Hot Wheels - How Kraftblock moves heat with a mobile storage solution

Heat makes up half of the global energy we use, accounting for 40% of CO2 emissions as a result. Our scale-up Kraftblock is providing solutions to decarbonize heat in industries and district heating, both major sectors that still rely heavily on fossil fuels. With Kraftbock's most recent project, they are taking things a step further: They developed a mobile heat storage unit that makes it possible to easily move thermal energy from A to B.

​New to Kraftblock? Here’s all you need to know in 5 bullet points!

- Direct heat-to-heat storage, or conversion from electricity

- Temperature range up to 1,300 C

- Modular with thermal capacity from a few MWhs to several GWhs

- Eco-conscious production from abundant non-toxic materials

- Launching customer PepsiCo in the Netherlands in implementation now

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Connecting excess production and demand for heat

Sometimes, factories and power plants generate excess heat that isn't used because they're not connected to a district heating network or the distance to its application is too far. Consequently, a large amount of energy is wasted through their chimneys, especially for small and medium-scale power plants such as those using biomass or natural gas. Kraftblock constructed a storage system designed for a truck that transports excess heat from various sources to locations where it can be utilized.

Buhck Gruppe, a German waste recycling firm, operates a combined heat and power plant (CHP) outside of Hamburg. The heat emitted by the plant's motor is lost at a temperature of about 450°C, which is valuable heat that can replace fossil fuels in other processes. Kraftblock and Buhck collaborated to harness this heat. The pilot has been operating on streets near the city since April 2023.

Buhk Gruppe earlier shared this about the project’s impact:

"With the project, we achieve up to 100% savings on fossil fuels, no waste of precious heat, reduction of CO2 and protection of the environment.”

How it works

Step 1: Heat capture

The flue gases of the waste heat source are directed into the Kraftblock storage unit instead of going through the chimney system. In the case of the Buhck project, this is the off gas from an engine to produce power and heat. In a normal container used on the streets, up to 4 MWh can be stored.

Step 2: Undocking and loading of container

After the storage unit is charged at the docking station, the container is loaded on one of Buhck’s trucks. Kraftblock also provides the solution on a trailer to fit a wide range of standard trucks. The concept works both on regular roads and within factory areas, where the container can be heavier and thus store more energy.

Step 3: Unloading and connecting

Just like the charging process, discharging is done via a docking station. After the storage unit or trailer is connected to the docking station, a fan pulls out the energy and transports it to the application. From here, the integration is the same as with a stationary storage: The system is connected to the plant. If the energy is not needed in the form of hot air, it is transferred to another medium like hot water or thermal oil depending on the factory’s needs.

Step 4: Return logistics

Once the storage unit is almost empty, it is returned and charged again. With multiple container solutions, you can just switch energy supply from an empty to a full storage that is delivered to the application. This way, trucks don’t need to do empty journeys.

Impact on the environment & new business models

Buhck uses the Kraftblock solution for multiple purposes. It is currently being used to dry out large construction sites that would otherwise rely on fossil fuel-fired heat generators. It is also utilized in a production facility and for regular heating. Through this solution, Buhck can establish unique business models and acquire new customers, while conserving fossil fuels and curbing their emissions.

Next steps

The collaboration with Buhk Gruppe is not the only project that Kraftblock is working on.

An EU-funded project will finish this year, which uses flare gases from the steel industry as an energy source. Heat emissions from burned gases will be transported to Kraftblock's production hall to provide energy. Temperatures of up to 1,300°C will be tested. The project is considered a likely game-changer in the steel industry by using storage to time-shift heat from flare gases for their processes.