At a time when the whole world is looking for ways to decarbonize its power usage, whilst simultaneously requiring even more power to meet demand, it’s reassuring to know that at least one alternative fuel is approaching maturity.

While hydrogen as a primary fuel source is still several years away, hydrotreated vegetable oil (HVO) can be used as an alternative to traditional diesel in gensets for backup power supply, yet has a carbon footprint up to 90 percent lower.

Better still, its performance is comparable to traditional fossil fuels. As the production and supply chain of HVO has ramped up, the price has dropped and it is now considered a serious alternative for data center operators looking for a more sustainable form of backup power.

Moteurs Baudouin, based in Cassis, France, has over a century of experience in designing and building engines, making them the perfect advocates for this breakthrough fuel.

In a recent webinar, Enrique Moraga, business development director for data centers in EMEA at Baudouin, and Dimitrios Kontopanagos, head of power generation engineering at Baudouin, take us through the advantages of HVO in the data center, and how it applies to the mandatory ISO8528 infrastructure regarding combustion engine standards, making it easier for data center operators to meet these stringent requirements.

“HVO is produced from waste vegetable oil, making it carbon neutral and completely compatible with diesel engines," explains Moraga. “It is a biofuel, created by hydrogenating the oil using catalysts, at very high temperatures between 300 and 400 degrees Celsius.”

Drilling down the details: Understanding HVO

HVO is a second-generation biofuel that, thanks to the removal of oxygen during the process, can be stored for longer periods than predecessors because, as the name suggests, there is no way for oxidation to occur.

Such is the purity and compatibility of HVO that it can be put straight into an existing diesel tank without cleaning, and even mixed with any remaining diesel, thus reducing waste.

Even the engines themselves can be switched to HVO without additional maintenance. Kontopanagos tells the audience, “It's not like the biofuels where you have to change the fuel lines or you risk microbial growth over time. You can use it directly, without modifications.”

Although no fuel is truly carbon-free, the emissions from HVO are significantly lower, and the carbon released is the same carbon that is absorbed during plant growth, thus backing up the claim that this is a ‘carbon neutral’ alternative.

HVO can be refined to conform to Class A or B E15940 (EU) and ASTM D975 (US) standards. Class A is the cleaner of the two fuels, designed to offer lower nitric oxide and nitrogen dioxide (collectively known as NOx) emissions.

Class B is less clean, but offers a performance almost indistinguishable from traditional diesel. This comes in part as a result of the origin of the oil being used. Cooking oil, for example, has proved to be an excellent, clean source. Other oils may result in HVO with a higher level of carbon and NOx.

That’s why the HVO used in data centers must be certified by International Sustainability and Carbon Certification (ISCC) to authenticate its source.

“In addition, any HVO producer must provide a certificate indicating CO2 savings to be considered in the calculation for the sustainability report for the data center,” adds Moraga.

The number of producers has increased in recent years, reflecting the demand for cleaner fuels in a range of sectors, with Moraga pointing to Spain and the Netherlands as being amongst the countries leading the charge.

“We assume that there will be even more in the future. In fact, in the Middle East, we are seeing some joint ventures and collaborations to start producing HVO,” he tells the audience, offering reassurance that this potential wonder fuel will be easily available.

Using examples of Baudouin’s M33 and M55 gensets, which are specifically aimed at the data center market, Moraga was able to demonstrate a three to five percent reduction in NOx emissions, using Class B HVO. There is also a reduction in CO2 and particulate matter. “Why? Because HVO is a cleaner fuel, with cleaner combustion compared to fossil fuel.”

In other words, it’s not just how it’s made, or what it releases, but the fact that it burns in a more efficient way.

Why does all this matter?

Well, apart from the desire to be kinder to the planet, we must also consider the ISO8528, which sets out the requirements for stable voltage and frequency in reciprocating engines of all kinds, regardless of changes in the load being applied.

For data centers, ISO8528-5 has specific relevance because that is the section covering gensets, used by most data centers to provide backup power generation. “Key performance parameters are captured within the ISO8528, not only transit performance, but also vibration characteristics, noise testing, and so on,” comments Kontopanagos.

“ISO8528-5 describes in detail the specific percentage of load steps that you need to test an engine and find whether it meets the performance class or not. This is all based on the brake mean, effective pressure, and value of your engines, and it's always something that you have to check during emergency standby, and also in a live trial.”

There are three performance classes covered under this standard, with G3, the most stringent, being the one relevant for data center use, due to the high voltages in use, and requiring a deviation of no more than one percent voltage rejection above or below steady-state.

Kontopanagos tells us more: “This is because it's used, typically, in telecommunications projects data centers – scenarios where you have a bunch of nodes that are very sensitive to voltage and frequency regulation and you need to maintain quite tight steady-state conditions with low frequency and voltage dips.

“What is important here,” says Kontopanagos, “is not only to meet our customers' requirements but also not to end up with an oversized genset – an uneconomical and impractical solution. We need to minimize the voltage and frequency peaks, and also the frequency and voltage overshoots when we have load rejection scenarios.”

Previous generations of biofuel could not offer the same level of performance as the fossil fuels they were designed to replace, and that was reflected in the way the engine processed them, leading to fluctuations that exceeded the limits of ISO8528-5. Because HVO burns as efficiently, sometimes more efficiently than diesel, it allows compliant engines to transition and keep, or even exceed their existing metrics.

Real-world applications: Baudouin’s success stories

Baudouin has worked with a range of clients in many different territories to create gensets that comply with or exceed IS8528-5.

One example given by Moraga is a 2021 project in Switzerland, which had a specific baffle requirement of 2000mg NOx. “The importance of this project was because this engine could meet it without any kind of selective catalytic reduction (SCR) installation,” he explains.

That is to say, because the Baudouin engine burned its HVO so cleanly, there was no need for any additional measures to ensure compliance with emissions targets.

You may be wondering why, if HVO is such a game-changer, it hasn’t been universally adopted. The answer, hitherto, was price and availability, but in recent years, both have improved dramatically, though this does vary by region.

He tells us, “All fuels are subject to different subsidies and mandates, depending on the region. The States is one way, Europe is another. The best thing is to go directly and ask the producer, but there is very little difference in price with normal fossil fuel at this point.”

Another significant advantage of HVO is that, as a cleaner fuel, it requires less intensive maintenance for the gensets and diesel tanks.

Kontopanagos suggests that for an engine running at a good, steady closed load of 70-75 percent, the time between servicing can be as much as 1000 hours (around 41 days):

“The burn and consumption of the HVO itself helps to remove some of the wear and tear in all the moving parts of the engine. It sort of works as an external lubrication for the engine itself. However, that figure of 1000 hours will depend on the operating cycle, the QT cycle, and HVO composition itself.”

In conclusion, the shift to HVO represents a pivotal moment for industries reliant on gensets, especially in high-demand sectors like data centers. By combining significant environmental benefits – up to 90 percent lower carbon emissions – with seamless integration into existing systems, HVO stands out as a rare innovation that balances sustainability with practicality.

While global adoption still faces hurdles like regional availability, the fuel's growing accessibility and competitive pricing make it clear: HVO is not just an alternative – it’s a game-changer for cleaner, more efficient power generation.

Watch Baudouin's webinar “Understanding the use of HVO and ISO 8528 in data center engines” on Crowdcast here.