31 Aug 06
DME, like LPG, is a liquid under light pressure, which turns to gas in the atmosphere. It can be made from any hydrocarbon, including oil, coal and even methane created by organic decomposition. It's a gas that's present wherever there's crude oil. In remote oilfields, since it isn't economical to run gas pipelines to users, it is simply burned off to get rid of it. That's a criminal waste of good energy, and an awful lot of pointless CO2 (carbon dioxide) pumped into the sky. But thanks to a Gas-to-Liquid process perfected by an American company called Syntroleum, this lot is now being tapped, converted and dispensed as a super-clean, super-cheap diesel fuel.
Biodiesels, of which there are different types, are known as esters. Biodiesel is usually either the ethyl or methyl ester of the base oil used to produce it. Most commonly this is rapeseed oil, or blends of this with other oils such as sunflower and soya.
These plant-derived esters are broadly classified as VOME (Vegetable Oil Methyl Esters) which include RME (Rapeseed oil Methyl Ester), also known as Diester - a contraction of diesel and ester. When 'biodiesel' is referred to, this generally means RME.
Sometimes these are grouped together as FAME (Fatty Acid Methyl Esters) where waste cooking oils and animal fats are included. Yes, you can make biodiesel from used cooking oil (with the crunchy bits filtered out, of course) and even from the waste water from dishwashers, although gathering the requisite quantities of fats from the latter can be rather time-intensive... We also must stress strongly that synthesizing your own fuels is dangerous and not recommended unless you have extensive professional experience in this area.
