Danielle Fong has a clever way to widen the
use of renewable power: take the electricity
produced by, say, a wind farm and use it to
compress air in carbon-fiber tanks. When
the wind quiets down, use the compressed
air to drive an electric generator, eliminating the intermittency that consigns wind
farms to a small role on the grid. The
concept isn’t new, but it has been limited
because air heats up as it is compressed,
making it difficult to store. Fong figured
out that spraying water into the tank to
cool the air makes it possible to store so
much energy that it could be cheaper than
using batteries. In 2009, she cofounded a
company called LightSail Energy that has
raised $70 million from the likes of Bill
Gates and Peter Thiel, but it still is only
on the verge of key demonstration projects. Fong, 28, spoke to MIT Technology
Review’s executive editor, Brian Bergstein,
about the challenges of commercializing energy technologies.
You’re planning to begin pilot
tests in 2016. Why is it taking this
long to scale up your technology
from the lab?
We thought that we would be
out in the market about twice as
fast. We were going to cut some
corners by converting an off-the-shelf natural-gas compressor. Ultimately, we decided that would be
too much of a compromise. In early
2012 we decided to switch and just
go directly to the product that we
would ultimately want.
Part of it is there’s a lot more to
do than we expected. Part of it is it’s
difficult to find financing, although
we have raised a decent amount.
Why hasn’t the money you’ve raised
It’s not actually a lot of money compared
with how much it takes to develop an
engine, for example, or a compressor.
Say you’re a power plant company, and
you’re trying to make a better gas turbine. Even when you hit volume, you’re
going to be spending more than $100
million, maybe a couple hundred million dollars. Who writes those checks?
There just aren’t that many. There used
to be. Those times are over. Now what
you need to do is figure out how to get to
a commercial scale so that you can bring
the unit cost down without spending that
kind of money.
Our answer to that, by the way, is
our tanks. We have the most advanced
carbon-fiber tanks, we think, on the
planet for bulk storage of gases. We’re
manufacturing and selling the tanks,
with a healthy profit, [to] the natural-
And yet you still need to raise more
Our plan has us going profitable on less
than $30 million [of] additional capital.
Technically, we wouldn’t need to raise
money after that, if all goes according
There were so many things when we
started out that people said, “This is impossible. If you spray water into an air compressor, it’ll break. Will it transfer heat fast
enough? Can you separate the water from
the air? Can you compress and expand out
of the same system? Can you build all of
this stuff?” We’ve done the impossible on,
I think, a reasonable budget.
Does it frustrate you that in
other tech sectors, money is
very easy to come by?
I will admit a fair amount of
frustration. There are a dozen
venture-funded apps to pick up
your dry cleaning.
If we fail here, and it may well
be the right solution, no one is
ever going to get funded to do it
It must seem both promising and
daunting that the opportunity is
We need energy storage in the tera-watts. We’re talking about getting
to half a megawatt [with each of
LightSail’s storage machines].
That’s a factor of a million. That’s
where my head is at.
The Energy Startup
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