Excess heat utilization combined with thermal storage integration in district heating systems using renewables

Abstract

District heating systems already play an important role in increasing the sustainability of the heating sector and decreasing its environmental impact. However, a high share of these systems is old and inefficient and therefore needs to change towards the 4th generation district heating, which will incorporate various energy sources, including renewables and excess heat of different origins. Especially excess heat from industrial and service sector facilities is an interesting source since its potential has already been proven to be highly significant, with some researches showing that it could cover the heat demand of the entire residential and service sector in Europe. However, most analysis of its utilization in district heating are not done on the hourly level, therefore not taking into account the variability of its availability. For that reason, the main goal of this work was to analyse the integration of industrial excess heat into the district heating system consisting of different configurations, including the zero fuel cost technologies like solar thermal. Furthermore, cogeneration units were a part of every simulated configuration, providing the link to the power sector. Excess heat was shown to decrease the operation of peak load boiler and cogeneration, that way decreasing the costs and environmental effect of the system. However, since its hourly availability differs from the heat demand, thermal storage needs to be implemented in order to increase the utilization of this source. The analysis was performed on the hourly level in the energyPRO software.

Techno-economic modelling and optimisation of excess heat and cold recovery for industries: A review

“…TIMES [46,76] has been extensively modified to suit the specific requirements of various regions and has high flexibility, while Balmorel [117] has been modified in a few studies and is assigned to have medium to high flexibility. Oemof [108][109][110][111] has also been modified to create different versions of the tool in several previous studies to suit the requirements. Although no literature has been found on the flexibility of Calliope, several additions and changes have been made to enhance the functionality of the tool [141].…”

“…Andersen et al used EnergyPRO to compare different policies for providing support schemes to increase flexibility in DHCS [110]. Doračić et al modelled the utilization of EH combined with the implementation of thermal energy storage in a DHS [111]. The availability of EH was modelled at an hourly resolution to account for its variability.…”

Utilizing excess heat through a wholesale day ahead heat market – The DARKO model

“…First of all, the available excess heat from the refinery has been calculated by combining the Heat Roadmap Europe method presented in [37] and the maximum available excess heat potential from chemical industry in Croatia presented in [12], giving the maximum availability of this source 10.3 GWh. Its availability has not been assumed constant but variable (Figure A 3) , by applying the variation presented in the previous research of the authors [18], while the temperature level has been assumed high enough for the direct utilization through the heat exchanger. Service sector excess heat facilities have been added to the analysis to also consider the low temperature excess heat sources, which need a heat pump to increase the temperature level to the required district heating supply temperature.…”

“…Through the previous research of the authors, mainly Refs. [17] and [18], it has been concluded that the main competitors of excess heat sources in terms of feasibility are low cost technologies like solar thermal. Furthermore, there is a plan in development to include solar district heating into the system in Sisak in the near future.…”

“…Therefore, in most cases there is a need for a thermal storage, as shown in e.g. [18] and [19]. Despite all the benefits mentioned above, district heating is still regulated as a monopoly in many cases, with one company being responsible for production, distribution, and supply of heat [20].…”