In this series exploring potential substitutes for diesel generators, we have examined battery energy storage systems (BESS) (Part 1); advanced power electronics (Part 2); and gas engines, gas turbines, and steam turbines (Part 3). In this final installment, we look at technologies that are less mature or not yet widely deployed but are gaining attention.. Hydrogen Backup: Promise Meets Practical Limits. Hydrogen-based backup generators are already on offer from several suppliers. Innio Jenbacher, for example, provides multiple hydrogen engine options. Where hydrogen supply is limited, operators can blend a small share of hydrogen with natural gas to support up to 10 MW. For facilities targeting 100% on hydrogen, the company currently offers units up to 1 MW, with 3 MW models planned.. Most of the interest in these systems is in Europe. Innio reported an order from NorthC Datacenters in the Netherlands for six Jenbacher hydrogen engines for emergency backup power. These dual-gas engines run on on-site hydrogen during short outages and switch to natural gas for longer events. The Dutch government has invested heavily in hydrogen infrastructure, including a roughly 300 km national hydrogen network repurposed from natural gas pipelines. Despite this, broader market traction remains elusive.. Related:Can Data Centers Ditch Concrete – or Just Use Less of It?. In the US, manufacturing giants such as Caterpillar and Generac aren’t aggressively pushing hydrogen engines. Outside refineries, hydrogen isn’t readily available in large quantities; it’s expensive; distribution would require significant pipeline and storage upgrades; and safety and permitting concerns persist.. Policy has moved in a cautious direction. In mid-2024, the US Environmental Protection Agency (EPA) finalized greenhouse gas standards for fossil-fuel power plants without including hydrogen co-firing requirements in its New Source Performance Standards (NSPS). An earlier proposal contemplated co-firing 30% hydrogen by volume with natural gas by 2032, ramping to 96% by 2038, but those requirements were removed, leaving no hydrogen mandate in place.. “Hydrogen was excluded due to its production being expensive and the fact that the US has limited infrastructure to produce, transport, or store it,” said Megan Reusser, technology manager at Burns & McDonnell.. For now, hydrogen engines for data center backup in the US appear limited to experimental or lab-scale deployments. Even in Europe, where policy is generally supportive, practical constraints are slowing adoption. Niche opportunities may exist where hydrogen is plentiful, such as data centers adjacent to refineries, or where grids with heavy wind and solar face curtailment and excess energy can feed electrolyzers. Even in those cases, directing surplus power into BESS is often more efficient and cost-effective for backup needs.. Related:Water Is the New Constraint for AI Data Centers. “Investment in hydrogen peaked in 2023,” said Jon Moore, CEO of energy transition analyst firm BloombergNEF, in a March 2026 interview with Energy Transition Insider.. Fuel Cells for AI-Scale Power: Closer to Prime Time. Fuel cells have been touted as “the next big thing” for two decades. Hydrogen-powered versions briefly looked poised to take the world by storm. NorthC Datacenters installed Europe’s first 500 kW hydrogen fuel cell backup system at its Groningen facility in 2022 – a milestone at the time – but few have followed, despite supportive policy and a developing Dutch hydrogen pipeline network.. In the US, Microsoft is a leading advocate, with pilots including a 3 MW hydrogen fuel cell system in Latham, N.Y., developed with Plug Power, that kept a data center online for two days to demonstrate the potential to replace diesel generators. Microsoft also partnered with the Irish energy company ESB on a pilot that provided up to 250 kW at its Dublin campus. Additional hydrogen fuel cell deployments at data centers have been completed or are underway in California, Wyoming, North Carolina, Utah, and Texas, with Bloom Energy and Ballard Power Systems among the main vendors.. Related:How a Coal Plant in Buffalo Became TeraWulf’s 500 MW AI Campus. The 3 MW hydrogen fuel cell system, which includes two 40-foot-long shipping containers, was developed by Microsoft and Power Plug. (Source: Microsoft/Photo by John Brecher). Remove hydrogen from the equation, and the fuel cell picture looks brighter for the near-term scale. In April 2026, Bloom Energy expanded its relationship with Oracle to support up to 2.8 GW of fuel cell capacity, aimed at enabling higher-density AI workloads with faster deployment timelines than traditional power solutions. These solid oxide systems generate electricity from natural gas, biogas, or hydrogen without combustion.. Beyond Oracle, Bloom has announced deals with Equinix and Compass Datacenters, as well as a $5 billion strategic partnership with asset manager Brookfield to accelerate fuel cell capacity for AI-focused facilities.. “Behind-the-meter power solutions are essential to closing the grid gap for AI factories,” said Sikander Rashid, global head of AI Infrastructure at Brookfield, in an October 2025 press release.. Renewable Fuels in Data Centers. Renewable fuels come from biomass sources, including plants, animal fats, and waste streams. They include ethanol, biodiesel, renewable diesel, renewable natural gas, and e-fuels. Renewable diesel, produced by hydrotreating waste fats and oils, is chemically similar to petroleum diesel and has gained ground in transportation, surpassing biodiesel in market share.. In data centers, renewable diesel remains a niche option. Major manufacturers like Caterpillar and Cummins approve its use in many diesel gensets. Although it can reduce lifecycle emissions by up to 90%, conventional diesel continues to dominate backup applications due to availability and lower cost. Microsoft has championed renewable diesel in its data centers, and, in 2020, pledged to eliminate diesel from its facilities by 2030. But the rapid build-out of AI has prompted some operators – including Microsoft – to revisit timelines for sustainability and net-zero commitments.. Renewable diesel is a drop‑in option approved by many OEMs, but supply and pricing keep it a niche choice for backup fleets. (Image: Getty). Near-Term Winners: What’s Likely to Scale (and What Isn’t). Some of these technologies will win a place in the data center power mix; others will fade. Fuel cells powered by natural gas or biogas appear most poised to scale in the near term, especially for behind-the-meter capacity that can be deployed quickly to meet rising AI loads. Hydrogen engines and hydrogen fuel cells will likely progress in niche or policy-supported contexts as infrastructure develops and costs fall. Renewable diesel will remain a practical option where supply and cost align, but it is unlikely to displace conventional diesel broadly in the near future.. As promising innovations face the tests of economics, infrastructure, and scalability, operators will mix solutions to balance resilience, cost, and sustainability at a pace shaped by local market realities.
