**5. Conclusion**

Supercritical transesterification is a promising method for a more environmentally friendly biodiesel production as a result of its feedstock flexibility, production efficiency and environmentally friendly benefits. For extended details, the review articles on supercritical transesterification with methanol (de Boer & Bahri, 2011; Sawangkeaw et al., 2010), or ethanol (Balat, 2008; Pinnarat & Savage, 2008) and other supercritical technologies (Lee & Saka, 2010; Tan & Lee, 2011) are also available elsewhere.

Even though the knowledgebase of this process has been growing the past decade, more work is still required for an adequate understanding of the process. In spite of its advantage of feedstock flexibility, there has so far been very little research on the use of low-grade feedstocks in supercritical transformation. Furthermore, prospective studies for both the low-temperature and high-temperature approaches, as mentioned previously, are required to realize supercritical transesterification at an industrial scale.
