Small scale hydropower is one of the most cost-effective energy technologies to be considered for electrification in developing countries. The technology is very robust and mature so systems can last up to 50 years with little maintenance. Moreover, it has low environmental impacts and can have a significant benefit if implemented in rural areas for electricity production, either in on or off grid applications.The thesis reviews several small scale hydropower projects, in order to identify potential risks and propose guidelines to help future implementation of this technology in a better way than the one currently done. An on-going project was taken as a case study to identify different elements that have to be present in the planning and future development of small scale hydro projects in developing countries. Technical, managerial, socio-economical and environmental aspects around the project were analyzed within a sustainability framework.

Every marine energy source presents advantages and disadvantages. For example, they are not atthe same stage of maturity. Tidal range power is fully mature but the limited number of sitesavailable, combined with the large environmental impacts and investment costs limit itsdevelopment. The idea of artificial lagoons that will be offshore tidal range plant could create a newinterest for this technology. But for the moment, no plant of this type has been constructed yet. Tidalstream power is the next mature technology of marine energy after tidal range. Its development willrequire public subsidies but is supposed to be commercial in 2015. Systems are already indemonstration in several countries (UK, France and Canada). Wave power is less mature but it willbenefit from the development of tidal stream power and will probably be commercial in 2020. Somesystems are also in demonstration but challenges seem greater in wave power than in tidal power.Wave power conversion systems have to extract energy from the waves, even the largest ones, butat the same time resist to them. Contrary to tidal stream which has a predictable resource, waves areway less predictable and systems will have to be able to resist and valorize waves. OTEC (OceanThermal Energy Conversion) has been studied for years but it is still not mature. Its development forelectricity production needs technology research to develop cheaper and more compact systems(heat exchangers, pipes…). Air conditioning applications are developing and also require the use ofpipes and heat exchangers. Advances in this utilization could maybe help the development of OTECsystems for electricity production. Osmosis is the less mature and the most challenging technology. Atechnological breakthrough in the membrane could allow a rapid development. This breakthroughwill probably come from other sectors so it is important for the industries to get ready in order todevelop the system as soon as this technological improvement will be made.

Bifacial solar modules can absorb and convert solar irradiance to current on both their front side and back side. Several elements affects the bifacial yield, especially the ground albedo around the system or the installation configuration. In this document, investigations carried out at EDF R&D facilities regarding the use of bifacial modules in large scale PV farm are presented. Tests on the outdoor facilities were conducted to validate and improve a bifacial stand model developed under a Dymola/Modelica environement. Furthermore, a global optimization method was implemented to determine the optimal configuration of a large bifacial plant with modules facing south. Investigations showed the importance of a new albedo model to accurately evaluate the irradiance received on the rear side. The new model shows a relative error on the rear irradiance under 5% when compared with experimental data. Techno-economical optimization of a bifacial plant was conducted at different locations and for different ground albedo. The results shows that the gain on the specific production can vary between 7.2 and 14.2% for a bifacial plant when compared with a monofacial plant. Bifacial plants are expected to become more profitable than monofacial plants in some of the cases tested when their module cost will reach 68 c€/Wp.

The Photovoltaic (PV) systems and the semiconductor PV technologies are heavily impacted by shading conditions; total or partial. Nearby residential buildings, commercial buildings, objects, etc. are likely to cause shade on the PV installations.  This study focuses on the evaluation of the effect of shading on thin-film PV modules, which were analyzed under two categories: single thin-film module and a string of modules installed at the University of Gävle, Sweden. The measurement was made by using METREL MI 3109 Euro test instrument. The study intends to help researchers to analyze the variation in the output performance parameters and behavior considering different types of shading on the thin-film modules. Experiments have been performed by creating full and partial shading (uniform and nonuniform) by using plastic foil, opaque board, wooden pole, and tape to emulate different types of natural shading conditions.  The findings show a loss in power due to shading. In the single thin-film modules, which do not have any diode between the cells; reverse breakdown, power dissipation and generation of hot spots are caused by the cells which are partially shaded.  In the string of modules installed at the University of Gävle, Sweden; under partial shading conditions the diodes are activated below certain voltage when current is high, leading to current bypass and therefore prevents the module from the damage caused by high heat generation. Under the condition of extremely low shading by a wooden pole, the diodes were not activated; however reverse breakdown was observed similar to the case of partial shading in single thin-film modules.

In Gävle there exists a residential area called Lindbacka where some of the houses are supplied with heat from both district heating and exhaust air heat pump. Gävle Energi owns the district heating system in Gävle and are interested in evaluating the effects from a combined heating system. Based on that, the aim of this study has been to evaluate the impacts a combined system with both district heating and heat pump can have compared to if only one of the two is installed in a house. The thesis has studied these perspectives in an energy, environmental and economic analysis. The results from the energy analysis display that the heat losses in the district heating system relative to the amount of heat sold to customers are relatively large during the year, especially in the summer when the losses are larger than sold amount of energy. The results from the environmental analysis indicates that heat pumps have a larger climate impact during operation measured in tons of carbon dioxide equivalents compared to district heating. On the other hand, the economic analysis present heat pumps to be the cheapest heating option for a customer. The most expensive option for a customer is to install both an exhaust air heat pump and connect to the district heating system since this leads to double fixed and variable costs during the year. For Gävle Energi the economic analysis indicates that the investment cost of building the district heating system to Lindbacka was not profitable since the investment cost does not pay back in 30 years. Some of the houses in Lindbacka has been excluded in the thesis due to insufficient data. This will have an impact on the results in the thesis.

In today's society, it's becoming increasingly important to find methods which useenergy more efficiently. One established method is night time set-back. When usingnight time set-back the indoor temperature is lowered during the night. This result ina smaller temperature difference between indoors and outdoors, which in turnreduces heat losses. The method requiers that heat can be stored into and emittedfrom the building's frame. This thesis examines the effects of night time set-back on four different building types.The building types are: a concrete building from the 1960s, a concrete building fromthe 1960s with new windows and doors, a concrete building from the 2010s and awooden building from the 2020s. The thesis examines how the night time set-backaffect the heat demand, the heat power demand and the cost of heat. The results show that the night time set-back reduces the heat demand by 5-11 % forall building types that are examined. The daily average power reduces by 1-4 % for allbuilding types, which results in the cost of heating reduces by 3-7 %for all buildingtypes. The maximum power peak increases by 1-12 %. The set-up of the districitheating price model is critical for the economical outcomes. Since night time set-backcontributes to increased power peaks, new calculations for the economics can beneeded in the future if the price model change from daily power to maxiumum power(on hourly basis).

Energiomställningen är avgörande för att begränsa de globala koldioxidutsläppen. Det blir det allt viktigare att hitta sätt att ta tillvara på elöverskott och kunna lagra energi från förnybara energikällor som vind och sol. Vätgas är en energibärare och har stor potential för att ha en nyckelroll i ett hundraprocentigt förnybart energisystem. Syftet med studien var att undersöka förutsättningarna för ett ekonomiskt och tekniskt håll- bart logistiksystem för vätgastransport. Målet var att beräkna överföringskostnader och jämföra olika tekniker för transport av vätgas. Studien inleddes med en djupgående litte- raturstudie och omvärldsanalys. Därefter valdes två olika fall i norra Sverige och utifrån de förutsättningar som fanns på platserna jämfördes transport via pipeline, vägtransport och järnvägstransport. Resultaten för vägtransport via komprimerad form tyder på att det krävs ett stort antal transporter för att leverera den analyserade mängden i de olika fallen vilket resulterar i höga kostnader. Transport via järnväg tyder på relativt hög investeringskostnad och ingen större skillnad mellan fallen. Resultaten tyder på att transport via pipeline har relativt låga överföringskostnader för båda fallen och man kan se en skillnad i investeringskostnad mellan fallen. Överföringskostnader via pipeline tyder på lägre kostnader än att överföra el. Överföringskostnader kan bero på olika faktorer som förutsättningar på platsen, elkostnader, avstånd och volym. Det finns osäkerheter i resultaten för vägtransport och järnväg vilket gör det svårt att dra slutsaster utifrån den data som presenteras. Jämförelsen mellan vätgas och el ska ses som en grov uppskattning på grund av de osäkerheter som finns kopplat till elöverföringen. / The energy transition is crucial to limit the global carbon dioxide emissions. Renewable energy sources like wind and solar are intermittent and we need to find ways to use the electricity surplus and store energy. Hydrogen is an energy carrier and has the potential to be a key to achieve a renewable energy system. The aim of the study is to investigate the feasibility for an economic and technical sustainable system for hydrogen distribution. The goal was to calculate transmission cost for different types of hydrogen transport. A profound literature study and external analysis was made in the beginning. Then two cases were selected in the northern part of Sweden. Based on the conditions, transport through pipeline, road transport and transport by rail were choosen. The results for transport by road suggests that very frequent transports are required to deliver the quantity in the cases taken up, which results in high costs. Distribution cost by rail implies high investment costs and there are no significant difference between distribution cost for the cases. Furthermore the results implies that pipeline has low operating costs for both cases and it also implies a difference between investments cost for the cases. The result also indicates that transmission cost by pipelines is cheaper than transmission cost for electricity. Which one is the best option depends on many different factors such as conditions at the location, electricity price, distance and the volume. There are uncertainties in the results for transport by road and by rail, which makes it difficult to conclude based on the current findings. The comparision between hydrogen and electricity should be seen as a rough estimate due to the uncertanties.

In Almunge, east of Uppsala, there is a relative new health care center which has solar power installed on the roof. The solar cells annually produce approximately 62 000 kWh of electricity that are beneficial to store. Batteries can be used for short-term storage and to reduce peak power, but hydrogen storage can be used as long-term storage. Therefore, this study aims to evaluate if it is profitable to implement a hybrid energy storage compared to a single battery storage. The hybrid energy storage is a combination of a saltwater battery that reduces the peak power every month, and a hydrogen storage that functions as back-up power and long-term storage. This is compared to a single saltwater battery that is used to increase the self-sufficiency of the health care center. This is evaluated with respect to feasibility, profitability, sustainability and safety. In this study it turns out that it is not reasonable to install a hybrid energy storage using hydrogen both as back-up power and long-term storage, due to the risks. However, it could be feasible to install a hybrid energy storage where the hydrogens storage only act as back-up power. In the economic analysis, the lifecycle cost (LCC) and pay-back time were compared for five different energy storage solutions. The first solution is a hybrid energy storage, where the hydrogen storage act back-up power for three days, combined with a saltwater battery of 25 kWh to reduce peak power. The second solution is a hybrid energy storage, where the hydrogen storage act back-up power for seven days, combined with a saltwater battery of 25 kWh to reduce peak power. The third solution is a saltwater battery with a capacity of 60 kWh. The fourth solution is a saltwater battery with a capacity of 90 kWh. The fifth solution is a saltwater battery with a capacity of 120 kWh. It turns out that a saltwater battery of 60 kWh has the lowest LCC and shortest pay-back time that is shorter than its lifetime. Therefore, it is most profitable to install a saltwater battery of 60 kWh to increase the self-sufficiency of the health care center.

The building sector is responsible for approximately 40 % of the total energy usage in Sweden. In office buildings the heating, ventilation and air conditioning system can account for up to 55 % of the energy usage. In order to reduce the energy usage of the heating, ventilation and air conditioning system different control methods are often used. One of these control methods is demand controlled ventilation, where the ventilation system is controlled with regard to occupancy with the help of motion and/or CO2 sensors. The aim of this thesis was to determine the energy savings potential of a heat recovery unit as well as demand controlled ventilation in an office building. The effect of longer intervals between sensor control signals to the ventilation system was also investigated. This is done by creating schedules, gathered from actual building occupancy, that are being used to control the occupancy and ventilation in a building model in the building performance simulation software IDA ICE. As a reference building, the fifth floor of the LU1 section of the natural science building at Umeå University is used. The reference building consists of 40 offices for which the occupancies are known. The average occupancy for all the offices combined throughout the investigated time period is determined to be 34.8 %. The results from the simulations indicate that an energy savings potential of 52.98 % can be achieved by a heat recovery unit with an efficiency of 80 % or 95 %, when compared to not having a heat recovery unit. When implementing demand controlled ventilation an energy savings potential of 2.8-11.0 % can be achieved, with the energy savings potential decreasing when the efficiency of the heat recovery unit increases. Finally, it is shown that longer intervals between sensor control signals to the ventilation system leads to a small increase in energy usage and poorer indoor air quality.

Energiutredning av gamla fastigheter är en betydelsefull åtgärd i dagens samhälle för att kunna identifiera och föreslå energieffektiviseringsåtgärder för att kunna minska dess totala energianvändning.Avsikten med denna utredning är att framställa olika förslag för att minimera energianvändningen för en villa i Älvkarleby samt analysera lönsamheten för en installation av en solcellsanläggning. Det undersökta objektet är en 1860-tals timmervilla med en boarea på cirka 400 m2 uppdelat på två våningar, villan renoverades ett antal gånger, då senast tilläggisolerades taket och installerades en luft-luftvärmepump för att minimera elkostnader.En modell skapades i IDA ICE-programmet i avsikt att kunna dela upp de olika energiförluster genom byggnadsskalet såsom tak, golv, väggar och fönster.En installation av en ny luft-luftvärmepump kan ge till resultat att energianvändningen minskas ytterligare med 20 %, detta eftersom den aktuella luft-luftvärmepumpen redan har minskat energianvändningen och därmed elkostnader. Denna typ av värmepump valdes då den har låga installationskostnader samt att det redan existerar en luft-luftvärmepump. Återbetalningstiden för den nya luft-luftvärmepumpen blir 3 år, detta kan dock variera beroende på drifttiderna genom åren.Solcellernas lutning och orientering är oftast optimerade för att maximera den totala årliga elproduktionen. Ändå kan detta inte alltid vara lönsamt utifrån det ekonomiska perspektivet.Ett flertal anläggningar testades med avseende på deras effekt och väderstreck då fastigheten har ett begränsat tak area i söderläge, detta gjordes med hjälp av WINSUN PV-programmet. En solcellsanläggning riktad mot syd och öster på 4,1 kW ansågs vara mest lönsamt bland de undersökta anläggningar då denna anläggning sparar nästan 89% av den producerade elen, då den används direkt i fastigheten.Kostnaden per kW blir lägre ju större anläggningen blir, vilket gör att anläggningen kommer att ha en ungefärlig återbetalningstid på 15 år. Men detta kan troligen påverkas av framtida elpriser, ekonomiska understöd samt fastighetens elanvändning under sommarperioden.