Two of the biggest sectors in the decarbonization game are teaming up to revolutionize clean energy. Electric cars have the ability to kill two climate action birds with one stone by combining clean energy production with energy storage. The key to this marriage is not a cutting-edge innovation, but one of the oldest tricks in the book: gravity storage. The technology has already produced trains and trucks capable of traveling huge distances and carrying heavy loads without needing any energy inputs at all. The sector is small and expensive at present, but it is poised to explode as the technology becomes cheaper and more efficient.

One of the most intriguing and promising aspects of electric vehicles is that they don’t just use clean energy, they can also create it through the use of a process known as “regenerative braking”. Here’s how it works. A vehicle in motion has kinetic energy. When the vehicle is slowed by something (in this case, a brake pad), all that energy is generally lost in the form of heat. Electric vehicles, however, are typically designed in such a way that all of that energy is captured and returned to the vehicle’s battery, thereby recharging your car every time you hit the brakes. Of course, some energy will inevitably be lost in the capture stage, and another 10-20% is lost when converted back into acceleration, with the overall efficiency of regenerative braking usually in the range of 70%.

Where this gets really exciting is when the technology behind regenerative braking is combined with gravity-powered energy storage. When going downhill, a vehicle will be doing more braking and therefore generating more energy. By optimizing these processes, a vehicle can use gravity to generate and store enough energy going downhill to power its trip back up the hill, making infinite energy feedback loops. In fact, if the vehicle goes downhill for an optimal distance at a steep grade carrying a significant load before dropping off its cargo, it could even generate more energy than is needed to make the trip back uphill.

This will have massive implications for heavy industry, transportation, and other sectors currently reliant on diesel-fuelled transport. It’s already proven to be particularly effective and relevant in the mining industry, where the vehicles often need to carry extremely heavy loads on steep grades. If gravity-powered vehicles could replace even a fraction of that fleet, it would be a huge win for decarbonization. Already, electric dump trucks are hauling 70-ton mining loads in Switzerland and electric trains carrying iron ore are getting ready to criss-cross the Australian outback without ever needing a drop of gasoline, and rarely needing an additional recharge.

The power and potential of gravity-powered electric vehicles are currently on display outside of a quarry in Switzerland, where a 65-ton electric dump truck called the eDumper – supposedly the largest electric vehicle on the planet – can be seen hauling 70-ton loads. “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 told NBC. “You generate enough energy going downhill as you need to get back up again.” So why hasn’t the eDumper taken over the mining industry? It costs about double what a conventional diesel truck does. But it saves from 11,000 to 22,000 gallons of diesel a year. And when environmental externalities are factored in, it’s a no-brainer. In fact, German mines have already purchased three more eDumpers and the company is currently designing even larger electric dump trucks.

In Australia, an “Infinity Train” is currently in the works, which would allow heavy iron ore to be transported across the Outback without needing any fuel or extra charge to power its return trip. Australian mining company Fortescue is leading the charge, and could potentially replace its current annual consumption of 20 million gallons of diesel fuel with completely clean, gravity-powered energy.

As these technologies evolve, expand, and become more efficient, gravity-powered vehicles are certain to pop up in more industries in more places, and could even begin to supply energy to local grids rather than keeping it in a closed loop. The field of research is still new, and full of creative pursuits that are ready to explode, with the potential to seriously disrupt the way we think of energy and transportation.