In the evolving landscape of energy and sustainability, Hydrotreated Vegetable Oil (HVO) has emerged as a viable alternative to traditional fossil fuels. But when evaluating HVO’s practical application — whether for transportation, heating, or industrial use — one critical factor stands out: energy density.
Energy density is a measure of how much energy is stored in a given volume or mass of fuel. This affects everything from how far a vehicle can travel to how efficiently a boiler can heat a home. For UK consumers and businesses exploring the shift to renewable fuels, understanding how HVO compares to traditional fuels in terms of energy density is essential for making informed, cost-effective, and sustainable decisions.
What Is Energy Density?
Energy density comes in two forms:
-
Gravimetric energy density: energy per unit of mass (typically measured in megajoules per kilogram – MJ/kg)
-
Volumetric energy density: energy per unit of volume (megajoules per litre – MJ/L)
These measurements influence everything from fuel storage needs to fuel economy. For example, a fuel with high volumetric energy density will require less tank space to deliver the same amount of energy — important for industries relying on compact fuel storage systems.
HVO Fuel: A Quick Overview
HVO is a renewable diesel made by hydrotreating vegetable oils, waste cooking oils, and animal fats. Unlike traditional biodiesel (FAME), HVO is paraffinic, meaning it has a similar structure to fossil diesel. This makes it compatible with most modern diesel engines without requiring modifications.
In the UK, HVO is gaining attention due to its low greenhouse gas emissions, cleaner combustion, and ease of use in transport, off-road machinery, generators, and even domestic heating systems.
Energy Density: HVO vs Traditional Fuels
Let’s examine how HVO stacks up against conventional fossil fuels in terms of energy density, based on commonly accepted values:
| Fuel Type | Gravimetric Energy Density (MJ/kg) | Volumetric Energy Density (MJ/L) |
|---|---|---|
| HVO | ~44 MJ/kg | ~34 MJ/L |
| Fossil Diesel (EN590) | ~45.5 MJ/kg | ~36 MJ/L |
| Petrol (Gasoline) | ~46.4 MJ/kg | ~34.2 MJ/L |
| Biodiesel (FAME) | ~37 MJ/kg | ~33 MJ/L |
| Kerosene | ~43 MJ/kg | ~34 MJ/L |
From the table, it’s clear:
-
HVO has slightly lower energy density than fossil diesel, both by weight and by volume.
-
However, it outperforms FAME biodiesel in both energy metrics, which is a major improvement over first-generation biofuels.
What Does This Mean in Practical Terms?
While the difference in energy density between HVO and conventional diesel may seem minimal — roughly 5–6% lower — it has implications in real-world usage, particularly in the following ways:
1. Fuel Consumption
Vehicles or equipment running on HVO may require slightly more fuel (by volume) to achieve the same output as diesel. However, this difference is often negligible, especially when balanced against HVO’s environmental benefits.
2. Storage Requirements
Due to its similar volumetric energy density to diesel, no additional tank space is generally needed. This makes HVO a drop-in replacement for diesel in existing storage and distribution systems — a huge advantage for fleet operators and agricultural users in the UK.
3. Operational Efficiency
HVO’s higher cetane number (typically around 70+) compared to diesel (usually 51) actually results in more efficient combustion, smoother engine operation, and reduced wear. This can offset minor losses in energy density through better overall performance and engine longevity.
UK-Specific Considerations
Environmental Incentives
In the UK, reducing carbon emissions is a top priority. HVO offers up to 90% reduction in greenhouse gas emissions over its lifecycle compared to fossil diesel. Despite slightly lower energy density, it is a more sustainable choice in line with the UK government’s net-zero targets.
Renewable Fuel Obligations
Suppliers in the UK are increasingly turning to HVO to meet Renewable Transport Fuel Obligations (RTFO). Its blend compatibility and cleaner profile make it a more viable alternative to older biodiesel solutions — without compromising too much on performance.
Cold Weather Performance
HVO performs better than biodiesel in cold temperatures due to its paraffinic nature. This is crucial for the UK, where winter fuel reliability is vital for industries, transport fleets, and rural heating systems.
Why Energy Density Isn’t Everything
While energy density is important, it’s not the only factor worth considering. HVO brings a range of benefits that go beyond raw energy values:
-
Lower particulate emissions
-
Reduced NOx emissions
-
Biodegradability
-
Longer storage life compared to biodiesel
These advantages make HVO an attractive choice even with a slight drop in energy density — especially for businesses looking to improve environmental credentials without investing in new equipment.
Conclusion: HVO Delivers Value Beyond Energy Density
For UK audiences — from logistics and agriculture to domestic consumers — the transition to renewable fuels like HVO fuel is becoming more than just a trend; it’s a necessity. While HVO has marginally lower energy density than fossil diesel, the difference is minor and often outweighed by operational and environmental gains.
Its ease of integration, clean-burning properties, and support for UK climate goals make it a powerful tool for sustainable energy transition. When evaluating fuels, don’t focus solely on energy density — look at the bigger picture. And in that picture, HVO is a clear frontrunner.