Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Environmental Engineering and Earth Sciences

Committee Member

Cindy M. Lee, Committee Chair

Committee Member

Terry Walker

Committee Member

David A. Ladner

Committee Member

Michael Carbajales-Dale


This study approached the conflict between energy and food needs by balancing the allocation of land area devoted to food and feed with land area to grow biofuel feedstocks. The selected optimization model was a tool that included a regional approach to determine the optimum potential land area of Thailand to use in biofuel production without affecting the supply of food and feed. The selected crops were sugarcane, cassava, and palm oil with consideration of four geographic regions of Thailand, which were the Northern, Northeastern, Central and Southern regions. The optimum cropland area and crop types in each region were obtained based on the maximum energy production given the constraints. The total optimum land area was 3.24 million hectare (ha) with 3,476 Peta Joules (PJ) of maximum energy production, which were 61 and 39 percentage of the total available land for the purpose of food energy and biofuel energy, respectively. The optimum cropland area for biofuel energy, which was approximately 1.35 million ha, was for sugarcane for bio-ethanol and palm oil for biodiesel with no area allocated for cassava. Of the 1.35 million ha, about 46 percent was allocated for sugarcane located in all regions, except the Southern region, and 54 percent for palm oil located only in the Southern region. Moreover, the energy production from crop residues of the selected crops was also estimated by using a crop-to-residue ratio and higher heating value based on the optimum cropland area. The total energy production from crop residue was 897 PJ.

The potential of the optimized land area in terms of energy return was 342 Giga Joules (GJ)/ha. Taking crop residue into account, the biofuel energy production per area was increased to 998 GJ/ha, which was almost three times the energy production from the crop feedstock alone.

In terms of the energy efficiency, Net Energy Ratio (NER) and Fossil Energy Ratio (FER) of the potential area in hectare were studied and found that NER and FER of the production of sugarcane ethanol and palm oil biodiesel were greater than 1 that indicated an energy gain.

Due to many uncertainties that affect energy production and land area allocation, a sensitivity analysis showed that the land area for sugarcane and cassava in the Northern, Central and Northeastern regions was sensitive to energy content. Only the land areas of cassava in the Northeastern region were sensitive to the land area devoted to food and feed consumption.

Based on the optimum cropland area, the amounts of biofuel production in liters of bio-ethanol and biodiesel were approximately 3,123 and 2,300 million liters, respectively. These volumes were only about 76 and 45 percentage of the biofuel targets set by the Thai government in 2036 for bio-ethanol and biodiesel, respectively. The optimization model showed there was a gap between the optimized production of biofuel feedstock to achieve the government's targets. However, if crop residues of sugarcane, cassava and palm oil were included, the volume of biofuel production would be 16,845 million liters for bio-ethanol, and 8,419 million liters for biodiesel, which would exceed the targets for bio-ethanol and biodiesel in 2036, which are 4,124 and 5,110 million liters, respectively.

Moreover, the recommendations are that the Thai government support using crop residue for biofuel, as well as technology research and economic support. The Thai government should also support research to increase the productivity of biofuel crops and search for other potential biofuel crops to grow while preventing food versus fuel conflicts.



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