We’re switching to HVO
What this means for our customers

Fuel Supply Options & Logistics for Customers 

Q: What if I don’t want HVO fuel? Can I opt to use standard diesel instead? 
A: No, our default is to supply equipment filled with HVO, but you do have options if you prefer to manage fuel yourself. We offer to deliver your hired compressor pre-filled with HVO (on a sale-or-return basis) or empty so that you can supply your own fuel. If you do not want HVO, you can choose to have the machine delivered empty and then use your own diesel fuel. This means you’ll need to arrange for diesel on site and fill the machine before operation. Please keep in mind that if the unit arrives empty, it cannot be run until you’ve obtained and added fuel – so plan for any fuel delivery to coincide with the equipment delivery to avoid downtime. Also consider that by using regular diesel, you won’t benefit from the reduced emissions and environmental advantages that HVO provides. We strongly encourage customers to try HVO for both its performance and sustainability benefits, but ultimately the choice is yours. Just let us know your preference when booking the equipment. 

Q: How does the HVO “sale or return” fuel service work? 
A: “Sale or return” means we can supply the rental unit with HVO fuel and only charge you for what you use. Here’s how it works: We’ll deliver the compressor with a full tank of HVO (or a specified amount). We meter or record the fuel level at delivery and again upon collection. You will be billed for the HVO consumed during your hire period, and any unused HVO left in the tank will be credited back (effectively returned) to you. This way, you have the convenience of a full tank to start with, without paying for fuel you didn’t use. However, this applies only if the returned fuel is still 100% HVO. If you mix in your own diesel or the fuel is otherwise contaminated, we cannot re-use that fuel for another customer as pure HVO. In such cases – for example, if you top up the tank with diesel after our delivery – we will have to charge for the full amount of HVO we initially supplied, because the remaining fuel on return is no longer the original product. Tip: If you do end up adding diesel to a tank we filled with HVO, it’s best to run the tank as low as possible before returning the equipment. Any returned mixture of diesel/HVO will not be credited, so minimizing the leftover fuel saves you money. Overall, our sale-or-return service is designed to be fair: you get flexibility in fuel management, and you only pay for pure HVO fuel that you actually consume. 

Q: If I start with HVO from GenAir but then arrange my own fuel top-ups, can I still mix in diesel during the hire? 
A: Yes, you are free to manage fuel deliveries on site as needed. If we deliver the machine full of HVO and you later have your own diesel supplier refuel it, the HVO and diesel will blend and the equipment will run without issue (HVO is fully compatible with diesel blends). Just be aware of the billing implications – as explained, any HVO we supplied that gets mixed with outside diesel will be considered used (since the returned fuel isn’t pure HVO). You can certainly use your own fuel management service during the hire to keep the machine running; just coordinate with us on whether you want an initial fill of HVO or not. Many customers choose to take the first tank of HVO from GenAir for convenience and guaranteed fuel quality, then handle subsequent refuelling themselves if the project is long. This is perfectly fine. Just remember that if you choose the initial HVO fill on a sale/return and then mix in diesel, we will charge for that initial full tank of HVO regardless of what’s left at the end. To avoid any unnecessary fuel charges, you might opt to return the machine with as little fuel left as possible (or request it delivered empty from the start and handle all fuel on your own). We aim to be flexible – the key is to communicate your fuel plan with our team upfront so we can accommodate your needs in the most cost-effective way. 

Q: What happens if I return the equipment with a full tank of fuel? 
A: If we supplied HVO on a sale-or-return basis and you return the unit with unused HVO still in it, we will measure the remaining fuel and credit you back for that amount (you only pay for what you actually used). So, returning with a full or partly full tank of pure HVO simply means you’ll pay little or nothing for fuel, since most of it is returned. On the other hand, if the fuel in the tank is not pure HVO (e.g. you refilled it with standard diesel or a mix), then any fuel left can’t be reused as HVO. In that case, you would be charged for the full HVO supply we provided initially, regardless of the return level, because we have to assume the HVO was consumed or tainted. In summary: Returning full with pure HVO = full credit for unused fuel. Returning full with mixed/other fuel = no credit for that fuel. If you anticipate not using much fuel during your hire, it might be wise to let us know so we can supply a partial tank or work out the best approach, minimizing any hassle with returns. 

Q: How will you know if the Returned Fuel is HVO or Diesel? 
A: HVO is a clear odorless liquid, whereas Diesel is often pale yellow or light amber and has a very distinctive smell, so the first test is a visual inspection. This is then followed up with a simple Dip Test kit which quickly and easily tells you whether there is diesel fuel mixed into the mixture, and more importantly to want degree. If there is only minimal trace diesel we will consider this fuel returned as HVO for the “sale or return” billing process, if there is any significant amount of diesel mixed in with the HVO will consider this a waste product (or non-HVO) for the “sale or return” billing process. 

General Questions About HVO

Q: What is HVO fuel? 
A: HVO (Hydrotreated Vegetable Oil) is a clean, renewable diesel alternative made from vegetable oils or animal fats that have been treated with hydrogen. The result is a fuel that is chemically very similar to regular diesel, so it can directly replace fossil diesel in engines. It’s often called “renewable diesel” or HVO100 when used pure. (Note: HVO is different from traditional biodiesel (FAME) – it’s a more advanced fuel that doesn’t have the same limitations as FAME biodiesel. Unlike biodiesel, which is usually blended up to 7% in regular diesel, HVO can be used at 100% and still meets diesel fuel standards.) 

Q: Can HVO be used in any diesel engine? Do we need modifications or special steps? 
A: Yes. HVO is a true “drop-in” replacement for regular diesel, meaning you can use it in any diesel engine without modifications or additional equipment. You simply fuel up with HVO just as you would with normal diesel. Most major engine manufacturers (Caterpillar, Cummins, John Deere, Volvo, and others) officially approve the use of HVO in their engines, provided the fuel meets the appropriate standards (HVO fuel conforms to the EN15940 standard for paraffinic diesel). Using HVO will not void warranties in these cases. You can also mix HVO and conventional diesel in any ratio – they are fully compatible with each other. This means if you have some diesel in the tank and add HVO (or vice versa), the engine will run fine on the mixture. No special handling is required either: storing and dispensing HVO is done exactly the same way as regular diesel. 

Q: Will using HVO affect engine performance or fuel consumption? 
A: Performance: You should experience no loss in performance when switching to HVO. In fact, many users report that engines run just as well, if not smoother. HVO fuel has a higher cetane number (typically 70–90) than standard diesel (~50), which means it ignites more readily and burns more completely. This can make the engine run a bit quieter and start easier, especially in cold conditions or with older engines. Power and torque output remain essentially the same as with normal diesel. There’s no noticeable difference in engine responsiveness or horsepower. 
Fuel Consumption: The energy content of HVO per litre is slightly lower than that of fossil diesel (by a few percent). In practice, this might result in a small increase in fuel consumption on a volume basis – roughly an extra 1%-2% of fuel might be used to do the same work compared to standard diesel. However, this difference is minor and often hard to notice in day-to-day operation. In summary, switching to HVO should not negatively impact the performance of your equipment. Your machines will run with the same power output, and any change in fuel efficiency will be very small. 

Q: Does HVO fuel impact engine maintenance or longevity? 
A: HVO actually tends to be gentler on engines in several ways. Because it’s an extremely pure fuel (no sulphur, no aromatics, and very low impurities), it burns cleaner than normal diesel. This cleaner combustion means less soot and deposit buildup inside the engine and exhaust after-treatment systems. With HVO, you’ll get fewer particulates clogging up filters and less frequent diesel particulate filter (DPF) regenerations. Engine oil stays cleaner for longer, which could extend oil change intervals. Over time, using HVO can lead to reduced wear on components like injectors and particulate filters, potentially improving engine longevity. Another maintenance advantage is fuel storage life: HVO is more stable than regular diesel (especially diesel that contains biodiesel content). HVO can be stored for a long period without significant degradation or microbial growth – in some cases up to several years – whereas standard diesel might start to go “off” after about 12 months in storage. This means HVO is great for standby equipment or rental machines that may sit unused for a while; the fuel remains usable and won’t gum things up. Overall, there are no additional maintenance tasks required for using HVO, and it may even reduce some maintenance needs thanks to its cleaner-burning nature. 

Q: What are the environmental benefits of HVO? 
A: HVO offers two major environmental benefits: a big reduction in net carbon emissions, and a cleaner exhaust in terms of air pollutants. 
– Lower Carbon Footprint: Because HVO is made from renewable, biogenic materials (like waste vegetable oils), the CO₂ released when it burns is largely offset by the CO₂ those plants absorbed while growing. In life-cycle analyses, using HVO fuel can cut net CO₂ emissions by up to 90% compared to using fossil diesel. Even in more conservative cases, a well-sourced HVO will typically reduce greenhouse gas emissions by around 75% or more. This is a huge benefit for companies looking to meet sustainability or Net Zero targets – you get a major reduction in carbon emissions simply by changing the fuel. 
– Cleaner Air (Lower Emissions at the Tailpipe): HVO combusts more completely and contains no sulphur or heavy aromatics, so the exhaust from HVO-powered equipment is significantly cleaner. Particulate matter (soot) emissions are greatly reduced (in many cases by 30–80% less PM than diesel), and nitrogen oxide (NOₓ) emissions are also lower (often in the range of 10–30% less NOₓ). In real-world terms, this means less black smoke and particulate blowing around job sites and fewer smog-forming pollutants. For example, tests have shown machines running on HVO can emit around 80% less particulate and 20–25% less NOₓ than the same machines running on regular diesel. This cleaner exhaust improves air quality for workers on-site and for the surrounding community. And unlike some other solutions, these environmental gains come without any modifications or complex technology – it’s an immediate way to run cleaner just by using a different fuel. 

Q: Is HVO fuel truly sustainable? What about the feedstocks used to make it? 
A: The sustainability of HVO depends on what it’s made from – and the good news is that reputable HVO suppliers use 100% waste or residual feedstocks. In the UK (and many other regions), HVO fuel is required to meet strict sustainability criteria. Most HVO on the market (and any HVO that GenAir sources) is produced from waste products like used cooking oil, other waste vegetable oils, animal fats, or similar residues. When HVO is made from these non-food waste materials, it delivers the maximum environmental benefit (the ~90% CO₂ reduction mentioned above). It’s also certified via schemes like ISCC to ensure the feedstock is sustainable and not linked to deforestation or unsustainable practices. On the other hand, if HVO were made from virgin crops like palm oil grown on cleared land, the carbon savings would be much smaller and there would be other negative impacts – but GenAir will avoid any unsustainable HVO sources. Current regulations and certifications effectively prevent that unsustainable fuel from entering the supply chain. In summary, HVO is as sustainable as its source – and in our case, it is sourced from waste-derived feedstocks to ensure the fuel truly provides an environmental good without unintended consequences. By recycling waste oils into fuel, HVO offers a sustainable way to power diesel engines. 

Q: What are the drawbacks or challenges of using HVO? 
A: While HVO is an excellent diesel substitute, there are a few practical considerations to keep in mind: 
– Fuel Cost: HVO currently costs more than conventional diesel. The price can fluctuate, but on average you might pay around 10–20% per litre more for HVO than for regular road diesel (and sometimes the premium can be a bit higher depending on market conditions). This price gap is largely due to limited supply and the costs of producing HVO. The hope is that as production capacity increases and more suppliers enter the market, the cost difference will come down. Some companies have decided that the environmental benefits are worth the extra cost, or have passed on the cost to customers as a premium green option. It’s something to budget for: using HVO will likely increase fuel costs in the short term, although it requires no investment in new equipment (unlike other low-carbon solutions). 
– Availability: HVO is not yet as widely available as standard diesel fuel. You won’t find HVO at every fuel station. It is mainly supplied through fuel distributors, and you often have to arrange delivery to your site or buy in bulk. However, availability is improving rapidly. Many fuel providers in the UK now carry HVO, and its use is growing quickly in construction and rental fleets. If you need HVO, you can get it – it just takes a bit more planning than pulling up to any petrol pump. GenAir can help facilitate HVO supply for your rental equipment if needed. In general, as demand has grown, suppliers like Crown Oil, New Era, and others have expanded distribution, so HVO can be obtained in most regions – it just may not be as on-demand convenient as regular diesel yet. 
(In addition to cost and supply, one consideration is ensuring the HVO is of good quality and sustainably sourced – but as noted, in the UK market this is standard. There is no technical downside to using HVO in your machines; it’s more about these logistical and cost factors.) 

Q: Are other companies using HVO, and will GenAir offer it to customers? 
A: Yes, HVO fuel has already been adopted by many organizations in the industry, and GenAir is moving in the same direction. A number of major equipment rental companies and construction firms have embraced HVO as a way to cut emissions. For example, Aggreko (a large generator rental company) switched to using 100% HVO fuel for all its UK fleet in 2022, eliminating standard diesel from its rental operations. They and others have reported no loss of performance or reliability with this change. Sunbelt Rentals, another big name in the equipment hire sector, also offers HVO for their machinery and has formed partnerships to ensure a steady supply to their customers’ sites. These early adopters have demonstrated that HVO can be rolled out on a large scale successfully. 

GenAir is also committed to helping customers reduce their environmental impact. We are offering HVO as a cleaner fuel option for our diesel-powered compressor fleet. In practical terms, this means GenAir will supply rental equipment fuelled with HVO. Because HVO is a drop-in replacement, our clients won’t need to do anything different – you get the same reliable diesel equipment, but running on a much greener fuel. By integrating HVO into our operations, GenAir and our customers can achieve up to a 90% reduction in carbon emissions from fuel, significantly lower air pollutant emissions on site, and do so immediately without waiting for new technologies. It’s a straightforward change that delivers substantial environmental benefits. GenAir is excited to offer this solution and support our customers in making their projects more sustainable.