Carbon Intensity Scoring
Carbon intensity is the greenhouse-gas score of a fuel across its life, from the kitchen or the farm to the vehicle. Fuels made from used cooking oil often score lower than petroleum diesel because the oil was already used to cook food.
This page explains that idea for collectors and fuel buyers. Grease.org does not score a load of grease and does not assign a carbon number.
A carbon score is a buyer's calculation, not a job for the cook. What the kitchen controls is the oil it sets aside and the record of who picked it up. Those are the facts a later score is built from. Grease.org does not assign a carbon number to a load.
What the kitchen can actually control
A carbon-intensity score is built from a pathway model. The model counts farming or collection, transport, the fuel process, and combustion. Used cooking oil enters with an advantage in many of those models because the oil was already produced to cook food. The fuel system is using a waste, not growing a new crop. That advantage is not automatic. If the paperwork cannot show where the oil was cooked and who hauled it, the producer may have to use a less favorable pathway, or the load may be turned away.
The useful record from a pickup is ordinary: the kitchen, the date, the volume, and a note if the tank was wet or full of food scraps. Those facts are what a later affidavit is made of. A verbal promise that the oil is low carbon does not survive an audit. A log does. Keep the same name on the container, the ticket, and the invoice so the three documents describe one tank.
Water and the wrong fat change the pathway in practice even before anyone opens a spreadsheet. A tank padded with wash water weighs more and yields less fuel, so the real emissions per gallon of finished fuel get worse. A tank of trap waste labeled as used cooking oil is a different feedstock, brown grease, and it does not belong in a used-cooking-oil pathway. Separating those two wastes is the carbon decision a kitchen actually makes.
Renewable diesel and sustainable aviation fuel are the finished goods people mean when they talk about a score. Biodiesel blends are a different molecule. The score belongs to the fuel that was produced, under the rule of the state or country that asked for it. Quoting a number from a conference slide onto a kitchen invoice is how those programs get a bad name. Quote the pickup. Let the fuel producer quote the score.