A study on generation and usages of compressed biogas from Napier grass | |
| Author | Sittichoke Meekaew |
| Call Number | AIT Thesis no.ET-15-07 |
| Subject(s) | Biogas--Thailand Grasses--Thailand |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Energy |
| Publisher | Asian Institute of Technology |
| Abstract | The compressed biogas production from energy crop particularly Napier grass is promoted by Ministry of Energy of Thailand. The techno-economic assessment of Napier grass based compressed biogas production is divided into three parts 1) batch biogas production experiment from Napier grass as single substrate to evaluate biogas production characteristics, 2) identification of biogas and CBG production systems based on experimental information to identify the associated cost and preliminary evaluation of CBG production project and 3) financial evaluation and sensitivity analysis of CBG production project. The lab scale anaerobic digestion from Napier grass as single substrate operated at different OLRs under mesophilic condition demonstrates that the average biogas production at OLR at 2 and 3 kgvs/m3 are 0.316 and 0.350 m3biogas/kgVS with average CH4 content of 67.5% and 62.7% respectively, then, average methane yields are 0.214 and 0.217 m3CH4/kgvs respectively. The experiment is achieved at volatile solid removal efficiency at OLR of 2 and 3 kgvs/m3of 97.2% and 83.1% respectively and digestate production at 35% MC are 1.2% and 1.3% wet basis respectively with HRT of 19 days for both OLRs. The preliminary evaluation on CBG project reveals that total cost associated with CBG production project is proportional to CBG production scale whereas unit cost of CBG is proportional to CBG production scale with reverse relationship and reaches the lowest value at plantation area of 480 rai which is considered as the most viable option for CBG production project. The result reveals that higher OLR produces more biogas, CBG and digestate yield with smaller digester volume at identical amount of feedstock and option resulting in lower capital and total cost. Self-growing grass option has lower total cost and unit CBG cost than that of buying grass option at identical OLRs. The financial analysis demonstrates that Napier grass based compressed biogas production project at different OLRs and Napier grass provided options are not feasible for investment since it shows negative project NPV for all conditions. The break-even analysis and sensitivity analysis expose that self-growing of Napier grass at higher OLR is the better option for Napier grass based CBG production project since it has lowest minimum CBG price that make project NPV = 0 and CBG price that make project IRR > 12.0%. Self-growing of Napier grass at OLR of 3 kgvs/m3 is the most suitable option for CBG project since it has the highest NPV and lowest CBG cost, break-even CBG price and CBG price at project IRR of 12.0%. The minimum CBG production cost is 25.95 THB/kg, break-even CBG price is 24.1 THB/kg and CBG price at IRR of 12.0% is 31.7 THB/kg respectively for Self-growing of Napier grass option at OLR of 3 kgvs/m3. |
| Year | 2015 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Salam, Abdul P.; |
| Examination Committee(s) | Kumar, Sivanappan;Dhakal, Shobhakar; |
| Scholarship Donor(s) | HM Queen; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2015 |