IN THE WORLD of energy harvesting, stress
Whether it’s commuters pounding the pavement or the weight of a car on a road, applied
mechanical strains can be converted into clean
energy using piezoelectricity. Capable of generating
electric current flow, the natural effect allows vibrations to be harvested and the exerted energy stored
in capacitors, circuits or batteries for later use.
And in the search for green power, piezoelectricity is fast emerging as the go-to source of
A team working on the 2012 Olympics in
London, England, for example, is building a staircase that will harvest vibrations from the footsteps
of about 22,000 passersby each day, says Oliver
Schneider, commercial director of The Facility,
the London-based architecture and design firm
commissioned for the project.
“Every time we take a step, we are all dissipat-
ing energy into our environment—energy that is
wasted,” he explains. “The devices we developed
convert the mechanical movement associated with
building, infrastructure or transport vibration into
useful electricity. The dissipated energy captured
would typically produce unwanted noise or damag-
Instead, the energy harvested from the staircase
will be enough to power up to 80 square meters
(861 square feet) of organic LED (light-emitting
diode) illumination used for displays and lighting
within the Olympic park.
A PIECE OF THE PIEZOELECTRIC PIE
Although piezoelectricity was discovered as early as
the 19th century, projects tapping into the natural
phenomenon have only recently starting truly taking off. In 2009, the energy-harvesting market
was US$611 million, but over the next decade,
those numbers are expected to jump to more
than US$4 billion, according to Energy Harvesting Journal.
The reason for the boom? “You have a way of
generating electricity from ambient sources, without worrying about replacing the harvester the
way you would worry about replacing a battery,”
says Harry Zervos, PhD, technology analyst at
IDTechEx, a global scientific research and analysis company in Cambridge, England.
Yet harnessing a not-quite-mainstream effect
often requires developing some extensive work-arounds for research and development (R&D).
The Olympic gateway team, for example, bankrolled the early research itself, then introduced
both private- and public-sector funding later.
“We sat in what is termed the ‘R&D Death
Valley’—somewhere between raw research, which
is favorably funded by academic and research
institutions, and product development,
which is favorably funded by venture capi-
talists,” Mr. Schneider says.
Even once the money was secured, the
team was “careful of project costs,” he says.
“It is easy to let R&D costs spiral out of control, especially when you receive large injections of grant funding.”
Not all energy-harvesting projects require piezoelectricity—some just
require some good old-fashioned sweat.
In Stockholm, Sweden, for example, engineers found a way to harness
body heat from the 250,000 commuters packed in Central Station, Scandinavia’s busiest travel hub, to warm nearby buildings.
“This is old technology but used in a new way,” Karl Sundholm, project
manager at Jernhusen, a Stockholm real estate company, and one of the cre-
ators of the system, told Time magazine. “It’s just pipes, water and pumps.”
Commuters produce body heat, which is captured by the train station’s
ventilation system and then used to warm water in underground tanks. The
water is pumped to an office building about 100 yards (91.4 meters) away
and integrated into the main heating system.
But it can be difficult to contain energy across long distances, which limits the project to buildings close by. “The farther you move away, the more
energy will be lost. Finally, there will be nothing left,” Mr. Sundholm says.
The company’s ultimate goal is to transfer body heat generated in residential areas at night to buildings in the morning, and back in the afternoon.
“It could even be our next project,” he told Time.
IF IT AIN’T BROKE…
Part of the problem with piezoelectricity
projects is proving that they’re worth the possibility of a new technology interfering with
existing—and fully functioning—systems.
Innowattech was commissioned to dig up
33 feet ( 10 meters) of a road in Haifa, Israel
to insert piezoelectric generators 2 inches
( 51 millimeters) below the surface. But first
the energy-harvesting company had to prove
that the highway wouldn’t be damaged.