Study on the Potential of Rice Straws as a Supplementary Fuel in Very Small Power Plants in Thailand

Abstract

Agricultural residue is a major raw material for renewable energy production, particularly heat production, in Thailand. Meanwhile, the process-based residue, such as bagasse, rice husk, wood residue, palm fiber, palm shell, and saw dust, is used as a fuel for energy production in the agro-industry. Hence, this study is intended to assess the net potential and capacity of alternative agricultural residues, specifically rice straws, to serve as the supplementary fuel for very small power plants (VSPPs) in Thailand. According to the results obtained during the crop season of 2015/2016, approximately 26 Mt of rice straws were generated upon the harvesting process. The net potential of rice straws, including those that were burned and those that were left in the fields, was only about 15% or 3.85 Mt, which could be used for heat and electricity production at 1331 kilotons of oil equivalent (ktoe) or 457 MWe. As agro-residues vary by seasonality, the peak season of rice straws was in November, where approximately 1.64 Mt (43%) were generated, followed by December, at 1.32 Mt (34%). On the basis of the results, rice straw has the potential to serve as a fuel supply for VSPPs at 14.2%, 21.6%, 26.3%, and 29.0% for the radii of compilation at 24, 36, 48 km and 60 km, respectively.

Emission of Air Pollutants from Rice Residue Open Burning in Thailand, 2018

“…Because the rice residue generated located in rain-fed filed can be burned in the long period from the after harvesting to before tillage (October to April for next year) while the rice residue generated located in irrigated-fed filed was immediately burned after harvesting, in order to present a result as accurate as possible. This information indicated that there is a large gap between the seasonal variation of burned area from MCD64A1 and the previous studies [2,45] (shown in Figure 3) and the PM2.5 emission or rice residue burned (shown in Figure 5). It can be explained that the rice residue burned was calculated from 4 parameters which included the harvested area (ha), biomass load (t/ha), fraction of rice residue subjected to open burning (unitless) and combustion factor (unitless).…”

“…This information indicated that there is a large gap between the seasonal variation of burned area from MCD64A1 and the previous studies [2,45] (shown in Figure 3) and the PM 2.5 emission or rice residue burned (shown in Figure 5). It can be explained that the rice residue burned was calculated from 4 parameters which included the harvested area (ha), biomass load (t/ha), fraction of rice residue subjected to open burning (unitless) and combustion factor (unitless).…”

“…The fraction of rice residue subjected to open burning was lay in the range of 0.16 to 0.79 varied from a region (an average equal to 0.45). According to the results of Cheewaphongphan P. et al (2018) [45], the fraction of rice residue subjected to open burning was presently in the range of 0-0.36 (an average of 0.25 for irrigated field, 0.22 for rain-fed field and 0.23 for whole country), which substantially decreases from the value of the previous studies. This information indicates that the changes in the farmers' behaviors are as a result of the government policy that discourages the open burning of agricultural residues.…”

“…This study used the results of Cheewaphongphan P. et al (2018) [45] which estimated the rice residue density in each provinces and irrigation systems. Their research developed the average density of rice residue in 14 rice varieties which reported that the density of rice residue lay in the range of 4.18 ton per hectare (t/ha) to 8.02 t/ha (dried weight), with an average value of 5.81 t/ha.…”

“…This study used the fraction of rice residue subjected to open burning from the result of Cheewaphongphan P. et al (2018) [45]. Their study used the questionnaire survey as a tool to observe the farming behaviors in Thailand during 2015/2016.…”