BIODIESEL

1. BIODIESEL Renewable Energy From Oils and Fats Clint Johnson Energy Technology and Policy University of Texas Fall 2006

2. French Fried Fuel

3. Biodiesel = FAME • Fatty Acid Methyl Esters (FAME) • Fatty acids taken from oils or fats • Reacted with MeOH • Washed, dried to remove impurities • Must comply with fuel standards (U.S., European, etc.) • Variety of blends, from B5 to B100 FAME

4. Chemistry of Oils and Fats • Fatty acids are long-chain carboxylic acids • A glycerol bonded to 3 fatty acids is called a triglyceride • Oils/fats contain triglycerides and unbonded, or free, fatty acids (FFA’s) A Fatty Acid A Triglyceride

5. Transesterification • First observed in 1850’s • One main reaction for biodiesel production • Exchanges an ester’s functional group • Must be catalyzed, either base or acid • R’ (below) is methyl, and it replaces glycerol group • Viscosity is reduced significantly Transesterification

6. Feedstock Selection Source: Kemp, William H. “Biodiesel Basics and Beyond.” p. 108

7. Catalyst Selection • Acid or base catalyst • Base is faster, more economic • With high FFA, base catalyst will produce soap • Base catalyst also produces glycerol as coproduct • Acid catalysis can fix the soap problem • Most commercial processes use base catalysis

8. Production

9. Emissions • Biodiesel reduces most problematic emissions • NOx (greenhouse) emissions are increased • Led to regulatory problems with TCEQ • Can be addressed with NOx reducing additives Source: U.S. EPA

10. Future Biodiesel Research • Processing and marketing of waste glycerin • Improved FAME yields, residence times • New techniques for using cheap, high FFA oils: Fischer esterification, pyrolysis, micro emulsion • Engine performance testing

11. Questions?