The tiny component that could make electric cars and wind turbines more efficient
Most people have never heard of a capacitor. Yet it is found in almost all modern electronics – from electric cars to wind turbines. In his PhD at the University of Southern Denmark in Sønderborg, Jonas Wittmaack developed a new type of capacitor that can reduce energy losses, save weight, and make electronics easier to recycle. He is now working to turn the research into a company.
- If you tried to use a battery for the job a capacitor does, the battery would basically just explode.
Jonas Wittmaack places three small components on the table.
They do not look like much. Small metal cylinders and a square prototype. But they represent three generations of a technology that is present in almost all modern electronics: capacitors. And these are exactly what he has spent several years rethinking.
When he recently defended his PhD at the University of Southern Denmark in Sønderborg, it focused on a component most people never think about – yet one that is crucial for everything from a camera flash to large energy systems in electric cars and wind turbines. Jonas has developed the capacitor technology within his PhD thesis in the capacitor group led by Prof. Thomas Ebel, CIE, University of Southern Denmark.
The invisible workhorse of electronics
While a battery stores energy chemically and releases it over longer periods, a capacitor works in a completely different way. It stores energy physically – and only for very brief moments. In return, it can deliver power extremely quickly.
This makes it a key component in modern power electronics, where electricity is constantly converted, controlled, and stabilised.
Take an electric car, for example. The battery supplies direct current, while the motor uses alternating current. This means the electricity must constantly be converted back and forth in electronic systems.
And every time that happens, capacitors play a crucial role. But there is a problem. When electricity passes through components, some of the energy is lost. It turns into heat.
- A large part of my research was about reducing the losses that occur inside the capacitor, explains Jonas Wittmaack.
And the higher the frequencies at which modern electronics operate, the greater the challenge becomes.
A weak point in the technology
Many of the capacitors used today contain a liquid electrolyte. It conducts electricity inside the component – but it can also cause problems. If the capacitor is damaged, the liquid can leak out. Because it is highly conductive, it can create short circuits in the surrounding electronics.
For this reason, Jonas Wittmaack has worked with a different approach. Instead of a liquid, he uses a solid polymer that also conducts electricity. At the same time, he has changed the component’s physical construction.
Traditional aluminium electrolytic capacitors are typically cylindrical and built as a rolled layer of foil and paper. The new prototype is instead constructed as a compact sandwich, where materials are stacked in layers. This change reduces both electrical resistance and the so-called inductance – two factors that cause energy loss.
Laboratory measurements have shown that the resistance can be reduced by up to 12 times in some cases. That means less heat and higher efficiency.
Lighter – and easier to recycle
The new design could also influence the sustainability of future energy systems.
Today, film capacitors are often used in powerful electronic systems. They work well, but they are relatively large and contain significant amounts of plastic. The new capacitor consists primarily of aluminium and polymer.
- That makes the materials much easier to recycle later, says Jonas Wittmaack.
At the same time, several smaller components can replace a single large one. Even if more units are used, the overall solution can still become both lighter and more compact. This can be an advantage in everything from industrial equipment to transportation technology, where weight and size are crucial parameters.
From research to a potential spinout
Although the work began as a research project, industry interest quickly emerged. Whenever the research group presents the technology to potential users, one question keeps coming up: When can we buy it?
- That was actually the first thing people asked, says Jonas Wittmaack.
He is therefore continuing the work with the ambition of moving the technology out of the laboratory to mature it toward a potential spinout. The plan is to develop the capacitor in close collaboration with industry and eventually establish production.
To support this effort, the research project collaborates with STEAR, which specialises in maturing pre-startup projects with commercial potential. Through mentoring and advisory services, STEAR supports ideas originating from both university researchers and industry entrepreneurs.
The vision is that the technology may eventually be produced in Sønderborg and become part of future energy technology.
The small component behind the big transition
When people talk about the green transition, the focus is often on batteries, wind turbines, and solar panels.
But behind the scenes, a long list of smaller components must also improve if energy systems are to become more efficient. Capacitors are one of them. And that is precisely why a seemingly small invention can have a large impact.
- Most people never think about capacitors, says Jonas Wittmaack.
- But without them, much of the technology we take for granted today simply wouldn’t work.