Sorry, but I couldn't find our "green" thread. This is too cool! I guess Saudi Arabia is the only economy that could invest in this technology. Too bad for Canada, but great for Ted!
Paint-on solar cells: The next game-changer?
Ted Sargent holds a small paint-on solar cell, about the size of a postage stamp, between his thumb and index finger.
It does not look like it could change the world, but Sargent's backers say the technology just might.
They
talk of coating cellphones, e-readers and computers with the energy
harvesting cells, not to mention cars, walls and rooftops. Inexpensive
sheets of the stuff could even be rolled out across deserts to create
huge solar farms.
Sargent, a Canada Research Chair in nanotechnology, has been working on, and talking up, paint-on solar cells for years.
And
the Toronto man has parlayed his ingenuity into a $10-million deal with
the Saudi Arabians, who are looking to alternatives to help keep the
energy wealth flowing.
Sargent's solar technology is still in the
early stages but his Saudi backers, who recently announced a deal to
licence his technology, describe it as a "potential game changer."
And
game change is what the world needs, according to delegates heading for
the United Nations climate talks that start in South Africa on Monday.
Burning
coal, oil and gas pumps so much carbon dioxide into the atmosphere that
it threatens to melt polar ice, fuel heat waves, and leave millions
homeless as sea levels rise.
Climatologists say emissions of CO2
and other greenhouse gases must be slashed dramatically in coming
decades to prevent the planet from overheating.
There is, however, no obvious or easy path to a clean energy future.
None
of the alternatives is as convenient or packs the power of the oil,
coal and gas now fuelling vehicles, factories, power plants and planes.
Nuclear
is plagued by accidents and political problems, geothermal is still in
its infancy, biofuels are land-hungry, wind turbines don't always turn,
and solar energy is only available half the day.
The sun does,
however, have superpower potential. It is free, clean and bathes Earth
with 100 terawatts of energy, which far exceeds the 15 terawatts
humanity now consumes.
Enough sunshine hits Earth in just an hour
to power the planet for an entire year, Sargent says. So covering just
150,000 square kilometres - an area about a quarter of Alberta - with
solar cells could, in theory, fulfil world energy demand.
Solar
farms already dot the planet. A $400-million operation near Sarnia, Ont.
- billed as the world's largest solar farm when it opened a year ago -
has 1.3 million solar panels converting sunshine into electricity that
lights up more than 12,000 homes.
The solar industry is dealing with huge challenges, however, chief among them the high cost of making solar panels.
Sargent
and his competitors in labs around the world are determined to come up
ways to harvest solar energy that do not need to be subsidized. The
trick, they say, is to create cells so cheaply that plugging into the
sun will become the sensible, easy and obvious thing to do.
The
rigid semiconductors at the heart of solar cells today are expensive to
make because they entail growing large silicon crystals in high
temperature furnaces, then cooling and slicing them up into thin wafers
in clean rooms.
Some teams are working on super thin semiconductor technology, and others are engineering new compounds to harvest sunshine.
"We
know the energy is there," says Sargent. And he is seemingly undaunted
by what he describes as a ``fundamental engineering problem.''
His
money - along with the $10 million from his Saudi backers - is on those
postage-stamped sized solar cells, which he paints with quantum dots.
The
dots, first created about 30 years ago, can capture energy from light
and convert it into electricity like the semiconductors inside
traditional solar panels.
But unlike rigid semiconductors solar panels, the dots can be whipped up at minimal cost.
"We can make enough of our semiconductor paint to coat a square metre of film for $15 to $20," says Sargent.
He makes it as sound like cooking.
Take
"scientific grade olive oil" and heat it up. Then add key ingredients -
tin, bismuth, lead, sulphur and selenium are common components - and
sit back and wait for the dots to grow.
The end result looks like
oily black ink, but it is loaded with discrete dots a few nanometres -
or billionths of a metre - across. ``Each one is a little crystal,''
says Sargent.
The dots could eventually be mass-produced and
layered onto flexible materials that could be used to coat anything from
phones to deserts. But for now they are being cooked up by students and
technicians in Sargent's cramped, bustling Toronto laboratory.
Using
test-tubes, pipettes and tiny spinning disks, they spread droplets of
the dots across small stamp-sized glass wafers in controlled environment
chambers. Then they wait for them to dry.
The researchers say the dots are not only applied like paint, but are also ``tunable.''
"By
changing their size, we can change the colour and type of light they
absorb," explains PhD student Illan Kramer, as he puts a solar cell to
the test using an "artificial sun." The sun, a wide-spectrum light
source about the size of a golf ball, is set up in the back corner of a
lab jammed with equipment.
Sargent's team showed in 2005 that
quantum dots can capture energy from not only visible light but also
infrared light, which carries almost half the solar energy hitting
earth.
Capturing the energy is, however, just part of the challenge. It also has to be harvested.
When
light hits the cells, Sargent says it "excites" electrons in the
quantum dots and the excited electrons need a clear path out of the
solar cells.
"If you have a little impurity or a little space,
there is the potential for the electrons to get stuck, which is bad
thing," he says.
One of the scientists' latest tricks is to wrap
the quantum dots with a compound that reduces electron "traps'' enabling
the energy to move smoothly across the cells to tiny electrodes.
Their
best-published result so far, reported in September, is cells that
harvest six per cent of the solar energy that hits them. That's
progress. "Five years ago it was zero,'' says Sargent.
At 10 per
cent "you start to have something compelling,'' says Sargent, who has
several patents to his name and rich foreign partners keen on
commercialization.
The King Abdullah University of Science and
Technology in Saudi Arabia, or KAUST, is one of several new universities
in the Arab world spending big money to attract top talent. It has
$10-million, five-year collaboration with Sargent, who has been working
with KAUST since 2008 as one of its 12 global research partnership
investigators.
KAUST announced in September signing a
"first-of-its-kind'' agreement for rights to Sargent's quantum dot solar
cell technology. The license covers 38 countries in the Middle East,
Western Asia, Russia and India. Sargent and the University of Toronto
retain the rights for the rest of the world.
Sargent says the KAUST collaboration helps fuel the research, while the licensing agreement "extends our reach."
"We'll
figure out together how to take it forward commercially when the time
comes," says Sargent, who travels to the Saudi Arabian campus on the Red
Sea for a couple of weeks each year. "It has amazing resources, some of
the best I've ever seen.''
While scientists see a bright future
for solar, Sargent notes they also needed to come up with better ways to
store solar energy until it is needed.
Solar electricity now
supplies less that one per cent of humanity's energy needs. But with
engineering breakthroughs, forecasters predict solar could hit 15 per
cent or more by 2030. "That's only 19 years out," notes Sargent.
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