Conventional diesel has a slightly higher fuel density than Prema HVO (770-790kg/m3 compared to 820-835kg/m3). You might think this means you would consume more fuel when using HVO, but you’d be wrong. The consumption rate of Prema HVO is actually very similar to conventional diesel. Here’s why.
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The science…
It is the ‘heating value’ of fuel, also known as calorific value, that has the greatest effect on volumetric consumption, not the density. Calorific value describes the amount of heat released in an energy source during combustion, expressed in MJ/litre.
The calorific value of Prema HVO and conventional diesel are very similar (34.4MJ/litre compared to 36MJ/litre).
This is largely due to the fact that conventional diesel, unlike Prema HVO, typically contains biodiesel FAME (Fatty Acid Methyl Ester). The calorific value of this biodiesel element is lower than Prema HVO by mass, partly because it contains oxygen. As such, the heating value of conventional diesel overall is comparable to HVO, despite the higher density.
The biodiesel component of diesel can also cause operational inefficiencies that lead to greater real-world consumption. It’s therefore not surprising that we have received reports that Prema HVO consumption is actually better than conventional diesel.
Putting it to the test…
In tests, Heavy Goods Vehicle (HGVs) and passenger cars have shown an average increase in fuel consumption of about 3% with neat Prema HVO compared to 100% fossil diesel (Karavalakis et al., 2015). However, these tests used 100% fossil diesel, not the conventional diesel you’ll find at the pump – which typically contains about 6% biodiesel FAME.
When comparing Prema HVO with conventional diesel, some studies have actually discovered a slight tendency (0.5%) towards lower energy consumption in MJ/km and better engine efficiency with Prema HVO (Nylund et al., 2011).
It’s worth noting that the amount of FAME in conventional diesel is likely to increase in the coming years, thereby tipping the balance further in favour of Prema HVO.
IMPORTANT: Why Prema HVO performs better than other HVOs…
Not all HVOs are alike. Some are made from one type of oil, whereas others are made from multiple types, from vegetable cooking oil to animal fat residue, non-food grade vegetable oils and ‘tall oil’ from wood pulp manufacture. The real-world consumption of HVO fuel will vary depending on what it’s made from.
Prema HVO is made from just one feedstock – used cooking oil. It’s a single-source product supplied by one supplier, Neste, and its provenance can be proven through its International Sustainability and Carbon Certification (ISCC) status. Having this chain of custody means Prema HVO can guarantee credible and accurate consumption forecasting.
More about biodiesel FAME…
As explained above, biodiesel FAME is the culprit for bringing down conventional diesel’s performance. It’s important to reiterate that Prema HVO is fundamentally different to biodiesel FAME. The latter is produced from vegetable oils and animal fats that have undergone a process called ‘transesterification’ – producing a liquid that contains oxygen and is hygroscopic. This means FAME is prone to absorbing water and oxidation, causing degradation and other performance issues.
In contrast, Prema HVO is produced through hydrotreatment, where hydrogen is used to remove oxygen from vegetable oil molecules – creating hydrocarbons which are similar to fossil diesel fuel and are not prone to degradation.
We hope this gives you a clearer understanding of Prema HVO and its consumption properties. Should you require further help or information, please do contact us.
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