That hourglass-shaped device is the PowerPac, an energy storage device meant to be powered by a human on a stationary bicycle. Conceived of by South African design firm Ideso, the PowerPac won a Red Dot Design Award in the "Best of the Best" category.
"Our aim was to create an aesthetically pleasing, user-friendly and functional design that marries the fluidity of cycling with dynamic power generation," says Ideso MD, Marc Ruwiel. "It can be used by avid cyclists who can reduce CO2 emissions and generate their own electrical power, while enjoying a good workout at home."
I'm all for people-powered electricity generators, and I would've loved to have one of these during the recent blackout, but something struck me in the copy: "...An average cyclist could fully charge the battery from empty with 80 minutes of cycling and 132Wh of charge/potential energy can be stored in the battery." The "Wh" designation stands for watt-hour, and "132Wh" means you could power a 132-watt device for 1 hour. For 80 minutes of cycling to yield, say, just over two hours of light from a 60-watt bulb sounds like a low yield, doesn't it? My first thought was, can that be right?
I did a little digging, and here's what I found. It turns out hooking a bicycle up to something that directly powers a mechanical device is a fairly efficient way to generate energy. Rig a bicycle up to drive a sewing machine or a hand mixer and you get decent bang for your buck. But the second you get batteries and electricity involved, the efficiency drops way, way off. An article in Low-tech Magazine called "Bike powered electricity generators are not sustainable" explains why:
...Generating electricity is far from the most efficient way to apply pedal power, due to the internal energy losses in the battery, the battery management system, other electronic parts, and the motor/generator. These energy losses add up quickly: 10 to 35 percent in the battery, 10 to 20 percent in the motor/generator and 5 to 15 percent in the converter (which converts direct current to alternate current). The energy loss in the voltage regulator (or DC to DC converter, which prevents you from blowing up the battery) is about 25 percent. This means that the total energy loss in a pedal powered generator will be 42 to 67.5 percent....
And it even turns out that the bicycle itself has mechanical inefficiencies that suck up more energy:
The second problem with the present approach to pedal power is that it uses a traditional bicycle on a training stand instead of a pedal powered machine built from scratch —as was the case at the end of the 19th century....
...This approach is considerably less efficient. One reason is the use of a so-called friction drive—the rear bicycle wheel acts upon the small roller of the motor/generator. While chain and belt drives (used in late 19th century pedal powered machines) have an efficiency of up to 98 percent, a friction drive is only 80 to 90 percent efficient (and wears much faster). This energy loss should be added to the 42 to 67.5 percent efficiency loss calculated above, which rises to 48 to 73.5 percent. Low tyre pressure will further decrease efficiency.
...There is also energy loss in the bicycle itself: your pedals are not attached to the rear wheel itself. You turn a sprocket, which turns a chain, which turns a sprocket, which turns the rear wheel. So, on top of the efficiency loss of the friction drive should be added the efficiency loss of a chain drive (plus the energy loss in the derailleur, if your bike has one).
To be clear, I'm not listing these facts to pooh-pooh Ideso's design. They're trying to get the PowerPac into production, and for those off-the grid, inefficient juice is better than no juice at all. But I was surprised to learn of the inefficiencies of pedal power, and I'm hoping that once interested designers become aware of the problems, they'll then figure out ways to solve them.