POWER August 2014 - 28

PLANT OF THE YEAR
1. Simply enormous. The Ivanpah site
near Las Vegas covers 3,500 acres of the Mojave
Desert. Each heliostat field is more than
a mile across. Courtesy: NRG
100-MW units and four for a single 200-MW
unit. Construction was set to begin in 2009,
with completion slated for 2012. As is often
the case with power plant development, especially
large, groundbreaking projects like
Ivanpah, those dates would slip.
In October 2007, BrightSource was invited
mal plant. In practice, the plant has been even
more water-thrifty than expected: Through
the first hundred days of operation, it used
only 6% of its allotted 100 acre-feet of water,
just under 20,000 gallons. The plant's only
water needs are boiler makeup and mirror
cleaning. Water is sourced from two wells on
the site and purified for use.
Ivanpah's operating parameters are given
in Table 1.
Development
Oakland, Calif.-based BrightSource began
development of Ivanpah in 2006. At the time,
the CSP sector-especially solar towers-
was still nascent, with only a few relatively
small demonstration projects in operation.
But BrightSource already had substantial
experience developing solar thermal technology,
including the 6-MWt Solar Energy Development
Center in Israel's Negev Desert,
which came online in 2008. Ivanpah would
follow a similar design-but on a much larger
scale. Originally planned for 400 MW, the
proposed site at Ivanpah dwarfed those earlier
systems.
After selecting the site, BrightSource
filed for prequalification for the DOE's Loan
Guarantee Program in December 2006 and
submitted its application for certification with
the California Energy Commission (CEC) in
August 2007.
The design for Ivanpah underwent a
number of changes during development. As
originally proposed, it would have involved
10 smaller power towers, three each for two
28
by the DOE to submit a formal application for
a loan guarantee, which was completed the following
November. The application proceeded
swiftly by DOE standards, and the LPO would
give conditional approval for $1.37 billion in
loan guarantees (an amount later increased to
$1.6 billion) in February 2010.
The site for Ivanpah, on Bureau of Land
Management (BLM) land near Interstate 15,
was carefully chosen to leverage a number
of advantages. Foremost among these was
supplying renewable energy to California's
investor-owned utilities, which are required
to obtain 33% of their electricity from renewable
sources by 2020. Power purchase agreements
(PPAs) for Ivanpah's production were
signed with Pacific Gas & Electric (PG&E,
for 118 MW to 126 MW from Unit 1 and 126
MW to 133 MW from Unit 3) and Southern
California Edison (SCE, for 126 MW to 133
MW from Unit 2) in 2009.
The Mojave Desert location enjoys some
of the highest insolation in the United States
(around 2,700 kWh/m2/yr), making it ideal
for CSP. It is also close to the 500-kV Eldorado-Lugo
transmission line, which supplies
electricity to Southern California. This meant
that relatively little transmission infrastructure
was needed despite Ivanpah's remote
location. Only one new substation and upgrades
to an existing substation and a 115-kV
line (upgraded to 220 kV) were ultimately
needed. Finally, natural gas for backup and
startup generation could be supplied from a
pipeline just half a mile to the north.
Construction
In September 2009, BrightSource selected
Bechtel as the EPC contractor for Ivanpah.
In December, Bechtel signed a project labor
agreement with the State Building and Construction
Trades Council of California and the
Building & Construction Trades Council of
San Bernardino and Riverside counties to ensure
that California's local union workforce
would benefit from the project. Ultimately,
on-site construction staff would peak at about
2,650, the majority of whom were local.
Meanwhile, the California Public Utilities
Commission (CPUC) approved the PPA with
PG&E in August 2009 and the contract with
SCE the following August.
The enormous size of the site and its impact
on the desert environment proved to be
the first roadblock. Among the concerns was
a need to relocate desert tortoises, which
www.powermag.com
Table 1. Key operating parameters
for Ivanpah Solar Electric Generating
System. Ivanpah uses concentrated
sunlight to provide the heat for its steam generators.
Source: NRG and National Renewable
Energy Laboratory
Parameter
Output
Boiler inlet temp
Steam temp
Steam pressure
Heliostats
Heliostat solar-field
aperture area
Tower height
Net generation (first
100 days)
Gross efficiency
Ivanpah
392 MW (gross), 377 MW
(net)
368F
1,013F
2,479 psi
173,500 (each holds two
mirrors)
2,600,000 m3
459 ft
116,000 MWh
28.72%
are native to the area and federally listed as
threatened under the Endangered Species
Act, and avoid damage to several protected
plant species. In February 2010, BrightSource
agreed with the CEC and the BLM to
revise the initial design to reduce the overall
footprint. This was done largely by reducing
the number of power towers from 10 to three.
The new towers would also be substantially
taller: 459 feet vs. 371 feet (Unit 3) and 262
feet (Units 1 and 2) in the initial design.
This more focused layout would reduce
the overall footprint by about 12% and reduce
the footprint of the larger Unit 3-where the
greatest environmental concerns lay-by
about 23%. The new design would have a
slightly smaller output but would need 40,000
fewer heliostats (Figure 2).
The new approach passed muster with the
CEC, which issued an operating license in
September 2010, and the BLM, which approved
the project in October. BrightSource
and Bechtel broke ground shortly thereafter.
With licenses now in hand, NRG Energy
stepped forward to join the project, committing
up to $300 million in funding. NRG
Renew had been on a shopping spree in California
and Arizona, having agreed that June
to acquire nine solar development projects
from US Solar, an affiliate of Arclight Capital
Partners. Ivanpah would be its largest solar
project to date.
One last partner would come aboard, but it
came from a sector not normally known for
investments in power generation. Yet for several
years prior, Google had been investing
more than $300 million in various renewable
energy initiatives, including $10 million in
BrightSource. None of its prior solar investments
were the size of Ivanpah, however. In
POWER | August 2014
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POWER August 2014

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