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Fuel combustion in the transport sector significantly contributes to the total greenhouse gas emissions (GHG). In the European Union (EU) member states transport accounts for 33.1% of total final energy consumption, while the share of transport in total greenhouse gas emissions is 23%. Enabling electrification of the transport sector, as well as promoting electricity production based mainly on RES, would enable achieving EU's policy of low-carbon economy, which aims to reduce GHG by 80-95% by 2050. EVs provide the possibility of storing electricity, which opens new possibilities for integration of RES into the grid In order to achieve set goals in reduction GHG emissions, it is paramount to change the way electricity is produced, distributed and consumed While RES contributes to a decrease of the environmental impact and to an increase in self-sustainability of national energy systems, many aspects of the power system are affected by the increased share of such sources. Electric vehicles and pumped-storage HPPs provide the possibility of storing electricity, which opens new opportunities for the integration of RES into the grid. Relatively large number of EVs is needed to ensure sufficient energy storage and, if the EVs are charging in periods of peak load, the conventional power plants with quick response must generate so that the additional load caused by high number of EVs is covered It would certainly be beneficial to analyse scenarios with and without electric vehicles, but to also include the costs of the building the needed infrastructure, especially the charging stations.

Urban heat islands (UHI) represent increase of temperature inside of cities in regard to their rural environment. Causes of their formation are diverse and multiple: reduced amount of vegetation and waterproofing of surfaces, changed radiation and thermal characteristics of materials, urban geometry. Consequences are also diverse and significant: increasing consumption of energy for cooling, negative impact on human health, deterioration of air quality. Conventional methods for mitigating their impact include reflective and green roofs and introduction of green and water surfaces in cities. Different renewable energy technologies can also have positive impact on urban heat islands, but at the same time they contribute to greater energy independency of cities what is goal of future urban development. Proposed and described technologies are solar cooling, groundair heat exchanger, passive cooling, solar pond.

The European Union's (EU) goals of reducing energy dependence and reducing greenhouse gas emissions (GHG) are to be achieved primarily by increasing production from renewable energy sources (RES). However, due to the features of renewable sources such as unpredictability and lack of availability, it is necessary to increase the flexibility of the systems themselves. In other words, large penetration of RES into the power system requires a substantial increase in the capacity of various energy storage technologies. Pumped storage hydroelectric power plants (HPPs) represent 99% of global installed capacity of energy storage and are widely spread, providing energy storage capacity and transmission grid ancillary benefits in the US and Europe since 1920s, as well as in the rest of the world. Besides, new technologies are considered worldwide, and as one of the most prominent options considered today is the penetration of electric vehicles (EVs) into the power systems. The use of EVs reduces air pollution while connecting them to the smart grids creates the possibility of increasing the flexibility of the power system since vehicle batteries could be used as storage but also as sources of electricity. Using the PLEXOS energy market simulation software, the power system of the Republic of Croatia was modelled in this paper and based on the results of different scenarios, the role of pumped-storage power plants and large penetration of electric vehicles in increasing the power system flexibility with a large share of renewable sources was observed.

This paper analyses and situates the role of the Agency for energy efficiency and renewable energy sources (Agency). In this sense the paper examines the coordination of the Agency's objectives of national programs for energy efficiency and renewable sources with the required financial support for their realization. Considering that Croatia spends a relatively high percentage of its Gross Domestic Product for the importation of quality energy sources, it is evident that it is necessary to undertake a series of measures for more efficient energy uses and to commence production from renewable sources. In Croatia a potential for more efficient uses of energy exists in all three main sectors of energy consumption, i.e. industry, transport and household. The paper also discusses the administrative aspect of the Agency and its aims and objectives, namely appropriate projects and initiatives. The Agency's organizational structure is also dealt with, in which local Agencies would play a particular role. It is understood that the relationship will be based on a partnership and that classical subordination will be avoided. This means that a cooperative working relationship will be undertaken in the sense of encouragement and support of local initiatives and projects in order to achieve the realization of common objectives.

In various developing strategies of Croatian power system usage of renewable energy sources (wind, solar and geothermal energy, biomass, wave energy and tidal energy) have to be consider. This paper analyses only renewable sources of energy for possible applicability in Croatian power system. These are solar and wind energy, as well as biomass. Considering technical and economic characteristics of the existing renewable sources in the world, applicability of a few specific locations in Croatia was analysed, primarily regarded to their economic parameters. Apart from that, environmental impact of the observed energy sources is given. Taking into account the calculated economic and environmental parameters, renewable sources as a possible developing option in Croatian power system is realistically estimated.

U tekstu je navedena pravna analiza postavljanja fotonaponskih panela na višestambene zgrade. Opisanu su pravni nazivi kao što su aktivni kupac, skupina krajnjih kupaca, korisnik postrojenja za samoopskrbu, kupac s vlastitom proizvodnjom. Navedena je zasada poznata dokumentacija i procedure te su opisani i obračuni cijene otkupa za korisnike. Opisane su i energetske zajednice građana kao i zajednice obnovljive energije. Odrađena je tehnička analiza ugradnje fotonaponskih panela na višestambenu zgradu u kojoj je navedena optimalna snaga s obzirom na površinu krova i godišnju prosječnu potrošnju kućanstva u Hrvatskoj. Odrađena je i ekonomska analiza projekta sa i bez baterijskog spremnika te je utvrđeno da sam zasada još uvijek nije isplativ. The text provides a legal analysis of the installation of photovoltaic panels on apartment buildings. Legal names such as active customer, group of end customers, user of self-supply facility, customer with own production are described. The currently known documentation and procedures are listed, and the calculations of the purchase price for users are also described. Energy communities of citizens as well as renewable energy communities are also described. A technical analysis of the installation of photovoltaic panels on a apartment building was carried out, in which the optimal power was specified with regard to the roof area and the annual average household consumption in Croatia. An economic analysis of the project with/without a battery system was also carried out, and it was determined that it is still not profitable.

Kako bi se postigla ugljična neutralnost i zadovoljili ciljevi Europske Unije potrebno je mijenjati energetski sustav. Kako bi se odredio optimalan smjer razvoja energetskog sustava potrebno je napraviti simulacije. U radu su napravljene simulacije u dva programa, ESST-u i Energyplanu. Analizirana su dva scenarija, S1 prema Zelenoj knjizi te njegova modifikacija. S obzirom da S1 ne zadovoljava uvjete postavljene do 2050. godine njegova modifikacija uključuje bržu tranziciju prema klimatskoj neutralnosti. Većim i intenzivnijim ulaganjem u obnovljive izvore i potencijalno nuklearnu energiju energetski sustav RH može postati klimatski neutralan te zadovoljiti ciljeve postavljene za 2050. godinu. In order to achieve carbon neutrality and all targets set by the European Union it is necessary to change the energy system. To determine the optimal direction of energy system development it is necessary to make simulations. Simulations were done in two different simulation tools: ESST and Energyplan. Two scenarios were analysed: S1 according to Green book (Zelena knjiga) and its modification. S1 does not satisfy all the goals set for year 2050, so its modification consists of quicker transition towards climate neutrality. With bigger and more intensive investing in renewable energy sources and optionally nuclear energy, energy system of Croatia can become carbon neutral and satisfy all the goals set for 2050.

Zadatak rada bio je pronaći optimalnu snagu fotonaponske elektrane za promatranu zgradu u Republici Hrvatskoj po ESCO modelu. Rad je podijeljen na teorijski i praktični dio. U teorijskom dijelu opisano je sunčevo zračenje, fotonaponske elektrane, ESCO model, financijski parametri i zakonska regulativa. Praktični dio je tehno ekonomska analiza i izrada idejnog rješenja fotonaponske elektrane koristeći program PV*Sol. Drugi dio praktičnog dijela je usporedba stvarnih mjerenja proizvodnje fotonaponske elektrane s dobivenim rezultatima proizvodnje fotonaponske elektrane programima PV*Sol, PVGIS, GSA i RETscreen. Dobiveni rezultati su prikazani u tablicama. The task of this study was to find the optimal power of a photovoltaic power plant for the observed building in the Republic of Croatia according to ESCO model. The paper is divided into theoretical and practical part. The theoretical part describes solar radiation, photovoltaic power plants, ESCO model, financial parameters and legislation. The practical part is the techno-economic analysis and conceptual design of the photovoltaic power plant using the PV*Sol program. The second part of the practical part is the comparison of actual measurements of photovoltaic power plant production with the obtained results of photovoltaic power plant production with PV * Sol, PVGIS, GSA and RETscreen programs. Final results ate presented in the tables.

U radu smo se upoznali s osnovama fotonaponskih sustava i sunčevom energijom. Opisan je postupak projektiranja i odabir optimalnog fotonaponskog sustava za HEP-ovu zgradu u Karlovcu. Optimalni fotonaponski sustav izrađen je po ESCO modelu, uključujući i troškovnik. Projektiranje i simulacija su odrađeni u PVSol i RETscreen programima. Rad je zaokružen detaljnim upoznavanjem sa zakonom za otkup električne energije, te pohranom u baterijske spremnike i usporednom simulacijom s i bez baterijskih spremnika. The thesis introduces concepts of photovoltaic systems and solar energy. The process of designing and choosing the optimal photovoltaic system for HEP building in Karlovac is described. Optimal photovoltaic system is designed following the ESCO model, including a bill of quantities for building such a system. For the design and simulation of the system, PVSol and RETscreen software programs were used. The thesis concludes with comparison of two different scenarios, with and without battery storage, considering energy buyback law which is also introduced in the thesis.

U radu je obrađena izrada idejnog rješenja fotonaponske elektrane za zgradu po ESCO modelu s analizom utjecaja nagiba i orijentacije elektrane na proizvodnju i isplativost. Zbog sve veće potrebe za energijom iz obnovljivih izvora energije, analizom fotonaponskih elektrana rad se bavi istraživanjem financijski i energetski optimalnog rješenja za stvarni primjer na zgradi Elektre. Rješenje je predstavljeno kao fotonaponski sustav na ravnom krovu zgrade, povezan na mrežu preko kućne instalacije. Sustav podrazumijeva optimalno dnevno ozračenje sunca, te ukupnu potrošnju energije zgrade s ciljem minimizacije gubitaka. Iskoristivost energije fotonaponskog sustava ostvarena je kao 85-90% ukupno proizvedene energije. The thesis analyses development of preliminary design of photovoltaic power plant for buildings according to ESCO model, with analysis of influence of slope and orientation of power plant on production and cost-effectiveness. As demands for renewable energy sources increase, by analysing photovoltaic power plants the thesis covers research of the optimal solution, both financially and energy-wise, for a particular real life example of Elektra building. The solution is proposed as a photovoltaic system on a flat surface of the building’s rooftop, connected to the grid by a consumer unit. The system considers optimal solar irradiation, as well as the total energy consumption of the building to minimise energy loss. Energy efficiency of the photovoltaic system is 85-90% of the total energy produced.

Ovisnost o fosilnim gorivima stvorila je nesiguran sustav koji prijeti zdravlju ljudi, ugrožava stabilnost Zemljine klime i lišava buduće generacije čistog zraka, pitke vode i energetske neovisnosti. Tranzicija sa neodrživog energetskog sustava baziranog na fosilnim gorivima ka sustavu pokretanom lokalno dostupnim i isplativim obnovljivim izvorima energije već je u tijeku diljem svijeta. Ta je tranzicija u narednim godinama spremna poboljšati kvalitetu života milijunima ljudi, smanjiti emisije štetnih stakleničkih plinova i izgraditi svijet naklonjen sadašnjim i budućim generacijama. Our dependence upon fossil resources has built a system that lacks diversity and security, threatens the health of our citizens, jeopardizes the stability of the earth’s climate, and robs future generations of clean air, clean water, and energy independence. A transition is underway around the world: away from an energy system powered by increasingly expensive and unsustainable fossil fuel resources toward one powered fully by abundant, local, and affordable renewable energy sources. In the years ahead, this transition is poised to improve the quality of life for millions, reduce harmful greenhouse gas emissions, and help forge a world that is more just toward both current and future generations.

Obnovljivi izvori energije (OIE) te njihova integracija na tržište električne energije dinamično se mijenjaju zadnjih godina. U početku promoviranja obnovljivih izvora, glavna ideja bila je povećanje udjela obnovljivih izvora kroz mehanizme subvencija takvih izvora te izoliranje od stanja na tržištu. Razvojem i povećanjem udjela obnovljivih izvora, s ciljem postizanja konkurentnog i stabilnog tržišta, obnovljivi izvori energije moraju sudjelovati na tržištu sukladno cijenama konvencionalnih izvora energije. To se postiže promjenom vrste potpore pojedine države. Glavna ideja je implementacija feed-in premija (FIP) ili sustav kvota (tržište zelenih certifikata) u sustav poticaja. Tako se smanjuju troškovi svih tržišnih sudionika kao i krajnjih korisnika potrošača. Postoje različite primjene navedenih modela u različitim zemljama članicama. U Republici Hrvatskoj na snagu je stupio novi zakon koji predstavlja prelazak s feed-in tarife (FIT) na feed-in premiju (FIP). Ključna i dominantna značajka novog modela (FIP) trebala bi biti tržišna integracija. Analizom feed-in-tarife u razdoblju od 2015. – 2016. godine vidjeli smo da je povećanje naknade za kupce neizbježno. Energy form renewable sources and their integration to electric enery market is dinamically changing thru recent years. In the beggining of renewable energy promotion, main idea was to increase their use thru subsidy mehanisms which would avoid compettitive energy markets. But, development and the additional increase of share and the intention to integrate this type of energy to competitive and stable market, renewables need to participate on the market according to prices of conventional energy sources. That is achieved by change of type of support by individual country. Main idea is implementation od feed in premium (FIP) or system of quotas (market of greeen certificates) into stimulus system. In that way it is achieved to lower the costs of all market stakeholders incuding the end consumer. There are various implementations of this model in different EU member states. In Republic of Croatia there is new law in power which represents swiching process from feed in tariff (FIT) to feed in premium (FIP). Key and dominant characteristic of the new model (FIP) is the market integration. Oni analisys of the feed in tariff (FIT) in the period of 2015-2016. we saw that the end result of this practice is increase of charge for the end consumer.

Niskougljična strategija razvoja temelj je za razvoj energetike s niskom razinom ugljika, ali i cjelokupnog gospodarstva. Europska unija predvodnik je u provođenju mjera smanjenja emisija posebice u energetici kao sektoru s najviše emisija. S ciljem smanjenja emisija istaknute su potrebne mjere za energetiku u zemljama EU-a, među njima i za Hrvatsku. Opisane su niskougljične strategije razvoja zemalja u EU i svijetu, a posebno su istaknute mogućnosti Hrvatske za ostvarivanje niskougljičnog razvoja. Kako bi se odredila odgovarajuća strategija izrađeni su alati za planiranje niskougljičnog razvoja. Posebno je opisan program EFFECT pomoću kojeg su napravljeni scenariji za elektroenergetski sektor Hrvatske te su analizirana predviđanja budućih emisija. Projekcije emisija napravljene su s obzirom na mogućnosti različitih provedbi niskougljičnih mjera te je napravljena usporedbena analiza scenarija. Low-carbon development strategy is fundamental for the development of the energetics with low rate of carbon, but also for the entire economy. European Union is the leader in the effort to reduce emissions especially in the energy sector as the sector with the highest rate of emission. With the goal of reducing emissions, necessary measures are accentuated for energy in the EU Countries, as well as in Croatia. Described low-carbon strategies are in the process of development in the EU Countries and globaly, and the possibilities for realization of Croatian low-carbon development are particularly emphasized. In order to determine the appropriate strategy for each country the tools have been made for planning low-carbon development. The EFFECT program, by which models of electric power system in Croatia are designed, is particularly described and predictions of future emissions are analyzed. Emission projections were made taking into account the implementation of various low-carbon measures and the comparative scenario analysis was done.

Power system planning and development face new pressing challenges from climate change including the need to reduce its GHG emissions (climate change mitigation through different mechanisms such as emission trading, transition to low emission power system); and the need to adapt to climate change (climate change adaptation and vulnerability). Also, the development of energy sector should take the responsibility for the sustainable development – delivering positive and measurable impact on society, economy and environment. The main objective of the research was to develop and verify methodology and models for the assessment of emission trading and climate change impacts on sustainable power system development. Two models were designed to fit the proposed methodology. The first model is for the assessment of emission trading and fuel price impacts on long term marginal costs for different power plants. The second designed model enables measuring sustainable development indicators from generation capacity expansion. This developed algorithm enables the power system model to include emission price in power system operation and planning. Data from Croatian power system are used for the verification of proposed methodology, designed models and algorithm,. Verification steps are included: power system modeling, modeling sustainable development indicators and assessment of climate change impacts on power system planning. Finally, the integrative model based on proposed methodology, developed models and algorithm performed a wide set of modeled scenarios. This holistic approach of modeling emission trading and climate change impacts on long-term power system planning is verified by using data for Croatian power system until 2030. Results from verification of the proposed modeling are presented and discussed. Based on these results, a summary of main findings, recommendations for policy makers and energy planners, and area for further research in this field are proposed. Planiranje elektroenergetskog sustava suočeno je s novim izazovima koji dolaze od istodobne potrebe smanjenja klimatskih promjena i prilagodbe na njih. Paralelno je potrebno smanjivati emisije stakleničkih plinova i predvoditi tranziciju u niskougljičnu ekonomiju; kao i prilagoditi se na postojeće i buduće utjecaje klimatskih promjena. Pritom, potrebno je mjeriti uspoređivati i pozitivne i negativne učinke na održivi razvoj – društvo, ekonomiju i okoliš. Da bi se mogli analizirati ovi izazovi prilikom planiranja elektroenergetskog sustava, potrebni su novi modeli, nove metodologije i novi algoritmi koji omogućuju planeru da procjeni utjecaj klimatskih promjena i trgovanja emisijama na održivi razvoj kroz povećanje konkurentnosti niskougljičnih tehnologija. U uvodnom poglavlju, predstavljeni su izazovi trgovanja emisijama i klimatskih promjena na planiranje i razvoj elektroenergetskog sustava. Definira se istraživački problem, hipoteze na kojima se temelji istraživanje i sveukupni cilj istraživanja. Diskutira se originalnost rada, očekivani znanstveni doprinosi, ciljana skupina kojoj su rezultati istraživanja namijenjeni te se navode glavna ograničenja rada. U drugom poglavlju („Niskougljični razvoj i klimatske promjene“) fokus je stavljen na važnost utjecaja klimatskih promjena, klimatskih pregovora i niskougljičnog razvoja na elektroenergetski sustav. Treće poglavlje („Trgovanje emisijama – teoretska i praktična pozadina“) analizira se utjecaj trgovanja emisijama na konkurentnost niskougljičnih tehnologija. Dan je pregled tržišta emisija stakleničkih plinova u svijetu, te teoretska pozadina trgovanja emisijama. U četvrtom poglavlju („Dugoročno planiranje elektroenergetskog sustava s trgovanjem emisijama“) analiziraju se utjecaji trgovanja emisijama na dugoročno planiranje elektroenergetskog sustava promatranjem marginalnih troškova proizvodnje električne energije i marginalnih krivulja smanjenja emisija stakleničkih plinova. U petom poglavlju („Modeliranje elektroenergetskog sustava i njegovog utjecaja na održivi razvoj“) istražena je klasifikacija modela za energetsko i elektroenergetsko planiranje, te su propitane njihove značajke važne za mjerenje utjecaja na održivi razvoj. Uvodna poglavlja daju osnove za predstavljanje glavnog predmeta istraživanja - razvoj i verifikacija razvijene metodologije i modela za procjenu utjecaja trgovanja emisijama i klimatskih promjena na održivi razvoj kroz porast konkurentnosti niskougljičnih tehnologija. Metodologija za procjenu utjecaja klimatskih promjena i trgovanja emisijama na planiranje elektroenergetskog sustava prikazana je u šestom poglavlju („Predložena metodologija i modeli“). Opisana je metodologija koja je razvijena u doktorskom radu, a koja će biti iskorištena za provjeru postavljene hipoteze putem shematski opisanih koraka planiranje elektroenergetskog sustava. U ovom poglavlju, opisana su i dva modela koja su predložena i dizajnirana, te razvijeni algoritam. Prvi od tih modela je nazvan „Model za procjenu pokazatelja održivog razvoja“ i omogućuje planeru usporedbu različitih scenarija novih proizvodnih kapaciteta, mjerenjem njihovog utjecaja na održivi razvoj. Drugi model je nazvan „Model za procjenu utjecaja trgovanja emisijama na granične troškove elektrana“ i on procjenjuje utjecaj cijene energenata i emisija na konkurentnost obnovljivih izvora energije. Razvijeni algoritam omogućava da se prilikom modeliranja elektroenergetskog sustava uključi i utjecaj trgovanja emisijama u planiranje i rad samog elektroenergetskog sustava. Sedmo poglavlje („Verifikacija predložene metodologije, modela i algoritma s upotrebom podataka iz Hrvatske“) koristi podatke iz Hrvatske da verificira predloženu metodologiju, modele i algoritam. Verifikacija je napravljena u nekoliko koraka, počevši od planiranja godine unaprijed do dugoročnog modeliranja elektroenergetskog sustava, modeliranja indikatora održivog razvoja i procjene utjecaja klimatskih promjena na elektroenergetski sustav. Cjelovit pristup modeliranju utjecaja klimatskih promjena i trgovanja emisijama na planiranje elektroenergetskog sustava verificiran je koristeći podatke iz Hrvatske za 2030. godinu, a rezultati modeliranja su opisani i prodiskutirani. Zaključak sadrži sažetak glavnih rezultata istraživanja, kritički osvrt na postignute rezultate s obzirom na postavljene hipoteze, daje preporuke donosiocima politika te utvrđuje temeljne smjerove nastavka istraživačkog rada. Glavni predmet istraživanja je razvoj i verifikacija razvijene metodologije i modela za procjenu utjecaja trgovanja emisijama i klimatskih promjena na održivi razvoj kroz porast konkurentnosti niskougljičnih tehnologija. Prilikom istraživanja, ostvaren je sljedeći izvorni znanstveni doprinos: - Predložena je metodologija za procjenu utjecaja trgovanja emisijama i klimatskih promjena na održivi razvoj. Metodologija uključuje holističku procjenu utjecaja klimatskih promjena na elektroenergetski sustav i procjenu utjecaja trgovanja emisijama na porast konkurentnosti obnovljivih izvora energije; - Dva modela su razvijena tijekom rada na disertaciji –Model za procjenu pokazatelja održivog razvoja koji omogućuje planeru usporedbu različitih scenarija novih izgrađenih elektrana u sustavu mjerenjem njihovog utjecaja na održivi razvoj; i Model za procjenu utjecaja trgovanja emisijama na granične troškove elektrana koji procjenjuje utjecaj cijene trgovanja emisijama i energenata na konkurentnost obnovljivih izvora energije. Primjena oba modela osnažuje proces dugoročno planiranja razvoja elektroenergetskog sustava, donošenje novih politika i strategija te pomaže prilikom donošenja odluka prilikom adresiranja izazova utjecaja klimatskih promjena; - Predložen je i razvijen algoritam za modeliranje utjecaja trgovanja emisijama na elektroenergetski sustav, koji je na kraju i implementiran u model PLEXOS. Time je model PLEXOS osposobljen prilikom simuliranja rada i planiranja elektroenergetskog sustava uzeti u obzir i utjecaj cijene emisija, te pratiti njen utjecaj na profitabilnost pojedinih elektrana, visinu cijene električne energije i promjenu u voznom redu elektrana; - Predložena metodologija i razvijeni modeli i algoritam su verificirani podacima iz hrvatskog elektroenergetskog sustava – to predstavlja prvi pokušaj procjene i modeliranja utjecaja klimatskih promjena na planiranje elektroenergetskog sustava; ali također i omogućuje razvoj i sagledavanje širokog raspona opcija i scenarija prilikom adresiranja trgovanja emisijama i procjene konkurentnosti niskougljičnih tehnologija.

Priprema projekta vjetroelektrane obuhvaća mnogo međusobno povezanih koraka, a jedan od najvažnijih je svakako pravilna procjena vjetropotencijala. Procjena vjetropotencijala tipično se temelji na mjerenju karakteristika vjetra korištenjem mjernog stupa, te modeliranjem unutar nekog softverskog/matematičkog modela. U situacijama kada na lokaciji potencijalne vjetroelektrane postoji nekoliko mjernih stupova i mjernih uređaja, često se postavlja pitanje kako optimalno iskoristiti te podatke. U ovom radu prikazana je metoda korištenja takvih podataka kroz primjenu teorije portfelja, etablirane u ekonomskoj teoriji, ali i u mnogim drugim znanstvenim disciplinama. Metoda je vrlo fleksibilna u smislu ulaznih podataka i softverskih/matematičkih modela, a rezultati dobiveni unutar rada pokazuju da je njezinom primjenom moguće povećati točnost i smanjiti nesigurnost procjene vjetropotencijala. Prikazana metoda otvara širok prostor za daljnja istraživanja i poboljšanja, a sve u svrhu boljih rezultata procjene vjetropotencijala i u konačnici kvalitetnije pripremljenog projekta vjetroelektrane. Development of a wind farm project includes a lot of interconnected steps, with one of the most important ones being a proper energy yield assesment. Wind energy yield assesment is typically based on wind measurements on a measurement mast that are later modeled in one of the software/mathematical models. In cases where there are multiple wind measurements on the potential wind farm site, a question arises on how to optimally use all the available data. This paper shows a method of using such data through the application of the portfolio theory, a well established theory in economics, but also in other scientific disciplines. The method shown is very flexible in terms of input data and software/mathematical models, and the results of its application show that it is possible to increase accuracy and reduce uncertainty of energy yield assesment. The method opens up a wide space for further research and improvements, all with the objective of achieving better results of energy yield assesment and finally, better prepared wind project. The objective of the research was to improve wind potential assessment by using portfolio theory in cases when there are more wind measurements on a prospective wind farm site, as well as to increase the efficiency of using the avaliable wind measurement data. The basic hypothesis was that by using more than one measurement it is possible to increase the accuracy and reduce uncertainty of wind potential assessment, compared to using only one measurement for the entire location. Also, by using available measurement from nearby measurement masts, it is possible to assess the potential on a reference position. The paper describes the method of using portfolio theory for wind potential assessment, that can be used to upgrade the standard method. The method can be used when there are multiple measurements on site, it is flexible enough to be used with new measurement technologies (i.e. SODAR, LIDAR), as well as new wind flow models (i.e. CFD models). The method is realized through three key components: i) standard wind potential assessment procedure, ii) application of portfolio theory and iii) analysis and interpretation of results. The fist component represents the standard method of wind potential assessment that is usually done for any planned wind farm project. It consists of preparation and processing of measurement data, preparation and processing of orography and roughness data, and application of mathematical model for wind potential assessment – in this paper EMD's WindPro with integrated WAsP. In standard method, this procedure is done once, using mostly one prepared set of measuremet data (the data set can be a combination of several measurement sets, but in the end it is only one input data set). This paper offers a different apporach – each measurement set is treated separately and independently of the remaining measurements. In other words, if there are multiple measurement devices on a measurement mast on different heights, easch measurement is treated separately. Consequently, there are multiple results of wind potential assessment, each based on its own data set. For each calculated assessment, uncertainty of the assessment is calculated separately, as described in detail in the paper. Calculated wind potential and uncertainty represent a pair of input data that will be used for applying portfolio theory. Correlation of measurements, required for using portfolio theory, is also calculated. The second component of the descirbed method is based on applying the laws of portfolio theory to calculated input data with given shares (in this paper in steps of 10%). The paper first shows combinations of two measurements in different heights and positions, and later describes the application to multiple data sets. The results show that it is possible to reach better accuracy and lower uncertainty by using the proposed method. The third component of the method is analysis and interpretation of results. The results must be critically observed and related to reality, so that proper conclusions can be drawn. In this paper there are several analyses done: the influence of uncertainty, reference measurement in shorter period, lack of reference measurement, connection of wind speed (m/s) and production (kWh) and using portfolios with minimal error and uncertainty. The latter shows very promising results for further research. The reults show that when we use shorter period measurements for calculating optimal shares (the shares where both error and uncertainty are equal to zero), we can transfer those shares to longer term meaurements and get very good results. In this case it is recommended to have at least one measurement on a proposed wind generator site, even in a shorter period, as the quality of results increases dramatically. The analyis has also shown that it is possible to apply the method for vertical extrapolation, instead of logarithmic law. Also, some „common truths“ are questioned here. For example, this paper showed that the measurement closer to the reference does not need to be more accurate than a measurement further away. In this case, measurement four kilometers away was more accurate than the one two kilometers away. This paper only opens up the topic of applying portfolio theory in wind potential assessment. There is a wide space for further application and research, that would enhance this method, but also the standard method of wind potential assessment.