Pedal Smoothie
Butcher, 55, has clocked his peak output at 265
watts (1/3 horsepower), but reckons a younger rider
could double that. At his home in San Jose, Calif., he
uses the PPPM to power laptops, TVs, a Roomba,
even a front-loading washer (with the help of a battery boost to surmount the spin cycles).
In his video on Make: television, he cranks up
enough juice to run a 500-watt blender and puree a
liter of smoothie in under 60 seconds. He’s cut his
energy bills, dropped 40 pounds, and gotten super fit.
“The longest I ever rode was at Maker Faire 2007,
from 9 to 6,” Butcher recalls excitedly. “I also watched
the entire Battlestar Galactica finale, powering it
myself. That was a big one for me!”
As a former competitive swimmer who could do
11 pool miles a day, David Butcher knew the human
body could crank out a couple hundred watts of work
for sustained periods. What if he could turn muscle
power into electricity?
Having witnessed the 1969 Santa Barbara oil spill,
Butcher is a dedicated environmentalist. He wanted
to get off the grid, but he found solar and wind projects unfeasible. “That left me,” he says.
So he built the Pedal Powered Prime Mover
(PPPM): a souped-up stationary bike generator that
boosts efficiency with a large particleboard flywheel
that smooths out the torque peaks of pedaling.
Its generator is a sealed ball-bearing motor from a
Photograph by Ed Troxell
Razor scooter, driven by a BMX crankset. Completing
the setup are a 1,000-watt inverter, Watts Up power
meter, and Maxwell Technologies 15-volt, 58-farad
ultracapacitor module to store power quickly and
dump it on demand.
Butcher sells detailed DIY plans for the PPPM
and promotes it for everyday and emergency power,
and for use in remote villages. But he says the most
efficient use of pedal power isn’t electricity — it’s
direct mechanical connection to turn a pump, fan, or
the like. As evidence, he’s also built a pedal-powered
pickup truck and a pedal-powered canoe.
—Keith Hammond
>> Pedal Powered Generator: makezine.com/go/pedgen
Make: television Episode 110: makezine.tv/episodes
25 Make:
