What We Know About Apple’s Secret Data Center: Project Isabel

February 21, 2017, 12:00 PM UTC

Apple is preparing to start construction on a new $50 million data center project as demand for its iCloud business—and all of those photos, documents, and music that it stores for its customers—continues to grow.

A contractor working for Apple (AAPL) submitted and then withdrew a permit earlier this month to build another data center complex codenamed Project Isabel at the company’s massive campus in Reno Technology Park.

An Apple spokesperson declined to comment.

The new 372,893-square-foot data center would include a build out of eight clusters as well as an administration building, garage and generator yard, according to a building permit accessed using Buildzoom, an online service that matches property owners with contractors.

The building permit was submitted to Washoe County on February 2 and withdrawn on the same day, according to the county’s records. Washoe County confirmed to Fortune that the permit was withdrawn by the contractor on the same day. Notes attached to the permit said changes could be made and the permit might be submitted again.

Project Isabel is located on a 345-acre parcel; the project is valued at $50.7 million.

Mike Kazmierski, president and CEO of the Economic Development Authority of Western Nevada, also declined to comment about Apple’s specific plans.

Northern Nevada, particularly the Reno-Sparks area on the western border has become a hotspot for data centers because of its abundance of land, climate, proximity to a fiber optic network, and access to clean energy sources such as solar and geothermal, Kazmierski said.

Switch, which already operates a massive cloud center in Las Vegas, is building the largest data center in the world at the nearby Tahoe-Reno Industrial Center. The Switch center, which sits on a 2,000-acre campus, is designed for up to 7.2 million square feet of data center space and 650 megawatts of power.

“We also have other data center projects that are looking at the region now,” Kazmierski said. “In the world of data, it’s just going to continue to explode; and we’re more and more a player in that data center world.”

Apple, Rackspace and Switch are the biggest data center operations in Northern Nevada.

Apple’s first set of data centers to be constructed at the Reno Technology Park—dubbed Project Mills—was approved in 2012. Apple received $89 million in tax abatements over 10 years from the Washoe County Commission in 2012 for its data center project.

Before the buildings were completed, Apple applied for permits to build another data center complex codenamed Project Huckleberry that is adjacent to Project Mills.

Now, Apple appears ready to begin building again. But because the company applied for permits and then withdrew those permits the same day, it’s unclear if the project’s size and scope might change.

Under One Roof

Apple’s iCloud business stores users’ contacts, calendars, photos, and documents and keeps that information up-to-date, across all of their Apple devices. Third-party apps can also use iCloud to store and sync documents.

That’s a lot of data.

An Apple white paper released in May 2016 revealed that the company actually relies, in part, on Amazon Web Services’ and Microsoft’s Azure public cloud services. Businesses that don’t want to invest in their own data center infrastructure can rent out compute power, storage, and networking bandwidth from public cloud companies like AWS.

But as Fortune‘s Barb Darrow noted last year, noting reports that Apple might move some workloads to Google’s cloud, given Apple’s famous insular nature, it’s hard to see it relying on these big players in the long term. It seemed more likely that Apple was using third-party clouds as a stopgap while it got its own cloud data centers in order.

It’s not surprising that Apple has been spending millions of dollars to build out its own data center infrastructure.

The Data Center-Renewable Energy Connection

Information contained in the submitted—and then withdrawn—permit does align with Apple’s recent renewable energy activities. NV Energy, which is owned by Warren Buffett’s Berkshire Hathaway, announced in January that it had reached an agreement with Apple to build 200 megawatts of additional solar energy in Nevada by early 2019. The projects are meant to support Apple’s renewable energy needs for its Reno data center, NV Energy said at the time.

Apple is investing in solar as part of its ambitious pledge to power all of its operations worldwide with renewable energy.

As of January 2016, the company was sourcing or generating enough renewable energy to cover 93% of the electricity it uses in its facilities worldwide. Every one of Apple’s data centers is run completely on clean power, which includes energy generated by solar panels, biogas, and wind.

The manufacturing and transport of Apple products accounts the majority of the company’s carbon footprint. However, it’s investment in renewable energy—by either buying from a power provider or in some cases, building its own solar farm—has helped reduce its reliance on fossil fuel energy to power its facilities to nearly zero.

As demand for cloud services rise, so does the need for data centers. To maintain its 100% clean-powered data center goal, Apple has to looks for new sources of renewable energy when it adds more facilities.

The project with NV Energy will bring the power provider’s total to more than 529 megawatts of new solar resources in construction in Nevada or under review for approval.