak hours, yet, only when there is a low electricity price and sufficient grid capacity.
Results show that EBs can be utilised as backup heat generation to a certain
extent in all zones, but at different installed capacities.
With the conditions from the investigated period, EBs are not economically viable
nor are they needed to fulfill the heat demand. Changing the conditions, the EB can
become economically viable, and for these scenarios the EBs act as a combination of
peak heat- and intermittent heat generation. The zones West, Frölunda and North
are most of interest for installing EBs. The results show that with increased cost for
bio-oil, an investment of about 30MW in North is interesting to further investigate.
The model also showed a need for additional heating in West and Frölunda, but with
less economical incentives for an investment in EBs due to cheaper heat generation
in adjacent zones. The Frölunda zone was also more constrained when it came to
available electricity.