Glycerol bassed (eco friendly) Antifreeze
One of the by-products of bio diesel production is glycerol (a.k.a. glycerine). Now that bio-diesel is becoming more readily available glycerol is now being considered as an alternative to normal glycol based anti-freeze.
" ...in the (1920s & 30s) glycerin saw some usage, but because of higher cost and weaker freeze point depression, it was not competitive with ethylene glycol. Glycerin is a by-product of the manufacture of biodiesel ... large amount of glycerin generated from high volume usage of biodiesel fuel has resulted in this chemical becoming cost competitive with the glycols currently used in engine coolants. For this reason, and lower toxicity comparable to that of propylene glycol, glycerin deserves to be reconsidered as a base for antifreeze/coolant."
Further work may be needed but this would result is less toxic environmentally friendly anti freeze.
Via: SAE Link