Key takeaways:
- As data centers pursue greater power density and efficiency, traditional power architectures are becoming increasingly inadequate.
- Industry momentum is building around 800 VDC architectures, with major technology companies announcing plans to support the new standard.
- Fuel cells are naturally suited to 800 VDC architectures because they generate DC power directly through an electrochemical reaction.
- Ultracapacitors can provide rapid AI load following, improve system efficiency, and reduce reliance on conventional UPS systems.
A dramatic change in data center architecture is underway. Led by NVIDIA and its latest GPUs, data center developers and equipment manufacturers are shifting to a model where power infrastructure is a central consideration. Electrical power is now “the primary factor that dictates the scale, location, and feasibility of new deployments,” as NVIDIA wrote last year.
Central to that transition is a shift to power distribution systems based on 800 volt direct current (800 VDC) power.
By using a higher voltage, electrical distribution within the data center can use lower levels of current (amps). 800 VDC also enables greater power density, meaning data centers can pack more GPUs into the same space, and it also increases the efficiency of power distribution within the data center.
From conventional AC to 800 VDC
Traditional data centers receive medium-voltage AC from the utility grid and convert it through multiple stages: transformers, switchgear, UPS systems, AC distribution, and rack-level power supplies. Each conversion introduces losses, equipment, maintenance requirements, and potential failure points.
A DC architecture can eliminate several of these conversions by delivering power in the form ultimately required by GPUs and other computing electronics.
The transition addresses two critical challenges facing AI data centers.
First, facilities are growing to hundreds of megawatts, making even modest efficiency improvements financially significant. This generates increasing interest in highly efficient, reliable onsite generation.
Second, AI workloads demand dramatically higher power density. Increasing distribution voltage allows more power to be delivered without proportionally increasing current, enabling higher-density computing while controlling electrical losses.
Why fuel cells are the optimal solution for 800 VDC
Fuel cells are particularly well suited to this architecture because they generate DC electricity directly through an electrochemical reaction. Unlike conventional rotating generators, they do not first convert mechanical energy into AC electricity.
With an appropriately designed DC architecture, fuel-cell power can remain in DC form from generation through distribution, with conversion occurring primarily at the final rack or server interface. This can reduce conversion equipment and associated losses while simplifying the electrical architecture.
Individual power-conversion devices can achieve efficiencies up to 97–99%, but losses accumulate across multiple stages. Compared to a typical conventional AC-to-DC architecture, a direct 800 VDC architecture can improve overall efficiency by 6-8% or more depending on system design and operating conditions.
As our recent report, “The New Rules of AI Power,” demonstrated, those efficiency gains translate into non-compute capital savings for a 1 GW AI data center of $3.6 billion, or 27%. They can also reduce the five-year total cost of ownership by $5.5 billion, or 9%.
Ultracapacitors for efficiency and AI load following
AI workloads can create rapid changes in electrical demand. Ultracapacitors can address these rapid fluctuations by acting as a high-power energy buffer directly on the fuel cells’ DC bus output.
During a sudden increase in GPU demand, ultracapacitors can immediately supply power while the fuel cells ramp to the new steady-state output. During a rapid decrease, they can temporarily absorb excess energy, helping maintain DC output stability.
This allows the fuel cells to operate closer to their optimal efficiency point while providing fast response to AI-driven load changes.
Ultracapacitors can also perform some of the fast-response functions traditionally provided by large UPS battery systems, potentially simplifying the overall power architecture while maintaining power quality and short-duration ride-through capability.
A scalable, modular platform for the future
The emergence of 800 VDC distribution represents a fundamental change in how data centers can generate and distribute power. Fuel cells, with their native DC output, modularity, scalability, and high efficiency, are well aligned with this architecture.
As AI data centers demand greater power density, efficiency, resilience, and flexibility, fuel-cell-based 800 VDC systems offer a path toward a simpler, more efficient, and highly scalable power infrastructure capable of supporting the next generation of high-performance computing.
For more information, including the results of AI load-following tests using fuel cells and direct DC power, download Bloom’s technical white paper: Leveraging Bloom Fuel Cells’ Native 800 VDC Output for Data Center DC Power.
The insights, projections, and forward-looking statements contained here are for informational purposes only. These are based on assumptions and information currently available.
