Decarbonizing the Cloud With Nuclear Energy

How can nuclear energy fuel a cleaner cloud?

Hana Chabinsky

When you upload a document to a cloud storage service like Google Drive, Apple iCloud, or Dropbox, your document isn’t uploaded to an invisible cloud or another immaterial entity.  

The data representing that document is stored in a data center: a physical building designed to house computer systems and associated components. 

In both business settings and everyday life, reliable data is a prerequisite for day-to-day operations and widespread human connection. This means that data centers and the nebulous “cloud” must operate at all hours of the year, and therefore rely on significant amounts of energy. 

Demystifying the Cloud 

Despite their casual usage in daily conversation, words like “data” and the “cloud” have serious implications for how we live our lives, as well as ongoing efforts to document and ultimately reduce the environmental impacts of data centers. 

To ground the cloud in reality, definitions are invaluable. As described by Microsoft, the cloud is the globally interconnected network of millions of computers in data centers. These computers work together to store and manage data, run applications, and deliver content and services.

Given the ease and ubiquity of this process, the cloud assumes a near-mystical quality. Many of us rely heavily on the cloud and associated data centers for our daily needs, often with little thought of the energy that follows a few clicks and a simple upload.

But this global network depends on physical computers and buildings, amplifying concerns about the carbon footprint and energy intensity of data centers that support the cloud. 

Private, Public, and Hybrid Clouds   

Microsoft’s definition of the cloud better describes a “public” cloud, which is the most common type of cloud computing. In a public cloud, servers, storage, and other cloud resources are owned and operated by a third-party cloud service provider and delivered via the Internet. To maintain more control over their data, however, some organizations are investing in private or “hybrid” cloud computing.   

Private clouds consist of cloud computing resources used exclusively by one organization. Subsequently, they can be located on-premise at a company’s existing data center or hosted by a third-party service provider, but always maintained on a private network.  

Hybrid clouds combine private, on-premise computing with a public cloud, which can be more flexible and cost-effective for some organizations.       

The Shift Toward Cloud Data Centers 

As the ​​market size for cloud computing expands, more companies are comparing these options and ultimately shifting toward cloud data centers, which house IT infrastructure for shared use by multiple customers through an Internet connection. 

Compared to traditional enterprise data centers, which tend to utilize more energy-intensive IT hardware and cooling systems, cloud data centers can use space and energy more efficiently, ideally reducing carbon emissions without implicating data storage. 

Like any other kind of data center, however, these facilities still rely on physical components and infrastructure. Consequently, the actual “sustainability” of cloud data centers depends on several factors including their size, physical location, energy sourcing, and workload configuration, which describes the efficiency of cloud services used to store data.    

Nuclear: An Alternative Energy Source for Cloud Data Centers 

For companies turning to the cloud as a long-term storage strategy, nuclear is a promising energy source, particularly as global data consumption increases. 

Although data center electricity consumption has been flat since 2015, the demand for data—and clean energy to sustain this demand—is growing worldwide. In response, many of the big names in the information and communication technology (ICT) space have already committed to carbon neutrality and renewable energy purchases. 

Carbon neutrality, also called “net zero,” occurs when a business or country balances its total CO2 emissions to zero by removing an equivalent amount of CO2, using carbon reduction technologies or nature-based solutions like reforestation. 

Renewables like wind and solar can help data centers reach carbon neutrality, but these energy sources function only intermittently, depending on the time of day and weather. When renewables are unavailable, many data centers draw from “dirty” electrical grids reliant on fossil fuels. Moreover, the infrastructure for renewable energy is an added cost not all organizations have the resources and capital to invest in.

Here, nuclear can provide year-round, zero-carbon power to meet data centers’ needs when renewables cannot. As a truly carbon-free energy source, nuclear allows companies to fully eliminate their carbon emissions, as opposed to counteracting their emissions with a complex (and often expensive) balance of technologies and initiatives. 

How Much Energy Does the Cloud Consume?   

As data centers explore nuclear as an alternative source of clean energy, researchers are developing better tools to calculate energy consumption by the cloud.  

This is a complicated calculation—one that depends on the data center’s size and business model, the cloud computing service, the protocols used to report carbon emissions, and the physical transmission of data.  

Physically, several steps must occur to transmit and store data in an off-site center. Fiber optic cables require energy to transport data to a data center; and once data arrives at the facility, data is stored multiple times on hard disks. These processes generate heat, and carbon-intensive air conditioners run constantly to prevent the equipment from overheating.  

Researchers have yet to agree on the precise numbers of this journey, but the transmission and storage of data in a cloud data center requires around 3-7 kilowatt hours (kWh) per gigabyte: about a million times more than the energy used to save data to a local hard drive.  

Based on available data, the U.S. Department of Energy reports that some of the world’s largest data centers require more than 100 megawatts (MW) of power capacity: enough to power around 80,000 U.S. households

While some of the largest cloud data centers, called hyperscale data centers, are generally regarded as more efficient, their sheer size can have major impacts on local power grids. Annually, hyperscale facilities require up to 100‑150 MW of grid capacity and consume hundreds of gigawatt hours (GWh) of electricity.   

Decarbonizing the Cloud With Nuclear Energy 

Given the lack of accurate information about data center energy consumption, contextualizing these numbers can be challenging—but their energy demands and environmental impact are undeniable. 

As we develop better tools to obtain and refine these statistics, nuclear energy offers several advantages for cloud data centers and other large carbon emitters, including:  

  • Dependable, 24/7 year-round energy, independent of weather conditions or time of day. 
  • Highly efficient and clean power, which also aids the transition to more efficient hyperscale data centers.  
  • Scalability and affordability through the use of small modular reactors (SMRs), which can be co-located with data center campuses due to their compact, scalable design.  

As companies consider the future of nuclear-powered data centers, nuclear-powered cloud computing facilities could also gain traction. Already, in January of 2023, Cumulus Data announced the completion of the shell for its first 48 MW, 300,000-square-foot data center, powered on-site by a direct connection to the 2.5 GW Susquehanna nuclear power station in northeast Pennsylvania.  

While the Susquehanna Station is the only completed nuclear power plant with a direct connection to a data center, similar projects are expected to follow, evidencing the value of nuclear as an integrable solution for data centers. In March of 2023, Last Energy secured contracts for 24 PWR-20s in the UK as part of three industrial partnerships, which include a developer of a hyperscale data center. 

The three core features of nuclear energy—reliable, zero-carbon, and low-cost—could attract cloud computing facilities and other data centers in the coming years. Given these assets, how can we deploy this energy source on-time, on-budget, and at scale? 

Powering Data Centers With the PWR-20 

In addition to the overarching benefits of nuclear energy, the PWR-20—a 20 MWe modular microreactor designed by Last Energy—offers two additional benefits for data centers. 

1. Rapid, Scalable Delivery

The PWR-20 is fully modular and standardized, meaning that every component and connection is factory-fabricated, tested under controlled conditions, and contained in standardized modules. This accelerates both the assembly of the PWR-20 and the distribution of clean power to data center customers, allowing them to scale the number of PWR-20 units to match their future energy demands.

The PWR-20’s scalable design also addresses the concern of downtime in the event of a plant outage by providing at least N+1 redundancy, meaning there are enough resources to provide backup and failover capabilities. For example, if a data center requires 100 MW of electricity to run, Last Energy commissions six power plants—20 MWe each—to provide at least 120 MW of electricity, eliminating the risk of downtime.  

2. Resilient Electric Interconnection

With a clear and finite delivery timeline, the PWR-20 offers a solution that stands out as a “distributed energy solution,” meaning that customers purchase power from Last Energy and connect directly to the source of power generation, rather than purchasing energy from the utility.  

This strategy eliminates the risk of a delayed electric interconnection while increasing data centers’ resilience to the volatility of grid prices. With nuclear as a source for consistent baseload power, data centers have enough resources to achieve their uptime requirements, provide failover capabilities, and minimize the risk of downtime.  

Comparison of Energy Solutions for Data Centers


Parting the Cloud and Looking Toward the Future 

As companies and countries consider applications of nuclear to the cloud, the Susquehanna Station is an exciting case study and potential blueprint, with similar projects soon to come. 

Given their size and global reach, cloud service providers such as Google, Amazon, and Microsoft are pivotal players in the push toward carbon-free data centers. 

Amazon outlines a goal to build “sustainability in the cloud,” redesigning data centers for optimal power and cooling efficiency. Similarly, Microsoft plans to shift to a 100% renewable energy supply to support its data centers by 2025 and to remove all of its carbon emissions by 2050. 

However, even if ICT companies commit to carbon neutrality and match 100% of their annual data demand with renewable energy purchases or certificates, wind and solar are naturally intermittent. Ultimately, this means data centers still need consistent, zero-carbon power to meet their annual demands, which SMRs are uniquely equipped to provide.  

Nuclear technologies like SMRs enable innovative paths to carbon-free data centers, including 24/7 carbon-free energy (CFE), first introduced by Google in 2018. By 2030, Google aims to source “carbon-free” electricity on a 24/7 basis, which includes deriving electricity from renewables as well as nuclear power.  

Several ICT leaders predict that nuclear-powered data centers are on the horizon and vital to achieve an environmentally-clean footprint across the industry. After all, millions of people utilize the cloud every day, and hundreds of cloud data centers work around-the-clock—and emit significant amounts of carbon—to fulfill their needs. 

Nuclear energy solutions like the PWR-20 present an opportunity to reflect on the physical and environmental impacts of the cloud, and to shift from carbon neutrality and dependence on renewables to truly carbon-free power.