Use of ethanol as a biofuel has several limitations, such as high vapor pressure, low energy density, and corrosiveness, which prevents its widespread utilization [73, 74, 76, 141]. Bioethanol production, higher alcohols, fatty acid derivatives including biodiesels, alkanes, and alkenes are more compatible with gasoline-based fuels and allow direct utilization. Some of these compounds are also important chemical feedstocks. Since native organisms do not produce these compounds naturally in high quantities, metabolic engineering becomes essential for producing these compounds in non-native producing organisms such as E. coli. The four major metabolic systems that allow the production of higher alcohols are the coenzyme-A mediated pathways, the keto acid pathways, the fatty acid pathway, and the isoprenoid pathways which have been discussed in the subsequent sections.