The Thai government has promoted the Renewable and Alternative Energy Development Plan for 25 percent in 10 years (AEDP 2012-2021) to reduce the energy importation. This study aimed to assess the potential development of alternative source for biodiesel sector. A case study of three provinces, Krabi, Suratthani, and Nakorn si thammarat, was considered to seek for suitable areas for oil palm expansion based on the land suitability guided by the Good Agriculture Practice (GAP) of the nation. The study emphasized on the AEDP policy implementation for forest conservation and the restriction of expansion only on the pre-existing croplands, mainly the rubber plantation. The results indicated that only the land availability and land suitability in the three provinces would be sufficient for oil palm expansion target as far as any ages of rubber plantation were considered. In fact, only the old plantation with lower production should be deliberated as suitable for land conversion to energy crops. An initial investigation of the possibility of rubber plantation age classification using remote sensing data from THEOS satellite was demonstrated.