Supermarket generates piezoelectric power in parking lot
By Joseph L. Flatley 
posted June 15th 2009 10:46AM
posted June 15th 2009 10:46AM
Remember that piezoelectric road prototype we saw late last year? Looks like someone (besides us) thought it was a good idea. According to The Daily Mail, a Sainsbury's supermarket in Gloucester, UK (you've never been there), has installed kinetic plates in the parking lot that use the weight of shopper's cars to pump a series of hydraulic pipes, which in turn drive a generator. The system is said to generate up to 30kw of energy an hour -- or enough to power the store's checkouts. And if that weren't enough, the store is also harvesting rainwater and heating it (during the summer, at least) with solar panels. The next in this store's "eco-friendly evolution?" Might we suggest Soylent in the deli? We hear the "green" stuff is particularly good.
[Via Green Launches, Thanks Deepa]
[Via Green Launches, Thanks Deepa]
It looks to me like the plates are not speed bumps, they simply move downward as the car travels over them. A parking lot seems like the perfect place to do that. Sure, it may slow the car down a tiny bit, but the energy you're transferring is probably just going to be lost to brake heat and road friction anyway. I would imagine that a study would find that the overall average MPG of all the cars traveling over these bumps is reduced by so small an amount that can't even be measured.
Sure, there's no such thing as free energy, but cars waste so much of it anyway that being able to recapture some of it is as good as pulling it out of thin air.
I deem this a great idea!!
I heard they are installing a similar thing inside of Lane Bryant stores to power their vending machines.
What if people had to walk a mile uphill to get a candy bar, or whatever distance would be break-even on the stored energy. That'd cure America's obesity problem!
@ everyone whining about the lowered gas miliage
Someone calculate the decrease in milage from driving a car up an incline of a couple of inches once a week. When that's done, go ahead and put your arguements into perspective.
1kWh = 3.6MJ
1L Gas = 32.0MJ (raw energy) [wikipedia]
1kWh = 0.1125L (burned with no loss)
Assume 20% efficiency of internal combustion engine, 80% drivetrain efficiency [wikipedia]
1kWh = 0.703125L
30kWh = 21.09375L
Of course, this assumes that the energy recovery is 100% efficient (which is highly unlikely) the figures in the article are correct (which is even less likely)
It doesn't matter that the cost to each driver is very small. The bottom line is that this scheme of having cars actuate hydraulic gnerators is necessarily more expensive and less efficient (and hence less "green") than, say, using an engine to turn a generator directly.
It's a retail store, they have no expertise in running generators whatsoever. The first time this thing breaks, and everything mechanical breaks eventually, it'll stay broken for years. Maybe until they pave over it and forget it was ever there.
the watt (as in kw) is a unit of power not energy...it doesn't make sense to say that something produces so many watts per hour. The "per time" part is built in to the watt unit. The joule is the mks unit for energy (m^2*kg/s^2), and a watt is defined as one joule per second. Power companies measure energy consumption most commonly in kwh (kilowatt hours), which IS an energy unit (1 kwh = 3600 joules = 3.6 kJ).
My guess is that the ENERGY output is in fact 30kwh (
no cars, no electricity, no sale
This is a great idea. I wonder how long it takes to pay for itself.
The reason this is being done is to make Sainsbury's _LOOK_ green, when in reality it is about getting someone else to pay for their electricity bill.
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