But while going underground solves the problem of limited space, it introduces a new set of challenges, especially when it comes to safety.
Why Underground Power Needs a Different Approach
Installing transformers below ground makes sense in crowded cities and environmentally sensitive locations. It keeps valuable surface space free and allows energy to be delivered closer to where it’s needed.
However, these environments come with higher risks:
-
Fires are harder to detect and control in enclosed spaces
-
Access for maintenance and emergency response is limited
-
Any fluid leak can have a greater environmental impact
-
Traditional protection systems can be bulky, expensive, and complex
For operators, the question becomes clear: how do you deliver reliable power underground without increasing risk?
MIDEL Ester Fluids
MIDEL ester fluids have become a trusted solution for underground transformer applications worldwide. Designed with both safety and sustainability in mind, they offer two critical advantages:
- A high fire point above 300°C, dramatically reducing the risk of ignition
- Readily biodegradable properties, minimizing environmental impact in case of leaks
These qualities make MIDEL fluids especially well suited for confined or sensitive environments where traditional mineral oils fall short.
Real-World Applications Across the Globe
MIDEL fluids have already proven their value in a wide range of underground projects. Here are just a few examples:
Urban Safety in Sweden
In Göteborg, underground transformers were installed in densely populated areas where fire safety was non-negotiable. MIDEL fluids provided peace of mind by significantly lowering fire risk, allowing safe operation beneath the city.
Hydropower Efficiency in Switzerland
At the Kraftwerke Oberhasli AG facility, four 50MVA converter transformers and several auxiliary units were installed underground. By using MIDEL, the project was able to eliminate the need for costly fire suppression systems, reducing both installation complexity and overall cost.
Environmental Protection in Sensitive Areas
At a Vattenfall hydropower station in Sweden, environmental protection was the top priority. Located in a sensitive area where any contamination would be unacceptable, MIDEL 7131 was selected for its biodegradability, ensuring that even in the unlikely event of a leak, the impact would be minimal.
The Benefits Go Beyond Safety
Choosing MIDEL isn’t just about reducing risk—it also brings practical advantages that simplify projects and improve long-term performance:
-
Improved fire safety without relying on complex suppression systems
-
Lower total project costs through simplified infrastructure
-
Greater design flexibility for tight or underground spaces
-
Environmental responsibility with reduced contamination risk
-
Proven reliability across demanding applications worldwide
In many cases, MIDEL allows engineers to rethink how underground systems are designed—making them simpler, safer, and more efficient from the start.
A Smarter Way to Power Below the Surface
As more infrastructure moves underground, the need for safer transformer solutions will only increase. MIDEL ester fluids are helping to meet that need, offering a smarter balance between performance, safety, and sustainability.
Whether it’s powering a city, supporting renewable energy, or enabling critical transport systems, MIDEL is quietly making underground power safer and more practical.
Because when you can’t see the infrastructure, you need to trust it even more.