I can’t get this paper, , out of my head and it’s not just the catchy title. The idea behind it is incredibly ingenious: a system that uses electric trucks to generate power in mountainous regions using gravity and regenerative braking.

Researchers from Brazil to the UK . It basically works like this: Empty electric trucks would travel up a steepish mountainside. At a refilling station up top, an empty water tank would be removed and a full one would be placed on the truck. By going downhill with the extra load, the potential energy of the water is converted into electricity by the trucks brakes and is stored in the truck’s battery. Once at the bottom of the mountain, the truck would either unload both the water and excess energy at a collection point before starting back up the mountain, or it would go on to make deliveries.

Right now, where we can utilize hydroelectric power is limited. A very specific set up is needed involving two set water levels connected via canals, tunnels, a system of vast reservoirs which often drastically change the surrounding habitat, and a turbine generation system converts the potential energy of the water into electricity — pretty tough to build in a mountainous region. What a steep mountainous region is good for, however, is sending things downhill fast. Researchers propose that electric trucks be used to capture some of the water’s potential energy at the top of the mountain (it was going down the mountain anyway after all) and, through regenerative braking, generate more energy than the truck needs to make the return journey up the hill using already existing roads.

The truck system is simple, using easily attainable technology and, with the advent of autonomous trucks, perhaps someday completely automatic. From the paper:

We propose a more flexible alternative for hydropower that features electric trucks. The proposed system consists of using existing road infrastructure that crosses mountain ranges to transport water down the mountain in electricity truck containers, transform the potential energy of the water into electricity with the of the truck and use this electricity to charge the battery of the truck. The ideal configuration of the ETH system is in with steep roads, where the same electrical trucks can be used to generate hydropower from different sites. This increases the chances that there will be water available to generate hydropower and thus increases the capacity factor of the system. 

They note that similar systems are in use at mining operations, where electric trucks carrying heavy loads can create an excess of electricity via braking on a downhill descent. Some electric trains also create more energy than they need to get back. The largest EV truck in the world, a dump truck working in a lime mine on the side of a mountain in Switzerland, almost never needs to be recharged. The authors note that such a system would be most beneficial in South America and Asia.

I just think it’s an incredibly neat solution to a difficult problem and one of the green energy ideas I’ve seen where vehicles are used in a clever way to make the world a little cleaner.