Barriers and opportunities to maximize the share of solar thermal energy in district heating networks – approaches within the IEA SHC Task 55, Subtask A and selected preliminary results

The aim of the ISORC/OPTIMISER project is to increase and improve the use of solar thermal energy in district heating networks. One of the main tasks of the project is to develop an optimization tool for the sizing and operation of a solar district heating network. This is the first optimization tool using an open-source interface (Julia, JuMP) and solver (Ipopt) to solve nonlinear problems. This paper presents the multi-period optimization problem which is implemented to consider the dynamic variations in a year, represented by four typical days, with an hourly resolution. The optimum is calculated for a total duration of 20 years. First, this paper presents the modeling of the different components of a solar district heating network production plant: district network demand, storage and three sources, i.e., a fossil (gas) and two renewable (solar and biomass) sources. In order to avoid prohibitive computational time, the modeling of sources and storage has to be fairly simple. The multi-period optimization problem was formulated. The chosen objective function is economic: The provided economic model is accurate and use nonlinear equations. Finally the formulated problem is a nonlinear Programming problem. Optimization of the studied case exhibits consistent operating profiles and design. A comparison is made of different types of storage connection at the production site, highlighting the relevance of placing the storage at the solar field outlet. The optimum configuration supplies 49% of demand using solar energy, achieving a renewable rate of 69% in combination with the biomass boiler.

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District heating network modelling for future integration of solar thermal energy

Journal of Physics Conference Series ◽

10.1088/1742-6596/2042/1/012089 ◽

2021 ◽

Vol 2042 (1) ◽

pp. 012089

Author(s):

Clement Dromart ◽

Loïc Puthod ◽

Jérôme H. Kämpf ◽

Diane von Gunten

Keyword(s):

Dynamic Models ◽

Renewable Energy Sources ◽

District Heating ◽

Solar Thermal ◽

Solar Thermal Energy ◽

Network Modelling ◽

Thermodynamic Conditions ◽

Solar Thermal Collectors ◽

The Impact ◽

Heating Networks

Abstract A key advantage of district heating networks is their ability to integrate different renewable energy sources, from geothermal to solar. However, the success of this integration depends on a variety of design and technical decisions, such as feed-in locations or operating temperatures, which need to be compared and analysed. For this purpose, dynamic models of district heating grids, which allow for an hourly representation of the thermodynamic conditions, are necessary. This type of models are nevertheless still uncommon, drastically limiting options to perform these comparisons accurately. To address this challenge, an open-source tool to model district heating networks is presented here and successfully applied to two case studies in western Switzerland. These simulations are then used in conjunction with simplified models of storage and solar thermal collectors to investigate, in a preliminary way, the impact of solar thermal integration on the mass flow and temperature of the network pipes, illustrating the interest of the proposed method to compare different configurations of renewable heat injections in district heating networks.

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Solar Thermal Energy Utilization. German Studies on Technology and Application

10.1007/978-3-662-09931-5 ◽

1992 ◽

Keyword(s):

Thermal Energy ◽

Energy Utilization ◽

Solar Thermal ◽

Solar Thermal Energy ◽

German Studies

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Pyrazolium Phase Change Materials for Solar-Thermal and Wind Energy Storage

10.26434/chemrxiv.9784595 ◽

2019 ◽

Author(s):

Karolina Matuszek ◽

R. Vijayaraghavan ◽

Craig Forsyth ◽

Surianarayanan Mahadevan ◽

Mega Kar ◽

...

Keyword(s):

Energy Storage ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Phase Change Materials ◽

High Efficiency ◽

Scale Up ◽

Solar Thermal ◽

Energy Storage Materials ◽

Solar Thermal Energy ◽

Storage Materials

Renewable energy has the ultimate capacity to resolve the environmental and scarcity challenges of the world’s energy supplies. However, both the utility of these sources and the economics of their implementation are strongly limited by their intermittent nature; inexpensive means of energy storage therefore needs to be part of the design. Distributed thermal energy storage is surprisingly underdeveloped in this context, in part due to the lack of advanced storage materials. Here, we describe a novel family of thermal energy storage materials based on pyrazolium cation, that operate in the 100-220°C temperature range, offering safe, inexpensive capacity, opening new pathways for high efficiency collection and storage of both solar-thermal energy, as well as excess wind power. We probe the molecular origins of the high thermal energy storage capacity of these ionic materials and demonstrate extended cycling that provides a basis for further scale up and development.

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