Amazon goes nuclear, acquires Cumulus Data's atomic datacenters for $650M

E-commerce giant on the hook for 480MW of power from Susquehanna plant

Amazon Web Services on Monday added a nuclear-powered datacenter campus to its public cloud empire as part of a $650 million deal with Talen Energy – an owner and operator of electricity generation and transmission facilities in the US.

The acquisition will see AWS take possession of a datacenter complex named Cumulus that Talen built adjacent to its 2.5 gigawatt Susquehanna nuclear power plant in northeast Pennsylvania.

When Cumulus opened in early 2023, it boasted 48 megawatts of capacity, and Talen planned to grow the facility to 475 megawatts upon completion. Under Amazon's ownership, the facility could become even larger.

Under the terms of the sale, Amazon will acquire the Cumulus facility and associated power infrastructure. Another facility on site, the Nautilus Cryptomine, will remain jointly owned by Talen and an outfit called TeraWulf.

It's not clear what the sale to AWS will mean for tenants already in the Cumulus facility. The Register asked Talen Energy for comment and we'll let you know if we hear anything back.

We do know that Talen won't get all of the cash up front. The electricity biz is due to receive $350 million when the deal closes and an additional $300 million which will be paid out upon the completion of development milestones over the course of 2024.

The energy provider will also continue to furnish Amazon with direct access to juice produced by the nuclear power plant. In coming years AWS expects to have a maximum of 960 megawatts at its disposal. The cloud giant also has a one-time option to cap its commitments at 480 megawatts.

The scope of Amazon's datacenter project remains unclear – an AWS spokesperson declined to comment on its build out plans.

The deal marks Amazon's latest investment in carbon-free and renewable energy to power its growing datacenter footprint. Last month the e-commerce leviathan signed a power purchase agreement with a wind farm in Gilliam County, Oregon. The operation, run by Avangrid, involves 40 turbines capable of churning out a combined 90 megawatts of power, or about 2.4 megawatts each – when the wind is blowing just right.

Amazon has also explored alternatives to traditional power plants. Early last year, it revealed that it planned to power three sites using about 75 megawatts of natural gas fuel cells and had an option to use the tech on a fourth site. These generators work similarly to the hydrogen fuel cells found on spacecraft but produce CO2 alongside electricity and water.

While these generators will initially run on natural gas, they can be converted to run on hydrogen – something that colocation specialist Equinix has been exploring as part of a collaboration with the National University of Singapore.

The nuclear option

Amazon is not the only large-scale datacenter operator considering nuclear energy.

Over the past year we've seen a number of projects targeting the use of a novel type of atomic power called small modular reactors.

As their name suggests, SMRs are much smaller and produce less power than the enormous reactors found at the Susquehanna site. What makes them attractive is their modularity and potential for build costs well below the sums required for other designs.

However, no functioning SMR has yet been built, and analysts predict it will be a while before we see these miniaturized reactors in action. In 2022 The Register interviewed Omdia analyst Alan Howard, who estimated that it could be 10 to 15 years before SMRs are deployed to power datacenters.

The cloudy future of SMRs hasn't stopped datacenter operators considering their use though. Last northern summer we reported on a Virginia datacenter campus that aimed to power its bit barns using a combination of SMRs and "green-hydrogen" generated onsite.

Bahnhof, a Swedish datacenter that supposedly hosted WikiLeaks at one time, is also investigating the use of SMRs to power a datacenter being built in the Hjorthagen district of Stockholm.

Microsoft is also exploring SMRs.

While the tech and energy industries explore SMRs, we expect cloud providers like AWS, Microsoft, and Google will continue to lean on power purchase agreements with wind, solar, nuclear and even geothermal to meet their energy needs and ambitious sustainability targets. ®

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