So, this is different. A team of researchers has calculated that the equivalent of 4% of global energy consumption could be generated by low-impact hydropower systems that consisted of driving electric trucks down mountains. That’s right, driving trucks down mountains.
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Electric Trucks For Low Impact Hydropower
The idea of deploying a fleet of electric trucks for hydropower might sound a bit like pie in the sky, but it does share similarities with other gravity-based systems and it was meticulously researched by a team at the International Institute for Applied Systems Analysis.
The team was intrigued by the potential for transforming electric trucks into mobile hydropower systems. The idea would be to leverage existing roads as a new hydropower resource, instead of building new dams and destroying entire ecosystems.
Think of the pumped storage hydropower area and you’re on the right track. Pumped storage hydropower is a large-scale energy storage technology that involves pumping water into an upper reservoir, then letting it flow downhill to a generating station when needed.
After passing through the turbines, the water can be pumped back uphill. This recycling system had limited use in the era of fossil energy. Under a renewable energy scenario, though, pumped storage provides the means to store wind and solar energy in bulk.
Regenerative Braking Gets Its Hydropower Moment
So, how do electric trucks come into the picture? That’s a good question! The IIASA proposal is intended as a way to tap into the untapped energy potential of small streams in mountainous regions, where technology barriers to new hydropower dams are considerable.
No upper reservoir is needed. If electric trucks do all the heavy lifting, they can collect water from multiple streams on the same mountain before ferrying it downhill. The research team explains:
“Electric Truck Hydropower would use the existing road infrastructure to transport water down the mountain in containers, applying the regenerative brakes of the electric truck to turn the potential energy of the water into electricity and charge the truck’s battery. The generated energy could then be sold to the grid or used by the truck itself to transport other goods.”
For those of you new to the topic, regenerative braking recaptures energy that would otherwise go to waste. Regenerative braking is used to recharge the small battery in conventional vehicles, but it really shines when used in tandem with hybrid or all-electric vehicle battery packs.
The Seeds Of An Idea For Electric Trucks
If you’re wondering how the research team came up with this idea, that’s another good question. You can get all the details from the journal Energyunder the title, “Electric Truck Hydropower, a flexible solution to hydropower in mountainous regions,” in which they note that comparable systems are already in use.
“A similar case to ETH happens in the mining industry in Poland, where the extracted minerals are transported down a mountain with electric trucks, and each truck can generate up to 200 kWh per day,” they explain.
The hydropower version of that operation would involve electric trucks with swappable batteries.
“The electric truck enters the discharge site with a container full of water, leaves it to be emptied, collects an empty container, and drives up the mountain. The charged battery is replaced by a discharged battery,” the team explains, cautioning that the replacement battery needs to have enough charge to get the truck back up the mountain.
The team also notes that in the hydropower version, disruption to aquatic systems can — and should — be minimized by regulating the extraction of water from steams and the discharge of water from the containers.
Electric Trucks: Who’s Gonna Pay For All This?
As for the expense of buying a new fleet of electric trucks, the researchers calculate that their Electric Truck Hydropower system is far less expensive than conventional hydropower, at a levelized cost of only $30–100 per megawatt hour compared to the $50–200 range typical of conventional hydropower.
They also point out that the electric truck fleet could be put to use on other duties when needed.
As large mobile energy storage devices, the fully charged electric trucks could also deploy their bi-directional charging capability to serve as emergency generators at various locations.
Hmmm…What About Retrofit Kits For Electric Trucks?
The idea of electric trucks subbing in for hydropower dams also begins to appear more do-able when you consider that EV battery technology is constantly improving and costs are coming down.
Another angle to consider is the potential for retrofitting an existing fleet of diesel trucks with electric drive. Activity in the retrofit area has been kicking up a storm in recent years, and costs have been coming down in that area as well.
One development to watch on that score is the California firm Romeo Power. The company has been suffering through a rough patch since going public on a SPAC in December of 2020, but last week it announced a mashup with the electric powertrain firm Wrightspeed, founded by Tesla co-founder Ian Wright, which makes it of interest to Tesla fans.
The two companies are eyeballing a market of a million or so trucks and buses that are candidates for retrofits. The idea is to hook Romeo Power’s battery packs with Wrightspeed’s “Powertrain in a Crate” kits.
As applied to the IIASA electric truck hydropower plan, a retrofit would need to maximize regenerative braking and accommodate battery-swapping, which could limit the playing field. However, the battery swapping field has also been heating up.
Critics have argued that battery swapping is out of date now that fast-charging and long range batteries are commonplace, but the electric truck hydropower plan suggests that niche markets for swapping can be created.
Meanwhile, when talk of pumped hydropower storage comes up, the topic naturally turns to long-term energy storage in general, meaning systems that can provide electricity for multiple days and not just a few hours.
In common with the electric truck proposal, some of the new systems under development in the bulk energy storage field leverage renewable energy and gravity to replace the massive infrastructure required of pumped storage hydropower systems, so stay tuned for more on that.
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Image credit: Electric trucks for low impact hydropower by IIASA via the journal Energy under Creative Commons license.
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