From enabling off-grid living to supplying towns with renewable energy, Long-Duration-Energy-Storage (LDES) could be one of the most important technologies of this century. As the world shifts away from fossil fuels, LDES allows for a steady energy supply even when the sun doesn’t shine. With the demand skyrocketing, we looked into the data to identify the startups leading the charge. Here are five LDES startups shaking up the energy sector.
Cartesian
Norwegian startup Cartesian unlocks the power of thermal energy storage to decarbonize buildings and industry processes – helping some of the world’s most energy-intensive sectors become more energy-efficient. Cartesian’s energy storage optimizes energy usage from large heating and cooling systems, balancing the grid by saving surplus energy for later use. Its systems are based on 10 years of research and development on thermal energy storage at SINTEF, one of Europe’s largest independent research organizations. Cartesian raised a $2.94M seed round from Norweigan incubator Kongsberg Innovasjon in February this year.
PolarNight Energy
PolarNight’s heat storage battery allows for long-duration solar energy storage for hours or months. Its mission is to provide Earth with stable, affordable, and clean energy – from big cities to distant villages. The Finish startup’s sand-based system uses soapstone, a byproduct from a fireplace manufacturer, to store up to 100 MWh of energy from the grid. This is equivalent to about one month of energy supply of a village in the summer, or one week in the winter. The Sand Battery will be integrated with Loviisan Lämpö’s district heating network to slash Pornainen’s carbon dioxide emissions by 70% annually. A mission that secured the company €7.6M in March 2024.
Cache Energy
Cache Energy has developed a new way to store renewable energy for longer periods. Rather than storing power as heat, Cache’s systems use pellets made from limestones. This means that the energy can be stored at room temperature, making it as easy to transport as coal. Moisture is then reintroduced to release heat up to 550°C, making it competitive with fossil fuels for heating homes and industries. The company recently secured a $8.5M seed round from investors including Cantos, Climate Capital, and Voyager Ventures, and aims to raise a Series A by the end of this year.
Photoncycle
Small-scale, distributed energy sources (DER) like rooftop solar panels could allow households to become self-sustained. However, the shift to renewable energy comes with a new set of challenges. The seasonal variations of solar power cause grid instability and bring high costs, since surplus energy needs to be stored for cloudy days. Photoncycle’s technology solves this by offering a cost-efficient way to store solar-generated electricity. With concerns about DERs increasing economic inequality by making electricity more affordable for wealthy early adopters while driving up the bills for those with less, solutions like Photoncycle are much needed.
Aquabattery
AquaBattery creates eco-friendly batteries using just water and table salt to store energy. Its acid-base flow battery technology helps integrate renewable energy sources like solar and wind into the grid by storing excess energy when it’s abundant and releasing it when needed. Unlike traditional batteries, AquaBattery’s solution is safe, non-toxic, and highly scalable, making it ideal for large-scale energy storage without environmental risk. Aquabattery has teamed up with Deltares, a leading research institute, to install a pilot battery system at Deltares’ campus in Delft in 2024. Their focus on large-scale projects could make them a major player in the energy storage market.
These startups are pushing the boundaries of LDES tech, paving the way for a future where clean energy is available around the clock. From PolarNight’s sand battery to Aquabattery’s saltwater-based storage, these companies are tackling the storage conundrum with innovative, scalable solutions.
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