Straight Vegetable Oils (SVO) / Pure Vegetable Oil (PVO)
Diesel engines can be modified to run on Straight Vegetable Oils (SVO), otherwise known as Pure Vegetable Oils (PVO). Waste Vegetable Oils (WVOs) - waste cooking oil from the food industry - are often viewed as being sustainable.
Decentralised small-scale production occurs in many European countries, including Germany, France, Netherlands and UK, for use in agriculture, private vehicles or municipal vehicles.
A report Pure plant oil as fuel - technical aspects and legislative context published by AgriforEnergy in 2011 provides a good overview of the current state of technology and the market.
PVO is addressed by the FP7 project 2ndVegOil - second generation vegetable oil (2008-2011), which has worked on PVO engine development for agricultural vehicles, among other topics.
Further information on SVO/PVO:
VROM (Netherlands)
Clean Cities fact sheet on SVO (US)
Straight Vegetable Oil - the French Experience