Over the last two decades, livestock operations have become highly concentrated due to growing trends towards larger, more confined facilities and a decrease in cropland on smaller farms. This has led to greater amounts of excess manure nutrients on farms, increasing the potential for nutrient pollution of water bodies from runoff. The purpose of this study was to determine if enhanced biological phosphorus removal (EBPR) is a viable alternative for managing excess manure nutrients on dairy farms. Assessment of EBPR involved the investigation of various aspects of wastewater treatment modeling and design and farm nutrient management. The fermentation potential (volatile fatty acid (VFA) production) of dairy manure was determined through laboratory analysis to be 15.3% of the total COD. Total VFA production was composed of 57, 23, and 20% acetic, propionic, and butyric acids, respectively. The EBPR component of the BioWin wastewater treatment model was evaluated through a sensitivity analysis. The parameters to which effluent phosphate (PO4) concentration was most sensitive were maximum specific growth rate, growth yield, aerobic PO4 uptake rate per unit poly-b-hydroxybutyrate (PHB) utilized, PHB yield from VFA, PO4 release per unit VFA uptake, and fraction of releasable PO4. An EBPR sequencing batch reactor (SBR) was designed for a dairy farm with 700 lactating cows and 325 ha of corn silage. An economic analysis of EBPR for dairy farms employing P-based manure applications was completed. The cost of hauling excess manure to nutrient deficient farms was the most significant expense in comparing costs of manure management with and without EBPR. For a herd of 700 lactating cows, utilizing EBPR was more economical for farms with 270 ha or less cropland, while EBPR did not offer an economic advantage for farms over 270 ha. / Master of Science

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In the developed and developing world, the use of lipids for the production of alkyl esters, also known as biodiesel, showed phenomenal growth during the ten year period up to the end of 2007. The main sources for these lipids are the oils extracted from oil seeds such as soya-, palm-, and rape seed, but other products in the food chain such as waste cooking oil (yellow grease) and animal fats are also used. In Africa and Asia vast tracks of land not previously tilled, are now being cultivated to yield oils which are not edible and in a number of countries intensive research is focused on lipid producing species such as algae. Meanwhile more evidence is coming to the fore pronouncing biodiesel and other first generation biofuels not to be the panacea for the predicament the world is facing on unbridled population growth, energy security concerns and environmental issues such as indirect land use changes, global warming and climate changes. The acceptance of the National Biofuels Industrial Strategy at Cabinet level has not yet resulted in significant commensurate activity in South Africa. The availability, other uses and volumes of selected feed stocks for biodiesel production invite debate on the choice between food- and energy security and the appropriateness of some identified socio-economical and socio-political drivers for a viable industry. Somehow the unique characteristics of South Africa and its resources seem not to feature in debate and constraints on the production of biodiesel, as described in this dissertation. The conventional process routes for commercial biodiesel production are based on a mature technology which has inherent pollution and economical limitations. This called for a detailed critical evaluation on process routes more environmentally friendly or involving fewer unit processes generating more desirable products, albeit with more severe process conditions. By comparison, the homogeneous alkali catalyst alcoholysis (HACA), the enzymatic catalyst alcoholysis (ECA) and the super critical alcoholysis (SCA) process routes as developed in this study, are found to be competitive on total manucturing costs as assessed, if results emanating from selected sensitivity analyses and optimisation studies, are accepted. The total manufacturing and operating costs in the selected process routes as estimated, assuming the same capacities for commercial biodiesel production, are dominated by feed stock costs. Incentives on depreciation and fuel levies are deemed not effective, if costs are compared to the price of fossil diesel at the retail level – October 2011. It is concluded that using the feed stocks indicated in the Strategy, commercial biodiesel production is not economically feasible in South Africa at present. In this study process routes and feed stocks were identified that can change this position. Note should be taken of the intensive research activities being conducted on second generation technologies and biorefineries in the developed world, as discussed in this dissertation. / AFRIKAANSE OPSOMMING: In die ontwikkelde en ontwikkelende wêreld het die gebruik van vette vir die produksie van alkielesters, ook bekend as biodiesel, in die tienjaarperiode tot die einde van 2007 fenomenale groei getoon. Die hoofbronne vir hierdie lipiede is die olies onttrek van oliesade soos soja-, palm-, en raapsaad, maar ander produkte in die voedselketting soos gebruikte kookolie en dierevette word ook gebruik. In Afrika en Asië word uitgestrekte stukke grond voorheen onbewerk, nou bewerk om olies wat nie eetbaar is nie, op te lewer, en in verskeie lande word intensiewe navorsing op vetproduserende spesies soos alge gedoen. Intussen kom meer bewyse na vore wat verklaar dat biodiesel en ander eerste-generasie biobrandstowwe nie die wondermiddel is vir die moeilike posisie wat die wêreld in die gesig staar oor onbeteuelde bevolkingsaanwas, kwellings oor energiesekuriteit en omgewingskwessies soos indirekte grondverbruike, aardverwarming en klimaatsveranderings nie . Die aanvaarding van die Nasionale Biobrandstowwe Industriële Strategie op kabinetsvlak het nog nie verhoogde soortgelyke aktiwiteite in Suid-Afrika tot gevolg gehad nie. Die beskikbaarheid, gebruike en volumes van gekose grondstowwe, lok debatte uit oor die keuse tussen voedsel- en energiesekuriteit en die toepaslikheid van sekere geïndentifiseerde sosio-ekonomiese en sosio-politieke stimulante vir ‘n lewensvatbare nywerheid. Op een of ander manier is die unieke kenmerke van Suid- Afrika en sy bronne nog nie in die debat op die knelpunte van biodiesel nie, soos beskryf in hierdie proefskrif. Die gewone prosesroetes vir kommersiële produksie van biodiesel is gebaseer op ‘n beproefde tegnologie met inherente besoedelings- en ekonomiese beperkings. Dit het gevra vir ‘n uitvoerige kritiese evaluasie van meer omgewingsvriendelike- en minder eenheidsprosesse wat meer gewensde produkte genereer, al is dit met erger prosesbepalings. By vergelyking, is dit bevind dat die homogene alkali-katalisator- alkoholisis (HAKA), ensiem-katalisator-alkoholisis (EKA) en die superkritiese-alkoholisis (SKA) prosesroetes soos in hierdie studie ontwikkel, mededingend is op ‘n totale vervaardigingskoste-vlak, as die resultate wat spruit uit geselekteerde sensiwiteitsanalises en optimiseringsstudies, aanvaar word. Die totale vervaardigings- en bedryfskostes soos beraam vir die gekose prosesroetes vir kommersiële biodieselvervaardiging vir dieselfde deursette, word oorheers deur grondstofkostes. Aansporings op afskrywings en brandstofheffings word gesien as nie effektief nie, as kostes vergelyk word met die prys van fossieldiesel op kleinhandelsvlak – Oktober 2011. Die gevolgtrekking word gemaak dat met die grondstowwe aangedui in die Strategie, kommersiële biodieselvervaardiging tans nie ekonomies gangbaar is vir Suid-Afrika nie. In hierdie studie is prosesroetes en grondstowwe geïdentifiseer wat die posisie kan verander. Kennis moet geneem word van die intensiewe navorsingsaktiwiteite op tweede-geslag tegnologieë en bioraffinaderye in die ontwikkelde wereld, soos in hierdie proefskrif bespreek.

<p>Doktorska disertacija obuhvata vi&scaron;egodi&scaron;nja istraživanja koja se odnose na razvoj u tehnolo&scaron;kom unapređenju održavanja jednodelnih točkova železničkih vučenih vozila, uz primenu savremenih metoda i postupka dijagnostikovanja u cilju postizanja zadovoljavajućeg nivoa pouzdanosti pri eksploataciji.<br />Sveobuhvatnim istraživanjem pokazano je da uvođenjem ovog novog tehničko-tehnolo&scaron;kog postupka održavanja venca monoblok točka kvaliteta ER7, čini veliki značaj u tehnolo&scaron;kom unapređenju održavanja vitalnog dela &scaron;inskih vozila-točka, u sopstvenim radioničkim kapacitetima na&scaron;ih železničkih uprava. Istraživanjem je, takođe, potvrđeno da implementacija ovog, sasvim novog tehničko-tehnolo&scaron;kog postupka održavanja venca monoblok točka, je primenljiv i izvodljiv tehničko-tehnički postupak, u postojećim radioničkim kapacitetima koje se bave problematikom održavanja železničkih vozila bez znatnih investicionih ulaganja.<br />Istraživanja su se odvijala po fazama. Prvo su detaljno implementirana teoretska istraživačka dostignuća, zasnovana na izučavanju i primjeni savremenih tehnika i tehnologija na održavanju vitalnih elementa železničkih tehničkih sistema. Implementacija ovog teorijskog istraživanja, realno je produkovalo u zdrav i sveobuhvatan naučno-istraživački temelj, koji je omogućio opravdan pristup eksperimentalnom, a potom i eksploatcaionom istraživanju. Takvim sveobuhvatnim naučno-istraživačkim procesom, rezultiralo je u zadovoljavajuća naučno-istraživačka saznanja, koja će, sigurni smo, stvoriti zdravu podlogu za naučno razmatranje, a potom, i pristup, ka praktičnoj primeni od strane železničkih uprava na&scaron;ih zemalja.<br />Ceo proces istraživanja predmeta disertacije, baziran je na najnovijim dostignućima naučnog saznanja iz oblasti ma&scaron;instva koje izučavaju: tehnologiju obrade metala, tehnologiju proizvodnje čelika, mehanike metala, otpornosti materijala, potom metalurgije zavarivanja, fizike, hemije itd.<br />Eksperimentalna i eksploataciona istraživanja, pratile su savremene dijagnostičke metode i postupci, meritorne za dono&scaron;enje naučnih odluka i dokaza o nivou kvaliteta i pouzdanosti. Pokazano je da pored metoda mehnike loma metala i standardnih metalru&scaron;kih metoda ispitivanja, uvođenjem savremenih ultrazvučnih dijagnostičkih tehnika i tehnologija, u proces dijagnostikovanja vitalniog dela žlezničkih vozila, to jest monoblok točka, uveliko obezbeđuju visok stepen pouzdanosti, dajući značajan doprinos ovom istrživačkom radu, za potvrdu izvodljivosti tehničko-tehnolo&scaron;kog procesa.<br />Tehničko-tehnolo&scaron;kog procesa obnavljanja venaca monoblok točka kvaliteta ER7, navarivanjem, a izloženi mehničkim procesom tro&scaron;enja i kombinovanim statičkim i dinamičkim opterećenjima, pri eksploatciji, ne može se zamisliti bez primene pouzdanih tehnika dijagnostikovanja. Na taj način, kroz vi&scaron;e tehničkih faza obimnih istraživanja, potvrđena je i dokazana neophodnost primene dijagnostičkih metoda bez razaranja zasnovanih na polju ultrazvučne defektoskopije, kako bi se potvrdio i uvećao uticaj na pouzdanost tehničkog sistema-železničko vozilo.</p> / <p>Doctoral dissertation includes several years of research concerning the development of technological<br />6<br />improvement in the maintenance of oneparted railway wheels towed vehicle, with modern methods of diagnosis and procedure in order to achieve satisfactory levels of reliability in operation. Comprehensive research has shown that the introduction of this new technological process of maintaining of the wreath of monoblock wheels, quality ER7, makes a great technological importance in improving the maintenance of vital rail vehicle-point in our own workshop facilities of railway direction. The study also confirmed that, the implementation of this, an entirely new technological maintenance procedures wreath monoblock wheel, is applicable and feasible technical and technical process for the existing workshop facilities to deal with the problem of maintenance of railway vehicles without significant investment. Surveys were conducted in stages. First in detail are implemented the theoretical research achievements, based on the study and application of modern techniques and technologies, made to maintain the vital elements of railway technical systems. Implementation of this theoretical study is produced by the realistic sound and comprehensive scientific foundation, which allowed reasonable access to experimental, and also exploitation research. This comprehensive scientific research process, resulted a satisfactory scientific research findings, which for sure will create a sound basis for scientific discussion and also access to practical use by the railway companies of our country. The whole process of dissertation research subjects is based on the latest achievements of scientific knowledge in mechanical engineering studies such as: the technology of metal processing, steel production technology, metal mechanics, strength of materials, welding metallurgy, physics, chemistry, etc.. Experimental research and exploitation, were accompanied by modern diagnostic methods and procedures, merit-making for the adoption of scientific decisions and evidence at the level of quality and reliability. It is shown that besides the methods of fracture of metals and mechanics metallurgy standard test methods, the introduction of modern ultrasonic diagnostic techniques and technologies in the process of diagnosing vital railway vehicle, as a monoblock points, largely provides a high degree of reliability by providing a significant contribution to this research for confirming technological feasibility of the process. Technological process of wreath restoring of monoblock wheels, quality ER7, which are subjected to the mechanical process of wear and combinated static and dynamic loads, in the process od exploitation, it can not be imagined without the use of reliable diagnostic techniques. Thus, through the more technical phases of extensive research, has been confirmed and proved the necessity of applying nondestructive diagnostic method based on the field of ultrasound defectoscopy, with the purpose of confirmation and increasing of impact on the reliability of technical systems and rail car.&nbsp;</p>

Este trabalho objetivou realizar a avaliação econômica comparativa entre as seguintes atividades na região sudoeste paulista: ovinocultura de corte, monocultura de eucalipto visando produção de madeira para celulose e dois modelos de sistema silvipastoril (SSP) composto por clones de eucalipto, pastagem pré-existente e ovinos para o módulo de 30 ha e horizonte de sete anos. Os SSP avaliados possuíam espaçamento 12 x 1 m (SSP I) e 2 x 2 x 12 m (SSP II). Os critérios econômicos utilizados foram o Valor Presente Líquido (VPL) à taxa de desconto de 8 % a.a. e a Taxa Interna de Retorno (TIR). As avaliações econômicas foram realizadas sob condições de risco utilizando-se a simulação Monte Carlo para as variáveis aleatórias consideradas mais relevantes do fluxo de caixa de cada atividade. Para realizar a avaliação econômica da ovinocultura foi necessário primeiramente caracterizar o sistema de produção ovina para a região de estudo mediante visitas técnicas às propriedades pertencentes ao Núcleo Sul Paulista de ovinocultores utilizando-se um questionário semi-estruturado. Na atividade ovina foram consideradas variáveis aleatórias a \"taxa de concepção das ovelhas, taxa de mortalidade dos cordeiros com até 60 dias de idade e taxa de reposição do rebanho\". Admitiu-se para as variáveis mencionadas a distribuição triangular. Na atividade florestal foram consideradas variáveis aleatórias as operações mecanizadas e manuais necessárias para a implantação e manutenção da cultura do eucalipto em espaçamento 3 x 2 m, coletadas da base de dados de uma empresa prestadora de serviços florestais da região. Foi analisado um total de 8.225 informações de implantação e tratos culturais (manutenções) permitindo constituir dois cenários: mecanizado e manual. Dezessete operações foram utilizadas e o rendimento operacional, suas distribuições de probabilidade e parâmetros foram determinados. Para as avaliações dos SSP foram utilizadas as variáveis aleatórias mencionadas de cada atividade, porém, no caso das variáveis aleatórias da atividade florestal, os rendimentos operacionais foram calculados proporcionalmente aos espaçamentos praticados. A análise Monte Carlo considerou 10.000 simulações e foi desenvolvida com o apoio do software @risk. O VPL médio da ovinocultura foi de R$ 2.618,35 para o módulo de 30 hectares e tem elevado desvio padrão, R$ 41.061,86. A TIR dessa atividade apresentou valor de 29,31 % a.a, porém também com desvio padrão elevado (27,70 %). A monocultura de eucalipto apresentou valores médios de VPL positivos para o cenário mecanizado e manual, correspondendo a R$ 71.963,42/30 ha e R$ 73.123,66/30 ha, respectivamente e TIR média superiores à taxa de desconto praticada nesse estudo, 15,58 % a.a. e 15,97 % a.a., respectivamente. O SSP I e o SSP II são economicamente viáveis, apresentando VPL médios de R$ 85.032,45 e R$ 69.521,20 e TIR média de 21,03 e 19,18 %, respectivamente. De acordo com o critério do VPL a atividade mais rentável é o SSP I, seguido pela monocultura de eucalipto (cenário manual e mecanizado, respectivamente), SSP II e ovinocultura. Segundo o critério da TIR a ovinocultura apresenta-se como a atividade mais viável, seguido pelo SSP I, SSP II e a monocultura de eucalipto (cenário manual e mecanizado, respectivamente). / This study aimed to perform an economic evaluation comparing the following activities in the southwestern region of São Paulo state: beef cattle sheep, eucalypt monoculture for pulpwood production and two models of silvopastoral system (SSP) composed of eucalypt clones, natural pasture and sheep to a module of 30 ha and a seven-year cycle. The SSP assessed had a 12 x 1 m spacing (SSP I) and 2 x 2 x 12 m (SSP II). The economic criteria used were the Net Present Value (NPV) at 8% interest rate and the Internal Rate of Return (IRR). The economic evaluations were performed under risk conditions using Monte Carlo simulation for the random variables considered most relevant for each activity´s cash flow. In order to perform an economic evaluation of cattle production it was first necessary to characterize the sheep production system for the study area through technical visits to properties belonging to the \"Núcleo Sul Paulista\" of sheep breeders using a semi-structured questionnaire. In the ovine activity variables random to \"conception rate of ewes, lambs mortality rate of up to 60 days of age and replacement rate of flock\" were considered. Triangular distribution was admitted to the mentioned variables. In forestry, mechanized and manual operations necessary for the implementation and maintenance of eucalypt plantation of 3 x 2 m spacing were considered random variables, collected from the data base of a forestry services company from the region. A total of 8,225 field information data on implantation and cultivation (maintenance) were analyzed, allowing the constitution of a mechanized and a manual scenario. Seventeen operations were used and the operational income, its probability distributions and parameters were determined. Random variables listed for each activity were used for the evaluation of SSP, however, in random variables of forestry activity, the operational earnings were calculated in proportion to the spacing practiced. The Monte Carlo analysis considered 10,000 simulations and was developed with the support of @ risk software. The average NPV of ovine culture was R$ 2,618.35 for the 30-hectare modulus and has a high standard deviation, R$ 41,061.86. IRR for this activity showed a value of 29.31%, but also with a high standard deviation (27.70%). The eucalypt monoculture showed average values of NPV, positive for both mechanized and manual scenarios, corresponding to R$ 71,963.42 / 30 ha and R$ 73,123.66 / 30 ha, respectively, and average IRR superior to the interest rate practiced in this study, 15.58% and 15.97% respectively. SSP I and SSP II are economically viable, with average NPV of R$ 85,032.45 and R$ 69,521.20 and average IRR of 21.03 and 19.18%, respectively. According to the NPV criteria, SSPI proved to be the most profitable activity, followed by eucalypt monoculture (manual and mechanized scenarios, respectively), SSP II and ovine culture. As determined by IRR criteria, cattle production presents itself as the most viable activity, followed by SSP I, SSP II and eucalypt monoculture (manual and mechanized scenarios, respectively).

Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Small-scale farmers have the opportunity to gain access to markets through a contract farming arrangement. The key question is whether it is financially feasible for a small-scale farmer to enter into a contract. The objectives of this study were to develop a model that could be used to determine the financial feasibility of small-scale contract broiler farming in an intensive production system, compare three different genotypes namely: Cobb500 males X Hybro G females, Ross 308 males X Potchefstroom Koekoek females (crossbred) and the purebred Potchefstroom Koekoek, and evaluate current smallscale farmers’ broiler production by means of a case study. Financial performance indicators such as the net present value, cash flow and profit and loss statements were used to analyze the feasibility of all the scenarios. The model was built in Microsoft Excel. Five hundred, 1500 and 2500 birds/cycle scale of production were analyzed. Results revealed that based on the capital costs used, a 500 birds/cycle scale of production was uneconomical and that a farmer would have to receive R25.01/kg broiler meat in order to break even. The 1500 scale of production showed much better results. A farmer could break even at R17.51/kg meat. The capital investment cost of the 2500 scale of production was so high that the farmer would have had to sell his broiler meat for R18.54/kg. Performance traits of genotypes were collected through an experiment and data was statistically analyzed using ‘Statistica 9’. Results showed that there were significant differences between the cumulative feed intake, feed conversion ratios and the European production efficiency ratio of the different genotypes. No significant difference was found in the liveability of the genotypes. Data on performance traits was used as input into the model so that the economic feasibility of the genotypes could be compared. Results showed that a purebred Potchefstroom Koekoek genotype was not suitable for an intensive production system and that the crossbreed did not perform as well as the broiler breed, but that it would be worthwhile investigating the performance traits of the cross breed under less optimal conditions or in a free-range system. The lower capital costs necessary for a freerange system, together with the high premium paid for free-range broiler meat, may give admirable results in the economic feasibility of a small-scale broiler farm. / AFRIKAANSE OPSOMMING: Kleinboere het die geleentheid om deur kontrak boerdery toegang tot markte te verkry. Die vraag is egter of dit finansieël haalbaar is vir 'n kleinboer om kontraktueel verbind te word? Die doelwitte van die studie was om: ‘n model te ontwikkel wat gebruik kan word om die finansiële lewensvatbaarheid van' n klein-skaalse braaikuikenboer te bepaal onder 'n intensiewe produksiestelsel; verskillende genotipes naamlik: Cobb500 hane X Hybro G henne, Ross 308 hane X Potchefstroom Koekoek henne (kruising) en die suiwer Potchefstroom Koekoek te evalueer en die die huidige klein-skaal boer se braaikuikenproduksie deur middel van 'n gevallestudie te evalueer. Finansiële prestasie aanwysers soos die netto huidige waarde, kontantvloei, asook wins en verlies state was gebruik om die haalbaarheid van die verskeie gevalle te analiseer. Die model is op Microsoft Excel gebou. ‘n Produksie skaal van 500, 1500 en 2500 kuikens/siklus is ontleed. Resultate het getoon dat, gebaseer op die kapitale koste wat gebruik is, 'n produksie skaal van 500 kuikens/siklus onekonomies is en dat ʼn boer R25.01/kg sal moet ontvang om gelyk te breek. Die produksie skaal van 1500 kuikens/siklus het beter resultate getoon. 'n Boer kan gelyk breek teen R17.51/kg vleis. Die kapitale beleggingskoste van die produksie skaal van 2500 kuikens/siklus was so hoog dat die boer R18.54/kg sou moes ontvang het om gelyk te breek. Prestasie van genotipes is ingesamel deur middel van 'n eksperiment en data is statisties ontleed met behulp van Statistica 9. Resultate het getoon dat daar hoogs beduidende verskille tussen die kumulatiewe voerinname, voeromsetsverhoudings en Europese produksie effektiwiteits verhouding van die verskillende genotipes is. Geen beduidende verskil is gevind in die leefbaarheid van die genotipes nie. Inligting oor die prestasie eienskappe is gebruik as insette tot die model sodat die ekonomiese haalbaarheid van die genotipes vergelyk kon word. Resultate het getoon dat 'n suiwer Potchefstroom Koekoek genotipe nie geskik is vir 'n intensiewe produksie stelsel nie en dat die kruising nie so goed soos die braaikuiken gevaar het nie, maar dat dit die moeite werd sal wees om ondersoek in te stel na die produksie potensiaal van die kruis kuiken in minder optimale toestande, soos ‘n vryloop stelsel. Die laer kapitale koste en die hoë premie wat betaal word vir vryloop braaikuikenvleis mag geloofwaardige resultate op die ekonomiese haalbaarheid van 'n kleinskaalse braaikuikenboer toon.

The solar PV modules are influenced by a variety of loss mechanisms by which the energy yield is affected. A PV system is the sum of individual PV modules which should ideally operate similarly, however, inhomogeneous soiling, mismatching, and degradation, which are the main focus in this study, lead to dissimilarities in PV modules operating behavior and thus, lead to losses which will be assessed intensively in terms of energy yield. The dissimilarities in PV modules are referred to the ambient conditions or the PV modules characteristics which result in different modules’ maximum power point (MPP) and thus, different currents generated by each PV modules which cause the mismatching. However, the weakest PV module current governs the string current, and the weakest string voltage governs the voltage. Power optimizers are electronic devices connected to the PV modules which adjust the voltages of the PV modules in order to obtain the same current as the weakest module and thus, extract the modules’ MPP. Hence, the overall performance of the PV plant is enhanced. On the other hand, the power optimizers add additional cost to the plant’s investment cost and thus, the extra energy yield achieved by utilizing the power optimizers must be sufficient to compensate the additional cost of the power optimizers. This is assessed by designing three systems, a reference system with SMA inverters, a system utilizes Tigo power optimizers and SMA inverters, and a system utilizes SolarEdge power optimizers and inverters. The study considers four different locations which are Borlänge, Madrid, Abu Dhabi, and New Delhi. An Excel model is created and validated to emulate the inhomogeneous soiling and to evaluate the economic feasibility of the power optimiz ers. The model’s inputs are obtained from PVsyst and the precipitation data is obtained from Meteoblue and SMHI database. The economic model is based on the relation between Levelized Cost of Electricity (LCOE) which will be used to derive the discount rate. Graphs representing the discounted payback period as a function of the feed-in tariff for different discount rates is created in order to obtain the discounted payback period. The amount of extra energy yielded by the Tigo and the SolarEdge systems is dependent on the soiling accumulated on the PV modules. Relative to the reference system, 6.5 % annual energy gain by the systems utilizing the power optimizers in soiling conditions, up to 2.1 % in the degradation conditions, and up to 9.7 % annual energy gain at 10 % mismatching rate. The extra energy yield is dependent on the location, however, the Tigo and the SolarEdge systems have yielded more energy than the reference system in all cases except one case when the mismatch losses is set to zero. The precipitation pattern is very influential, and a scare precipitation leads to a reduction in the energy yield, in this case, the Tigo and the SolarEdge systems overall performance is enhanced and the extra energy gain becomes greater. The Tigo system yield slightly more energy than the SolarEdge system in most cases, however, during the plant’s lifetime, the SolarEdge system could become more efficient than the Tigo system which is referred to the system’s sizing ratio. The degradation of the system or the soiling accumulation decreases the irradiation and thus, a slightly oversized PV array become suitable and deliver an optimal power to the inverters. The SolarEdge system is feasible in all scenarios in terms of LCOE and discounted payback period, although its slightly lower performance relative to the Tigo system, this is referred to its low initial cost in comparison to the other systems. The Tigo system is mostly infeasible although it yields more energy than the reference and the SolarEdge systems, this is referred iii to its relatively high initial cost. However, feed- in tariffs higher than 20 € cent / kWh make all systems payback within less than 10 years. The results have overall uncertainty within ± 6.5 % including PVsyst, Excel model, and the precipitation uncertainties. The uncertainty in the degradation and the mismatching calculations is limited to PVsyst uncertainty which is ± 5 %. The uncertainties in LCOE in the location of New Delhi, since it is the worst-case scenario, are 5.1 % and 4 % for the reference and the systems utilizing power optimizers, respectively. Consequently, accommodating the uncertainties to the benefits gained by utilizing power optimizers indicates that the energy gain would oscillate in the range of 6 % - 6.9 % for the soiling calculations, 2 % - 2.2 % for the degradation simulations, and 9.2 % - 10.2 % for the mismatching simulations at 10 % mismatchrate.

O elevado consumo energético de edificações para o seu condicionamento térmico já é um dos maiores impactos ambientais da construção civil nos países desenvolvidos e, progressivamente, vem se tornando uma preocupação também nos países em desenvolvimento. Uma alternativa renovável relativamente recente, tanto para aquecimento como para resfriamento, são as bombas de calor geotérmicas (ground source heat pumps, GSHPs), que se valem da inércia térmica do solo para reduzir significativamente a demanda energética em relação ao ar. Apesar do seu grande potencial em reduzir o consumo de energia e as emissões de carbono, esta tecnologia ainda é quase inexistente na América Latina, não somente devido à falta de conhecimento ao seu respeito, mas também pela incerteza quanto à sua viabilidade frente a um custo inicial mais elevado. Embora existam muitas pesquisas sobre o funcionamento de GSHPs, grande parte do conhecimento prático quanto ao projeto, desempenho e viabilidade é baseada na experiência dos primeiros países onde a tecnologia começou a se tornar popular, e não pode ser assumida automaticamente como válida em outras situações sem uma avaliação prévia Estudos anteriores apontaram que o retorno econômico de GSHPs tende a ser maior em climas mais frios, enquanto a eficiência tende a ser maior em climas mais amenos, mas com sazonalidade. Por apresentar um bom balanço destas características, o Estado do Rio Grande do Sul apresenta potencial para um desempenho elevado de GSHPs. O objetivo deste trabalho é estimar os níveis de eficiência que esta tecnologia pode atingir em uma cidade de referência no Estado, assim como seu retorno econômico frente a ASHPs (air source heat pumps, ou seja, aparelhos de ar condicionado, ou A/C), seus limitantes e as dificuldades de projeto. Uma edificação unifamiliar residencial em Porto Alegre, projetada especialmente para estudos de sustentabilidade, foi utilizada como caso de estudo para o projeto conceitual completo de um GSHP vertical, um GSHP horizontal e um ASHP. Foram estimadas a demanda de energia e os custos de operação e de implantação para determinadas condições, que foram comparadas em um estudo de viabilidade econômica. Após, os resultados foram extrapolados por uma análise de sensitividade para condições mais genéricas de consumo. Através dos cálculos, observou-se que a tecnologia de GSHPs atingiu o dobro da eficiência dos A/C mais eficientes disponíveis para o caso de estudo. Economicamente, a tecnologia também se mostrou viável, e foram estimados limitantes econômicos a esta viabilidade. Por fim, o processo de projeto desenvolvido pode servir de auxílio a novos projetistas na área. / The high energy consumption in buildings for their thermal conditioning is already one of the greatest environmental impacts of civil construction in developed countries and, progressively, is also becoming a concern in the developing countries. A relatively recent renewable alternative, as much for heating as for cooling, are the ground source heat pumps, GSHPs, which take advantage of the thermal inertia of the ground to significantly decrease the energy demand comparing to air as a source. In spite of their huge potential for decreasing energy comsumption and carbon emissions, this technology is still almost inexistent in Latin America, due not only to lack of awareness, but mainly to uncertainties about their feasibility because of their higher investment cost. Although there are many researches about the characteristics and operation of GSHPs, great part of the practical knowledge as to the design, performance and feasibility is based in the experience from the first countries where the technology spreaded, and cannot be automatically assumed as valid without a previous evaluation. Former studies indicated that the economic profit of GSHPs tends to be higher in colder climates, while the efficiency tends to be higher in milder, but still seasonal climates. For presenting a good balance among these factors, the Rio Grande do Sul State shows potential for a high performance of GSHPs The objective of this work is to estimate the efficiency levels that can be reached by this technology in a reference city in the State, as its financial feedback compared to ASHPs (air source heat pumps, the traditional air conditioners, or A/C), its limitations and the design difficulties. A residential single-family building in Porto Alegre, specifically designed for sustainability studies, was used as case study for the complete conceptual design of a vertical GSHP, a horizontal GSHP and an ASHP. The energy demand and operation and installation costs for specific conditions were estimated and compared in a economic feasibility study. After, the results were extrapolated through a sensitivity analysis for more generic situations of consumption. Through the calculations, it was observed that the technology achieved twice the efficiency of the most efficient A/C available for the case study. Economically, the technology showed itself viable, and economic limitations were also estimated. At last, the developed design process can also serve as aid to new designers in the field.

O elevado consumo energético de edificações para o seu condicionamento térmico já é um dos maiores impactos ambientais da construção civil nos países desenvolvidos e, progressivamente, vem se tornando uma preocupação também nos países em desenvolvimento. Uma alternativa renovável relativamente recente, tanto para aquecimento como para resfriamento, são as bombas de calor geotérmicas (ground source heat pumps, GSHPs), que se valem da inércia térmica do solo para reduzir significativamente a demanda energética em relação ao ar. Apesar do seu grande potencial em reduzir o consumo de energia e as emissões de carbono, esta tecnologia ainda é quase inexistente na América Latina, não somente devido à falta de conhecimento ao seu respeito, mas também pela incerteza quanto à sua viabilidade frente a um custo inicial mais elevado. Embora existam muitas pesquisas sobre o funcionamento de GSHPs, grande parte do conhecimento prático quanto ao projeto, desempenho e viabilidade é baseada na experiência dos primeiros países onde a tecnologia começou a se tornar popular, e não pode ser assumida automaticamente como válida em outras situações sem uma avaliação prévia Estudos anteriores apontaram que o retorno econômico de GSHPs tende a ser maior em climas mais frios, enquanto a eficiência tende a ser maior em climas mais amenos, mas com sazonalidade. Por apresentar um bom balanço destas características, o Estado do Rio Grande do Sul apresenta potencial para um desempenho elevado de GSHPs. O objetivo deste trabalho é estimar os níveis de eficiência que esta tecnologia pode atingir em uma cidade de referência no Estado, assim como seu retorno econômico frente a ASHPs (air source heat pumps, ou seja, aparelhos de ar condicionado, ou A/C), seus limitantes e as dificuldades de projeto. Uma edificação unifamiliar residencial em Porto Alegre, projetada especialmente para estudos de sustentabilidade, foi utilizada como caso de estudo para o projeto conceitual completo de um GSHP vertical, um GSHP horizontal e um ASHP. Foram estimadas a demanda de energia e os custos de operação e de implantação para determinadas condições, que foram comparadas em um estudo de viabilidade econômica. Após, os resultados foram extrapolados por uma análise de sensitividade para condições mais genéricas de consumo. Através dos cálculos, observou-se que a tecnologia de GSHPs atingiu o dobro da eficiência dos A/C mais eficientes disponíveis para o caso de estudo. Economicamente, a tecnologia também se mostrou viável, e foram estimados limitantes econômicos a esta viabilidade. Por fim, o processo de projeto desenvolvido pode servir de auxílio a novos projetistas na área. / The high energy consumption in buildings for their thermal conditioning is already one of the greatest environmental impacts of civil construction in developed countries and, progressively, is also becoming a concern in the developing countries. A relatively recent renewable alternative, as much for heating as for cooling, are the ground source heat pumps, GSHPs, which take advantage of the thermal inertia of the ground to significantly decrease the energy demand comparing to air as a source. In spite of their huge potential for decreasing energy comsumption and carbon emissions, this technology is still almost inexistent in Latin America, due not only to lack of awareness, but mainly to uncertainties about their feasibility because of their higher investment cost. Although there are many researches about the characteristics and operation of GSHPs, great part of the practical knowledge as to the design, performance and feasibility is based in the experience from the first countries where the technology spreaded, and cannot be automatically assumed as valid without a previous evaluation. Former studies indicated that the economic profit of GSHPs tends to be higher in colder climates, while the efficiency tends to be higher in milder, but still seasonal climates. For presenting a good balance among these factors, the Rio Grande do Sul State shows potential for a high performance of GSHPs The objective of this work is to estimate the efficiency levels that can be reached by this technology in a reference city in the State, as its financial feedback compared to ASHPs (air source heat pumps, the traditional air conditioners, or A/C), its limitations and the design difficulties. A residential single-family building in Porto Alegre, specifically designed for sustainability studies, was used as case study for the complete conceptual design of a vertical GSHP, a horizontal GSHP and an ASHP. The energy demand and operation and installation costs for specific conditions were estimated and compared in a economic feasibility study. After, the results were extrapolated through a sensitivity analysis for more generic situations of consumption. Through the calculations, it was observed that the technology achieved twice the efficiency of the most efficient A/C available for the case study. Economically, the technology showed itself viable, and economic limitations were also estimated. At last, the developed design process can also serve as aid to new designers in the field.

Este trabalho objetivou realizar a avaliação econômica comparativa entre as seguintes atividades na região sudoeste paulista: ovinocultura de corte, monocultura de eucalipto visando produção de madeira para celulose e dois modelos de sistema silvipastoril (SSP) composto por clones de eucalipto, pastagem pré-existente e ovinos para o módulo de 30 ha e horizonte de sete anos. Os SSP avaliados possuíam espaçamento 12 x 1 m (SSP I) e 2 x 2 x 12 m (SSP II). Os critérios econômicos utilizados foram o Valor Presente Líquido (VPL) à taxa de desconto de 8 % a.a. e a Taxa Interna de Retorno (TIR). As avaliações econômicas foram realizadas sob condições de risco utilizando-se a simulação Monte Carlo para as variáveis aleatórias consideradas mais relevantes do fluxo de caixa de cada atividade. Para realizar a avaliação econômica da ovinocultura foi necessário primeiramente caracterizar o sistema de produção ovina para a região de estudo mediante visitas técnicas às propriedades pertencentes ao Núcleo Sul Paulista de ovinocultores utilizando-se um questionário semi-estruturado. Na atividade ovina foram consideradas variáveis aleatórias a \"taxa de concepção das ovelhas, taxa de mortalidade dos cordeiros com até 60 dias de idade e taxa de reposição do rebanho\". Admitiu-se para as variáveis mencionadas a distribuição triangular. Na atividade florestal foram consideradas variáveis aleatórias as operações mecanizadas e manuais necessárias para a implantação e manutenção da cultura do eucalipto em espaçamento 3 x 2 m, coletadas da base de dados de uma empresa prestadora de serviços florestais da região. Foi analisado um total de 8.225 informações de implantação e tratos culturais (manutenções) permitindo constituir dois cenários: mecanizado e manual. Dezessete operações foram utilizadas e o rendimento operacional, suas distribuições de probabilidade e parâmetros foram determinados. Para as avaliações dos SSP foram utilizadas as variáveis aleatórias mencionadas de cada atividade, porém, no caso das variáveis aleatórias da atividade florestal, os rendimentos operacionais foram calculados proporcionalmente aos espaçamentos praticados. A análise Monte Carlo considerou 10.000 simulações e foi desenvolvida com o apoio do software @risk. O VPL médio da ovinocultura foi de R$ 2.618,35 para o módulo de 30 hectares e tem elevado desvio padrão, R$ 41.061,86. A TIR dessa atividade apresentou valor de 29,31 % a.a, porém também com desvio padrão elevado (27,70 %). A monocultura de eucalipto apresentou valores médios de VPL positivos para o cenário mecanizado e manual, correspondendo a R$ 71.963,42/30 ha e R$ 73.123,66/30 ha, respectivamente e TIR média superiores à taxa de desconto praticada nesse estudo, 15,58 % a.a. e 15,97 % a.a., respectivamente. O SSP I e o SSP II são economicamente viáveis, apresentando VPL médios de R$ 85.032,45 e R$ 69.521,20 e TIR média de 21,03 e 19,18 %, respectivamente. De acordo com o critério do VPL a atividade mais rentável é o SSP I, seguido pela monocultura de eucalipto (cenário manual e mecanizado, respectivamente), SSP II e ovinocultura. Segundo o critério da TIR a ovinocultura apresenta-se como a atividade mais viável, seguido pelo SSP I, SSP II e a monocultura de eucalipto (cenário manual e mecanizado, respectivamente). / This study aimed to perform an economic evaluation comparing the following activities in the southwestern region of São Paulo state: beef cattle sheep, eucalypt monoculture for pulpwood production and two models of silvopastoral system (SSP) composed of eucalypt clones, natural pasture and sheep to a module of 30 ha and a seven-year cycle. The SSP assessed had a 12 x 1 m spacing (SSP I) and 2 x 2 x 12 m (SSP II). The economic criteria used were the Net Present Value (NPV) at 8% interest rate and the Internal Rate of Return (IRR). The economic evaluations were performed under risk conditions using Monte Carlo simulation for the random variables considered most relevant for each activity´s cash flow. In order to perform an economic evaluation of cattle production it was first necessary to characterize the sheep production system for the study area through technical visits to properties belonging to the \"Núcleo Sul Paulista\" of sheep breeders using a semi-structured questionnaire. In the ovine activity variables random to \"conception rate of ewes, lambs mortality rate of up to 60 days of age and replacement rate of flock\" were considered. Triangular distribution was admitted to the mentioned variables. In forestry, mechanized and manual operations necessary for the implementation and maintenance of eucalypt plantation of 3 x 2 m spacing were considered random variables, collected from the data base of a forestry services company from the region. A total of 8,225 field information data on implantation and cultivation (maintenance) were analyzed, allowing the constitution of a mechanized and a manual scenario. Seventeen operations were used and the operational income, its probability distributions and parameters were determined. Random variables listed for each activity were used for the evaluation of SSP, however, in random variables of forestry activity, the operational earnings were calculated in proportion to the spacing practiced. The Monte Carlo analysis considered 10,000 simulations and was developed with the support of @ risk software. The average NPV of ovine culture was R$ 2,618.35 for the 30-hectare modulus and has a high standard deviation, R$ 41,061.86. IRR for this activity showed a value of 29.31%, but also with a high standard deviation (27.70%). The eucalypt monoculture showed average values of NPV, positive for both mechanized and manual scenarios, corresponding to R$ 71,963.42 / 30 ha and R$ 73,123.66 / 30 ha, respectively, and average IRR superior to the interest rate practiced in this study, 15.58% and 15.97% respectively. SSP I and SSP II are economically viable, with average NPV of R$ 85,032.45 and R$ 69,521.20 and average IRR of 21.03 and 19.18%, respectively. According to the NPV criteria, SSPI proved to be the most profitable activity, followed by eucalypt monoculture (manual and mechanized scenarios, respectively), SSP II and ovine culture. As determined by IRR criteria, cattle production presents itself as the most viable activity, followed by SSP I, SSP II and eucalypt monoculture (manual and mechanized scenarios, respectively).

O elevado consumo energético de edificações para o seu condicionamento térmico já é um dos maiores impactos ambientais da construção civil nos países desenvolvidos e, progressivamente, vem se tornando uma preocupação também nos países em desenvolvimento. Uma alternativa renovável relativamente recente, tanto para aquecimento como para resfriamento, são as bombas de calor geotérmicas (ground source heat pumps, GSHPs), que se valem da inércia térmica do solo para reduzir significativamente a demanda energética em relação ao ar. Apesar do seu grande potencial em reduzir o consumo de energia e as emissões de carbono, esta tecnologia ainda é quase inexistente na América Latina, não somente devido à falta de conhecimento ao seu respeito, mas também pela incerteza quanto à sua viabilidade frente a um custo inicial mais elevado. Embora existam muitas pesquisas sobre o funcionamento de GSHPs, grande parte do conhecimento prático quanto ao projeto, desempenho e viabilidade é baseada na experiência dos primeiros países onde a tecnologia começou a se tornar popular, e não pode ser assumida automaticamente como válida em outras situações sem uma avaliação prévia Estudos anteriores apontaram que o retorno econômico de GSHPs tende a ser maior em climas mais frios, enquanto a eficiência tende a ser maior em climas mais amenos, mas com sazonalidade. Por apresentar um bom balanço destas características, o Estado do Rio Grande do Sul apresenta potencial para um desempenho elevado de GSHPs. O objetivo deste trabalho é estimar os níveis de eficiência que esta tecnologia pode atingir em uma cidade de referência no Estado, assim como seu retorno econômico frente a ASHPs (air source heat pumps, ou seja, aparelhos de ar condicionado, ou A/C), seus limitantes e as dificuldades de projeto. Uma edificação unifamiliar residencial em Porto Alegre, projetada especialmente para estudos de sustentabilidade, foi utilizada como caso de estudo para o projeto conceitual completo de um GSHP vertical, um GSHP horizontal e um ASHP. Foram estimadas a demanda de energia e os custos de operação e de implantação para determinadas condições, que foram comparadas em um estudo de viabilidade econômica. Após, os resultados foram extrapolados por uma análise de sensitividade para condições mais genéricas de consumo. Através dos cálculos, observou-se que a tecnologia de GSHPs atingiu o dobro da eficiência dos A/C mais eficientes disponíveis para o caso de estudo. Economicamente, a tecnologia também se mostrou viável, e foram estimados limitantes econômicos a esta viabilidade. Por fim, o processo de projeto desenvolvido pode servir de auxílio a novos projetistas na área. / The high energy consumption in buildings for their thermal conditioning is already one of the greatest environmental impacts of civil construction in developed countries and, progressively, is also becoming a concern in the developing countries. A relatively recent renewable alternative, as much for heating as for cooling, are the ground source heat pumps, GSHPs, which take advantage of the thermal inertia of the ground to significantly decrease the energy demand comparing to air as a source. In spite of their huge potential for decreasing energy comsumption and carbon emissions, this technology is still almost inexistent in Latin America, due not only to lack of awareness, but mainly to uncertainties about their feasibility because of their higher investment cost. Although there are many researches about the characteristics and operation of GSHPs, great part of the practical knowledge as to the design, performance and feasibility is based in the experience from the first countries where the technology spreaded, and cannot be automatically assumed as valid without a previous evaluation. Former studies indicated that the economic profit of GSHPs tends to be higher in colder climates, while the efficiency tends to be higher in milder, but still seasonal climates. For presenting a good balance among these factors, the Rio Grande do Sul State shows potential for a high performance of GSHPs The objective of this work is to estimate the efficiency levels that can be reached by this technology in a reference city in the State, as its financial feedback compared to ASHPs (air source heat pumps, the traditional air conditioners, or A/C), its limitations and the design difficulties. A residential single-family building in Porto Alegre, specifically designed for sustainability studies, was used as case study for the complete conceptual design of a vertical GSHP, a horizontal GSHP and an ASHP. The energy demand and operation and installation costs for specific conditions were estimated and compared in a economic feasibility study. After, the results were extrapolated through a sensitivity analysis for more generic situations of consumption. Through the calculations, it was observed that the technology achieved twice the efficiency of the most efficient A/C available for the case study. Economically, the technology showed itself viable, and economic limitations were also estimated. At last, the developed design process can also serve as aid to new designers in the field.