Long duration energy storage (LDES) solutions are being developed, particularly to accelerate the decarbonization of the energy mix. Faced with this emerging trend, EDF Pulse Ventures - EDF group’s corporate venture capital, has carried out a deep dive with Enea and Compass to assess the geographic distribution of the demand, and to identify the technologies that can meet these needs while drawing up an inventory of relevant startups in this field.

To achieve carbon neutrality faster it is imperative to increase the share of low-carbon energy in the global energy mix. The EDF group, leader of low carbon energy production thanks to renewable and nuclear energy, is thus positioning itself as a key player in the energy transition.

However, the two main types of renewable energies that are being developed on a massive scale (wind and solar) are intermittent. In other words: the wind doesn’t blow continuously and the sun doesn’t’ shine every hour of the day. As these energies become more and more important in the electricity production, new ways must be found to ensure that the electricity system works properly at all times. In addition to this challenge, others exist such as responding to the growing increase in electricity demand, the decarbonization of industrial processes, the issues related to self-consumption and the increasing frequency of extreme weather events. Long duration energy storage is a solution to all these issues.

Long duration energy storage: different possible uses

EDF Pulse Ventures has identified several use cases for LDES . The following 4 are among the fastest developing:

  • To increase the share of renewables in the electricity mix and make the electricity system more resilient, particularly to extreme weather events.

  • Supporting commercial customers and industrials in their decarbonization process by enabling them to decarbonize some of their uses and process by benefiting from a renewable and less expensive energy.

  • Create a more energy self-sufficient housing, by facilitating the development of self-consumption for households, including during consumption periods.

  • Develop microgrids and offgrids by making it possible to create small, reliable, low-carbon electricity networks in secluded areas.

EDF Pulse Ventures analyses more specifically 6 technologies dedicated to LDES

For EDF Pulse Ventures, « long duration energy storage technologies » are those capable of storing energy for more than 6 hours. They guarantee flexibility at least over the day, and even over the week (up to 100 hours of storage) or the season (over 100 hours of storage). Their relevance varies according to needs, uses and economic constraints.

The most mature technology is that of “pumped-storage hydropower” (PSH), a technology that EDF has mastered for many years, with more than 5 GW of PSH in operation and many projects underway.

In its deep dive, EDF Pulse Ventures studied 6 other technologies more specifically, on which many innovations are emerging:

  • 1

    Evolution of lithium-ion batteries

    This is a fairly mature technology with few implementation constraints but relevant for a fairly short storage time (between 1 hour and up to 6-8 hours). Its compact size doesn’t require a particular installation environment. A lithium-ion battery is based on the reversible exchange of the lithium-ion between 2 electrodes. Lower costs of new batteries and the use of second life lithium-ion batteries could be two ways for this technology to be competitive over longer periods.

  • 2

    Redox Flow battery

    This kind of battery consists of 2 tanks in which 2 chemical compounds are dissolved and then pumped into an electrochemical cell that produces an electric current. It can store energy for between 8 and 24 hours.

  • 3


    Electricity is converted and stored as heat in a medium with or without phase change. This heat is then either used directly or to generate electricity via a turbine. This can store energy for 8 to 24 hours.

  • 4

    Solid gravity-based

    Gravitational energy storage involves using the potential energy of a mass. Unlike PSH, this technology relies on solid masses (e.g. piston or concrete block). During discharge, the potential energy of the falling object is converted into electricity by generator. This type of technology allows energy to be stored for 8 to 24 hours.

  • 5

    Air energy storage

    Energy is used to compress air during charging, which is then expanded in a turbine to produce electricity. It could store for between 6 and 100 hours in an underground cavity, depending on the technology used and the size of the cavity.

  • 6


    it is possible to store energy in the form of hydrogen, whether liquid or gas. To date, this is the solution offering the longest storage time, apart from technologies excluded from the study’s scope(1).

Other technologies exist, such as liquefied CO₂ storage, metal-air solutions and new chemistries. 

46 identified startups in the field of long duration energy storage (LDES)

During its deep dive, EDF Pulse Ventures has identified hundreds of companies developing these different technologies. Among them, 46 startups illustrate the dynamics of the ecosystem on the 6 technological paths analyzed.

Mapping: 46 identified startups in the field of long duration energy storage (LDES)

You work on the LDES field?

(1) The study’s scope concerns new innovative technologies that complement those already developed by the EDF group.