The energy flow through our urban society is an incredibly
wasteful process, with nearly everything that mankind generates
energy for becoming a waste product within half a century.
In just two centuries, humans have guzzled their way through
millions of years of the planet's stored energy in fossil fuels -
and the flood of oil that greeted early drillers is starting to
trickle out.
Researchers around the world are now tackling the problems of
our energy-hungry species from both the supply and demand ends,
with alternative sources and more efficient uses of energy both
urgently needed. And we are turning away from the profligate
approach to energy we had when we were energy rich, towards a
miserly scratching-out of our dwindling resources.
Since humans recognised that wind and water and the sun were
generating energy, we have been trying to harvest it, through such
things as windmills and waterwheels - but these were never
sufficient to satisfy the needs of a greedy, growing, industrial
world.
But the information revolution has introduced miniaturisation,
and from solar-powered calculators to motion-powered wristwatches,
we have been capturing tiny amounts of energy for our gadgets for
decades.
Now, it seems that our scavenging ways may allow us to squeeze
every last drop of the highend energy we produce by powering sensor
networks to control its use.
THE NANOTECH FUTURE
Professor Terry Turney heads the Green Chemistry Centre at
Monash University and also holds leadership positions in several
nanotechnology companies. He previously worked as a material
research scientist with the CSIRO and was head of the
Nanotechnology Centre.
Turney says that some of the most significant advances in
nanotechnology will require energy harvesting.
"The main economic advantage of nanotechnology (which is really
just any technology that miniaturised), is that it can give us a
big cost advantage." He cites sensors, which in earlier times might
have cost a thousand dollars, now costing a few cents - and
eventually costing fractions of a cent.
"When sensors are that cheap, you can put them everywhere, they
become pervasive - we can put them in walls, in furniture,
embedding intelligence into the very structure of a house," he
says. "The room can then become aware of - and respond to - its
environment, turning off lights and power when you walk out of
it."
These pervasive sensors will need to 'harvest' energy to obtain
power, and Turney says that enough energy exists in such things as
vibrations in the walls and pressure differentials in water pipes
to make these ubiquitous sensors reality.
"Miniature devices will be made by totally different methods,
printed like newsprint by the kilometre, then attaching them like
the paper on plaster board, installed when you're building a
house," he says.
"The ink used to print the device would contain nano-particles
that will form transistors and temperature sensors and so on, small
enough to pass through an inkjet head."
While energy harvesting will never generate enough energy to
power a household or a vehicle, Turney says that it is set to
become a key technology in energy conservation because of its
ability to power sensors that will control and optimise the usage
of energy and water.
He believes that using devices and sensors that rely on energy
harvesting also extracts the optimal use from all the energy that
is generated in an area.
"When you use energy, you degrade it," Turney explains. "For
example, as it reduces from high-energy heat to low-energy heat, it
gets harder to harvest the temperature difference."
The key to much of the research into thermodynamic energy -
which relies on temperature differences - lies in materials
science, he says. "We need material that is a good electrical
conductor but also a good thermal insulator, and they don't go
together."
Turney says that there is ongoing development into
nano-structured materials that create internal particle barriers to
give better thermoelectric properties. He expects to see
commercially successful outcomes in the next decade.
"We need to tackle the impending energy crisis from both ends;
we need to generate energy more effectively, and then we must
manage it more effectively. Pervasive sensors that run on scavenged
energy will allow us to manage the whole cycle far more
effectively."
HARVESTING THE ENERGY
The key to the success of many of these plans lies in our
ability to harvest the tiny amounts of energy that will power these
sensors.
Recently, energy harvesting has become a hot topic
internationally with, at time of writing, conference organisers
IDTechEx expecting hundreds of delegates at an upcoming conference
in Cambridge in the UK, with further events planned in the US and
Tokyo during 2009.
"The term energy harvesting usually applies to making small
things self-sufficient in their power needs - such as a laptop or
mobile phone or a small light or a sensor, and either avoids
batteries or uses rechargeable batteries that last for decades,"
says Dr Peter Harrop, who heads electronics research consultancy
IDTechEx Ltd.
Harrop says that a report on energy harvesting that his company
produced this year has already sold better than any of the dozens
of research publications into other technologies they have
published previously.
"People are very excited about it because it's an idea whose
time has come. It's been around for a long time in different forms
but is now much more feasible and very desperately needed for a lot
of new electronics."
He's not surprised that energy harvesting continues to grow
rapidly despite the global financial crisis. "It's recession proof.
Suppliers realise this is a business that takes you into the
future," he says.
Most research and development, and most of the investment in
energy worldwide, focuses on what Harrop calls 'the heavy end' -
generating energy for the grid or in volumes that will drive
machinery and power households.
"Energy harvesting is like the dynamo on your bicycle, the solar
cell on your calculator or on satellites, solar cells or wind
turbines on powered road signs, solar-powered or body-heat powered
wrist watches and so on," he explains.
At the moment, most small devices are powered by tiny one-use
'button' cell batteries. Around 30 billion button batteries are
produced each year - and theoretically, a large proportion of them
could be replaced by a form of energy harvesting.
However, at this stage, few commercial incentives exist to
replace these tiny batteries. They are very cheap, the smallest
costing around one US cent to produce, giving them huge price
elasticity.
And the market advantage of products that need to replace
batteries, rather than recharge them, is that they have created a
constant recurrent consumption need.
By comparison, energy harvesting components are usually more
expensive to produce - Harrop estimates around ten US cents for the
smallest solar-cell generator - and while many need batteries, they
may only need one rechargeable battery over the lifetime of the
device.
The convenience and efficiency of a device that does not need
its battery changed is more attractive to consumers - but is that
enough of a market incentive?
ENERGY HARVESTING FOR VEHICLES
For more than 20 years Australia has hosted the World Solar
Challenge, where cars travel over 3000 kilometres powered only by
sunlight. But while solar cars and hybrid cars are transforming the
vehicle engine, Harrop says that energy harvesting is set to
transform the vehicle's electrical support systems.
"Car manufacturers are now looking at thermoelectrics,
harvesting electricity from heat differentials that exist thanks to
the heat in exhaust pipes and engines," he says.
He says some car makers are installing solar cells on the
vehicle roof (and even transparent solar cells, across windows) to
generate power for instruments and car accessories.
Some vehicles contain instruments that include the means to
harvest enough energy from heat, sunlight or vibration for all
their power needs.
Harrop cites the Italian manufacturer, Fiat, which is developing
a car where most wiring is eliminated, with indicators and
headlights powered by solar cells and controlled through radio
signals.
Rather than rely on one power source for all our needs, Harrop
sees a future where a combination of energy gathered from many
different sources will supply the power needs for small
devices.
TYPES OF ENERGY HARVESTING
Popular sources of harvested energy include electrodynamics,
which gathers energy from vibration or motion - the bicycle dynamo
is a classic example.
One groundbreaking application is an electrodynamic motor that
uses the vibration of the beating heart to power a pacemaker. "This
is a much better option than the previous technology, where they
have to cut you open to change the battery," Harrop says.
Even the wind-up handle investigated as a potential power source
for the One Laptop One Child project uses electrodynamic energy,
Harrop adds.
Solar power - or photovoltaics - has been running calculators
and watches for decades and now all sorts of devices, from mobile
phones to laptops, are using solar cells for their power or to
boost battery power,
One of the less glamorous energy sources is piezoelectrics,
familiar to gas barbecue users as the spark-generating push-button
that lights the gas as it hisses from the jets under the hotplate.
Piezoelectricity works when certain materials (often crystals or
ceramics) generate an electric potential when mechanical friction
is applied to them.
Harrop says that in Europe, hundreds of thousands of moveable
piezo light switches have been sold. Normal pressure on the switch
generates enough of an electrical pulse to send a radio signal to
the light, switching it on or off. The installation of these
switches is simple and much cheaper than arranging hard wiring
between switch and light.
Harrop says that piezoelectrics is currently attracting a lot of
research interest - and a lot of funding - because it has
significant applications in nanotechnology.
And finally, Harrop cites thermoelectrics, which uses the heat
differential between two materials to generate energy. He believes
this has strong application in aircraft - where big temperature
differences exist - and also in biotechnology.
"Within your body, there are quite big temperature differences
and there are electronic devices in the pipeline that require
miniscule amounts of energy to run," he says. "Tiny sensors within
the body which report on changes can be incredibly useful for
managing conditions like, for example, diabetes."
THE PROBLEM OF STORAGE
However, there's a fly in the energy-harvesting ointment. Many
energy-harvesting technologies are not constant - solar cells, for
example, only generate power when the sun shines on the
photovoltaic collector cells.
Harvested energy has traditionally relied on bulky rechargeable
batteries with a limited lifespan - until recently, most would not
last more than ten years.
More recent advances in battery technology have produced
batteries based on lithium that last up to twenty years, although
these batteries do have safety issues.
Battery technology has improved, for now, however much research
in energy harvesting is investigating capacitators, which absorb
energy fast and transmit it more slowly, making the harvested
energy last longer.
Harvested energy is now producing low-tech, low-cost solutions
to introduce material comforts to the developing world that the
West takes for granted, for example, clockwork lanterns which store
energy in a spring and release it as constant torque to a generator
as needed.
THE SENSOR KING
James Eades has spent his working life as an innovator and
entrepreneur in high tech companies and after selling his latest
company, took early retirement in Victoria.
But then, after a series of devastating bushfires in Canberra in
2003, Eades set up a new company, TelepathX, to develop and
distribute tiny RFID (radio frequency identification) sensors
forming wide area networks for environmental monitoring.
The sensors contain a switch that responds to conductive or
convective heat within a certain range. There are twelve different
switch points covering a range from around 60 degrees to circa 120
degrees Celsius.
When a switch is triggered, the sensors transmit a radio signal
to a central access point, which then broadcasts the information
into a control room where a database collates the information from
the network, identifies the GPS access points and passes the key
data to an emergency response team.
The sensors are used to identify a range of electrical faults,
including heat build-up from arcing, cables degrading, current
leakage, electrical shorts, lightning strikes, fires and radiant
heat. Different sensors could potentially detect bushfires, power
outages, auto accidents, floods and mudslides.
"These sensors are detecting faults and incidents before they
become a big problem and they have the potential to save millions,"
Eades says. "The technology is taking off like crazy; we've got two
major pilots planned this year and one of them will be the world's
largest sensor network, right here in Australia."
The Victorian government is proceeding with a scheme that will
use a sensor network to monitor about 100,000 kilometres of rural
roads, including the energy infrastructure along the roadside.
"We will be able to tell the government exactly when and where a
bushfire has been ignited or we can tell the energy people they
have a fault in a certain place - and may possibly have started a
bushfire too."
Eades estimates that the project will involve between five and
ten million sensors, accessing existing cell phone networks.
He now plans to incorporate materials that will harvest energy
through piezoelectricity, or ceramic vibration, thus lowering the
cost of his sensors and extending their life to at least 30 years.
At the moment, the sensors are powered by a little coin cell
battery and are reactive in nature, lasting around ten years.
"It doesn't take much energy to power one of these little
sensors, so generating a couple of volts of AC though vibration
will be pretty easy to do," he says.
"Micro-vibration is the best thing to harvest when you are
monitoring energy assets, because the AC, the alternating current,
produces enough 'hum' to actually power sensors," he says.
At the end of their lives, the millions of tiny sensors in
existing wide area sensor networks will still hold toxic traces in
their miniscule dead batteries, another incentive for Eades to
switch to energy harvesting rather than battery power, he says.
But while piezoelectric energy will be ideal for sensors that
are placed near electric current, Eades says that for other sensor
applications, harvesting the energy generated when there is a
difference in the temperature of materials will be better.
"We're working with Pacific Northwest National Laboratories up
in Washington State, which has developed some energy harvesting
technology that uses heat differential," he says.
Although Eades has made wide-area sensing commercially viable,
he says that technology costs are still a barrier to pervasive
networks.
"More efficient energy harvesting is critical to our long term
strategy and this is why we want to start developing and
manufacturing the technology so we can get the cost of goods down,"
he says.
"We may already be the biggest consumer of these devices," he
says, adding that because there is little competition in the
market, costs are much higher than they need to be.
"As we increase our demand, the economies of scale will drive
down the price for us. We know we can do it, we've got the
technology and the brainpower here in Australia to do it, we just
need to allocate the funds and find the right research partners to
help us do that."
Although Australia is home to the solar challenge and its
climate theoretically ideal for harvesting solar energy, Harrop
says that he hasn't had any Australian academic or business
interest in energy harvesting conferences or publications, though
many other OECD nations are represented.
Terry Turney says that energy harvesting is a critical part of
our energy future, and commercial applications, such as those that
James Eades is involved in, will drive research in the area.
"This is actually going to change energy flow. Like you have a
biological ecosystem, you have an urban ecosystem and we are now
exploring how you best manage the flow of energy and indeed
materials, through this urban ecosystem," he says.
"Nature powers its ecosystem with the power of the sun and
doesn't produce any waste whatsoever, everything gets reused and
recycled. But everything we bring into the industrial ecosystem
leaves as waste."
Turney believes Australia has an opportunity to become a global
player in energy harvesting, changing the way that industry and
society operate.