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