Beyond the limits of electricity and hydrogen
The waste materials released from burning conventional fuels are a burden on our environment. Alternative energy sources and powertrains are rapidly gaining popularity. But it feels like the search for alternative energy focuses for a very large part on electricity. That is a perfect source of energy, but not exactly the holy grail in the search for answers to global energy demand.
Certainly not when it comes to the problem the project hopes to solve in this story: powering large machines and transport equipment.
Because propulsion based on electricity is a tricky challenge. And that is an understatement. Besides electricity, the term "hydrogen" sometimes pops up as a more efficient and less polluting alternative. But producing hydrogen is still expensive and difficult. That is why several specialists within TU/e are now getting down to the task with an unconventional alternative.
Metal fuels
For those unfamiliar with the phenomenon, this headline will sound like the name of a band leaning on a solid guitar section and a highly motivated drummer. But it is about a serious and promising substitute for conventional carbon-based fuels: metal particles, charged with energy, that release this energy in a controlled manner. The energy released lends itself perfectly to powering all kinds of especially heavier engines. The particles are captured and recharged after combustion, creating a fully circular process. We talk about it with Dr Mohammadreza Baigmohammadi, postdoctoral researcher at the Power&Flow group, led by Professor Phillip de Goey. This group focuses on innovations in 'combustion'.
Explosions and melting points
Metal powder can hold a lot of energy. It has been a favourite ingredient in explosives and fireworks for centuries. But an explosion is a short, violent discharge and this research focuses on releasing that energy over a longer period. And that presents unique challenges, says Mohammadreza; "For a start, we need to control the temperature. We want to heat the metal particles close to the melting point. If it gets too hot, the particles evaporate. Then they become nanoparticles, and these are a lot harder to recapture. We want to keep the particles whole. That is our focus"
Not all at once
Once the powder heats up, energy is released. And that discharge can in turn cause the temperature to rise. So far, that looks like standard fuel combustion. But there is a big difference, Mohammadreza explains: "Conventional fuel is predictable in its behaviour. Everything ignites at the same time. With metal powder, each particle burns on its own. But the particles react back to each other. And that makes it different from conventional fuels.
Sliders and knobs
According to Mohammadreza, the solution lies in controlling several parameters. He calls these the sliders and knobs of the project. "The oxygen content is one of them. To keep combustion manageable, we lower that content. But less oxygen in turn means less combustion. So, we look for methods to preheat the fuel. That way, it is already at a reasonable temperature when it enters the engine, and we need less oxygen to keep the process going."
The future
The team has now identified the key parameters for safe yet sufficiently violent ignition. "We are making serious progress. Now we need to start figuring out how those parameters work together and how we can apply them to this form of combustion." Metal powder-based propulsion is a method suitable for e.g. power plants. For ordinary engines in cars, it is trickier, says Mohammadreza: "The size of the engine is not that important. But fuel control is crucial. That is why we see future applications mainly in external engines, because it involves external heat dissipation. As soon as cars are created with external engines, we will have more opportunities to apply our methods to these too. "
Within two years, Mohammadreza expects to have a working demo; a lab prototype. "Then we can also show companies something during a demonstration. That's an important step to get new investments."
Only at TU/e: also looking at recycling
According to Mohammadreza, many other universities focus on improving processes around the familiar pyrotechnics and explosions. "We do it differently. The others focus on combustion only. We on combustion as well as recycling. We are unique in that aspect at TU/e. We really are a frontrunner in this field. Curently, only TU/e and McCale University in Canada are working on this process. It’s a completely new form of renewable energy and that will make you encounter scepticism every now and then. Some people want to see proof that it can work first. There are companies working on it and we do talk to them. But in general, everyone looks at each other to see what is happening. And it is in that context that we are going to pioneer."
Motivation
A whole new playing field, scepticism from the outside world and few others to lean on. There are plenty of researchers who would run away from lesser challenges. But Mohammadreza draws his energy and motivation from small, positive signs and the belief that technology offers hope. "That, and you have to be a little crazy, you have to look at existing systems and problems differently. If you don't, you will never discover anything new.
As a researcher, you must figure out where to start looking. Sometimes we don't know what the outcome will be. And research like this often takes a long time. But you persevere because you believe in it. And maybe, after digging for a long time, you do indeed stumble upon a treasure.
When I started, I knew we were about to do something crazy, but that feeling disappeared after about three months. That's when we saw the first positive signs."
Why is the University Fund important?
"If this fund had not existed, this research wouldn't exist. It's as simple as that. Phillip de Goey's research leans on it. The fund supports projects that do not immediately produce prototypes or concrete results. Those important projects that sometimes actually lay the foundations for bigger discoveries. Big companies want that too, but we prefer to have all the technology and key roles ourselves. That helps accumulate so much more technical knowledge. Which we can then share again with other parties."
Looking ahead
I try to look ahead every day. We work in the dark. You don't know anything, so anything you discover is progress. Chances are you won't see the light until afterwards.
We are working with iron now, but that could be a starting point for other ways of storing energy in materials. Who knows where this road will lead us? Not knowing that answer is one of the exciting elements of basic research.