Biodiesel

Biodiesel refers to a non-petroleum-based diesel fuel consisting of short chain alkyl (methyl or ethyl) esters, made by transesterification of vegetable oil or animal fat (tallow), which can be used (alone, or blended with conventional petrodiesel) in unmodified diesel-engine vehicles[1].
This liquid fuel, diesel like, is prospective to be developed. Biodiesel also has advantages compared to petroleum-based diesel:

• Environmentally friendly because has better emission than petrodiesel (free sulphur, low smoke number)
• higher cetane number (>57) thus has better burning efficiency compared to crude oil
• Have lubricant effect on engine's piston
• renewable energy
• biodegradable[2]
  

[1]wikipedia
[2]Teknologi bioenergi