For many data centre applications, hydrogen fuel cells can offer significant advantages over diesel generators, particularly where operators want lower emissions, quieter operation, reduced routine maintenance and scalable on-site power. Diesel generators are a widely available backup option, but hydrogen fuel cells provide a cleaner alternative that can support both short-term resilience and longer-duration power when an adequate hydrogen supply is available.
Organisations base their power supply decisions on several factors including: the individual site, power requirements, required backup duration, available space, hydrogen supply and existing electrical infrastructure.
Intelligent Energy’s fuel cells for data centres are designed to provide resilient power for applications where uptime, scalability and reduced local emissions are priorities.
Why are diesel generators still used in data centres?
Diesel generators have supported data centre backup power for decades. They are familiar to facilities teams, fuel is widely available, and established supply chains make it relatively straightforward to install, maintain and refuel them.
Their role is usually to sit on standby until the grid fails. UPS batteries bridge the immediate interruption before generators start and take over the load, allowing servers and other critical infrastructure to continue operating.
The challenge is that diesel generation comes with several drawbacks. Combustion produces carbon dioxide and local air pollutants, while engines create noise, vibration and heat. The increasing demand for data centres means that there is also an increased demand for the generators that power them, and therefore more emissions. They also require regular testing and mechanical maintenance to make sure they will perform when needed.
How do hydrogen fuel cells compare?
Hydrogen fuel cells generate electricity electrochemically rather than by burning fuel. The hydrogen supplied reacts with oxygen and ambient air inside the fuel cell to produce electricity, with water and heat as the by-products.
For a data centre, the main differences compared with diesel are:
- Zero harmful emissions at the point of use, rather than emissions produced through combustion
- Lower noise and vibration as there is no combustion engine
- Fewer moving parts, reducing many traditional engine maintenance requirements
This makes fuel cells suitable not only for emergency backup but potentially for prime power, distributed generation and microgrid applications too.
For a wider look at these applications, see can hydrogen fuel cells power data centres?
Emissions: hydrogen fuel cells vs diesel generators
This is one of the clearest differences between the technologies.
Diesel generators rely on combustion and therefore produce CO₂ alongside local pollutants such as nitrogen oxides and particulate matter. A hydrogen PEM fuel cell does not burn its fuel, so it produces no harmful emissions at the point where electricity is generated.
That being said, the overall carbon footprint of hydrogen does depend on how it was produced. Green hydrogen produced using renewable electricity offers the greatest potential for reducing lifecycle emissions, whereas hydrogen produced from fossil fuels has a higher upstream carbon footprint.
Even so, eliminating combustion at the data centre site itself can be particularly useful where local air quality, planning restrictions or corporate decarbonisation targets are important considerations.
Which requires more maintenance?
Diesel generators contain numerous mechanical components that require periodic servicing. This can include oil and filter changes, engine servicing, exhaust system inspections, cooling maintenance and checks on stored diesel quality.
Fuel cells also need planned maintenance, but the requirements are different. With fewer moving parts and no internal combustion process, many of the engine-related servicing tasks associated with diesel disappear. Maintenance instead focuses on the fuel cell system, hydrogen supply equipment, sensors, cooling components, electrical connections and safety controls. That does not make hydrogen fuel cell systems maintenance-free, but it can reduce routine mechanical maintenance.
For data centres, this distinction matters because backup systems must remain ready even when they spend long periods without being called upon.
Which is better for long-duration backup power?
Both technologies can provide extended backup power, provided they have enough fuel.
A diesel generator continues operating while diesel remains available. Similarly, a fuel cell can continue producing electricity for as long as its hydrogen supply is maintained. In this respect, both technologies avoid the fixed stored-energy limitation of battery-only backup systems.
Hydrogen also works well alongside batteries. A UPS can deal with the immediate power interruption while the fuel cell takes over the sustained load, allowing operators to combine fast battery response with longer-duration fuel cell generation.
This type of hybrid configuration can form part of a wider data centre microgrid. Read more about how hydrogen fuel cells strengthen microgrids and reduce pressure on the National Grid.
Which option supports scalability?
Data centre power demand rarely stays static. The IEA estimates that data centres could account for around 10% of global electricity demand growth by 2030.
AI computing, higher rack densities and additional server capacity can all increase the amount of electricity a facility requires.
Diesel generation can be expanded by adding additional gensets, but fuel cells also lend themselves particularly well to modular deployment. Additional fuel cell modules can be introduced as power requirements rise, helping operators match on-site generation more closely to actual growth.
Intelligent Energy’s IE-GRID™ platform is designed around this modular approach. The containerised system provides scalable stationary power that can be used for backup, distributed, microgrid and off-grid applications.
How do the two compare for AI data centres?
AI is making power availability an increasingly important consideration for data centres. High-density computing requires more electricity, while AI workloads can also create rapidly changing demand.
Diesel generators remain capable backup systems, but they are primarily designed around emergency generation. Fuel cells offer greater flexibility because they can form part of the site’s everyday energy strategy as well as its resilience plan.
Fuel cells can be combined with batteries, grid power and other distributed energy resources. This means they can support backup power, on-site generation and microgrid operation depending on the facility’s requirements.
Our article on how hydrogen fuel cells are addressing data centre power challenges in the age of AI looks at this growing demand in more detail.
Does hydrogen have any disadvantages compared with diesel?
Hydrogen fuel cells offer clear benefits, but there are practical considerations.
Diesel has a mature global supply and storage network. Hydrogen infrastructure is still developing, so availability and cost can vary considerably by location. A data centre may also require dedicated hydrogen storage, delivery arrangements and additional site planning.
Initial investment can also be higher than a conventional diesel system, particularly where hydrogen infrastructure needs to be installed at the same time.
For this reason, replacing diesel is not simply a matter of swapping one generator for another. Operators need to assess hydrogen availability, required runtime, storage space, electrical integration and expected future power demand.
As hydrogen production and distribution infrastructure expands, these barriers are expected to become easier to manage.
Can hydrogen fuel cells replace diesel generators completely?
Potentially, but it depends on the data centre. For some sites, hydrogen fuel cells may directly replace diesel backup generation. At others, they may initially be introduced alongside existing generators, batteries and grid power before taking on a greater proportion of the site’s resilience requirements.
A phased approach can be useful because it allows fuel cell capacity to be integrated into the existing electrical architecture without changing everything at once.
The wider objective does not necessarily need to be an immediate removal of every diesel generator. It can instead be a gradual reduction in diesel dependence as cleaner and more flexible power infrastructure is introduced.
Diesel generators remain a proven and widely available backup technology, particularly where low upfront cost and easy access to fuel are the main priorities.
FAQs
Are hydrogen fuel cells more reliable than diesel generators?
Both technologies can provide reliable backup power when correctly designed and maintained. Fuel cells have fewer moving parts and low vibration compared to combustion engines and can continue generating power for as long as hydrogen is supplied, making them well suited to high-reliability applications.
Do hydrogen fuel cells produce emissions?
PEM hydrogen fuel cells produce no combustion related CO2 NOx or particulate emissions at the point of generation. Their main by-products are water and heat. The overall carbon footprint depends on how the hydrogen itself is produced.
Are fuel cells cheaper to maintain than diesel generators?
Fuel cells avoid many routine engine maintenance tasks associated with diesel generators, such as oil changes and exhaust-system servicing. They still require planned inspections and maintenance of the fuel cell, hydrogen supply and supporting components.
Can hydrogen fuel cells provide backup power for several days?
Yes, provided sufficient hydrogen is available. Unlike batteries, the maximum runtime is not determined solely by the capacity of the power-generating equipment; additional hydrogen storage or supply can extend operation.
Can a data centre use both diesel generators and hydrogen fuel cells?
Yes. Fuel cells can be introduced alongside existing diesel generators, batteries and UPS systems, allowing operators to transition gradually rather than replacing their entire backup infrastructure at once.
Do fuel cells work with UPS batteries?
Yes. The technologies complement each other well. UPS batteries can provide immediate power during an interruption, while fuel cells provide sustained generation for longer-duration backup.
Are hydrogen fuel cells suitable for large data centres?
Yes. Modular fuel cell systems can be scaled to support increasing power requirements, making them relevant to both smaller edge facilities and larger data centres. The appropriate configuration depends on the site’s required capacity and hydrogen supply.
What is the biggest challenge when replacing diesel with hydrogen?
Hydrogen availability and infrastructure are currently among the main considerations. Operators need a dependable hydrogen supply and suitable on-site storage, alongside the necessary electrical and safety infrastructure.