FAQ

What is a thermal energy storage system?

A thermal energy storage (TES) system stores heat for later use—think of it as a thermos for energy.
It allows electricity, especially from renewable sources, to be converted into heat and stored
efficiently. The stored heat is released whenever process requires. TES helps balance supply and
demand, reduce fossil fuel use, and cut energy costs—all while making the energy system more
reliable and sustainable.

How does your energy storage system work?

TheStorage system consists of two insulated silos, an electric sand heater, heat exchanger, and of course sand. Sand circulates between two silos and creates miracles.

In our solution, the sand is heated using electricity either from a renewable source or from the grid when prices are low. Once heated to temperatures up to 1000 °C + in our patented electric heater, the hot sand is stored in a specially designed silo that contains no internal piping or heat transfer components. Because sand is an excellent insulator, we keep it stationary while stored to retain heat efficiently.

When it's time to transfer the heat, the sand is set in motion. Movement boosts heat transfer efficiency by more than tenfold. This means the maximum discharge power, heat output, is always available for the production - regardless of how much energy is stored.

When heat is needed, the hot sand flows through our proprietary heat exchanger, where the heat is transferred to a working medium such as steam, superheated steam, or thermal oil, depending on the industrial process requirements. After discharging its heat, the cooled sand is collected in a separate storage silo and returned to the heater for reuse.

What is the importance of storing renewable energy?
Why should you store energy?

Renewable sources like solar and wind are clean but inconsistent - sometimes they produce too much, sometimes not enough. Energy storage solves that.

By storing excess energy when it's plentiful and releasing it when it's scarce, energy storage systems:

- Ensure stable power supply even during production dips
- Reduce emissions by minimizing fossil fuel use
- Save money through smart energy use (store when cheap, use when expensive)
- Support grid stability and help avoid costly infrastructure upgrades

Storage makes renewable energy more reliable and usable - every hour of the day.

Why do you move sand?

Sand is great at holding heat when still—but not so great at transferring it. So, we keep it still when storing energy and move it when we need to extract or add heat.

When sand flows, millions of tiny particles come into contact with the heat exchanger, which:
- Dramatically boosts heat transfer (up to 10× more efficient)
- Ensures maximum thermal power is transferred quickly and evenly

In short: stationary sand stores well. Moving sand transfers well. We use both to our advantage.

Does the moving sand cause erosion?

Not really. Picture dragging your hand through warm beach sand—that’s the pace our sand moves.
Gentle and smooth.

In our system:

- Sand moves slowly and steadily
- It touches mostly steel surfaces, which are much tougher than your skin
- The amount of moving sand is relatively small

Result: negligible erosion. In fact, corrosion is usually a bigger issue in other systems—but not ours.

Our environment is hot, dry, and inert. No rust, no fuss.

Does it take a lot of energy to move the sand?

Not at all. The auxiliary power consumption—energy used to run the system—is typically less than
2% of the round-trip efficiency (RTE). And the larger the system, the smaller that share becomes.

Big heat. Tiny overhead.

How big are the heat losses?

Heat losses are typically around 5% per day, but they depend on:

- Size of the silos (larger = more efficient)
- Insulation thickness and quality
- How often the system is charged and discharged

More insulation = lower losses, but also higher cost. In daily-use cases, losses are minimal, especially if you're charging with low-cost electricity.

In large systems with good insulation, losses can drop below 1% per day. But in most cases, it’s not worth over-investing—if your electricity is cheap, your losses are too.

What is the roundtrip efficiency of your system?

Round-trip efficiency (RTE) reflects how much of the input energy you get back as usable heat.

The main loss in our system will be loss through insulation; the loss of electric equipment is minor.

In summary, the round-trip efficiency will be typically 90-98%, depending on the issues mentioned
above.

How hot can you heat the sand?

Sand can be heated up to 1100C, but usually it is not required to go that high. Most of the applications can be served with a storage temperature of 800C. Higher the storage temperature, the more energy you can store in the volume of the sand.

How is heat taken out for industrial processes?

We extract heat using our patent-pending heat exchanger. Here's what happens:

- Hot sand flows through the exchanger
- A working medium (like steam or air) flows on the other side
- The sand cools, the medium heats up

Efficient, direct, and fully customizable for your industrial process needs.

What kind of energy storage sizes do you offer?

Our systems are modular and customizable.

- Charger/discharger sizes: 1–20 MW
- Storage capacity: 20–500 MWh

You can configure charging, discharging, and storage levels to fit your specific process requirements.

Why do you use sand?

Sand is an ancient yet brilliant material for thermal storage. Here’s why we love it:

- Abundant and affordable: Found almost everywhere
- Non-toxic and non-reactive: Environmentally friendly
- Naturally insulative: Great for holding heat when still
- Great heat transfer when moving: Millions of grains = fast exchange

Old-school meets high-tech.

What kind of sand is used?

Nothing exotic—it’s natural sand, similar to what you’d find on a beach. The grain size is below 1mm, optimized for
flow and heat transfer.

Is this new technology?

It is a first-of-its-kind system. However, we use a combination of robust, proven technologies with added innovation to achieve this.

How long can you store energy?

The energy can be stored as long it is needed, however, in most cases the storage time is less than 2 days. We take advantage of the intermittent nature of renewable energy sources, i.e. daily fluctuations.

Longer-term (even seasonal) storage is possible too, with additional insulation and business case adjustments.

How much money and emissions can be saved?

Compared to fossil fuel usage, our solution can cut energy costs up to 70% and emissions more than 90%. A win for your budget—and for the planet.

Do the math yourself here.

100% heat power at all times

TheStorage uses robust and proven technologies in a groundbreaking way

Sand-in-Motion Thermal Energy Storage

Electrified thermal energy storage

TheStorage system uses two insulated silos, an electric heater, a proprietary heat exchanger - and plenty of sand

Pilot Plant Proves Technology at Finnish Brewery

Applications

Applications

Customized to your needs. Configure charging, discharging and storage size.

Still burning money on fossil fuels?

Customized to your needs. Configure charging, discharging and storage size

FAQ

No more burning fuel and money.

Want to hear the hottest news, developments and career opportunities first?

TheStorage uses robust and proven technologies in a groundbreaking way

Sand-in-Motion Thermal Energy Storage

Electrified thermal energy storage

TheStorage system uses two insulated silos, an electric heater, a proprietary heat exchanger - and plenty of sand

Pilot Plant Proves Technology at Finnish Brewery

Applications

Applications

Customized to your needs. Configure charging, discharging and storage size.

Still burning money on fossil fuels?

Customized to your needs. Configure charging, discharging and storage size

FAQ

What is a thermal energy storage system?

How does your energy storage system work?

What is the importance of storing renewable energy?Why should you store energy?

Why do you move sand?

Does the moving sand cause erosion?

Does it take a lot of energy to move the sand?

How big are the heat losses?

What is the roundtrip efficiency of your system?

How hot can you heat the sand?

How is heat taken out for industrial processes?

What kind of energy storage sizes do you offer?

Why do you use sand?

What kind of sand is used?

Is this new technology?

How long can you store energy?

How much money and emissions can be saved?

No more burning fuel and money.

Want to hear the hottest news, developments and career opportunities first?

What is the importance of storing renewable energy?
Why should you store energy?