NaOCH3 Biobased Catalyst Other Heterogeneous catalysts Toxic and flammable, based on non-renewable resource, environmentally unfriendly Non-toxic, cheap, based on renewable biomass, environmentally friendly Expensive, based on non-renewable resource, environmentally unfriendly Feedstock is refined oil which is a human food and expensive Can use waste oil and grease as feedstock Biodiesel synthesis are either derived from non-renewable resources such as rare metals, or have problems with toxicity or stability Main byproduct of the reaction, glycerol is not usable and is land filled or burned as waste Glycerol by product is clean and can be sold as high value product   Not useful for conversion of low cost feed-stocks such as waste oil and greases because their reactions produce soaps and clean up of the soap imposes additional processing cost Especially suited for trap grease and waste oil containing water and fatty acids

Table 1: Comparison of properties of sodium methoxide, biobased catalysts, and other heterogeneous catalysts.