Solar power—and battery storage—take off at Edwards Air Force Base

California's Edwards Air Force Base has a history of innovation&mdsah;it was home to Chuck Yeager's flight that broke the sound barrier—and it's now a leader in renewable energy technology, with the installation of a new 807 MW solar project, accomp

By Robin Brunet

Thomas Rademacher, Chief – Environmental Management Division of the 412th Civil Engineer Squadron at Edwards Air Force Base in California, explains why renewable energy projects are attractive to the military. “Energy, regardless of where it is sourced, is a primary driver for Department of Defense resilience,” he says. “Energy sourced as with solar is based on a commodity that does not have exposure to geopolitical or petrochemical processing needs.”

Rademacher makes these observations in the wake of the successful completion of the $2.4 billion Edwards Sanborn Solar and Energy Storage Project, 57 percent of which is located on the northwest corner of Edwards Air Force Base (EAFB) and which is currently generating 807 megawatts of electricity for clients, as well as a substantial amount of energy storage.

In total the facility, which was built in collaboration with Terra-Gen, consists of 1.9 million solar panels and will produce up to 1,300 megawatts (MW) of power to the California Independent System Operator (CAISO) grid. Under current estimates, this could supply power to over 238,000 homes and displace more than 320,000 tons of CO2 emissions annually.

The solar array itself, which is augmented with a battery storage capacity of over 3 gigawatt hours, spans over 4,600 acres and is the largest project of its kind in U.S. Air Force History.

In addition, the facility is intended to lower electricity costs for the civilian workforce, EAFB residents, and surrounding communities while providing power grid stability.

The Air Force estimates the project could yield cash rent of over $75.8 million throughout a 35-year lease arranged under the Edwards Solar Enhance Use Lease Project, a unique land management agreement that is the largest private–public partnership within the Department of Defense.

The base itself has a storied history; it was home to Chuck Yeager’s flight in 1947 that broke the sound barrier when the experimental XS-1 rocket-plane Yeager was flying dropped away from the B-29 that carried it aloft, and he fired its liquid oxygen rocket chambers to exceed the speed of sound.

Fast forward to more recent times, the solar project on the base originated in 2007, when the Air Force Real Property Agency released the Renewable Energy Enhanced Use Lease Opportunity Summary Report. “EAFB was identified and recommended as a top opportunity for solar development because of the strong renewable energy market, and because Edwards has access to transmission, flat under-utilized land, and some of the world’s best solar radiation resources,” Rademacher says.

Rademacher goes on to note that, “EAFB sits within the highest solar radiation in the contiguous United States. The radiation resources of the area made it highly suitable for solar development and attractive to commercial solar development, as well as out-leasing of this property.”

But as desirable as the site was, Simon Day, Vice-President and head of solar development for Terra-Gen LLC, one of the largest integrated and independent power producers in the U.S., points out that coordinating with all the various interested parties presented one of the biggest challenges of the project.

“Permitting was undertaken through two agencies, the United States Air Force, which complied with the National Environmental Policy Act, and Kern County, which complied with the California Environmental Quality Act,” he says. 

An Environmental Impact Statement and Environmental Impact Report was undertaken to analyze the project’s potential effects on the natural and human environment and identify mitigation measures and alternatives. Natural and cultural resources, air quality, noise, water quality, waste generation, geology, socioeconomic and other factors were studied.

The next phase of the project unfolded in 2016 with a feasibility analysis highlighting the unique siting of EAFB, with capacity on the existing wind hub transmission that could absorb the amount of solar energy to market in the CAISO service territory.

Rademacher says, “Once it was determined that the opportunity would be pursued, extensive collaboration with stakeholders was undertaken, starting with Kern County, in addition to numerous Federal Agencies, state and local governments, and federally recognized Indian tribes.”

	Renewable energy projects, such as the solar project at Edwards Air Force Base, are attractive to the military, as they can aid in the resilience of the U.S. Department of Defense. Energy sourced with solar is based on a commodity that does not have exposure to geopolitical or petrochemical processing needs.

In 2017, the Air Force selected as the project’s developer San Diego-based Terra-Gen, which is known for bringing affordable clean energy and meaningful economic growth to the U.S. communities in which it operates. Terra-Gen is also an end-to-end project development, financing and operating company: these services were crucial to the EAFB project (which was divided into two phases), which required financing on a huge scale.

John O’Connor, Terra-Gen’s Chief Financial Officer, says of the first phase (which was comprised of 346 MW of solar modules and 1,501 MWh of battery storage), “Working collaboratively, we were able to structure and deliver financing on a scale not previously seen for an integrated solar and energy storage project.”

Financing included $804 million in senior secured credit facilities comprising a $400 million construction and term loan facility, a $328 million tax equity bridge facility, and a $76 million construction and revolving letter of credit facility. JP Morgan provided the tax equity commitment, with Deutsche Bank leading the construction and term financing.

Financing of the second phase included $959 million in senior secured credit facilities comprising a $460 million construction and term loan facility, a $403 million tax equity bridge facility, and a $96 million construction and revolving letter of credit facility. U.S. Bank provided the tax equity commitment for the project, with BNP Paribas, CoBank, ING, and Nomura Securities leading the construction and term financing.

The $2.4 billion Edwards Sanborn Solar and Energy Storage Project, 57 percent of which is located on the northwest corner of Edwards Air Force Base, is currently generating 807 megawatts of electricity for clients, as well as a substantial amount of energy storage.

Terra-Gen CEO Jim Pagano notes that “the second phase deploys an innovative off-take structure that was well received in the financing markets and allowed us to raise the capital necessary to progress the construction.”

Without going into detail, Rademacher notes that between 2018 and 2023 “Environmental and other site challenges contributed to a longer delivery timeline for the project and promotion of the delivery; these factors presented an optimal approach to the final delivery and update for the facility.”

Rademacher also discusses the security considerations in developing a solar project on a military base. “The Civil Engineer Group determined the best location with factors considered including avoiding mission conflicts, access to necessary utility transmission, environmental resource constraints, and topography. Also, base access issues had to be worked out early on to ensure security was maintained.

“Access to the project site was restricted and segregated from the rest of the base,” he continues. “In other words, once the boundary fence was set up for the site, workers were no longer required to go through the base access process.”

Day adds, “The project had to secure and build a 14 mile, high voltage transmission line, which was a challenge. This line connected the project’s electrical substations to the grid at the Windhub substation. The area was heavily developed with wind projects, and Terra-Gen spent two years developing and securing the route that could get back to the substation interconnection point.” 

	The Edwards Air Force Base solar facility, which was built in collaboration with Terra-Gen, consists of 1.9 million solar panels and will produce up to 1,300 megawatts of power to the California Independent System Operator (CAISO) grid.

Terra-Gen selected Mortenson as the full engineering, procurement, and construction (EPC) contractor for both the solar and energy storage aspects of the project. Site construction began in early 2021, and Mortenson lists some of the elements that went into the development of the array: “Over 98 miles of MV wire; over 361 miles of DC wire; and over 3,000 MWh of battery capacity and 120,720 batteries installed at completion.”

All of this required the services of 890 people on site, and Mortenson CEO Dan Johnson notes that, “these skilled craft team members put in over one million hours of consecutive work without a recordable injury.”

First Solar supplied the solar modules, and LG Chem and Samsung supplied the batteries while BYD also supplied some of the batteries at Sanborn. “The panels were placed on single axis trackers manufactured by NexTracker of Fremont, California,” Day says. Inverters for the project are from Power Electronics.

The first 735 MWh of battery storage came on-line in the third quarter of 2021 with the balance fully operational by the second quarter of 2022. The second phase, composed of 410 MWac (megawatts, alternating current) of nameplate solar capacity (358 MWac at the point of interconnection) and 1,786 MWh (megawatt hours) of battery storage, was completed earlier this year. In total, the Edwards Sanborn project can place up to 1,300 MW of solar and energy storage onto the grid at any one time.

Future project phases that are currently in development will interconnect an additional 2,000 MW of solar and energy storage to the CAISO grid. When complete, the Edward Sanborn franchise will provide up to 3.35 gigawatts of solar storage onto the grid.

In the meantime, Day discusses the many economic benefits the project has delivered.  “Mortenson spent over $315 million on local wages in this part of southeast Kern County, paid more than $22 million in local sales and use tax to Kern County, and an additional $11 million to the state,” he says. The project will pay more than $135 million in property taxes during its life, given its large energy storage component ($100 million in the first 20 years).

Moreover, the project employs 36 O&M staff in Mojave and a further eight remote operations staff in the community of Hinkley, California. This staffing is in addition to Terra-Gen’s existing staff of more than 80 people in Mojave/Tehachapi.

As for clients, the project has more than 17 different power purchase agreements, including with Starbucks to power all of its Southern California coffee shops as well as with a brand name California grocery store chain. “Other contracts with SCE, PG&E and Community Choice Aggregators Clean Power Alliance and San Jose Clean Energy also exist,” Day says.

When the 412th Test Wing unveiled the Edwards Sanborn Solar and
Energy Storage Project earlier this year, Andrew Mayock, White House Federal Chief Sustainability Officer, summarized its success by stating it was “a triple win: it’s good for resilience, it’s good for energy security, and it’s good for the economy. We commend the U.S. Air Force for its leadership and for showing what’s possible when we invest in our nation’s clean energy future.”

Q4 2023