District heating networks are often characterized by significant peaks in the heat demand. The variation in demand is mainly due to the night shutdowns and attenuations operated in the buildings.
The additional energy provided during peaks is usually produced in an inefficient and expensive way, with a large impact on the environment. The proposed technology allows one mitigating the peaks in the thermal demand through an optimal management system of the network, performed by acting on the regulation of the valves in the heat exchange substations of the buildings and in the thermal barycenters of the network.
Patent status
SUBMITTED
Priority Number
102020000020344
Priority Date
24/08/2020
License
ITALY
Market
District heating is a widespread technology in Europe, with around 10,000 networks installed to cover over 10% of the thermal energy demand of buildings. The global district heating market reached $ 172 billion in 2020, with an annual growth rate of 0.5%. The problem of demand peaks is present in most of existing networks, due to the attenuation which is often carried out in certain hours of the day (usually at night). The problem becomes particularly relevant in the event of a night shutdown which is typical of less harsh climates.
Problem
The problem of peak demand is present in all networks where systems are shut down or attenuated at night. The first case is typical of less rigid climates; here the problem is more impactful. The shutdowns / attenuations cause a reduction in the temperature of the water in the network and of the entire infrastructure. The peak is due to the amount of extra energy needed to raise the system temperature to that of normal operation.
Energy peaks are usually met through the use of large gas boilers, which require 25 to 50% more fuel from cogeneration plants (the technology often used to power these plants).
The presence of peaks creates the following problems:
1) higher purchase costs of fuel to produce energy.
2) higher emissions of pollutants
3) higher energy consumption for pumping water (due to the large quantities of water in circulation)
4) need to install specific technologies suitable for covering peaks (usually large gas boilers)
5) worse exploitation of the network since, with the same infrastructure, the connection of new users is limited by the large quantities of flow rate circulating during peaks (there is a limitation on the maximum amount of water that can be distributed by the network)
Current technologies limits / Solutions
The problem of peak demand can be solved in two main ways. The first solution concerns the installation of ad hoc technologies used to produce the additional energy. Usually large gas boilers are used, which however require a quantity of fuel from 25 to 50% more in cogeneration plants.
A second possibility concerns the installation of thermal storage units. These are large tanks where significant quantities of hot water are stored during periods of lower thermal demand and discharged during peak hours, to cover the additional energy demand. The main disadvantages concern the installation costs and the need for large dedicated spaces in urban areas (where the available surface is small and very expensive).
A last innovative technique used concerns the variation of the schedules of the heating systems of the buildings. However, this interesting approach is dependent on the contractual specifics of action on ignition times and, if managed in an imprudent way, it can lead to significant variations in the degree of thermal comfort in buildings.
Killer Application
The application of the technology concerns the reduction of demand peaks for district heating networks without installing thermal storage systems or modifying the schedule of the heating systems in buildings. It is therefore an approach that allows the networks to be used as a large storage, using an innovative control strategy.
Technology and our solution
Technology can present opportunities in several ways:
1) The development of a regulation system (or modification of the current regulation system) that allows to intelligently manage some of the valves of some district heating users (even those that are normally only manually controlled) in order to allow a pre- network heating.
2) The provision of support services for the improvement of the management of district heating networks in order to give indications on how to act intelligently to ensure proper heating to the network and proper installation of by-pass pipes in points of interest.
3) The development of low-cost bypass systems, which make it possible to increase the flexibility of existing networks.
Advantages
The main advantages related to the possibility of reducing demand peaks without changing the schedules of building heating and without the need to allocate space and economic resources for the installation of large thermal accumulations.
Using the proposed technology, the district heating companies can make use of an efficient control system of the district heating network, based on a network model, which allows to minimize energy costs.
Roadmap
The production of an effective control system at the network level and the provision of services for optimal network management is divided into three phases. The first concerns the tests on an experimental network (currently under installation at Politecnico di Torino). The second concerns the development of a model that allows to act in an optimal way on the network in order to reduce the peak, without modifying the demand profile of the users. The third phase consists in the pilot application of the system on real networks that are representative of the existing types.
TRL
The Team
