Several new projects that aim to exploit the Earth’s gravity for power hint at how electric vehicles could unlock otherwise impossible ways of generating energy.
They include trains across the Australian Outback and dump trucks that need no gas. There’s even a proposal to haul water down a mountain to power the trip back up.
All three projects rely on a peculiarity of electric motors: they can generate electricity as well as use it. That means using the motor to slow an electric vehicle can recharge its batteries — a feature called “regenerative braking” in electric cars.
It turns out that under the right conditions — going far enough downhill at enough of an angle with a heavy load — electric vehicles can generate a useful amount of energy. They can make enough, in fact, to power their trip back up, and they often make electricity to spare — once they’ve dropped off their cargo.
“When you have a descent of 10 percent, from top to bottom, you never need to recharge,” said Roger Miauton, the chief executive of the Swiss electric vehicle firm eMining AG. “You generate enough energy going downhill as you need to get back up again.”
Miauton’s company manufactures the eDumper, a 65-ton dump truck that’s said to be the world’s largest electric vehicle. Its diesel engine and fuel tank have been replaced with electric motors, batteries and cooling machinery, and it’s now working at a quarry near Biel in Switzerland, hauling 70-ton loads of lime and rocks down a mountainside.
Thanks to the expense of the high-tech systems, an eDumper costs about twice as much as a diesel-powered truck. But it never needs any fuel — a savings of between 11,000 and 22,000 gallons of diesel a year, along with its carbon emissions — and it almost never needs recharging. Test drives show it generates about as much electricity going down as it uses going up. Miauton said the company is now making three more eDumpers for mines in Germany, and it has plans for even larger electric dump trucks.
The concept of making electricity on a downhill run will soon get an even bigger boost. The Australian mining company Fortescue, a major producer of iron ore, announced in March that it will build “Infinity Trains” to generate electricity while carrying loads of ore from mines in the Outback.
The company currently runs 16 trains in Western Australia driven by 54 locomotives that use a total of around 20 million gallons of diesel fuel every year. Each train has up to 244 cars. They can be almost two miles long and carry more than 37,000 tons of ore.
Fortescue chief executive Elizabeth Gaines said four routes from mines in the inland Pilbara region are sufficiently uphill of their final destination — Port Hedland on the northern coast — that they’re suitable for Infinity Trains. The company plans to have them working on all four routes before 2030 by developing the dynamic braking feature many locomotives already have to convert gravity into electricity, she said in an email. Some routes will generate even more energy than they need for the return trip, and the company will use the extra electricity elsewhere in its operations.
This article first appeared on NBC