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Ice Storage - Thermal Energy Storage for Solar and Wind Power

Excess solar and wind energy is stored in ice and used for cooling when needed

Importance of electricity storage: 24/7 use of renewable energy for cooling supply

The energy transition is a key societal challenge for the coming years. The goal is to make the energy system climate-neutral in terms of production and consumption. An important building block for this is the expansion of renewable energy sources so that e.g. in Germany 80% of electricity consumption can be covered by solar, wind and hydro power by 2030. This figure currently stands at 45%.

But building more renewable power plants 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 consumption. Either there is more green electricity available than needed, in which case the extra output puts a strain on the electricity grids and electricity is sold at very low, sometimes negative, prices. If too little power is produced, additional conventional power plants have to be started up.

Part of the solution - Thermal energy storage

 

In addition to expanding power grids, the energy transition will require a rapid expansion of electricity 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, considering that Germany currently has around 5 gigawatt-hours of storage capacity. Battery storage alone cannot meet the demand.

A mix of different power storage technologies is required, including pumped storage and hydrogen-based storage in addition to battery storage. Depending on the type and amount of energy required, long-term or short-term energy storage, stationary or mobile solutions can be used for storage.

If a portion of the electricity generated is to be used for cooling applications (e.g., air conditioning of buildings or cooling of industrial processes), the use of ice storage systems is an option.

As the demand for cooling increases, thermal energy storage will become an important part of this mix of much-needed storage technologies.

Sketch of solar and wind power plant with ice storage as power storage

What distinguishes ice storage technology for use as thermal energy storage

Ice storages make up a special category of thermal energy storage systems. Compared to other cold storage solutions, they have the advantage that a large amount of energy is released or absorbed during the transition from liquid to solid state. This means that an ice thermal storage has a much higher energy density than, for example, a cold water storage system.

The use of ice thermal energy storages is particularly suitable when some of the electricity generated is to be used for cooling applications, such as air conditioning in buildings or cooling industrial processes. The ice storage tank absorbs the energy in the form of cold and releases it when the cold is needed even when renewable energy is unavailable or insufficient.

Cooling supply even when power is low

At times when the output of the photovoltaic or wind power system is not sufficient to produce the required level of cooling using the chiller, the additional cooling required is supplied by the ice storage system. In other words, the ice thermal storage takes over some or all of the cooling. This ensures a reliable and on-demand supply. At the same time, the use of power-hungry chillers is avoided when there is not enough electricity available from renewable sources.

As part of cooling networks, ice storage systems can be used to store large amounts of excess renewable energy in the form of ice and make it available to customers on demand.

With the growing demand for cooling and the need to increase the share of renewable energy in electricity generation, ice energy storage can bridge the gap between these two developments. Ice thermal energy storage significantly improves the availability of renewable energy for cooling applications and offers the advantage of low losses and correspondingly high efficiency 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 cold storage tanks, which use the latent energy of water, in its high energy efficiency and particularly dynamic charging and discharging behavior. 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, compact design, our dynamic thermal energy storage system can be integrated into existing power plants and refrigeration systems at a manageable cost.

The central cooling plant at Europaplatz in Heidelberg converts solar power into cooling, saving 1,300 tons 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.

 

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