Highaltitude wind energy from kites Saul Griffith
if you’re at all like me this is what
you do with this sunny summer weekends
in San Francisco you build experimental
kite powered hydrofoils capable of more
than 30 knots and you realize that there
is incredible power in the wind and they
can do amazing things and one day a
vessel not unlike this will probably
break the world speed record but cards
aren’t just toys like this kites
I’m gonna give you a brief history and
tell you about the magnificent future of
every child’s favorite plaything so
kites are more than a thousand years old
and the Chinese use them for military
applications and even for lifting men so
they knew at that stage they could carry
large weights I’m not sure why there is
a hole in this particular man in 1827 a
fellow called George Pocock actually
pioneered the use of kites for towing
buggies in races against horse carriages
across the English countryside
then of course at the dawn of aviation
all of the great inventors at the time
like Hargreaves like Langley even
Alexander Graham Bell inventor of the
telephone was flying this kite we’re
doing so in the pursuit of aviation then
these two fellows came along and they
were flying kites to develop the control
systems that would ultimately enable
powered human flight so this is of
course oval and Wilbur Wright and the
Wright Flyer and their experiments with
kites led to this momentous occasion
where we powered up and took off for the
first ever 12 second human flight and
that was fantastic for the future of
commercial aviation but unfortunately it
relegated kites once again to be
considered children’s toys that was
until the 1970s where we had the last
energy crisis and a fabulous man called
miles Lloyd who lives on the outskirts
of San Francisco wrote this seminal
paper that was completely ignored in the
Journal of energy about how to use
basically an airplane on a piece of
string to generate enormous amounts of
electricity the real key observation he
made is that a free flying wing can
sweep through more sky and generate more
power in a unit of time than a
fixed-wing turbine so turbines grew and
they can now span up to 300 feet at the
hub height but they can’t really go a
lot higher and more height is where the
more wind is and more power as much as
twice as much so cut to now we have
still have an energy crisis and now we
have a climate crisis as well you know
so humans generate about 12 trillion
watts or 12 terra watts from fossil
fuels and Al Gore has spoken to why we
need to hit one of these targets and in
reality what that means is into the next
30 to 40 years we have to make 10
trillion watts or more of new clean
energy somehow wind is the second
largest renewable resource after a solar
3600 terawatts more than enough to
supply humanity 200 times over the
majority of it is in the higher
altitudes above 300 feet where we don’t
have a technology as yet
to get there so this is the dawn of the
new age of kites this is our test site
on Maui flying across the sky I’m now
going to show you the first autonomous
generation of power by every child’s
favorite plaything as you can tell you
need to be a robot to fly this thing for
thousands of hours makes you a little
nauseous and here we’re actually
generating about 10 kilowatts so enough
to power probably five united states
households with a kite not much larger
than this piano and the real significant
thing here is we’re developing the
control systems as did the Wright
brothers that would enable sustained
long-duration flight and it doesn’t hurt
to do it in a location like this either
so this is the equivalent for a kite
flier of peeing in the snow that’s
tracing your name in the sky and this is
where we’re actually going so we’re
beyond the 12 second steps and we’re
working towards megawatt scale machines
that fly at 2,000 feet and generate tons
of clean electricity so you ask how
bigger those machines
well this paper plane would be maybe a
that would be enough to power your cell
phone your Cessna would be 230 kilowatts
if you’d loan me your a Gulfstream I’ll
rip its wings off and generate your mega
one if you give me a 747 I’ll make six
megawatts which is more than the largest
wind turbines today and the Spruce Goose
would be a 15 megawatt wing so that is
audacious you say I agree but audacious
is what has happened many times before
in history this is a refrigerator
factory churning out airplanes for World
War two prior to World War two they were
making 1,000 planes a year by 1945 they
were making a hundred thousand with this
Factory and a hundred thousand planes a
year we could make all of America’s
electricity in about ten years so really
this is a story about the audacious
plans of young people with these dreams
there are many office I am lucky enough
to work with 30 of them and I think we
need to support all of the dreams of the
kids out there doing these crazy things
thank