Solar Fuel Plant Marks a Milestone in Clean Energy Production

The ETH spinoff Synhelion recently opened the world's first industrial plant for the production of solar fuel in Germany. The plant features a core component developed with Empa technology. Empa researchers collaborated with Synhelion to create a material for the plant's high-temperature thermal energy storage system, enabling continuous operation around the clock.

In June 2024, Synhelion opened DAWN, the world’s first industrial solar fuel production plant, in Jülich, Germany. With support from the Empa Laboratory for High-Performance Ceramics, DAWN can generate renewable fuels both day and night.

The concept behind Synhelion is to close the CO₂ cycle by capturing CO₂ and repurposing it as kerosene, gasoline, and diesel. The ETH spin-off converts CO₂ and water into synthetic fuels (Synfuels) using solar heat.

For DAWN to convert CO₂ and water back into fuels, energy is crucial. Sunlight is concentrated onto a single point on the solar receiver by a large array of mirrors. This concentrated solar energy heats the steam inside to temperatures of up to 1200 °C.

The reactor is powered by this high-temperature process heat, and any surplus heat is stored in a large chamber filled with specially designed bricks, developed in collaboration with Synhelion and Empa. These bricks serve as a temporary heat storage system, ensuring that the reactor can continue operating throughout the night.

Wanted: The “Super-Brick”

At 1200 °C, however, not all bricks are created equal. Even ceramics corrode when exposed to extremely hot steam. Synhelion approached Empa because no commercially available refractory bricks were designed to endure such harsh conditions.

The research group led by Empa researcher Gurdial Blugan is one of the few to study the corrosion behavior of ceramics at such high temperatures.

Lukas Geissbühler, Head Thermal Systems, Synhelion SA

Empa scientist Sena Yüzbasi, along with Blugan and Synhelion, embarked on a two-year project funded by Innosuisse to identify a suitable ceramic. Corrosion resistance was only one requirement; the material also needed to be mechanically robust, capable of withstanding thermal shocks when the system shuts down, and have a high heat capacity.  It also had to be inexpensive to produce, because the plant in Jülich is just the beginning for Synhelion.

In collaboration with Synhelion and the Empa workshop, the researchers developed a specialized high-temperature tube furnace. They exposed various ceramic samples to the corrosive steam environment for up to 500 hours.

It got pretty hot in our lab during these experiments.

Dr. Gurdial Blugan, Group Leader, Empa

The researchers discovered a material capable of withstanding the harsh conditions, making their effort worthwhile.

To further improve material properties and reduce costs, they optimized the manufacturing process and composition in collaboration with project partners. The bricks were then produced by a German company in Jülich.

As a researcher, it is not often that you get to see your research applied on such a scale; it is quite a unique experience.

Nur Sena Yüzbasi, Scientist, Empa

Now working in the energy sector, Yüzbasi is particularly proud that her research is contributing to the fight against climate change in the renewable energy field.

Forging on Together

Geissbühler added, “Empa has made a valuable contribution to the development of our thermal storage unit and was able to respond to Synhelion's specific requirements thanks to its flexibility.”

Even as DAWN launches, Synhelion and Empa are already planning their next collaborative project. They aim to further enhance the material's durability for future plants. Starting in 2025, Synhelion plans to build its second solar fuel production facility in Spain, targeting higher temperatures and larger heat storage units, as fuel production is more efficient at elevated temperatures.