There are a range of thermal storage solutions which allow excess thermal energy or heat to be stored and used hours or even days later at a more advantageous time.
Thermal energy storage is a critical enabler for the large scale deployment of renewable energy and supports the decarbonisation of thermal end uses, such as refrigeration, water heating and space heating and cooling.
Advances in and greater implementation of thermal batteries support lower energy costs, higher performing and more affordable heat pumps, as well as the flexibility to participate in load-shifting arrangements as part of more dynamic energy contracts and procurement arrangements. (Source: EERE)
HOW THERMAL BATTERIES WORK
Sources of thermal energy storage can include the heat (and cold) produced by heat pumps and combined heat and power systems, waste heat from industrial processes and excess renewable energy generation stored as heat.
A variety of materials are used to store the energy as heat, with water, aluminium and concrete-like materials common examples.
TYPES OF THERMAL BATTERIES
A variety of materials are used to store the energy as heat, with water, aluminium and concrete-like materials commercially available examples.
Water-based thermal batteries
Simply put, these batteries utilise excess renewable energy to heat or cool water to be used for other purposes, sometimes at different times.
A good example of a 'water battery' is the 4.5 megalitre battery in use at the University of Sunshine Coast (see case study).
An artist's impression of the 'water battery' at the University of the Sunshine Coast, QLD. Image: Veolia
Aluminium-based thermal batteries
With this kind of thermal battery, electricity is used to heat an aluminium alloy is heated to around 600 °C with the heat then able to be discharged over a period of up to 16 hours. This is a beneficial way of storing and utilising excess renewable energy for use at times of greater demand or benefit.
An example of such an aluminium-based battery is the Azelio Tes.Pod which is detailed on this webinar from October 2021.
The aluminium-based Tes.Pod battery from Azelio. Image: Azelio
Phase change materials
A phase change material (PCM) is a substance which, by melting and solidifying at certain temperatures, is capable of storing and releasing large amounts of energy (source: UniSA). PCM thermal batteries offer great potential as a low cost energy storage system which is particularly of interest to industrial and commercial refrigeration applications.
Learn more about this technology in a presentation by UniSA and Glaciem Cooling Technologies in a webinar from October 2021.
A PCM thermal energy storage system. Image: Glaciem Cooling Technologies
Concrete-based thermal batteries
There are a limited number of thermal battery technologies that utilise concrete for thermal storage. An example technology is from EnergyNest which uses a concrete-like material called HEATCRETE(R). High temperature heat is transferred into pipes in the thermal battery elements using a heat transfer fluid and stored until required. The heat is then accessed by reversing this and sending the heat to process.
Learn more about this technology in a presentation by EnergyNest in October 2021.
The HEATCRETE (R) thermal battery. Image: Energy Nest
Hybrid heat exchanger tanks
This type of thermal battery combines a traditional tank storage with a high efficiency heat exchanger which allows it to source and utilise energy from a number of sources, including solar (PV or thermal), a heat pump, waste heat recovery or geothermal, as well as grid electricity or gas. It can store thermal energy for discharge and use when needed, with a much smaller footprint than traditional tanks.
An example of this kind of technology is the ENERMAX SMARTcube.
The ENERMAX SMARTcube. Image: Energy Smart Water
Related reports and research
THERMAL BATTERY CASE STUDIES
There are more and more examples of heat pumps significantly reducing energy use and emissions in industrial processes by utilising waste heat. Here are some examples from Australia and around the world.
THERMAL BATTERY WEBINARS
Watch these webinars for the latest updates on thermal battery technologies and case studies on how they are being used more and more across a range of sectors.