Thesis (MScEng (Mechanical and Mechatronic Engineering)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: In the Greater Gariep agricultural area adjacent to the Orange River between Prieska and
the Vanderkloof dam alone an estimated 311 000 ton/yr of maize and wheat straw is
available. These agricultural residues have an energy equivalent of 196 000 ton of coal per
year and should be utilised as a renewable energy resource.
A technical and financial evaluation on the collection and transport of agricultural residue
showed that the Hopetown area has the highest concentration of agricultural residue in the
Greater Gariep agricultural area with approximately 68 000 ton/yr that is spread out over 76 kmª. Briquetting, combustion, pyrolysis and gasification were identified as the technologies with
the highest potential to convert agricultural residue into a higher grade energy product in this area. The expected overall energy conversion efficiency for a plant capacity between 5 000 to 100 000 ton/yr is 98.9%, 10-25%, 25-30% and 28-36% for the briquetting,
combustion, pyrolysis and gasification plants respectively. A financial evaluation based on the internal rate of return and the net present value of investment showed that the briquetting plant is financially feasible and the most profitable for capacities between 25 000 and 60 000 ton/yr while the pyrolysis plant was financially feasible and the most profitable technology for capacities greater than 60 000 ton/yr. A sensitivity and risk analysis done on the proposed briquetting and pyrolysis plants to
evaluate the impact of market fluctuations on the profitability of the power plants exposed the briquetting plant as a very high risk investment, mainly because of the sensitivity to the selling price of fuel briquettes and the high maintenance cost associated with the briquetting
equipment. Although the proposed pyrolysis plant is sensitive to variation in the electricity price, the risks associated with the market conditions for the pyrolysis plant is very low and an internal rate of return of 15% is still projected at the minimum expected electricity price.
From the study it is clear that the utilisation of agricultural residue available in the Greater Gariep agricultural area is technically and financially viable. / AFRIKAANSE OPSOMMING: In die Groter Gariep landbougebied langs die Oranjerivier, tussen Prieska en die Van Der Kloof Dam is daar jaarliks ’n beraamde 311 000 ton mielie- en koringstrooi beskikbaar. Hierdie landbou-reste het die energie-ekwivalent van 196 000 ton steenkool per jaar en behoort as hernubare energiebron benut te word.
’n Tegniese en finansiële evaluasie van die versamel en vervoer van landbou-reste het
getoon dat die Hopetown-area die hoogste konsentrasie landbou-reste in die Groter Gariep landbougebied het met ongeveer 68 000 ton/jaar wat versprei is oor 76 kmª. Brikettering, verbranding, pirolise en vergassing is geïdentifiseer as die tegnologieë met die hoogste potensiaal om landbou-reste te omskep in ’n hoër graad energieproduk vir hierdie gebied. Die verwagte totale energie-omsettingseffektiwiteit vir ’n aanlegkapasiteit van tussen 5 000 tot 10 000 ton/jaar is onderskeidelik 98.9%, 10-25%, 25-30% en 28-36% vir die brikettering, verbranding, pirolise en vergassingsaanlegte. ’n Finansiële evaluasie gebaseer op die opbrengs op aanvangskoste en die netto huidige
waarde van die belegging het getoon dat die briketteringsaanleg finansieel lewensvatbaar is en die winsgewendste is vir ’n aanlegkapasiteit tussen 25 000 en 60 000 ton/jaar terwyl die pirolise-aanleg finansieel lewensvatbaar is en die winsgewendste tegnologie is vir
kapasiteite van groter as 60 000 ton/jaar.
’n Sensitiwiteits- en risiko-analise is op die voorgestelde brikettings- en pirolise-aanlegte
gedoen om die impak van markskommelings op die winsgewendheid van die aanlegte te
evalueer. Die resultate het getoon dat die briketteringsaanleg ’n baie hoë-risiko belegging is as gevolg van die sensitiwiteit op die verkoopprys van brikette en die hoë onderhoudskoste van briketteringstoerusting. Alhoewel die voorgenome pirolise-aanleg sensitief is vir skommelings in die elektrisiteitsprys, is die risiko’s wat met die marktoestande vir die
pirolise-aanleg gepaardgaan, baie laag en ’n opbrengs op aanvangskoste van 15% word
steeds voorspel teen die minimum verwagte verkoopsprys van elektrisiteit. Vanuit die studie blyk dit duidelik dat die gebruik van landbou-reste wat beskikbaar is in die
Groter Gariep landbougebied, tegnies en finansieel lewensvatbaar is as hernubare
energiebron. / Sponsored by the Centre for Renewable and Sustainable Energy Studies
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/18160 |
| Date | 03 1900 |
| Creators | Potgieter, Johannes George |
| Contributors | Van Niekerk, J. L., De Lange, L., University of Stellenbosch. Faculty of Engineering. Centre for Renewable and Sustainable Energy Studies |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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