Life cycle assessment ofbio-ethanol as an alternative transportation fuel in Thailand

Name: Nguyen Thi Thu Lan

keyword: life cycle assessment

Abstract: This dissertation assesses energy and environmental impacts of ethanol produced in Thailand using a life cycle approach. The Introductory section serves as a basic framework for the detailed methodology used in the research study. It includes: 1) A review of related technology employed in ethanol production, 2) Case studies in ethanol fuel life cycle assessment, 3) Background information of ethanol's feasibility to be an alternative to gasoline in Thailand, and 4) Theories and Methodology for conducting the study. The Results and Discussion section details the findings reported in the thesis dissertation. It comprises six sub-sections with specific topic titles: 1) Full chain energy analysis of fuel ethanol from cassava in Thailand, 2) Energy balance and greenhouse gas (GHG) balance of cassava utilization for fuel ethanol in Thailand, 3) Life cycle assessment of fuel ethanol from cassava in Thailand, 4) Energy performance of fuel ethanol from cane molasses in Thailand, 5) Fossil energy savings and GHG mitigation potentials of ethanol from molasses, and 6) Life cycle assessment of fuel ethanol from cane molasses in Thailand. In sub-section 4.1, an assessment of net energy and supply potentials was performed to evaluate cassava utilization for fuel ethanol in Thailand. Conventionally, the first instrument used to assess ethanol's fuel efficiency is the net energy value which is defmed as the energy content of ethanol minus the net energy inputs to produce ethanol. The key implication addressed is whether ethanol production and use results in a gain of energy. Useful in assessing ethanol as an alternative fuel is a comparison with the conventional fuel (i.e. gasoline) to be replaced. The value, however, should not be used as the sole guide to assess ethanol's viability and practicability. With Thailand, a net oil importer, even more important is the opportunity of improving national energy security through the expansion of domestic production of biofuels. Positive Net Energy Value and Net Renewable Energy Value, 8.82 MJIL and 9.16 MJ/L, respectively, found for the cassava-based ethanol system in Thailand proved that it is energy efficient. Regarding supply potentials, a shift of cassava to ethanol fuel rather than its current use for chip/pellet products could be a probable solution. Sub-section 4.2 assesses the contribution of cassava-based ethanol to fossil energy savings and climate change mitigation using two relevant parameters, energy balance (EnB), and GHG balance. EnB compares the energy inputs in the production ofconventional gasoline (CG) that is avoided when ethanol is used instead of gasoline to the total fossil energy inputs in the production of ethanol. GHG balance computes net avoided GHG emissions when gasoline is displaced by ethanol. Positive energy balance of 22.4 MJIL and net avoided GHG emission of 1.6 kg CO2 eq.lL found for cassava-based ethanol proved that it is a good substitute for gasoline, effective in fossil energy savings and GHG reduction. Sub-section 4.3 performs a life cycle analysis of energy and environmental impacts of using cassava-based gasohol as a gasoline substitute in Thailand. All of the following parameters have been considered: 1) Energy use (Gross, Net, Fossil, and Petroleum use), 2) Environmental impact potentials (Global Warming, Acidification, Nutrient enrichment, and Photochemical Ozone Creation Potential). The results obtained show that cassava-ethanol (CE) in the form of EIO (10% ethanol blend in gasoline), along its whole life cycle, reduces certain environmental loads compared to CG. The percentage reductions relative to CG are 6.1% for fossil energy use, 6.0% for global warming potential, 6.8% for acidification, and 12.2% for nutrient enrichment. Concerned with the use of molasses as the main raw material for fuel ethanol in Thailand at present, sub-section 4.4 presents an analysis of full chain energy and supply potentials as the first step in the life cycle assessment of molasses-based ethanol. Negative net energy value found for MoE is a consequence of failure in utilization of system co-products (e.g. stillage and cane trash) for energy. Taking into account only fossil energy inputs in the fuel production cycle, the energy analysis provides results in favour of ethanol (5.95 MJ energy gain per litre). In terms of supply potentials, if only the surplus molasses (about 30-40% of the national molasses production) is utilized for ethanol, a shift of 8% sugar cane produce to ethanol fuel from its current use for sugar production seems to be a solution. Using the methodology followed in assessing cassava-based ethanol, sub-section 4.5 takes a closer look at fossil energy savings and GRG mitigation potentials of ethanol from molasses in Thailand. A baseline scenario representing the prevailing conditions of the fuel production cycle has been selected for the analysis of energy balance (EnB), and GRG balance. Positive EnB of 19.2 MJ/L implies that MoE is effective in fossil energy savings; it is thus a good option for national energy policy. GRG balance assessment made for the baseline scenario shows that emissions are most likely to increase with the substitution (31.1%). Projection scenario capturing biogas and using it in place of coal makes a 60.6% reduction in GRG emissions. A complete substitution ofbiogas and rice husk for coal brings the reduction rate to 83.3%, a 22.7% up from biogas substitution alone. Sub-section 4.6 completes a full picture of the environmental impacts of substituting conventional gasoline with molasses-based gasohol in Thailand. The characterization results show that molasses-based ethanol (MoE) in the form of E10, along its whole life cycle, consumes less fossil energy (5.3%), less petroleum (8.1%) and provides neutral impact on acidification compared to gasoline. The fuel, however, has inferior performance in other categories (Global Warming Potential, Nutrient Enrichment and Photochemical Ozone Creation Potential) indicated by increased impacts over gasoline. Through the LCA procedure, the key areas in the MoE production cycle where changes are required to improve fuel performance whilst minimizing adverse effects are identified. Possible improvement measures are recommended in the section as well. Among the key fmdings are the following: 1) Full chain energy analysis to estimate NEV indicates that thermal energy content of ethanol produced from cassava is in excess of the energy inputs required for its production. The excess energy represented by NRnEV is even more favourable since only fossil energy inputs are taken into account. In contrast, the same estimation procedures provide less favorable results for molasses ethanol than for cassava ethanol. The reason for this is due mainly to the contribution rate of energy recovered from biogas (a by-product of the system) substituting for fossil fuels in ethanol conversion. 2) To evaluate whether a substitution of ethanol for CG in transportation can contribute to fossil energy savings, a proper instrument is energy balance (EnB). The analysis comes out with favourable results for both CE and MoE compared to gasoline. Per litre of CE and MoE produced would save approximately 0.6 and 0.5 litre gasoline equivalent, respectively. 3) Another parameter that needs to be considered in assessing biofuels' performance is GHG balance. The results are in favour of CE but disfavour of MoE, 63% reduction versus 31% increase compared to gasoline. However, for a compatible comparison, GHG impacts of MoE should be based on the projection scenario capturing biogas from 100% spent wash and using it in place of coal for which 61% reduction in GHG emissions is obtained. 4) Life cycle assessment of ethanol in the form of gasohol EI0 is the main objective of the study. In addition to Energy use, four environmental impact potentials (Global warming, Acidification, Nutrient enrichment and Photochemical ozone creation potential) have been addressed. In a baseline scenario, cassava-based gasohol appears to be competitive with its counterpart (CG) in all impact categories except Photochemical ozone creation potential. Supporting from previous analyses, molasses-based gasohol is only competitive with CG when fossil energy and petroleum use are considered.

King Mongkut's University of Technology Thonburi. KMUTT Library.

Address: BANGKOK

Email: info.lib@mail.kmutt.ac.th

Name: Shabbir H. Gheewala

Role: Advisor

Created: 2007

Modified: 2557-04-22

Issued: 2553-01-01

วิทยานิพนธ์/Thesis

application/pdf

JGSEE125

tha

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Environmental Technology

Grantor: King Mongkut's University of Technology Thonburi

©copyrights มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

ลำดับที่.	ชื่อแฟ้มข้อมูล	ขนาดแฟ้มข้อมูล	จำนวนเข้าถึง	วัน-เวลาเข้าถึงล่าสุด
1	JGSEE125.pdf	3.28 MB	100	2024-11-08 14:48:50
2	JGSEE125ab.pdf	173.64 KB	46	2021-10-14 03:25:59

ใช้เวลา

0.025066 วินาที