r.energy reports about Long Duration Energy Storage with Iron-Salt from VoltStorage

Long Duration Energy Storage with Iron-Salt: The link between Sustainable Energy Generation and Reliable Energy Supply

(This abstract is based on the article published in r.energy, issue 4/23, September 2023)

For solar and wind power operators bridging supply gaps during periods of low wind and sunlight and thus securing the provision of the base load will become increasingly important in the coming years. This is not least because an increasing number of companies are relying on renewable energies to reduce emissions and achieve the goal of carbon neutrality, and ultimately utilities will also have to be prepared for this. However, in order to ensure a continuous base load supply not only on a daily basis, but also on an annual basis, even when there is no wind or little sunlight, appropriate storage systems for so-called Long Duration Energy Storage play a central role.

What is Long Duration Energy Storage?

Long Duration Energy Storage refers to energy storage systems that can be charged or discharged over a period of more than eight hours. In order to bridge the supply of fluctuating renewable energy such as wind and solar power and thus make it available to the power grid, discharge times of up to 48 consecutive hours are required in Germany.

This calls for technologies that can ensure base-load supply from wind and solar energy. At the same time, such solutions should be more efficient and also more cost-effective than conventional solutions such as Li-ion or lead-acid batteries. Another need arises from the fact that there is as yet no system on the market that can be set up virtually anywhere and that covers the usual service agreements of conventional power plants of 95 percent. This is typically the availability rate to provide baseload power at a given power setting throughout the year.

What is the iron-salt battery?

The answer to these requirements is provided by the iron-salt battery. It is based on the proven redox flow technology, which offers clear advantages in terms of long-term storage compared to conventional storage technologies.

In a test facility installed by VoltStorage in 2020, an iron-salt battery was used as a storage solution with a storage capacity of 10kWh. At the dimensions of a conventional 20-foot ISO container, it was designed to provide up to 9.4 MW of power, or 235 MWh per acre. The battery is suitable for stationary applications with power requirements of 10 to 100 hours and achieves an efficiency of about 70 percent. This is well above the levels that can be achieved by other long-term storage technologies such as iron-air batteries (45 percent), power-to-gas-to-power (P2G2P, 35 percent), thermal energy storage or compressed air energy storage (CAES, 40-55 percent).

Read the full article here (in German, page 11ff): https://www.r-energy.eu/wp-con...

More information about our Long Duration Energy Storage development can be found here.