How Christian Appel is helping get a fuel-cell truck on the road
The Bosch engineer Christian Appel is working with the Nikola Motor Company startup to develop the world’s first 40-ton truck to feature a fuel-cell powertrain. It’s an electrifying opportunity — and it could well herald the start of a new era in freight haulage.
Truck tuning in Arizona
Shimmering heat waves ripple across the asphalt of the test and engineering center situated on the edge of the Phoenix Sonoran Preserve in Arizona. Christian Appel briefly removes his baseball cap to wipe the sweat from his brow. He fixes his gaze on the horizon, where the outline of a snow-white truck is just about visible. The team around him is busy adjusting settings, calibrating equipment, and calling out the latest status updates. “OK, let’s get the truck back on the track,” Appel says into his radio. This is the fifth time they have carried out the procedure today. It’s all about fine-tuning. Soon everything will be exactly right: the control system, fuel cell, and steering. Soon it will be showtime.
“We’re redefining truck driving from scratch. We’re helping a startup turn its vision into reality.”
Christian Appel, customer chief engineer, Bosch Engineering
Time to get trucking
The 32-year-old German has been living and working in Phoenix in the U.S. for close to a year. Together with various other Bosch associates, Appel has been assigned to work with Nikola Motor Company to help get the emerging technology of fuel cells up to speed for commercial truck production. “A fuel-cell powertrain is lighter and takes up less space than its battery-driven equivalent,” the engineer says.
Nikola Motor Company has come up with a smart business model that involves leasing its semi-trucks on a mileage basis including fuel. The startup is also building filling stations that process hydrogen using renewable forms of energy and store it until it’s needed. The electricity required is purchased when it’s cheap — a sustainable model that makes the use of fuel-cell trucks economically viable.
The mission: to achieve a world first
As customer chief engineer, Appel is responsible for the technical coordination of the Bosch components in the truck known as Nikola Two. There are plenty of those components: electric motors for the e-axle, the vehicle control unit, and key components of the hydrogen fuel cell. What’s more, the new Bosch mirror camera system has replaced the truck’s side-view mirrors, and the Bosch Perfectly Keyless system means truck drivers no longer have to search for their keys.
Appel’s biggest challenge is the sheer volume of different challenges thrown up by the project. “We’re not just improving a vehicle that has already been launched, but rather working with the customer to essentially redefine truck driving from scratch. We’re helping a startup turn its vision into reality,” Appel says. And Bosch also benefits, he explains: “Our in-depth knowledge of a powertrain technology that could revolutionize freight haulage is giving us a competitive edge.”
“Christian may not be the father of the Nikola Two, but he is definitely our godfather! Without him and Bosch, we would never have achieved all this. Bosch is our most important supplier.”
Mark Russell, president of Nikola Motor Company
How the Nikola Two fuel-cell powertrain works
How it works
Since trucks like the Nikola Two model weigh around 40 metric tons, running them solely on battery power would not be efficient. There would not be enough energy at reasonable weight and volume, and range would be too low. This prompted Bosch and Nikola Motor Company to develop a fuel-cell powertrain for trucks. In a fuel cell, hydrogen and oxygen are brought together. The resulting chemical reaction converts the hydrogen into electricity. This energy flows into the truck’s high-voltage electrical system, which is connected with the electric motors and the battery. In this way, the fuel cell delivers power directly to the powertrain, while recharging the battery at the same time. Instead of carbon dioxide and soot, the only waste product emitted by the fuel-cell truck’s tailpipe is water.
The truck’s energy store comprises nine high-pressure hydrogen tanks, each with a capacity of nine kilograms. To meter and govern the pressure of the gas flow, Bosch has developed a hydrogen gas injector for the Nikola Two truck. This compact injector unit works at inlet pressures of up to 16 bar, and is designed for proportional-mode operation. In other words, the amount of gas injected can be infinitely varied. This differs from valves with pulsed-mode operation. These can only be open or closed, and can only ever meter the same amount of gas. The injector’s integrated shut-off function saves costs and complexity in the overall system.
The stack is the central component of the fuel-cell system. It is here that the reaction between hydrogen and oxygen takes place. Temperatures in the stack, which comprises 419 individual cells, reach around 80 degrees Celsius. As a result of a chemical reaction, the potential energy in the fuel is converted into electrical energy, which flows to the power electronics.
Anode recirculation blower
When the oxygen and hydrogen react, not all the hydrogen fed into the cell is used up at once. For the Nikola Two truck, Bosch developed the anode recirculation blower, which prevents the surplus hydrogen from being emitted from the system unused. Many systems work solely with a jet pump. The Bosch pump, however, is active and electrically driven, and supplements the passive jet pump. This means that gas flows back into the cell faster. In addition, it offers more flexibility in shut-down procedures, and thus greater efficiency and safety.
Electric air compressor
The supply of oxygen is governed by the electric air compressor, also developed by Bosch. It compresses the air at speeds of up to 120,000 rpm. This is necessary to ensure a sufficient supply of oxygen to the fuel cell.
Fuel-cell control unit
The fuel-cell control unit manages and controls the fuel-cell system. This includes functions such as the hydrogen and air supply, and the cooling and operating strategy for the fuel-cell stack.
A team for any task
But Appel’s work as an engineer involves more than just developing truck components: “Networking is really the key to what I do. I talk to customers and pass on their requirements to the relevant Bosch colleagues,” he says. He utilizes a worldwide network. Over 200 associates from six divisions worked on the development of the truck. “Whether automated, connected, or electrified — we have the right experts who can provide support. There aren’t many companies that can offer that,” Appel says. What he prizes above all is the sense of team spirit: “The teamwork on the project is fantastic. Everyone is doing the best they can to help get a truly unique truck on the road. That’s a great feeling!”
Five facts about work on the Nikola Two project
Time to recharge
Ten days later, they've achieved their goal. Nikola Two is unveiled to huge crowds at a public demo day in Scottsdale, drawing an enthusiastic response from the trade press. The next job for the truck godfather is to help get Nikola Two into production. The goal is to make 35,000 trucks a year, with production kicking off in 2022. But first it’s time for a well-earned break.
“There’s a great hiking trail through the desert that starts just behind our house. Walking that trail with my son is exactly the kind of break I need,” Appel says. The sun slowly sets behind Arizona’s desert mountains as both Christian Appel and the Nikola Two recharge their batteries, ready for their next mission.
customer chief engineer, Bosch Engineering
After studying mathematics, Appel joined Bosch seven years ago. He is currently working in Phoenix, Arizona, living an authentic startup experience with Nikola Motor Company — and relishing every moment. Once this project is over, he will be transferring what he has learned back into the Bosch world, and there will be plenty of memories of his time in the U.S. that he will never forget: “We went night diving with manta rays in Hawaii. It was a truly unforgettable experience — and it even inspired me to get a tattoo!”