Power
by the People: Generating Electricity From Human Activity
“Small Is Beautiful,” proclaimed economist E. F.
Schumacher in his 1973 book of that title, extolling the virtues of a
decentralized economy. And when it comes to power generation, what could be
more decentralized than the harvesting of energy from everyday human
activities? (See this introduction to E. F. Schumacher by Noah
Enelow.)
Recent news reports have cast the spotlight on a
Portland, Ore., health club that is generating electricity from its exercise
machines. Such developments call attention to the advances companies are making
in harvesting kinetic energy from everyday activity and movement.
Using new energy technologies, transportation
agencies could conceivably collect such power on a large scale from roadways,
railways, and pedestrian walkways. But electricity can also be generated at the
level of an individual person. As a well-known example, a small pedal-driven
generator can power a bicycle headlight. A rechargeable battery charged up with
a crank can power a personal device such as a flashlight or radio. Such
applications have long been available commercially.
Technology companies are continuing to develop
personal electronics such as mobile phones and music players — or even
implanted medical devices — that require ever-smaller levels of electricity.
For these small-scale applications, electrical energy generated by an
individual could serve as a power source when channeled to a rechargeable
battery. This promises to be a less expensive and cleaner source of power for
such devices.
Workout Works
out in Generating Electricity
The health club I mentioned before, the Green Microgym, based in Portland, Ore., bills itself as the
“world’s first electricity generating” gym. Company background information says
that in 2009 the club generated 36 percent of its own electricity by combining
human and solar power. The Green Microgym claims that it saved 37,000 kWh, or
85 percent compared to regular gyms.
The company employs many conventional methods for
saving energy, such as using LCD televisions rather than plasma TVs, using
energy-efficient ceiling fans and lights, and controlling electrical devices
such as lights and televisions so they are on only when needed. Solar panels on
the building exterior generate power.
But one of the key features of the gym for our
purposes is the specialized exercise equipment that generates electricity from
human power. The Green Microgym’s equipment includes cross-trainers and
stationary bikes that use the power of a human workout to turn a dynamo and
generate electricity at up to 250 watts. The equipment plugs into a standard
wall outlet so it can feed power back to the electric grid. The club’s exercise
equipment is made by PlugOut, a company founded by
Adam Boesel, also founder of the Green Microgym. (Photo used with permission
from PlugOut Inc.)
Pavement Power
A company in Rotterdam, Netherlands, is
pioneering another source of human kinetic energy: the fancy footwork and gyrations
of dancing nightclubbers.Sustainable Dance Club (SDC) has developed a
patented technology, Sustainable Dance Floor, that converts dancers’ energy
into electricity to power the club’s lighting and special effects. The
technology has been installed at Club Watt, a nightclub in Rotterdam; at Eco
House, an event location in Sao Paulo, Brazil; the Miami Science Museum, where
the floor powers music and lighting; and the Australian Museum. (Drawing used
with permission from Sustainable Dance Club.)
Perhaps the most practical application of the
Sustainable Dance Floor is in Toulouse, France, where the city is employing the
technology for a “pavement power” project. Foot traffic along a stretch of
sidewalk in the city center is used to power street lighting in the area.
A group of researchers at San Jose State
University writes that the SDC dance floor “utilizes a spring-loaded flooring
system of independently moving tiles … each tile can compress up to 2 cm,
activating a flywheel mechanism which powers a small electrical generator …
LEDs embedded in the floor are sustained entirely by the approximately 20 watts
generated by each dancer.” (“Piezoelectric Harvesting: A sustainable approach to
clean energy generation in airport terminals,” Christopher Scholer et al, entry
for FAA Design Competition for Universities, April 2009)
Jaap van den Braak, SDC’s marketing director,
told The Guardian in 2010 that Rotterdam’s football
stadium had signed up to do a pilot project with the technology. He said that
other pilot projects were under consideration “which use the modules in public
spaces where there is a high traffic movement, such as train stations and
sports stadiums.” (See “Pavement Power Lights Up Toulouse,” by
Lizzy Davies, April 13, 2010.)
Power Walker
Bionic Power, a Canadian company, has
developed the PowerWalk, a wearable device for harvesting human energy. The
PowerWalk, now in prototype form, is a leg brace worn from thigh to shin with a
pivot at the knee, where a generator captures a walker’s movement to charge up
a battery pack. Intended initially for military use, the device “uses
principles similar to regenerative braking in hybrid cars to unobtrusively
generate electricity from the natural motion of walking and then use it to
charge a wide range of portable battery-powered devices,” according to company
background materials. (Photo used with permission from Bionic Power Inc.) The
company describes its technology in this way:
It resembles an athletic knee brace and weighs
about 750 grams (1.7 lbs) per leg. With a device on each leg, a user walking at
a comfortable speed generates an average of 12 watts of electricity. At this
rate, a little over one hour of walking generates enough electricity to charge
four mobile phones. The PowerWalk M-Series intelligently adjusts the amount of
energy that it harvests as a function of walking speed and terrain, harvesting
more energy when available and dialing back energy harvesting when it might be
obtrusive.
Rather than forcing a walker to do extra work, it
sounds to me as if the PowerWalk could actually provide some relief for those
of us whose knees have seen better days. Discussing their technology, Bionic
Power says,
The knee is the best location for energy
harvesting as it primarily performs negative work during walking, unlike the
hip or the ankle joints, making it a good candidate for generative braking.
While the knee power profile varies substantially during level ground walking …
there is significant negative power during swing extension, stance flexion, and
swing flexion. It is desirable to target these regions for power generation as
the generator can assist the muscles in slowing down the body.
The Power of
Rolling Wheels
A technology developed in Israel is harvesting
human energy on a much larger scale. Israel’s National Railway Company is
testing a technology by Israeli company Innowattech that
captures energy from trains rumbling along railroad tracks. In January of 2011,
Innowattech replaced 32 conventional railroad pads along a stretch of railway
with the company’s IPEG pads containing piezoelectric disks. (Piezoelectric
technologies collect the electricity that is generated when certain crystalline
materials are compressed.) A report from Selected Science News says that
Preliminary results suggest that areas of
railway track that get between 10 and 20 ten-car trains an hour can produce 120
kWh of renewable energy per hour, which could be used to help power trains
and/or signals, or be routed to the power grid for use elsewhere.
Innowattech also makes power-generating
pedestrian tiles, pads for highways, and tiles that can be installed under
heavy machinery to harvest kinetic energy normally wasted in manufacturing. The
company has also developed an accompanying information technology solution that
monitors and analyzes the movement of vehicles along a roadway or railroad
track while energy is being generated.
Think “small” is beautiful? Like the idea of
decentralized power generation? Your opportunity might come soon to turn your
own body into a renewable energy source.
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