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Think outside the battery: Weird, clever, crazy tech driving green cars further

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The multi-voltaic paint slathered over Mercedes’ G-Code concept doesn’t just convert sunlight to electricity, it harnesses electrostatic potential in the wind. Image used with permission by copyright holder
Efficiency isn’t sexy, and the sorts of technologies that improve it don’t help matters much either. Small engines, lightweight, aerodynamic designs, and slow speed just doesn’t do much to get the heart racing.

Despite that, automakers aren’t content to leave it at that. In the last year, automakers from Mercedes to Peugeot to Volvo have announced paint that collects power from the sun, batteries built into body panels, and hybrids that run on compressed air.

These oddball technologies not only show that green can be sexy, albeit sexy with nerd glasses, but may also revolutionize the cars we drive.

Power from the air and sky

No doubt the biggest green news of the week came from the Mercedes with the debut of the insane G-Code concept crossover. Though the Mercedes concept is host to a laundry list of innovations, the most compelling is its ‘multi-voltaic’ paint. This paint, in essence, turns the car into one giant solar cell.

This paint, in essence, turns the car into one giant solar cell.

The details of just how this works weren’t forthcoming, but the claims didn’t stop there. Mercedes also says that the paint is capable of generating electricity from the electrostatic potential of either the relative wind from the car’s movement, or from natural wind when the car is standing still. Again, Mercedes wasn’t parting with details, but the obvious inference is that the paint is capable of generating and then harvesting the static electricity built up by air molecules passing over the car.

Just how much electricity these systems can gather isn’t specified, but judging from the fact that Mercedes has included a speculative hydrogen fuel cell in the design, it sounds as if it won’t be nearly enough to power the entire vehicle. Still, when combined with other new technologies, the system could help make the most of range and efficiency.

Mercedes, for example, has announced that the G-Code will feature a suspension that recovers energy from the travel of the wheels. Again, the recovery may not be large but every little bit helps. Once captured, however, where does one store that energy?

An electric body

Traditional batteries come with a host of problems: expense, bulk, weight and – most of all – a low energy density. For the Tesla Model S to achieve its 265-mile range, it has to have 1,300 pounds of batteries. A 30-mpg internal combustion-powered car can make the same journey on just 75 pounds of polar-bear-melting fossil fuels. This makes batteries an inherently difficult technology to work with in a competitive market. However, there are alternatives.

Volvo has been experimenting with turning entire cars into batteries.

Volvo has been experimenting with turning entire cars into batteries. Well, to be technically accurate, super capacitors. The technology involves sandwiching a polymer resin between layers of carbon fiber to create a super capacitor thinner than a dime, proving that everything is better with carbon fiber.

When the hood, roof, and trunk of an electric Volvo S80 are replaced with these carbon capacitors vehicle weight drops 15 percent and range is extended 80 miles.

There are already examples of what super capacitors can do in the real world. Mazda’s i-Eloop system uses a capacitor and regenerative braking to run its cars’ accessories. Under ideal conditions, this system can save close to 10 percent on fuel usage.

Volvo S80 electric Nano battery project
A composite blend of carbon fibres and polymer can store and charge more energy faster than conventional batteries can. Image used with permission by copyright holder

Capacitors, like the ones being proposed by Volvo have the additional benefit of not containing rare-earth metals like lithium. These are difficult and environmentally costly to mine and refine, and making batteries with them is so energy intensive that it can completely cancel out the environmental benefit of driving an EV.

Just imagine pairing this with some of Mercedes innovations; the result would be a car that took full advantage of the environment and didn’t waste precious space and weight on big batteries. A car like that might shatter what our expectations of efficiency and environmental protection.

Cars that run on air

If all this talk of capacitors and solar cell paint sounds a little complicated, don’t worry. The French have a much simpler idea: using compressed air.

Small engines, lightweight, aerodynamic designs, and slow speed just doesn’t do much to get the heart racing.

Peugeot Citroën PSA  has been quietly working on a technology that replaces the batteries in hybrids with simple air. The system works like this: as in a normal hybrid, most of the power comes from a gas engine. In the air hybrid, however, this is supplemented with a holding tank, a hydraulic compressor, and hydraulic motor.

When the driver applies the brakes, he or she activates the compressor, which charges the holding tank with air. This compressed air can then be used to run the hydraulic motor to supplement the gas engine, just as the electric motors do in a traditional hybrid.

The advantages of this system are that the technology is brutally simple, and – compared to big batteries – light. Conceivably, this sort of system could be included in a broad array of vehicles with considerably fewer modifications than are typically required to build a true hybrid.

Mazda i-Eloop system
Mazda i-Eloop system Image used with permission by copyright holder

The downside is that compressed air isn’t a great storage medium. Unless automakers are willing to invest in insanely strong containers, it is difficult to store sufficient energy to make a dramatic difference in fuel economy. Then there is the small fact that a compressed air cylinder is essentially a bomb. But still, of all the technologies we have covered this is by far the closest to fruition. In fact, if Peugeot remains committed to the technology, it could be in cars in a matter of years.


Amazingly, some or all of these technologies could actually appear in show rooms. Even if they don’t, though, they show that thinking sideways has its advantages. By avoiding battering their heads into the wall in a futile attempt to improving batteries, companies like Volvo and Mercedes are placing themselves at the forefront of innovation.

Like the creation of hybrid drivetrains in the first place, these ideas have the prospect of dramatically changing the way the average driver thinks about cars and efficiency. I for one am excited to see what happens next.

Peter Braun
Former Digital Trends Contributor
Peter is a freelance contributor to Digital Trends and almost a lawyer. He has loved thinking, writing and talking about cars…
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