Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: As the push continues for increased use of renewables on the electricity grid, the
problem of energy storage is becoming more urgent than ever. Flywheels with
wound, composite rotors represent an efficient and environmentally friendly option
for energy storage. They have already been applied successfully for voltage control
on electrical rail networks and for bridging power in backup UPS systems, but lately
they have also proven useful for grid-scale frequency regulation.
For flywheels to be deployed on a wider scale, the high cost associated with the
technology will have to be addressed. An important driver of cost is the density at
which energy can be stored. Currently, flywheel designs do not consistently achieve
high energy density, and this study investigates the reasons for this.
A critical analysis is made of the design methodologies that have been proposed in
the available literature, and some improvements are suggested. Most notably it is
shown that significant improvements in energy density may be possible if the design
optimization problem is formulated carefully.
In addition, the problem of material selection is discussed, because material properties
have a significant influence on energy density. Some guidance is given for
flywheel designers on how to choose an optimal set of materials without invoking
undue computational effort. It is hoped that these suggestions may be carried
forward as a topic of further research. / AFRIKAANSE OPSOMMING: Namate die aanvraag vir hernubare energie op die elektrisiteit netwerk vergroot,
word die probleem van energie berging van kardinale belang. Vliegwiele met silindriese
rotors van samegestelde materiale bied ’n effektiewe en omgewingsvriendelike
opsie vir energieberging. Hierdie tipe vliegwiele is reeds suksesvol aangewend
vir spanningsbeheer op elektriese spoornetwerke en om oorbruggingskrag te voorsien
aan rugsteun sisteme. Meer onlangs is hulle ook nuttig bewys vir die regulasie
van frekwensie op die elektrisiteit netwerk.
Grootskaalse aanwending van vliegwiele kan egter slegs oorweeg word indien die
hoë koste van die tegnologie aangespreek word. Een van die onderliggende redes
vir die hoë koste van vliegwiele is die relatiewe lae digtheid waarby energie geberg
kan word, en hierdie studie ondersoek die redes hiervoor.
Die ontwerpmetodiek wat in die beskikbare literatuur voorgestel is, word krities
geanaliseer en ’n paar verbeteringe word aanbeveel. Mees noemenswaardig is
die opmerklike verbeteringe in energie-digtheid wat soms moontlik is indien die
optimerings-probleem deurdag geformuleer word.
Omdat materiaaleienskappe ’n bepalende invloed op energie digtheid uitoefen word
die probleem van materiaalseleksie ook verder bespreek. ’n Paar riglyne vir die
seleksie van ’n optimale stel materiale sonder om oordrewe berekenings-inspanning
te veroorsaak, word aan vliegwielontwerpers gegee. Hierdie voorstelle kan hopelik
in die toekoms verder deurgetrap word as onderwerp vir verdere studies.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/17864 |
| Date | 12 1900 |
| Creators | Janse van Rensburg, Petrus J. |
| Contributors | Groenwold, A. A., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 91 p. : ill. |
| Rights | Stellenbosch University |
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