APELDOORN, NETHERLANDS — The quiet of the mild, grey June morning is broken only periodically by the chime and crackling of the intercom system as a pleasant monotone enumerates minor delays and other updates. A church bell tolls solemnly in the distance. And then it begins. At first, it’s just a scarcely perceptible rumbling underfoot, and then the breeze starts to pick up, violently scattering stray pieces of litter. The rumbling vibrations become thunder and then, 320 tons of bright blue and yellow steel come hurtling down the tracks at 140 km/hr.
For most people, gathered on the platform in business suits and light trench coats, the scene is mundane. It’s just a train, pulling into the Apeldoorn station to take them to work. But Arjan Heinen, an engineer and inventor, sees something more. As the train screeches to a halt, Heinen sees 60 kilowatt-hours of energy — enough to drive a Tesla 300 km — being wasted.
“It’s just right there before you,” he said. “And you have to get rid of it to stop the train.”
Every six minutes or so, another train will pull into this station, some weighing as much as 1,000 tons. Heinen estimates that every hour, at just this one train station in the Netherlands, half a megawatt-hour of energy is lost as waste heat, as straining brake pads bring speeding trains to a standstill in just 40 seconds.
All the passenger trains in the Netherlands are already equipped with the technology for regenerative braking which can capture the energy that is currently being lost as heat when the train slows. Similar technology is used by every Toyota Prius driver around the world. With this technology, when a train needs to slow, it can brake using its motor rather than friction on the wheels. The motor essentially acts as a generator, turning the kinetic energy of the train back into electrical energy.
Heinen wants to use that waste heat for something beneficial, but there’s a problem, because the railway system in the Netherlands receives subsidized electricity from the government, there is no incentive to do anything about the lost energy.
“If you own a Tesla, you pay 20 cents per kilowatt-hour,”explained Heinen. “But the price that train operators pay is just 1.5 cents per kilowatt-hour. That’s nothing, there’s no reason for them to care that they are just throwing that away.”
In the city center of Apeldoorn, however, there’s another problem that, from Heinen’s perspective, might actually be the missing puzzle piece to ending train energy waste.
It’s the city’s fleet of 30 diesel buses: for most people, just a convenient mode of transport to get from point A to point B. But when Heinen sees the buses, he sees 2,500 liters of diesel needlessly being burned every day in the heart of the city. It’s expensive, it’s bad for the environment, and it’s harmful to the health of everyone who lives and works there.
“Right now we are setting 37 liters of fuel on fire in exchange for every 100 kilometers by bus, and paying dearly for it.” said Heinen. “And right next door to the bus terminal, we have all of this perfectly good energy just heating up the tracks.”
Heinen’s plan, to be implemented first at the Apeldoorn train station, but eventually all around the Netherlands, is to connect these two inefficient systems together to make a more efficient whole. He has a plan to capture the energy from the trains and use it to power all of the city’s buses, simultaneously solving both the problem of the neglected wasted energy and the expensive, dirty emissions of the diesel buses. The two systems mesh together well because they are already designed to operate synchronously, so that commuters can move from one form of transport to the next.
That electrical energy can then be stored in a 3 megawatt lithium ion battery pack at the train station and be used to recharge the city’s buses in between routes. There wouldn’t even need to be a new fleet of buses, as the existing buses can easily be retrofitted to run on the rescued energy.
One of his partners on the project, Auke Huisman, has considerable experience in integrating different transportation systems. Huisman, who for years worked for Nederlandse Spoorwegen (NS) the principal passenger railway operator in the Netherlands, helped to create the O.V. chipcard. Similar to the Oyster card in London or the Octopus card in Hong Kong, the card can be used on virtually all forms of public transportation in the country, from trains and buses to taxis and ferries.
“For me, this is just the next step in making everything work better for everyone who uses public transport,” said Huisman, who likes to explain the project from what he jokingly calls his “office” a small shelter on a platform at Apeldoorn station.
In the U.S. a related system is already in place in Philadelphia. Since 2012, the South Eastern Pennsylvania Transportation Authority (SEPTA) has been capturing energy from braking trains along the Market-Frankford line. The saved electricity is stored in a 800-kilowatt lithium-ion battery at the Letterly Substation and is used to help nearby trains accelerate. More recently, SEPTA has partnered with the Philadelphia-based utility Viridity Energy and is selling a portion of the battery power back to the grid. SEPTA is earning $150,000–200,000 a year as a power provider and the substation has cut its energy use by nearly 20 percent.
Because Apeldoorn is a relatively small city with only one train stationed at a time, trains can’t trade energy the way they do in Philadelphia. The substantial subsidies given to train operators in the Netherlands also making selling energy back to the grid a dubious option. But the economics of Heinen’s plan are still promising.
Heinen and Huisman have calculated that over the next 12 years, the bus operators will spend €20 million on diesel fuel for just the small fleet of 30 buses that service Apeldoorn, a city of just 150,000.
That’s about €8 million more than it will cost to pay for the infrastructure to capture the energy being lost when trains brake and use it to power the buses on electricity. Heinen believes that the project can break even in 7 years.
“The money we would spend on the infrastructure to make this work is going to be spent anyway on fuel,” said Heinen. “It’s not a question of whether the money is there, it’s just a question of how we decide to spend it. Whether we want to continue throwing energy away and pouring diesel emissions into our city, or whether we want to use what we have to make a cleaner, cheaper and more efficient system.”