AI Data Centres
As other sectors decarbonise, data centre emissions are growing. Thanks to rising demand for AI, cloud computing, and digital transformation, the industry is expected to contribute around 1% of global CO2 emissions by 2030 under the International Energy Agency’s central scenario, or 1.4% in a faster growth scenario.
The obvious reason the data centre industry needs to decarbonise is, well, the fact that climate change is a thing. But if we place that very fatal threat to humanity to one side for a moment, there are also some self-serving reasons the industry might want to start being greener. Fuel prices are increasing, and planning applications are coming under greater scrutiny as governments and local councils face mounting pressure to hit their emissions targets.
There are many ways data centres can decarbonise, but in this article we are specifically looking at Scope 1 emissions, the direct emissions generated by data centres themselves. These include emissions from backup generators and other on site energy sources. They are often referred to as operational emissions, because they are produced once a facility is running rather than during the construction phase.
Data centres rely on backup generation to provide a continuous power supply. In the UK they are recognised as critical national infrastructure, because they underpin the internet and ensure that crucial software, systems, and information remain accessible. If the grid fails, data centres must be able to keep operating. Outages could lead to serious downstream disruption and significant economic losses, which is why backup power systems are essential to keeping the digital world running.
Diesel: the industry’s default backup fuel
One of the most widely used forms of backup generation is diesel, which currently leads the market with around 72.6% market share in 2024. Its popularity comes down to practicality. Diesel is a dependable fuel that is relatively easy to transport and store, and generators can run for as long as fuel supplies last. This allows operators to maintain a continuous and reliable power supply during outages.
Diesel generators also have fast start up times, meaning they can be switched on quickly in the event of a grid failure. That responsiveness is particularly important for facilities that cannot afford even a brief interruption in power.
It is also worth noting that data centre operators genuinely treat backup generation as exactly that, a backup. Generators are typically only switched on for maintenance testing, which may only amount to a few hours each month. However, as electricity grids become more constrained, there is growing concern that data centres could end up relying on fossil fuel generation during periods of peak demand, particularly as ageing grid infrastructure struggles to keep pace with the rapidly increasing power requirements of AI driven data centres.
Rising costs and planning pressure
We have already covered the point about climate change and the world ending. But in case you had not noticed, we may also be drifting toward World War Three. So, if data centre companies do not want to decarbonise for the greater good, they may choose to do so simply to control operational costs. As a result of the conflict in the Middle East, diesel prices in the UK recently reached a 16-month high, as conflict between several states around the Persian Gulf pushed oil prices higher and disrupted shipping through the Strait of Hormuz.
And if that is not enough incentive, sticking with diesel also presents a planning risk. In Scotland, plans for a 210MW data centre near Edinburgh were rejected after local campaigners questioned whether a development relying on traditional diesel backup generators could genuinely be considered sustainable. In other words, diesel is not just an emissions issue anymore. It is becoming a commercial and regulatory problem.
The cleaner backup options gaining traction
There are several alternatives to diesel backup generators, and many are gaining popularity as the industry faces growing pressure to decarbonise.
Batteries
- For short term power needs, and we are literally talking seconds or minutes, batteries already play an important role as uninterruptible power supply systems (UPS). They bridge the gap between a grid outage and backup generators starting up, ensuring systems continue running without interruption.
- For longer outages, battery energy storage systems (BESS) are becoming more widely deployed. Google recently announced that it has deployed 100 million lithium ion cells in battery packs across its global data centre fleet, demonstrating how large scale battery infrastructure is becoming an increasingly important part of data centre energy systems.
- The challenge with batteries is duration. They work well for short outages, but if power is lost for many hours or even days, batteries alone may not be sufficient. In those situations, operators still need another form of backup generation capable of delivering power for extended periods.
HVO
- Another increasingly popular alternative is hydrogenated vegetable oil (HVO). This fuel can be used instead of traditional diesel and is significantly less carbon intensive because it is produced from waste fats and vegetable oils rather than fossil fuels. Instead of releasing new carbon into the atmosphere, it largely releases carbon that was already captured during the growth of the feedstock.
One major advantage is that existing diesel generators can often run on HVO with relatively minor modifications, making it an attractive transition option for operators looking to reduce emissions without replacing entire generator fleets. - In 2021, Kao Data became the first data centre operator in Europe to transition to 100% HVO fuel for backup power generation, demonstrating how existing infrastructure can be adapted to reduce emissions. Other operators are following the same path. In 2025, Verne announced it would transition to HVO at its London data centre, allowing the company to cut up to 90% of net CO2 emissions from its generators.
- Other fuels such as methanol or natural gas can also be used instead of diesel. These options are generally cleaner and produce fewer harmful byproducts, but they still contribute to CO2 emissions. For that reason they are often seen as a step forward rather than a complete solution.
Hydrogen
- For operators that want to remove carbon emissions entirely, hydrogen fuel cells are another option. Much like hydrogen powered buses, fuel cells generate electricity through a chemical reaction between hydrogen and oxygen. When hydrogen is used as the fuel source, the only byproducts are water and heat, meaning no carbon dioxide is produced at the point of use.
- One company working at the cutting edge of this technology is GeoPura. Its hydrogen power units (HPUs) convert green hydrogen into electricity through an electrochemical process, producing only electricity, heat, and water.
- The technology is beginning to move beyond pilots. In 2024, Microsoft announced plans to power a data centre in Dublin using zero emissions green hydrogen, highlighting growing interest in hydrogen based backup power.
Data centres as future energy hubs
Backup generation will always be essential for data centres. These facilities must operate 24 hours a day, seven days a week without interruption, and the ageing power grid cannot always guarantee that level of reliability. However, more operators are beginning to adopt cleaner forms of backup generation, whether through HVO, hydrogen fuel cells, batteries, or other emerging technologies. At the same time, a broader shift is beginning to take shape within the industry. Increasingly, data centres are being designed to operate as energy hubs, with their own microgrids and on site energy infrastructure. Private wire connections to nearby wind farms, large scale battery storage, and multiple energy sources can reduce reliance on both fossil fuel generators and the local grid.
The transition will not happen overnight. But the way forward starts with collaboration and companies willing to pioneer new technologies. Coalitions such as the iMasons Climate Accord help accelerate this shift by bringing together operators, suppliers, and technology companies to develop shared standards and drive industry wide progress on decarbonisation.
