than food crops. Biofuels produce fewer
carbon emissions than oil because the
plants suck up carbon as they grow and
because it’s simpler to harvest plants
than to drill for crude. The goal was to
make a “drop-in compatible” fuel–one
that could be used in a vehicle without
modifying the engine.
It was a popular idea a decade ago
as oil prices were well above $100
a barrel, but it became a tougher sell
when oil got cheaper. Biofuels remained
stubbornly expensive. Kior Inc., a
once-promising startup backed by the
venture capitalist Vinod Khosla, made
fuel from wood chips. With production
costs above $6 a gallon, it went bankrupt
in 2014. Renmatix Inc. sought to convert
wood into fuel but shifted to turning
plants into specialty chemicals for the
food and beauty industries. Solazyme
Inc. engineered strains of algae that
could be processed into fuels but
eventually followed a similar path into
chemicals. In 2016 the company changed
its name to TerraVia Holdings Inc., and
a year later it filed for bankruptcy.
- Solar Power Tower
The power tower might be the most
dramatic energy idea: miles of garage-
door-size mirrors focusing sunshine onto a
boiler at the top of a tall tower to generate
steam and produce electricity. It’s cool,
but costly. California’s Ivanpah, the world’s
biggest power-tower project with a cost of
$2.2 billion, has 377 megawatts of capacity.
That just can’t compete with photovoltaic
solar. The beams of focused sunlight have
also been known to fry birds midflight.
Bechtel Group, which built Ivanpah
for owners BrightSource Energy,
NRG Energy, and Google, has said power
towers aren’t competitive with other
sources of electricity. But the technology
has one advantage over solar panels:
Developers can add vats of molten salt
that retain heat for hours, enabling the
towers to produce electricity after
sundown. That’s one reason the towers
have the potential to provide electricity
in remote areas, where it’s expensive.
Construction on a project in the Atacama
Desert of northern Chile was
resumed last year, two years after
former co-owner Abengoa SA put it on
hold because of financial issues.
SolarReserve Inc., which built the only
other U.S. facility in Nevada, is
developing projects in other parts of the
world but this year canceled plans for
Australia’s first power tower when it
couldn’t line up financing.- Small Wind Turbines
You’ve probably seen homes topped
with solar panels. What about rooftop
wind power? Urban Green Energy Inc.
tried that.
The company offered turbines
small enough to be installed on homes,
with curved blades that spun around
a vertical axis. Larger models were
provided for commercial rooftops,
remote mobile phone towers, and public
sites, and the company landed well-
publicized deals to help power the Eiffel
Tower and Lincoln Financial Field, home
to the Philadelphia Eagles football team.
But the concept faced challenges.
Wind turbines convert kinetic energy—
the motion of the blades—into electricity.
Smaller blades produce less power.
The vertical design was less efficient
than standard turbines. UGE struggled
with high costs and maintenance issues.
In 2016 the company sold its wind
operations and shifted its focus to solar.
6. Marine Energy
The ocean’s never-ending motion can be
converted into electricity, but it’s not
easy. The sea is a harsh environment for
mechanical systems. Still, the idea of
harnessing the kinetic energy of waves,
tides, or currents to generate power has
fueled several startups.
Ocean Power Technologies Inc.
developed a power buoy that’s anchored
offshore and moves up and down with the
waves. The company teamed up with
Lockheed Martin Corp. in 2012 to build
a large-scale wave energy project in
Australia that would have used rows and
rows of the buoys. Ocean Power pulled
the plug in 2014, saying the project wasn’t
“commercially viable,” and changed its
strategy. It’s still pursuing the technology
but is now seeking to power remote sites
such as offshore oil rigs.
U.K.-based Tidal Lagoon Power
Ltd. set out to build turbines on a
barrage across Swansea Bay, in South
Wales, that would draw power from the
motion of the tides. The U.K. government
rejected the £1.3 billion ($1.6 billion)
project in 2018, in part because offshore
wind could supply the same amount of
power for about one-third the cost.
Other companies are having more
success with grid-scale marine power.
Simec Atlantis Energy Ltd. operates the
world’s first commercial tidal stream
project, the 6MW MeyGen facility that
went into service in Scotland in 2016.
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