The rising costs, power deficit and environmental concerns about fossil fuel-based energy resources
have led to significant research effort in renewable and cleaner energy resources. Globally, governments
are adopting policies to promote the development and application of various renewable energy (RE)
technologies for generating electricity. The main challenge associated with RE technologies such
as solar and wind generation is their intermittent nature, which affects their ability to provide 100%
supply reliability. Combining these RE sources with energy storage systems such as battery storage
and hydrogen can be cost-effective. Currently there are limitations to the fraction of RE that can be
incorporated in the grid system because of their intermittency and base load considerations. The major
challenge is the escalating power demand, far above the installed capacity in most countries. This
requires urgent mitigation of demand side management(DSM), in order to stabilize the imbalance in
the short, medium and long term. Energy efficiency and optimal integration could provide one of the
most effective technological solutions, with the usage of energy-efficient devices such as heat pump
water heaters (HPWH).
These collective efforts at energy saving should involve proper selection of an appropriate technology,
application of optimal control (OC) in RE, usage of energy-efficient equipment, green building
materials and an effective energy policy. The proper integration of these sources and the use of HPWH
could reduce the power utility?s maximum demand and improve the security of the supply. Most
countries at policy level are beginning to introduce attractive feed-in tariffs, dynamic energy pricing
(time-of-use) and rebate systems for using greener energy and energy-efficient load such as HPWHs.
Hence, this thesis provides the first practical attempt to integrate various distributed energy resources
(DRE) effectively into the grid, using HPWHs for the generation of the required thermal energy. This
multi-directional approach in this work has proven that OC strategy could significantly reduce the cost
of energy and provide an opportunity for power trade-off/feed-in in the electricity market.
This thesis developed four main models that meet both the technical and operational constraints of
DSM and optimal integration of DREs. Solar energy is abundant in Africa, its exploitation in addition
to other REs is a priority in this work. The first model is an optimal scheduling strategy of a gridtied/
battery/PV system supplying HPWH. Secondly, an optimal energy management model with a
diesel generator back-up system is developed that minimizes the fuel cost, while maximizing the
utilization of renewable energy with a HPWH. Thirdly, in OC model of a HPWH, the thermal output
is state variable. It is supplied by the second abundant wind energy hybrid resources. An economic
analysis is done in this model to assess the break-even period, which is important to every investor.
Finally, the future green energy hydrogen fuel cell hybrid system is modeled. Hydrogen has attracted
attention in modern research owing to its ability to reduce carbon dioxide emissions, thus helping
to mitigate climate change, improve local air quality, improve energy security by reducing energy
imports, increase energy supply options and reduce dependence on fossil fuels.
These models are suitable for application in both urban and rural areas where the electrical power power
supply is intermittent. These models have several advantages for building owners intending to turn
their dwelling into zero/positive energy buildings and enter electricity market. However, engineering
solutions alone cannot yield much success on DSM, sensitization and education on energy savings at
individual level and how these are intertwined with climate change are of the utmost importance.
Die stygende koste, kragtekort en besorgdheid oor die uitwerking van fossielgebaseerde energie op die
omgewing het tot beduidende navorsingspogings rakende hernubare en skoner energiebronne gelei.
W?reldwyd aanvaar regerings beleid om die ontwikkeling en aanwending van verskeie hernubare
energietegnologie? vir die opwekking van elektrisiteit te bevorder. Die hoofuitdaging in verband
met hiedie tegnologie?, soos sonkrag- en windopwekking, is hulle wisselvallige aard, wat ?n invloed
het op hulle vermo? om volledige betroubaarheid van voorsiening te verseker. ?n Kombinasie van
hierdie hernubare energiebronne met energiebergingsisteme soos batteryberging en waterstof kan kosteeffektief
wees. Daar is tans beperkings op die gedeelte van die hernubare energie wat in die netwerk
ingesluit kan word, omrede hulle wisselvalligheid en basisladingoorwegings. Die hoofuitdaging is die
groeiende aanvraag vir krag, ver meer as die ge?nstalleerde kapasiteit in die meeste lande. Gevolglik
is dringende ingryping deur aanvraagkantbestuur nodig om die wanbalans in die kort, medium en
lang termyn te stabiliseer. Energiedoeltreffendheid en optimale integrasie kan een van die mees
effektiewe tegnologiese oplossings verskaf, deur die gebruik van energie-effektiewe toestelle soos
hittepompwaterverhitters.
Hierdie kollektiewe pogings om energie te bespaar behoort ?n toepaslike keuse van geskikte tenologie,
aanwending van optimale kontrole in hernubare energie, gebruik van energie-doeltreffende
toerusting, groen boumateriale en ?n effektiewe energiebeleid in te sluit. Die behoorlike integrasie
van hierdie bronne en die gebruik van hittepompwaterverwarmers mag die maksimunaanvraag van
die energievoorsiener verminder en die sekuriteit van voorsiening verbeter. Op beleidsvlak begin
die meeste lande aanloklike invoertariewe, dimamiese energieprysbepaling (tyd-van-gebruik) en
kortingsisteme invoer om die gebruik van groener energie en energie-doeltreffende belading soos
hittepompwaterverhitters te bewerkstellig. Hierdie tesis bied die eerste praktiese poging om verskeie
verspreide energiebronne in die netwerk te integreer deur die gebruik van hittepompwaterverhitters vir
die opwekking van die vereiste hitte-energie. Die multi-gerigte benadering in hierdie werk het bewys
dat optimale kontrolestrategie die koste van energie beduidend kan verminder en die geleentheid bied
vir kragruil/krag-invoer in die elektrisiteitsmark.
Hierdie tesis het vier hoofmodelle ontwikkel wat sowel die tegniese en operasionele beperkings van
aanvraagkantbestuur en optimale integrasie van verspreide energiebronne kan hanteer. Sonkrag-energie
is oorvloedig beskikbaar in Afrika en die benutting daarvan saam met ander hernubare energiebronne
is ?n prioriteit in hierdie werk. Die eerste model is ?n optimale skeduleringstrategie van ?n netwerkgebonde/
battery/fotovolta?ese sisteem wat krag voorsien aan ?n hittepompwaterverhitter. Tweedens word
?n optimale energiebestuurmodel met ?n dieselgeneratorrugsteunsisteem ontwikkel wat die brandstofkoste
minimeer, terwyl dit die gebruik van hernubare energie met ?n hittepompwaterverhitter
maksimeer. Derdens is die hitte-uitset in ?n optimale-kontrolemodel van ?n hittepompwaterverhitter
veranderlik volgens toestand. Dit word verskaf deur die tweede oorvloedige hibridiese bron,
windenergie. ?n Ekonomiese analise word in hierdie model gedoen om die gelykopuitkomsperiode te
bepaal, wat vir alle beleggers belangrik is. Laastens word die toekomstige groen-energie waterstofbrandstofselhibriedsisteem
gemodelleer. Waterstof het in moderne navorsing aandag getrek deur sy
vermo? om koolstofdioksieduitlatings te verminder en sodoende te help om klimaatverandering te
beperk, plaaslike lugkwaliteit te verbeter, energiesekuriteit te verbeter deur energie-invoer te verminder,
energievoorsieningopsies te vermeerder en afhanklikheid van fossielbrandstowwe te verminder.
Hierdie modelle is geskik vir aanwending in sowel stedelike as landelike gebiede waar kragvoorsiening
ongereeld is. Hulle het verskeie voordele, byvoorbeeld vir eienaars van geboue wat hulle woonplekke
wil omskep in zero/positiewe energiegeboue en die elektrisiteitsmark wil betree. Desnieteenstaande
kan ingenieursoplossings op hulle eie nie veel sukses behaal met aanvraagkantbestuur nie; sensitering
en opvoeding oor energiebesparing op persoonlike vlak en bewustheid van hoe dit vervleg is met
klimaatverandering is van die uiterste belang.
