Hydrotreated vegetable oil, commonly called HVO, is a renewable diesel fuel made by reacting plant oils or animal fats with hydrogen to produce hydrocarbons chemically identical to those in petroleum diesel. Unlike traditional biodiesel, HVO contains only hydrogen and carbon atoms, with zero oxygen, zero sulfur, and no aromatic compounds. This makes it a true “drop-in” replacement: you can run it in any diesel engine without modifications or blending.
How HVO Differs From Regular Biodiesel
The distinction matters because most people use “biodiesel” as a catch-all term. Traditional biodiesel (technically called FAME, or fatty acid methyl ester) is made through a different chemical process called transesterification. FAME still contains oxygen in its molecular structure, which creates three practical problems. It holds about 7% less energy per liter than petroleum diesel. It degrades in storage because oxygen promotes corrosion. And its chemical makeup makes it more vulnerable to microbial growth in fuel tanks, which can clog fuel lines.
HVO sidesteps all of these issues. Because the hydrotreatment process strips out every oxygen atom, the finished fuel is a straight-chain paraffinic hydrocarbon with the formula CₙH₂ₙ₊₂. In plain terms, it’s structurally the same type of molecule found in fossil diesel, just sourced from biological material instead of crude oil. This gives HVO excellent oxidation stability and long storage life.
What It’s Made From
HVO can be produced from a surprisingly wide range of raw materials. The most common feedstocks are vegetable oils (rapeseed, soybean, palm), beef tallow, and used cooking oil. But producers are increasingly turning to lower-grade waste streams: nonfood-grade vegetable oils, low-quality animal fats, sludge from palm oil mills, distillers corn oil, and refining byproducts like acid oils and fatty acid distillates.
High-quality feedstocks like fresh vegetable oil and used cooking oil require relatively straightforward pretreatment, similar to what’s already done in edible oil refining. Lower-quality materials need extra steps: prefiltration to remove solid impurities and plastics, heat treatment to strip out phosphorus and metals from animal byproducts, or specialized processes for the worst-quality inputs like trap grease and distillation pitches. The ability to use waste fats that would otherwise be discarded is a significant part of HVO’s environmental appeal.
How the Hydrotreatment Process Works
The production process uses hydrogen gas and specialized catalysts under high temperature and pressure. It unfolds in stages. First, hydrogen saturates the double bonds in the fatty acid chains of the feedstock oil, converting unsaturated fats into saturated ones. Then the saturated triglyceride molecules break apart into smaller intermediates: monoglycerides, diglycerides, and free fatty acids.
These intermediates are then converted into pure hydrocarbons through three possible chemical pathways. One adds hydrogen to replace oxygen atoms. Another removes oxygen as carbon dioxide. A third removes it as carbon monoxide and water. All three produce the same end result: clean alkane chains that behave identically to the hydrocarbons in conventional diesel fuel. Producers can also adjust the process to “crack” longer chains into shorter ones, tailoring the fuel’s properties for different climates or applications.
Performance Compared to Fossil Diesel
HVO generally outperforms petroleum diesel on several key metrics. Its cetane number, which measures how easily the fuel ignites under compression, is notably higher. The European standard for paraffinic diesel fuels (EN 15940) sets a minimum cetane number of 70 for HVO-type fuels, while conventional diesel typically falls between 45 and 55. A higher cetane number means smoother combustion, easier cold starts, and quieter engine operation.
HVO also has a very narrow boiling range positioned at the midpoint of the diesel range, which contributes to cleaner, more complete combustion. Its sulfur content is essentially zero (the EN 15940 standard allows a maximum of just 5 milligrams per kilogram). It’s lighter than petroleum diesel, with a density between 765 and 800 kg/m³ at 15°C, so fuel economy on a per-liter basis can be slightly lower, though the energy content per kilogram is competitive.
Greenhouse Gas Reductions
The lifecycle carbon savings are HVO’s headline benefit. Because the carbon released during combustion was originally absorbed from the atmosphere by the plants or animals that produced the feedstock, HVO can achieve lifecycle CO₂ reductions of over 90% compared to fossil diesel. The exact figure depends on the feedstock: waste-based HVO from used cooking oil or tallow scores higher than HVO made from virgin crops, which carry the carbon cost of farming, fertilizers, and land use.
These savings apply across the full lifecycle, from growing or collecting the feedstock through processing and final combustion. At the tailpipe, HVO also tends to produce lower levels of particulate matter and other local pollutants compared to conventional diesel, though the magnitude varies by engine type and operating conditions.
Engine Compatibility
One of HVO’s biggest practical advantages is that it works in existing diesel engines without any hardware changes. A long and growing list of major manufacturers have officially approved 100% HVO (sometimes labeled HVO100) for their engines. In the truck sector, Volvo, Mack, Scania, Mercedes-Benz Trucks, DAF, MAN, Iveco, and Renault Trucks all give it the green light. Engine makers Cummins and Caterpillar approve it for their powertrains, and John Deere has approved it for agricultural and construction equipment.
This “drop-in” compatibility is a major differentiator from traditional biodiesel, which is typically limited to blends of 5% to 20% in most engines and can void warranties at higher concentrations. HVO meets the EN 15940 paraffinic diesel standard, and because its chemical structure mirrors petroleum diesel so closely, it doesn’t cause the seal degradation or injector fouling that high-concentration FAME blends sometimes do.
Where HVO Fits in the Fuel Landscape
HVO occupies a specific niche: it’s the most practical near-term decarbonization option for vehicles, machinery, and equipment that run on diesel and can’t easily switch to electric power. Think long-haul trucks, construction equipment, agricultural machinery, marine vessels, and backup generators. For these applications, HVO offers immediate emissions reductions using existing infrastructure, from refineries to fuel stations to the engines themselves.
Production capacity is expanding rapidly, with major refineries in Finland, Singapore, the United States, and elsewhere scaling up output. The main constraints are feedstock availability (there’s only so much used cooking oil in the world) and cost, since HVO typically carries a premium over fossil diesel. As waste feedstock supply chains mature and production scales, that gap is expected to narrow, but for now, HVO remains more expensive than the petroleum product it replaces.