Three new large-scale solar power plants began operating in the western US in 2013, significantly increasing solar power capacity. The three plants use different solar technologies - one uses photovoltaic panels, two use concentrating solar power that collects and stores thermal energy. Combined, they can produce over 800 MW of electricity, equal to a large fossil fuel plant. Their success will influence whether more large solar plants are built and determine the future of utility-scale solar energy in the US. However, concerns remain about the environmental impacts of siting large plants in fragile desert ecosystems.

1. 9CEN.ACS.ORG DECEMBER 16, 2013
COVER STORY
THIS FALL, three new solar power plants
came to life on large tracts of undeveloped,
remote lands in the western U.S. Although
solar, these three installations are huge
when compared with familiar, traditional
rooftop photovoltaic (PV) systems.
Combined, these utility-scale power
plants have the capacity to produce more
than 800 MW of electricity, equal in output
to a large coal- or gas-fired power plant.
And one has the capability of storing and
providing electricity to the grid for six
hours—without sunshine.
The three are the California Valley Solar
Ranch near San Luis Obispo in central Cali-
fornia; the Abengoa Solana project in Gila
Bend, Ariz.; and the Ivanpah Solar Electric
Generating System in California’s Mojave
Desert.
These are just the first wave of a poten-
tial tsunami of large solar plants that are
newly operating, under construction, or
being planned for the southwestern U.S.
They are the fastest-growing sector of a
rapidly increasing solar marketplace. How-
ever, whether more of these large plants
follow will depend on how well these first
few fare, and specifically if electric utilities
want to buy more of the electricity these
plants generate.
Success will also turn on whether devel-
opers can overcome growing opposition
to the projects’ large size and the environ-
mental damage and habitat destruction
that can occur with their placement. Of
particular concern is their effect on fragile
desert ecosystems.
These plants are being built by a mix
of engineering firms, energy companies,
and solar equipment manufacturers that
are benefiting from a host of state and
federal incentives intended to reduce
carbon dioxide and other greenhouse gas
emissions from fossil-fuel power plants.
The incentives require electric utilities to
purchase growing amounts of renewable
energy, such as solar-generated electricity,
and these companies are quickly building
A NEW RACE FOR SOLAR
The fate of three new power plants may set the future for U.S. SOLAR ENERGY
JEFF JOHNSON, C&EN WASHINGTON
ABENGOA
INTO THE HORIZON The Abengoa Solana
concentrating solar power project began
operating this year at Gila Bend, Ariz., generating
280 MW, using a system of parabolic troughs.

2. 10CEN.ACS.ORG DECEMBER 16, 2013
COVER STORY
new solar power plants to make money and
meet that demand.
One of the most powerful drivers has
been state renewable portfolio standards,
particularly California’s requirement that
electric utilities obtain 33% of their elec-
tricity from renewable energy sources by
2020. The requirement has put utilities on
a hunt to purchase electricity generated by
solar and wind to meet state quotas.
Also backing up these incentives and
the push for renewable energy is a billion-
dollar Department of Energy program to
provide loan guarantees for large-scale
renewable energy projects and a federal in-
vestment tax credit that provides a 30% tax
credit for solar construction.
It’s a perfect storm for solar generation,
notes Katherine Gensler, director of fed-
eral affairs for the Solar Energy Industries
Association (SEIA), a trade group. By the
end of the year, about half of the U.S.’s
9,500 MW of solar power will be generated
by utility-scale power plants; most of this
capacity came on-line in the past year.
SEIA figures show some 4,200 MW of
utility-scale generation is now under con-
struction and another 23,000 MW of utili-
ty-scale projects are being developed. More
deals are being negotiated, analysts say.
California accounts for about half the
installed utility-scale solar capacity as well
as some 13,000 MW of the projects under
development.
Whatwillactuallybebuilt,Genslerand
otheranalystsnote,isabigquestion—one
withtoomanyvariablesthatcanbean-
sweredonlyovertimeasthesolarmarket-
placeshiftsawayfromgovernmentsupport.
The federal tax incentive program ends
in 2016, and it is unlikely DOE’s loan guar-
antee program will keep its pace. Conse-
quently, the solar expansion numbers are
murky, and although solar energy has been
on a sharp growth curve over the past cou-
ABENGOA(ABENGOASOLARSOLANA);SUNPOWER(CALIFORNIAVALLEYSOLARRANCH);
BRIGHTSOURCEENERGY/GILLESMINGASSON/GETTYIMAGESFORBECHTEL(IVANPAH)
AT A GLANCE Three installations, three directions for the U.S. solar economy.
Location
Type
Output capacity
Start-up date
Storage
capacity
Design
Electricity
purchase
agreement
Cost
Owner(s)
Facility footprint
Ivanpah Solar Electric
Generating System
California Mojave desert
on California-Nevada border
Concentrated solar power
392 MW
First of three towers began
operating in 2013
No
More than 300,000 flat mirrors
that focus sunlight on three towers
Pacific Gas Electric and Southern
California Edison
$2.2 billion with $1.6 billion DOE
loan guarantee
BrightSource Energy, NRG Energy,
Google, and Bechtel
6.2 sq miles on Bureau of Land
Management land
California Valley
Solar Ranch
San Luis Obispo, Calif.
Photovoltaic
250 MW
October 2013
No
88,000 photovoltaic-panel-tracking
devices
Pacific Gas Electric
$1.6 billion with $1.2 billion DOE
loan guarantee
NRG Energy and SunPower, a solar
cell company
3 sq miles of development on 6.5
sq-mile site
Abengoa Solar
Solana Project
Gila Bend, Ariz.
Concentrated solar power
280 MW
October 2013
Yes: thermal energy storage
system, provides electricity for six
hours without generation
32,700 collector assemblies,
each with 28 curved parabolic
trough mirrors
Arizona Public Service
$2.0 billion with $1.5 billion DOE
loan guarantee
Abengoa, a global company based
in Spain
3 sq miles, including storage
facilities

3. 11CEN.ACS.ORG DECEMBER 16, 2013
MORE ONLINE
ple of years, it still produces only around
1% of U.S. electricity. But that could swiftly
change in the topsy-turvy world of energy.
Eachofthethreenewlyoperatingunits
embracesslightlydifferenttechnologies.
TheCaliforniaValleySolarRanchuses
88,000PVpanels,awell-knowntechnol-
ogyusedinrooftopsolarinstallationsthat
convertsthesun’senergydirectlyinto
electricity.Butunlikeusualrooftopunits
thatvaryfromacoupleofkilowattsofelec-
tricityonahousetoacoupleofmegawatts
onaWalmartorIKEAwarehouse,thesolar
ranchproduces250MWandisoneofthe
largestPVsystemsintheworld.Currently,
PVinstallations,overall,makeupabout
80%oftheutility-scaleprojects,SEIAnotes.
The Abengoa Solana project and Ivan-
pah Solar Electric Generating System are
concentrated solar power (CSP) systems
that together will produce more than 650
MW of electricity. Solana generates 280
MW by using a system of curved mirrors to
focus solar energy. Ivanpah generates 130
MW of electricity now but will grow to 390
MW next year as its system of flat concen-
trating mirrors, coupled with three power
towers, is finally complete.
Like PV, these CSP systems use sunlight
as fuel, but they focus the sun’s thermal en-
ergy to heat a conducting medium, such as
oil or molten salt. The medium carries heat
that is used to drive water to steam, and
like a conventional power plant, the steam
spins a turbine to do work, in this case gen-
erate electricity.
Because CSP uses a medium that retains
thermal energy, it can smooth out tempo-
rary generation fluctuations in sunlight
from storms or a passing cloud, which
interrupts PV-generated electricity pro-
duction. On the other hand, CSP systems
need intense light levels for its mirrors and
lenses to properly focus light and energy.
Therefore, CSP is usually limited to deserts
and other high-sunlight areas.
A key advantage of CSP is that it can
incorporate storage into its design. The
Solana project does this by storing thermal
energy in molten salts, from which it is
released over time. Solana can stretch out
electrical output for six hours without sun-
shine. Similar plants with storage are in the
works. Storage could be a game changer for
solar power.
But this solar expansion—whether PV
or CSP—has a steep price tag. These three
installations are billion-dollar projects:
The two CSP facilities run at around $2 bil-
lion each; the PV ranch costs $1.6 billion.
The estimates are fluid, and the CSP de-
velopers hope costs will drop with more
construction.
DOE HAS THROWN its weight behind
utility-scale solar installations, offering
$10.5 billion in loan guarantees to help
developers obtain funding for 11 projects.
About one-quarter of the total dollars back
up five CSP plants, two with storage. The
rest of the money supports six PV plants.
Of the 11, three are the large plants that
just came on-line. Two are smaller PV proj-
ects that received loan guarantees and are
in operation; they have a combined capac-
ity of 200 MW. The remaining six projects
that are in development will generate
1,700 MW.
One huge PV unit—the Desert Sunlight
Solar Farm—will produce 550 MW when
complete. It will be built by the thin-film
solar manufacturer First Solar with sup-
port and financing from a consortium of
solar developers. First Solar claims the fa-
cility will be the world’s largest solar farm.
Electric utilities like these big projects,
explains Bob Gibson, vice president for
education and communication at the Solar
Electric Power Association, a nonprofit
organization of utilities and solar-related
manufacturers. Utilities, he notes, are
familiar with the large size and can easily
manage these installations.
“Right now, there are 300,000 small
rooftop photovoltaic solar units operating
in the U.S. and feeding electricity into the
electric grid,” he notes. “That is a lot of in-
dividual transactions for an electric utility
to manage.”
The big units, Gibson says, might help
encourage a “solar evolution” for utilities
and might lift solar beyond the niche tech-
nology it has been in the past and elevate it
to coal-plant size.
Butthereareproblemswiththejumbo
sizeandlocationoftheselargeplants.The
Ivanpahproject,forinstance,willtakeup
asmuchas6sqmilesandissitedonthe
California-Nevadaborder.Itishundredsof
milesfromthehomesandbusinessesofthe
SouthernCaliforniapopulationitwillserve
andsoneedslong-distancetransmission
lines.Itisalsolocatedonfragiledesertlands
thatturnedouttobehometoseveralhun-
dredthreateneddeserttortoises.Thisfact
wasonlydiscoveredafterdeveloperBright-
SourceEnergybeganthe$2.2billionproject.
A preliminary survey estimated that just
35 tortoises were on the site, and Bright-
Source planned to move them. However, as
construction advanced, more were found,
and the number of tortoises reached some
300, according to Ileene Anderson, a biolo-
gist and senior researcher with the Center
for Biological Diversity, a nonprofit conser-
vation group.
BrightSource did not return CEN’s
calls seeking comments beyond prepared
statements. The firm estimated that the
cost to relocate these newly found tortois-
es worked out to $55,000 each. Addressing
these turtles also greatly stalled the proj-
ect, the company says.
Anderson says Ivanpah and several
other solar projects are part of a “green
rush” to obtain DOE project loan support
and federal tax breaks before they expire,
as well as to comply with California renew-
able energy requirements. As a result, she
says, many of these projects are not well
suited for their location.
OTHER SOLAR SITES faced similar delays
and restrictions as work began owing to a
poor site selection process, she notes. One
found ancient human cultural artifacts,
and several turned up more threatened
species living on proposed solar sites.
The proposed 250-MW Genesis Solar
Energy Project site, near Blythe, Calif., for
instance was found to be home to many
families of kit foxes. Developer NextEra
Energy Resources began harassing the fox
families to drive them from their burrows
at the site. Then state wildlife biologists
found several foxes to be suffering from an
outbreak of canine distemper, an unusual
virus for foxes, and began an investigation
that further delayed the solar project’s
construction.
“There are so many new PV and
CSP projects being discussed
today, I really can’t keep up.”
To read more about how desert ecosystems may be affect-
ed by new solar installations, visit http://cenm.ag/crusts.

4. 12CEN.ACS.ORG DECEMBER 16, 2013
COVER STORY
Groups like Anderson’s want to over-
haul and closely regulate the site selection
process. They also want to restrict solar
sites to a negotiated system of state and
federal “solar zones,” which is under de-
velopment and where solar projects will be
allowed and disruptions will be minimal.
“We want solar,” she says, “but our first
choice is to put them on every rooftop in
the Los Angeles Basin, not way out in the
fragile desert.”
Utilities, however, need the renewable
solar electricity. In a statement to CEN,
Southern California Edison, which is buy-
ing part of Ivanpah’s output, notes pres-
sure is on to buy solar, and the utility will
need to add thousands of megawatts of
new projects. The California Public Utili-
ties Commission prefers the generation
source be within the state, the utility notes,
and Ivanpah is just on the California side of
the California-Nevada border.
“It takes a whole lot of 3- to 5-kW roof-
top PV systems to make just one California
Solar Ranch or an Ivanpah,” notes Cara
Libby, solar research project manager at
the Electric Power Research Institute, a
utility-funded nonprofit.
THE RECENT GROWTH of utility-scale
projects as well as the new expansion of
CSP technologies has changed the solar
formula, she adds. “There are so many new
PV and CSP projects being discussed today,
I really can’t keep up.”
Libby describes a race between PV and
CSP technologies, both of which have
inherent advantages and problems. Cur-
rently, PV is winning on market share, with
about 80% of operating or under-construc-
tion utility-scale power plants. However,
that could change.
“If the first utility-scale 100-MW-plus
CSP projects are really successful, and we
build more of them, and the cost really
comes down nicely, CSP will perhaps be
more attractive than PV at that point,”
Libby says. “But who knows?”
Afewyearsago,shesays,itappearedCSP
systemswouldofferthe lowestcostand
havetheadvantageofan economyof scale,
similartoacentralpowersystem, aswellas
storage.
Utility-scale CSP with storage goes back
decades. The technology got its first big
start in the 1980s and ’90s when nine CSP
power plants were built in the California
desert. The Solar Energy Generating Sys-
tems (SEGS) produced 354 MW, making
it the largest solar power installation in
the world at that time. The company that
built the plants morphed into what became
BrightSource Energy, Ivanpah’s builder.
Initially,someoftheninefacilitiesinthe
complexhadtheabilitytoprovidethree
hoursofthermalenergystorage,butin1999,
SEGScaughtfireandthestoragesystemwas
damaged.Itwasnotreplacedwhenthefacil-
itywasrebuiltandimproved,accordingto
DOE.MostofSEGSisstilloperationaltoday.
“The SEGS plants have been
operating reliably, providing
steady power for over 20 years,”
notes Frank (Tex) Wilkins, an
energy consultant who is retired
but worked for DOE on ex-
perimental solar projects when
SEGS was under construction. “Their track
record convinced the financial sector that
there was little risk with the technology,
making it easier for today’s CSP industry to
get project financing.”
But,Libbynotes,bigCSPunitshavebeen
more difficult to permit and require sig-
nificant up-front investments. PV systems
also have the advantage of being built in-
crementally, she says, making construction
easier to start without a large cash outlay.
She notes that a few years back when the
recession hit and solar panels plummeted
in price, some solar builders switched from
proposed CSP installations to PV projects.
Energy analysts say the near future of
solar is unclear. “We see a lot of companies
doing internal wrangling,” an analyst says.
“Should we move forward with another
round of projects, or should we wait and
see how government policies develop?”
Gibsonadds:“Futureprospectsforsolar
aregood,butwithoutstaterenewableport-
foliostandards,thescaleoftheplantsis
likelytocomedown.Ithinkthereisasweet
spotforutilitieswhenbuildingnewplants
atabout15to20MW.PVpricesareunlikely
tocontinuetodrop,butnaturalgasprices
cangoupaswellasdown,and
coalseemstooriskyforinves-
tors.Nuclearisjustsoexpensive.
Allthisgivesaboosttosolar.”
Gibson and other analysts
think PV construction is more
likely in the near term, unless
storage appears to be a highly valuable at-
tribute, which will drive utilities to CSP.
Solarsupporterswereheartenedbya
recentannouncementbyXcelEnergy,a
Coloradoutility,topurchase170MWof
utility-scalePVpowerwithouttheentice-
mentoffederalorstateincentives.
“For the first time,” notes Xcel spokes-
man Mark Stutz, “our analysis determined
that utility-scale solar was competitive
in price with other sources of electricity,
including fossil-fuel-generated electricity,
even without a carbon penalty.” ◾
“Future prospects for solar are good, but without state renewable
portfolio standards the scale of the plants is likely to come down.”
BRILLIANT Flat
mirrors focus
sunlight on a tower
that is part of the
Ivanpah solar
installation.
BRIGHTSOURCEENERGY/GILLESMINGASSON/GETTYIMAGESFORBECHTEL