Reportage

 

Who drives
the future?

When thinking about electromobility, one of the first things that comes to mind is batteries. But electric cars can also run on a different technology: fuel cells. A journey into two different laboratories. 

Text Susanne Theisen  Photos Norman Konrad

Get in, buckle up, start the engine. What you hear: almost nothing. That’s the first thing almost everyone notices their first time in an electric vehicle. The car seems to be slumbering, but if you step on the gas, you really take off. You could say the driving experience in an electric car has a lot of “spark.”

For Dr. Mareike Wolter and Prof. Dr. Thomas von Unwerth, this driving experience is nothing new, but they both still enjoy it. The two scientists are proponents of electromobility—but from two different camps. Wolter, an electrochemist, is director of the Mobile Energy Storage and Electrochemistry department at the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) in Dresden. Her research is attempting to advance battery-driven electromobility. Von Unwerth, a mechanical engineer, is a fuel-cell man. He is also chair of the Department of Advanced Powertrains in the Faculty of Mechanical Engineering at Technical University Chemnitz. He’s developing powertrains based on hydrogen.

Yet even if they’re taking different approaches, there’s one thing that Wolter and von Unwerth agree on: electromobility desperately needs a jump-start in Germany. Currently the German Federal Government is a long way from meeting its original goal of one million electric vehicles on the roads by 2020. The country’s Federal Motor Transport Authority reports that by early 2018 there were only 98,280 licensed electric vehicles (EVs) and 209 electric buses in the country. More EVs on German roads would do a world of good to help the government meet its climate targets. If greenhouse gas emissions are to be reduced by 80 to 95 percent of 1990 levels by the year 2050, the transport sector, particularly road traffic, has a key role to play. Currently, it’s responsible for one-fifth of total emissions in Germany. With the help of electromobility, ideally based on eco-friendly electricity, emissions could be considerably reduced. Doctors Wolter and von Unwerth are both working full power on their conceptions for electromobility. All that is needed is a brilliant idea or two. Which raises the question: Whose ideas are more brilliant?


“Our battery saves on weight, on space and on costs.”

Mareike Wolter enters a laboratory at IKTS and heads over to an extractor hood with a mixer. A new slurry—the material with which the electrode foils and batteries are coated—will soon be mixed and tested. The laboratory scale is at the ready, and components are being fetched from the nearby safety cabinet. Wolter, the department director, puts on protective glasses, gloves and a lab coat, and then starts the process. The fan of the extractor hood hums above the silver appliance while a lab employee weighs the ingredients and adds them to the mixer. The timer and mixing speed are set, and the slurry is ready within minutes. It drips like watery honey from the beater.

“Our department develops materials and processes to produce battery cells,” Wolter explains. “There’s one question above all that drives us: How can we improve the performance and service life of battery cells?” That’s precisely the criticism that is always leveled against battery-driven electromobility: worries about the operating range. Customers shy away from battery-driven electric vehicles because they’re afraid they won’t be able to drive far enough. Right now, lithium-ion-based battery systems have a maximum range of five hundred kilometers on one charge. But that is only true when the materials and workmanship are absolutely first rate and everything is working perfectly.

Wolter is satisfied with the mixed slurry’s viscosity. Now it can be used on the electrodes and evaluated, which is why the next stop leads directly to the casting machine in the drying room—a converted, windowless laboratory. An important goal for Wolter and her team is to make battery production less expensive with regard to both the raw materials and the energy needed for production. “Cobalt and nickel are two of the substances found in most batteries these days,” she says. “Both of these materials are mined in what are usually unpleasant conditions, particularly with regard to the environment. In addition, refining requires a lot of energy. So we’re looking for better possibilities here.”

A turning point in her research came in 2014. That was when the department developed what they call the EMBATT concept. “The idea came about quite spontaneously,” she says. “The team was sitting around, eating some pastries, looking at the installation space in a Tesla and thinking: How could we do this better? How do we get more performance and operating range into that space?” EMBATT should allow vehicles to be able to drive up to one thousand kilometers on one battery charge. It’s a fairly ambitious goal, but how will it work? “The battery structure is completely different, using what’s known as a bipolar approach,” Wolter explains. “We essentially use the same materials and instead of placing each cell into a separate enclosure, we stack them without one. With that we save on weight, on space and on costs—and also enormously increase the energy density.” With the cells connected directly to one another in a stack, the energy flows across the entire surface of the battery, which lowers the electrical resistance and increases the performance.

Experts in the field sat up and took notice: fuel cells also work using the bipolar principle. Did the scientists in Dresden look over the shoulder of the competition? Wolter laughs: “I’m an electrochemist, which is why I was well aware of the principle. We simply adapted it to the lithium-ion battery. People thought we were crazy at first, but the idea has been accepted in the meantime.”

Wolter returns to her office. She sits down at the conference table with the subproject directors who are working with her on EMBATT. They’re presenting the results from the most recent series of tests, with figures and diagrams flickering on the screen at the head of the table. Wolter and her team are analyzing the uniformity of the electrodes and whether the slurry was applied to the surfaces homogenously enough. “The challenge with using the bipolar principle is to produce and stack the individual cells and components very accurately so that the electricity is evenly distributed,” she explains.

To optimize the processes, IKTS is working on EMBATT with two partners. While Wolter’s department develops the electrodes and electrode materials, ThyssenKrupp is developing the process and systems solutions. The third partner, IAV Automotive Engineering, is designing the concepts to integrate these batteries into electric vehicles, the first of which is set to be out on the roads in 2020. If the price-performance ratio works out and the number of charging stations has increased sufficiently in Germany, Wolter has no doubt about which technology will come out as the winner in the close race for the leading role in electromobility:

 

 

“Fossil fuels are finite—
hydrogen isn’t.”

Something is bubbling next to Thomas von Unwerth, who is seated at the conference table in his office. At the far edge of the table, a mini-electrolyzer is separating water into its individual components thanks to electricity from a solar cell. In one of the two tubes, the substance of this engineer’s dreams bubbles upward: hydrogen. H2.

“Fossil fuels are finite, but our stocks of hydrogen are nearly inexhaustible,” von Unwerth explains. “In the oceans alone, there is enough of it to meet humankind’s energy needs for 50 million years.” To be fair, he directly addresses the obstacles associated with this scenario: “Hydrogen is only found bound up in molecules, which means we always have to obtain it first. If we want to do this in a climate-neutral manner, we have to release it using renewable energy. Afterwards, it can easily be stored and transported. Much better than electricity.” As an alternative, using hydrogen that occurs as an industrial byproduct could also be tested.

In von Unwerth’s opinion, his technology’s second advantage is that electricity can be generated from stored hydrogen as needed. The critique that half of the original amount of energy is lost in the process—for batteries it’s only about 10 percent—doesn’t ruffle him: “That’s true, but rather than let excess energy, especially green energy, simply go to waste unused, it would be preferable to store it in the form of hydrogen and use it later, even if it’s only half as much.”

Increasing numbers of bubbles gather in the electrolyzer as von Unwerth continues: “Hydrogen vehicles can be fueled in just a few minutes, even larger ones such as buses or cargo trucks. Refueling is much faster than it is for electric-battery vehicles—and the operating range ƒis greater.” However, he adds, the filling station infrastructure remains inadequate. Right now, around fifty filling stations offer hydrogen in Germany, while experts estimate that around one thousand would be needed. Von Unwerth is well aware that this isn’t enough for an extensive market breakthrough: “A lot more needs to happen in this area, but things are moving forward. By 2019 there should be about one hundred filling stations and more and more after that.” He gets up from the conference table and smooths his shirt. Then he heads down to the labor­atory on the ground floor to approve a performance test for new fuel cells. Along with increasing performance, the engineer and his team are also working on reducing the fuel cell’s complexity. “At the moment it’s made up of about six hundred individual parts, which is far more than a battery has,” he says while walking down the stairs. “So that makes fuel cells too expensive right now. We’re looking for ways to make mass production cost-effective. We need the volume effect to establish fuel-cell technology on the market.” The raw materials costs must also be optimized for this. But von Unwerth believes things are on the right path. In the past, for instance, around 100 grams of platinum was required in a fuel cell, while now it only needs just 10 grams. “And this shouldn’t be a problem as there’s just as much in the catalytic converters for combustion engines,” he says. “You just have to reallocate the resource.”

He opens the heavy, metal door that leads into the laboratory. The two rooms are packed full of test stations. The gases needed for fuel cell research—which include oxygen, argon, hydrogen and high-purity hydrogen—are distributed through thin brass tubes running in parallel along the walls and ceilings. There’s a test in the fuel cell system laboratory scheduled for today. The four hundred cells have already been placed in a row, and their performance in the entire vehicle system is being closely scrutinized. “As soon as we supply the hydrogen, four hundred columns will rise up on the monitor—we call this the picket fence,” von Unwerth explains. “Each column represents the voltage in a cell.” The experiment is started and the cells are subjected to stress. “The moments when the load on the cells is increased and decreased are always the most exciting for me,” he says. “That’s when it becomes clear whether they are stable and respond evenly.” The testing measures few fluctuations today, pleasing von Unwerth.

He is certain that, very soon, fuel cell technology in electromobility will be making some major advances. “The first German carmakers have announced they’ll be mass-producing hydrogen-powered vehicles in appreciable quantities at the start of the next decade,” he says. “The topic even seems to have arrived at the political level. In the previous government coalition agreement, fuel cells weren’t mentioned at all. In the current one, they’re mentioned at least seven times,” he adds with a laugh.

Looking to the future, there’s no question for the fuel cell expert about which technology will be calling the shots in electromobility:


“Both,” the two of them agree. But their reasoning differs. “Batteries and fuel cells complement each other,” von Unwerth says. “Batteries provide power immediately, while fuel cells need a little longer when you step on the gas. So hydrogen-powered vehicles also need a battery in order to quickly reach peak power. Conversely, battery-driven vehicles can benefit from the range that fuel cells provide. I think fuel cells and batteries complement each other to form a fully-fledged propulsion system. We need highly efficient batteries that are smaller, more durable, more powerful and more environmentally friendly.” He also feels that batteries by themselves are not an option for the masses: “Right now there are than 1.3 billion vehicles worldwide, and the trend is rising. I think it is impossible to set up a charging station infrastructure for so many vehicles.” Wolter agrees: “Setting up a charging infrastructure of this size is certainly challenging. But I think it would therefore be better to focus on more efficient concepts for mobility, which could include car sharing and expanding public transport systems as examples.”

There’s also another reason Wolter doesn’t think that her work is competing with research into fuel cells: “There are scenarios in which battery-driven electric vehicles work well, in urban spaces for example, and others in which fuel cells are better, for heavy-cargo transport for instance.”

The scientists also agree that there must be more political pressure to get electric mobility moving in Germany. “Why should car manufacturers go out on a limb if they have cars with internal combustion engines that are still selling like hotcakes?” von Unwerth asks. “Many consumers simply don’t like the electric cars available at the moment, or they are too expensive for them. Legislators need to do something about it.” Wolter would like to see more government involvement in financing: “In China, where legislation requires it, German carmakers are already implementing major projects in the field of electromobility, but in Germany there is a great reluctance to make any financial commitments when research is still at an early phase.” So both researchers are hoping politicians will do something about it—and otherwise see themselves in peaceful coexistence: “Everything will find its place”, they say.