Humble beginnings to big business
The first large-scale solar plant, located on California’s Carizzo
Plain, went into operation in 1983 as the largest solar array in
the world with a peak output of 5. 2 megawatts (MW). It was
decommissioned just 11 years later in 1994 when oil prices,
which had been on the rise, stagnated and fell, making the
plant’s output too expensive to maintain. The first large U.S.
wind farm, at Crotched Mountain in New Hampshire, powered
up in 1980 with 20 30-kilowatt (k W) turbines. Due to equipment malfunctions, that installation failed after just a year or so.
Things have changed more than a little since those early
days. In 2012, wind and solar became the two fastest growing electric-generation technologies in the United States, and
production capabilities have climbed just as dramatically. The
Topaz Solar Farm, in the same general Carizzo Plain region as
the failed first installation, went online in late 2013 with 5 million panels and a rated output of 550 MW.
Wind has grown even faster.
As of 2013, the Alta Wind Energy
Center in Kern County, Calif.,
was the largest wind farm in the
world with an installed capacity
of 1,320 MW. Planned additions
are expected to boost that figure
to 3,000 MW by 2019.
In fact, we may be close to
reaching the outer limits of
solar- and wind-farm production with current approaches. The photovoltaic panels of the
Topaz solar farm are spread over 9. 5 square miles—yes, miles—
and the Alta wind project’s turbines, many of which have
nameplate production capacity of 3 MW, occupy approximately
9,000 acres. Getting rights or ownership of that much property
is an expensive and contentious process, so researchers and
developers are looking at new ways to get more output without
simply adding more panels or bigger turbines.
Solar’s game of concentration
For solar developers, boosting performance means looking beyond traditional PV panels to more advanced means
of extracting energy from the sun’s rays. Concentrated solar
power (CSP) approaches, for example, are making inroads in
the United States with the launch of the Ivanpah plant in California’s Mojave Desert and, perhaps more important, the Solana
plant near Gila Bend, Ariz., about 70 miles southwest of Phoenix.
Both plants produce electricity the old-fashioned way, through a
steam-driven turbine. What’s unique is that they combine traditional thermal generation with heat from the sun instead of from
combusted fossil fuel. Solana takes this technology a step further
by storing solar heat in molten salt and extending production for
up to six hours after the sun goes down.
Utility-scale concentrated solar plants were first con-
structed in Spain. More than 50 such facilities were brought
online during that country’s boom years in the late 1990s and
early 2000s. However, the international financial downturn hit
Spain hard, and subsidies that supported construction have dis-
appeared. Today, the United States is seen as a bright spot for
concentrated solar innovation.
“The plants that are coming online are U.S. plants,” said
Mark Mehos, CSP program manager for the National Renew-
able Energy Laboratory (NREL) in Boulder, Colo. “But in the
U.S., it’s been more of a one-off. I think that building these
plants at scale will begin to help the utilities become more
comfortable with the technology.”
Instead of photovoltaic panels, which produce electricity
directly through sunlight-stimulated electrochemical reactions,
CSP operations use mirrors or lenses to concentrate and direct
solar energy to a collection point, where it heats steam for a tra-
ditional turbine. Designs for these plants vary. Some use mirrors
to focus sunlight onto boilers located on central lighthouse-style
Mehos sees storage as a major differentiator for Solana and
other plants like it. Such plants are expensive to construct, but
thermal storage allows system operators to treat them more like
base-load natural gas, coal and nuclear generators. Such plants’
output is steady and dependable and doesn’t suffer from the
momentary voltage drops that challenge PV panel operations
(and the grids to which they are connected).
“It becomes more significant when you start [estimating] the
value of PV,” Mehos said.
At higher penetration levels, the value of each added PV
panel drops for the whole system because of the technology’s
intermittent output and the fact that its production drops off
just as demand is hitting its peak.
Building better blade runners
The 30-k W output of the original Crotched Mountain wind turbines would barely register in today’s commercial market. Today,
“I think that building these
plants at scale will begin to
help the utilities become more
comfortable with the technology.”
National Renewable Energy Laboratory