Thesis (MBA (Business Management))--University of Stellenbosch, 2007. / ENGLISH SUMMARY: Fossil fuel has been the preferred source for the production of transportation fuel for many
years. However, this is not a renewable resource. Many conflicting reports have been
published as to how long this resource will last. One thing is certain: eventually the supply
of cheap crude oil will run out. It is therefore crucial to start the search for renewable
alternatives now.
There are a number of possible candidates vying for replacing fossil fuel as primary
transportation fuel. Hydrogen, methanol, biodiesel and bioethanol all have the
characteristics required of a good transportation fuel. It is unlikely that only one of these
will replace oil. A more likely scenario would be that they all play a role in transportation in
the future. Apart from being renewable, these alternatives have the further advantage of
being less damaging to the environment, something that will become essential in future.
Among the renewable alternatives, bioethanol has the second highest energy density.
Currently, ethanol production worldwide almost exclusively uses sugarcane and maize as
raw material. However, both these are food crops and using them for ethanol could lead
to an increase in food prices. Furthermore, there is not enough agricultural land available
to produce sufficient quantities of sugarcane and maize for ethanol to replace fossil fuel.
Producing ethanol from plant material has the potential to meet the capacity requirements
without impacting directly on food production. Approximately 180 million tons of
agricultural biomass are produced in the United States each year, sufficient to produce 75
to 110 billion litres of ethanol.
Despite its abundance, the technical challenges in converting cellulose to ethanol are
significant. One major obstacle to the production of ethanol out of plant material is that
most of the sugar in plant material is unavailable for fermentation by micro-organisms. In order to render the sugars in the cellulose fraction accessible to conversion, it is necessary
to treat the plant fibres with a combination of chemical and enzymatic processes. Only
when a complex mixture of enzymes is used, does it become possible to break down
cellulose to glucose for subsequent fermentation to ethanol. Biomass processing by means of enzymes currently involves four separate biological
steps: (i) production of enzymes (cellullases and hemicellulases), (ii) hydrolysis of cellulose
and hemicellulose to sugars, (iii) fermentation of hexose sugars and (iv) fermentation of
pentose sugars. Consolidated BioProcessing (CBP) will combine all these steps into one.
However, CBP is not yet possible and the magnitude of research and developmental
advancement required to realize this goal is significant.
Both sugar and starch ethanol technologies are well established and major process
advances are therefore unlikely. Currently there are no commercial-sized plants for the
production of ethanol from lignocellulosics, however this is likely to change in the near
future considering the progress made in this field during recent years. This study will focus
on the current status of the bioethanol industry, as well as on the potential for future
development. / AFRIKAANSE OPSOMMING: Fossielbrandstof was vir baie jare die hoofbron vir die produksie van brandstof vir die vervoerbedryf. Fossielbrandstof is nie ’n hernubare energiebron nie en daar is al baie gespekuleer oor presies hoe lank daar nog goedkoop olie beskikbaar sal wees. Baie min
van die gepubliseerde bronne stem ooreen, maar almal is dit eens dat olie op een of ander
stadium sal opraak. Om hierdie rede is dit noodsaaklik om nou reeds te soek na
alternatiewe.
Daar is ’n hele aantal hernubare alternatiewe wat gebruik kan word in die plek van olie.
Waterstof, metanol, biodiesel en bioetanol beskik almal oor die nodige eienskappe om ’n
effektiewe vervoerbrandstof te wees. Die hoofvoordeel van hierdie brandstowwe is dat
hulle minder skadelik is vir die omgewing as olie, ’n eienskap wat baie belangrik sal wees
in die toekoms. Die kans is eger skraal dat een van bogenoemde bronne die mark totaal
sal oorheers soos wat olie tot op hede oorheers het. ’n Meer waarskynlik uitkoms sou
wees dat al hierdie bronne op een of ander manier ’n rol gaan speel in die vervoerbedryf in
die toekoms.
Etanol het die tweede hoogste energie digtheid van die vier genoemde hernubare
brandstowwe. Etanol word tans uitsluitlik van suikerriet en mielies geproduseer. Beide
suikerriet en mielies is voedselgewasse en die gebruik daarvan vir brandstof kan lei tot ’n
toename in voedselpryse. Daar is ook nie genoeg landbougrond beskikbaar vir die
verbouing van suikerriet en mieles sodat genoeg etanol geproduseer kan word om
fosielbranstof te vergang nie. Die vervaardiging van etanol vanaf lignosellulose het die
potensiaal om etanolkapasiteitprobleme te oorkom sonder om direk met voedselproduksie
te kompeteer. Ongeveer 180 miljoen ton landbouafval word jaarliks in die Verenigde State
geproduseer, genoeg vir die vervaardiging van tussen 75 en 110 biljoen liter etanol.
Die tegniese kompleksiteit gekoppel aan die omskakeling van sellulose na etanol is
beduidend. Die belangrikste hindernis vir die produksie van etanol vanaf plantmateriaal is
die feit dat die meeste van die suiker nie beskibaar is vir fermentasie deur
mikroörganismes nie. Plantvesels moet daarom met ’n kombinasie van chemikalieë en
ensieme behandel word om sodoende die suiker beskikbaar te maak vir omskakeling.
Sellulose kan slegs met ’n komplekse mengsel van ensieme afgebreek word tot glukose
wat dan daarna gefermenteer kan word tot etanol.
Die verwerking van biomassa met behulp van ensieme behels tans vier afsonderlike
biologiese stappe: (i) ensiemproduksie (sellulases en hemisellulases), (ii) hidrolise van
sellulose en hemisellulose tot fermenteerbare suikers, (iii) fermentasie van heksose suikers
en (iv) fermentasie van pentose suikers. Consolidate BioProcessing (CBP) poog om al vier
hierdie stappe te kombineer. Ongelukkig is die CBP proses nog nie moontlik nie en daar
moet nog baie navorsing en ontwikkeling gedoen word om dit ’n realiteit te maak.
Beide die metodes vir suiker- en styseletanolproduksie is goed gevestig, dus is die kans vir
beduidende verbeteringe klein. Daar is tans geen aanlegte van kommersiële grootte vir die
produksie van etanol vanaf lignocellulose nie, maar dit gaan waarskynlik binnekort
verander as ’n mens die vordering in ag neem wat daar onlangs gemaak is in hierdie veld.
Hierdie studie fokus op die huidige stand van sake in die etanolbedryf en die
ontwikkelingsmoontlikhede vir die toekoms.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/837 |
| Date | 12 1900 |
| Creators | La Grange, Daniel Coenrad |
| Contributors | Volschenk, Jako, University of Stellenbosch. Faculty of Economic and Management Sciences. Graduate School of Business. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | University of Stellenbosch |
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