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Ice Storage - Thermal Energy Storage to Optimise Renewable Energy Use

Dynamic charge and discharge. Excess energy can be quickly stored and made available for cooling when needed

24/7 use of renewable energy for cooling

The energy transition is a key societal challenge for the coming years. By 2045, the energy system e.g. in Germany should be climate-neutral in terms of production and consumption. This includes expanding renewable energy sources so that by 2030, 80% of electricity consumption can be met by solar, wind and hydro power. The current figure is 45%. 

Building more power stations for renewable energy sources is not enough. The main problem with solar and wind energy is that, unlike nuclear or fossil fuel energy sources, they are not always available. The availability of solar and wind power often does not coincide with peak electricity demand. Either there is more green electricity available than needed, in which case the extra demand puts pressure on the electricity grids and electricity is paid for at very low, sometimes negative, prices. If too little electricity is produced, additional conventional power plants have to be started up. 

Part of the solution - thermal energy storage

In addition to expanding electricity grids, the energy transition will require a rapid expansion of storage capacity. According to calculations by the Fraunhofer Institute for Solar Energy Systems, around 100 gigawatt hours of additional electricity storage capacity will be needed by 2030 to achieve the goals of the energy transition. This is a Herculean task, given that storage capacity in Germany currently stands at around 5 gigawatt hours. Battery storage alone cannot meet the demand.

What is needed is a mix of different energy storage technologies, including pumped storage and hydrogen-based storage in addition to battery storage. Depending on the type and level of energy demand, long-term or short-term, stationary or mobile storage solutions will be used.

If part of the electricity generated is to be used for cooling applications (e.g. air conditioning of buildings or cooling of industrial processes), ice storage systems can be used.

Thermal energy storage systems are an important component of this mix of storage technologies.

Wind and solar power plant with ice storage as thermal energy storage

What makes ice storage technology suitable for use in thermal energy storage systems

Ice storage represents one such thermal storage systems. Compared to other thermal storage technologies, it has the advantage that a large amount of energy is released or absorbed during the transition from liquid to solid state. This means that ice storage has a much higher energy density than, for example, cold water storage.

The use of ice storage systems is particularly suitable when some of the energy generated is to be used for cooling applications, such as air conditioning in buildings or cooling in industrial processes. The ice storage system absorbs the energy in the form of cold and releases it when the cold is needed but there is no or insufficient energy available from renewable sources.

Cooling supply even when little energy is available

At times when the output of the photovoltaic or wind power system is not sufficient to produce the required amount of cold using the chiller, the additional cold is provided by the ice storage system. This means that the ice storage system takes over either part or all of the cold supply. This ensures a reliable and demand-driven supply, while avoiding the use of power-hungry chillers when there is not enough electricity available from renewable sources.

In the context of cooling networks, large amounts of surplus energy from renewable sources can be stored in the form of ice and made available to customers at any time to meet their needs.

With the growing demand for cooling and the need to increase the share of renewable energy in electricity generation, ice storage can bridge the gap between these two trends. Ice storage significantly improves the availability of renewable energy for cooling applications and offers the advantage of low losses and correspondingly high efficiencies compared to other storage technologies such as batteries or hydrogen.

A new dynamic for ice storage - the sp.ICE

Our sp.ICE ice storage tank differs from most conventional storage tanks, which use the latent energy of water, in its high energy efficiency and particularly dynamic charging and discharging behaviour. This is made possible by a newly developed heat exchanger using capillary tube technology.

Ice formation in the sp.ICE can be completed in as little as 6 hours. If required, the cooling capacity can be released just as quickly. This makes the sp.ICE particularly interesting for covering peak loads in cooling networks, for reducing energy-intensive chillers in refrigeration systems and also as an emergency cooler for industrial processes.

Thanks to its modular design, the sp.ICE ice storage system can be integrated into existing power plant and refrigeration technology at a manageable cost.

The central cooling plant at Europaplatz in Heidelberg saves 1,300 tonnes of CO2 per year. This is equivalent to the CO2 emissions of 900 cars. How is this possible? With sp.ICE ice storage systems, of course.

 

Read more about the project