The ups and downs of regenerative damping

UK newspaper The Guardian recently ran a fascinating story about cunning plans to capture wasted energy, for example the impact energy of commuters walking across a railway station concourse is estimated to peak in the kilowatts. Not much to do with cars, obviously, but the article goes on to note that dampers used to halt the swaying of bridges could capture the energy they absorb, rather than simply allowing it to warm up the dampers.

This set Auto-IT thinking. Hybrids like Toyota's Prius and electric noddy cars like the G-Wiz make a point of using regenerative braking - essentially using the resistance of a dynamo to slow the car, turning the unwanted kinetic energy into electricity rather than allowing a simple disc or drum brake to translate momentum into waste heat.

These eco-friendly, efficiency-obsessed cars are clearly missing a trick. The reciprocating motion of wheels bouncing up and down over the potholes that pockmark the average patch of UK asphalt is clearly an untapped mine of energy. Wheels do tend to travel up and down, and energy has be removed from the system to prevent nauseating bounciness – not to mention the loss of control that results when a wheel bounces right off the road. Dampers do that job, typically by forcing a viscous oil to pass through a constriction inside the damper tube. Viscosity is the fluid equivalent of friction, so the dampers effectively turn motion into waste heat, just as brakes do.

Clearly the amount of energy involved is very different – as witness the fact that dampers are seldom fitted with fins to aid their cooling, whereas discs are often cross-drilled, slotted or vented. However, the energy involved cannot be negligible.

Current state-of-the-art active dampers employ a fluid suffused with magnetic particles to allow the viscosity to be computer controlled, so they are already wired up to the vehicle. One wonders if the movement of the same magnetic fluid might conceivably be inverted to generate a little extra juice.

Sun-in-the-hair motoring

Auto-IT likes Lotuses (Loti?) and especially likes reskinned Lotuses powered entirely by batteries. Fortunately Tesla Motors has done the hard work of building such a thing, although it’s not imminently about to be sold in the UK, sadly. The startup is bankrolled by Elon Musk, internet entrepreneur and car nut.

One of the nice things about Tesla is that it has a blog, offering an insight to where the firm might be headed.

One of the various pies containing a Musk finger is SolarCity, which specialises in installing solar power systems. So it’s natural for the Tesla blog to address the question of solar-powered cars.

You may have heard that solar panels use a lot of energy to make, and never recoup that energy debt before they fall to bits and have to be replaced. According to Musk, at least, this is fortunately not the case, and that covering your garage roof with solar panels could be enough to power your Tesla roadster.

Well, it might in the sunnier US states. In Britain it might work in July...