Most kitchens never find out where their oil ends up. It goes in a drum, a van takes it away, and that is the last anyone thinks about it. It is worth knowing, partly because it explains why anyone is willing to pay you for a waste product, and partly because it is a genuinely good story to tell your own customers.
Step one: measured at your door
Collection starts with measurement. Your drums are measured at the point of collection so both sides can see the volume, and clean empties are left in their place.
Measuring in front of you matters more than it sounds. Volume is what you are paid on, and it is the figure that appears on your waste transfer note. A collector who measures out of sight, or estimates from the look of a drum, is asking you to take their word for both the payment and the paperwork.
Step two: filtering and dewatering
Oil arriving at a processing site is rarely clean. It carries food particles, batter, salt and, almost always, water.
The first stage is mechanical. Settling and filtering drop out the solids that accumulate at the bottom of every drum. Then the water is removed, which usually means heating the oil so the water separates and can be drawn off.
This is why storage habits matter so much. Every litre of water and every kilo of sediment in your drum has to be taken back out again, and the value of the load reflects that.
Step three: from oil to fuel
Cleaned used cooking oil is a feedstock, and there is more than one route it can take.
Biodiesel (FAME)
The established route. The oil is reacted with an alcohol in the presence of a catalyst, a process called transesterification. This breaks the fats down and produces fatty acid methyl esters, or FAME, which is biodiesel. It is blended into road diesel and burns in ordinary diesel engines with no modification.
HVO and sustainable aviation fuel
The newer route is hydrotreatment, which produces HVO, hydrotreated vegetable oil. Hydrogen is used to strip the oxygen out of the fats, leaving a fuel chemically very similar to fossil diesel. HVO can be used at full strength without blending, which is why fleets, generators and construction sites have adopted it quickly. The same processing pathway is used to make sustainable aviation fuel.
Either way, the residues are not wasted. The heavy sludge and food solids filtered out at the start generally go to anaerobic digestion, where they produce biogas.
Why the carbon saving is up to around 88%
Fuel made from used cooking oil produces up to around 88% less CO2 than fossil diesel. The reason is what chemists call the carbon cycle.
The carbon in your fryer oil was in the atmosphere very recently. It was absorbed by the sunflowers, rapeseed or olives the oil was pressed from, over a single growing season. Burning the fuel returns carbon that was already in circulation. Fossil diesel, by contrast, releases carbon that has been locked underground for millions of years, adding to the total in the atmosphere.
The saving is not quite total because the fuel still has to be collected, processed and distributed, and that activity has its own footprint. Hence “up to around 88%” rather than a clean sweep. Anyone quoting you a round 100% is not being straight with you.
Why used cooking oil beats crop-grown biofuel
Used cooking oil has an advantage over biofuels made from purpose-grown crops: nothing was planted to produce it.
There is no land taken out of food production, no irrigation, no fertiliser, and no food-versus-fuel argument to have. The oil already existed. It had already done its job in your fryer. The only alternative was disposal. That is why waste-derived feedstocks are treated more favourably than crop-derived ones in fuel policy.
What this means for your business
Two practical things.
First, this is why your waste has value. You are not paying someone to take away a problem, you are selling a feedstock into a real market. Any collector telling you otherwise, or charging you for pickups, is relying on you not knowing. It is also why some collectors set a minimum volume before they will pay you anything, and why we do not.
Second, it is a claim you can make honestly. If a customer, landlord, delivery platform or corporate client asks about your sustainability, “our used cooking oil is collected by an Environment Agency registered carrier and recycled into renewable fuel” is true, specific and verifiable. Very few kitchens bother to say it.
Can you use this in your own marketing?
Yes, provided you keep it accurate. Stick to what you can evidence:
- That your oil is collected by a licensed waste carrier, with the registration number to prove it
- That it is recycled into renewable fuel rather than sent to landfill
- That the resulting fuel produces substantially less CO2 than fossil diesel
What you should avoid is inventing a number for your own carbon saving, or implying your kitchen is carbon neutral because of it. The claim is strong enough without being stretched, and a specific verifiable statement beats a vague impressive one every time.
Nothing we collect goes to landfill or down a drain. It leaves your kitchen as a waste product and re-enters the economy as fuel, which is about as close to a closed loop as a takeaway is likely to get.