Energy from passing cars

The push to create and implement greener energy sources has mostly centered on thermal, hydroelectric, solar and wind power. But innovators are always thinking of ways to produce and/or harness power to fuel our world. UK grocery chain Sainsbury's has begun using kinetic power from their parking lots to fuel checkout stands in one of their new locations.

The Sainsbury's in Gloucester, UK, which opened in June 2009, has several kinetic energy plates installed in their parking lot. Each time a car drives over the plates, the motion of the plate creates energy. The energy is then stored and sent to the store to provide power to the checkout stations. Sainsburys says that the plates can supply 30 kWh of energy per hour. This type of kinetic energy-gathering isn't entirely free: it does bump up the fuel consumption of each car a very small amount when driving over the plates. And, of course, since most cars are still fueled with eco-unfriendly fossil fuels, the weekly shopping trip is still hard on the environment if you're driving there. But if we assume that the kinetic energy plates are being used in place of speed bumps that are frequently found in supermarket parking lots, the energy expended by each car will be the same as it was before.

Highway Energy Systems, the company that designed the kinetic plates for Sainsbury's, also designed an electro-kinetic road ramp for widespread usage on public streets. They address the question of whether this type of energy costs users money in this way: "The ramp is designed to be situated in parts of the roadway where vehicles are having to slow down, for example on downhill gradients, when approaching traffic lights or roundabouts as well as replacing sleeping policemen and traditional traffic calming measures. In the these situations, the kinetic energy of the car is being dissipated into heat (i.e. through the braking system) anyway; the ramp at this point scavenges a degree of kinetic energy as the car passes over it, but this is far less than is lost through other mechanisms."

Sainsbury's expects that the kinetic energy plates will have paid for themselves within two years of their inception. The supermarket giant is doing more than just harnessing the energy of passing motorists, however. The Gloucester Quays store also boasts a rainwater collection system that will use rainwater to flush its toilets. The store is equipped with large windows for letting in natural light and decreasing the dependence on artificial lighting, and solar thermal panels will heat the store's water in the summer.