Feedstock is the largest single cost in biodiesel and renewable diesel production, and it also decides the fuel's cold-flow behaviour, its oxidation stability and its compliance status. Choosing a feedstock slate is therefore a commercial decision and a technical one at the same time.
The benchmark waste feedstock. Low free fatty acid when well collected and pre-treated, strong sustainability credentials, double counting under European rules, and the widest acceptance across HVO, HEFA and FAME plants. Its drawback is that it is the most expensive waste lipid because everyone wants it.
Recovered from palm oil mill effluent. Cheaper than UCO and waste-derived for compliance purposes, but higher in free fatty acid, moisture and solids, so it suits converters with pretreatment capacity or those blending it into a wider slate.
Rendered animal fat. Cheap and abundant, with high saturated fat content that gives good oxidation stability but poor cold flow. Category 1 and 2 tallow face regulatory restrictions on use, and most buyers restrict themselves to category 3 material.
The cheapest lipid by volume and historically the default for biodiesel in Indonesia and Malaysia, but increasingly constrained. Crop-based feedstocks are capped under European rules and palm carries high indirect land-use change risk, which has pushed most export-oriented capacity toward waste feedstocks.
The European and American defaults respectively. Excellent cold flow from rapeseed, good oxidation stability from soybean, both easy to process — but both are crop-based, both carry land-use debate, and both are priced against food markets rather than against waste.
Very few plants run a single feedstock. A typical European renewable diesel plant blends UCO, POME oil and tallow to hit a target FFA, a target cold-flow specification and a target greenhouse gas saving, while keeping the weighted cost inside what the fuel price and the mandate credit will support.
Crude palm oil is usually the cheapest per tonne, followed by POME-derived oil and tallow. Used cooking oil and rapeseed or soybean oil are the most expensive. Cost per tonne is misleading on its own, though, because yield, pretreatment cost and compliance value all differ.
High FFA consumes catalyst, causes soap formation and yield loss in FAME production, and increases corrosion and pretreatment load in hydrotreating. It is the specification that most directly discounts the value of a waste lipid parcel.
Rapeseed and soybean oil, because they are high in unsaturated fatty acids, give the best cold filter plugging point. Palm and tallow, being highly saturated, gel at much higher temperatures and need winterisation, blending or heating.
In Europe, effectively capped rather than banned. The Renewable Energy Directive limits the contribution of crop-based biofuels and sets a trajectory down for high indirect land-use change risk feedstocks such as palm, which is why investment has moved to waste lipids.
Yes, and blending is the norm. Plants blend to manage cost, free fatty acid, cold flow and sustainability accounting simultaneously, and most purchasing is done against a specification band rather than for a single named feedstock.
