The Terra Economy: Terabytes (TB) and Terawatts (TW)

Big Data, Big Power

Data centers are the physical backbone of the ubiquitous digital infrastructure that supports Big Data thus our data-reliant global economy. A data center is a facility that houses computing resources used by organizations to collect, store, process and provide access to data. The major components of a data center include:

• Computing infrastructure: different types of servers (rack, blade, etc.)

• Storage infrastructure: different types of storage devices (block, file, etc.)

• Network infrastructure: includes cables, routers, switches, firewalls, controllers, gateways, etc.

• Support infrastructure: power system (utility lines and back-up resources), thermal management system (chillers, HVACs, etc.) and fire suppression system (dry pipe fire sprinkler system, clean agent fire sprinkler agent, etc.)

This article focuses on data center power systems.

With 44 zettabytes (44 trillion gigabytes) created in 2023 alone, data center markets are growing to keep pace. These data centers consumed 220 terrawatt-hours (TWh) of electricity globally. Being among the top energy consuming sectors, it is no surprise that the size of a data center is typically expressed in terms of its power consumption. A data center can consume over 100 megawatts (MW). The United States hosts more than 50% of the world’s data centers and contributes commensurately to their energy consumption.

The nature of a state’s electricity market plays a big role in a data center’s ability to decarbonize its electricity supply. In a deregulated market, end consumers can choose their energy suppliers typically referred to as consumer choice while in a regulated market, vertically integrated utilities are responsible for the entire electricity value chain namely, generation, transmission and distribution. As such, the decarbonization efforts of end users in a regulated market are largely tied to those of their utility. Renewable energy credits (RECs) are a tool that can be used to get around this limitation. More on RECs later. Did you know that the leading data center markets in the US, based on power consumption, are Northern Virginia, Dallas and the Silicon Valley? It is worth noting that Virginia is a deregulated electricity market for industrial consumers, Texas is a deregulated market and California is largely deregulated. This can be interpreted as a more manageable path to electricity decarbonization for these data centers markets.

Advanced power systems for data centers

With the proportion of energy demand of data centers to global energy consumption expected to increase exponentially, there is great need to take another look at the power systems of data centers given their carbon footprint (CFP). Data centers and data transmission infrastructure were responsible for about 0.6% of total global greenhouse gas (GHG) emissions in 2020. The data center industry is currently facing both internal and external pressure to reduce its scope 1,2 and 3 greenhouse gas (GHG) emissions while meeting its increasing energy consumption, a no mean fete to achieve. Some of the top questions for data center owners and/or operators are:

1. For data centers in regulated markets: is your utility’s integrated resource plan (IRP) sufficient to meet your decarbonization targets?

2. For data centers in deregulated markets: is your distribution-only utility’s long-term procurement plan sufficient to meet your decarbonization targets?

3. For data centers in both regulated and deregulated markets: can your utility provide the best financial and resiliency value for your data center?

The power systems of data centers are typically designed to maximize reliability. While a data center’s base load is served by a utility line, utility supply is usually backed up by interruptible power supplies (UPSs) and diesel generator sets (gensets). The UPS serves the load for up to 15 minutes during grid outages while the diesel genset ramps up to full capacity to replace grid supply. Depending on redundancy needs of a facility, there can be multiple layers of electrical circuits - multiple utility connections, UPSs and diesel gensets. UPSs have traditionally leveraged lead-acid batteries (LABs) but other battery technologies including lithium-ion batteries (LIBs) and nickel-zinc batteries (NZBs) have been gaining prominence. Some of the leading UPS providers include EnerSys (LABs), Vertiv (LIBs) and ZincFive (NZBs).

Scope 1 emissions of data centers stem from back up diesel gensets while scope 2 emissions originate from the electricity supplied by the utility. Scope 3 emissions emanate from the supply chain associated with the equipment and electricity generation and is the most difficult category to combat given its complexity. Mitigation of scope 3 emissions for data centers shall be addressed in a future issue of this series.

Scope 1 GHG emissions

Scope 1 emissions are considered the low hanging fruits when it comes to GHG emissions reduction targets. The best alternative to diesel generators are energy storage systems (ESSs). ESSs have largely been limited to serving as UPSs in the past but their potential to replace diesel gensets is coming into serious consideration. This has been made possible by the advancement in energy storage technologies yielding cost-effective ESSs capable of discharge durations exceeding 4 hours. Currently, lithium-ion battery technology is the front-runner for data center applications but other battery, supercapacitor, flywheel and even thermal energy storage technologies have received some attention too.

Scope 2 GHG emissions

Scope 2 emissions can be mitigated through demand side or behind-the-meter (BTM) solutions such as:

1. Mini-grid solutions: solar plants leveraging various energy storage technologies including batteries and super capacitors.

2. Localized small modular reactors (SMRs): the power capacity of an SMR can range between 1 MW and 300 MW.

Grid-tied and off-grid mini-grids leveraging solar plus storage solutions have long been utilized to boost resiliency by mitigating outages; to reduce electricity cost by eliminating demand charges and to provide electricity access to areas without utility lines. The figure below depicts a block diagram of an advanced data center power system that leverages a grid-tied solar plus energy storage mini-grid.

The projected data center power demand has gifted nuclear power an unexpected renaissance. Proponents of nuclear power have presented both large and small nuclear reactors as the best candidates to meet the growing data center energy demand, citing their superior availability as the technology is fully dispatchable (available when needed). For comparison, renewable sources such as solar require coupling with an energy storage system to be dispatchable. That said, solar power generation has notable benefits such as safety, which nuclear power generation has struggled with in the past. The smaller footprint and potentially lower safety risks of small modular reactors (SMRs) offer a largely viable path to a localized data center power plant.

Conclusion

Alternative energy sources such solar power generation coupled with energy storage systems and small modular nuclear power generation provide viable paths for data centers to serve their increasing energy demand, meet their decarbonization and resiliency goals while reducing their electricity bills. The next issues of this data center series shall cover the pros and cons of the various alternatives to diesel gensets as well as mitigation measures for scope 3 emissions.