The purpose of this study was to contribute to sustainable development in the Pampanga province, Philippines. The Philippines are facing several major environmental problems; pig production represents a major contributing factor to pollution and eutrophication of water bodies in the country. At present there is no requirement for purification of wastewater from backyard (small-scale) farms. With the help of anaerobic digestion the manure could be used to produce biogas. The study’s objective was to determine an anaerobic digester design and substrate composition for small-scale biogas production in backyard farms (20 pigs). To achieve this objective, several goals were defined; (1) determine the best substrate composition for biogas production, through the use of lab experiments, (2) determine a design best suited for small-scale use, (3) test the substrate and design in-field, (4) determine the impact of different inoculum, (5) determine a small-scale design based on local conditions such as finance, building materials, climate etc., (6) evaluate the digestates’ properties as a bio-fertilizer and (7) compare the biogas production with an existing biogas plant in Pampanga. Four combinations of food waste and pig manure were tested at Karlstad University’s biogas lab. The best composition had VS-ratio 1:2 for pig manure to food waste, and produced 111.1 NmL CH4/g VSadded. The chosen design was a floating drum digester. It was tested together with the substrate and two inoculums (cow manure and digestate from an existing biogas plant) in four pilot plants during 32 days. The plants showed symptoms of inhibition in biogas production and the pH dropped to toxic levels (below pH 6). At the end of the study, the plants had similar cumulative biogas production. The mean production was 1764 NmL and the average methane content was 33.6%. The plants with inoculum from an existing biogas plant showed signs of recovering from the low pH. The plants with cow manure as inoculum showed increasing signs of inhibition. The mean phosphorus content of the digestate was 1.3% TS and nitrogen content was 6% TS. The carbon to nitrogen ratio was on average 8:1, which had a positive impact on nitrogen mineralization in the soil (if used as bio-fertilizer). The digestate had high levels of VFA, which reflected improper substrate composition. The large fraction of food waste was the likely cause of inhibition; easily digestible carbohydrates lead to the pH drop and high levels of VFA. Based on the field study and literature, another substrate composition was recommended for the final design. The suggested substrate had VS-ratio 2:1 for pig manure to food waste. A variant of the floating drum digester was recommended, where several digesters could be connected in series and the number of digesters could be adapted to the number of pigs. The digester volume was 6.2 m3; the expected biogas production was 2.6 m3 with 70% methane content. This facility would result in a digestate containing 0.2 kg phosphorus and 0.7 kg nitrogen per day. Comparisons between the existing plants’ biogas production and the pilot plants could not be done due to the fact that the plant lacked methods for measuring their biogas production and methane content. However, the study’s overall findings make a strong argument for the use of biogas in backyard farms, for mitigating many of the Philippines’ water quality issues arising from pig production.

<p>Biogas mainly consists of methane and carbon dioxide, where methane is theenergy-rich gas, and is naturally created when organic matter breaks down in absenceof oxygen, also known as anaerobic digestion. A biogas plant re-creates the anaerobicconditions inside a digester where the organic substrate is fed into and digests toproduce biogas. The gas is then used to produce energy by combustion and can beseen as a completely renewable fuel.Today, energy from biogas is used primarily by major stakeholders such asmunicipalities and thus the plants become very large with high investment- andconstruction costs. There are currently few small plants in Sweden, even though thepotential for agriculture and medium-sized to smaller farms to become self-sufficientin terms of electricity and heat is great. Farms have a natural stock of digestibleorganic material in form of manure or crops for example, which are constantlyavailable. A reason that only a few small plants exists are the large investment costs.A study focusing on the actors who supply these smaller plants today was made withthe intention to find out where the large investment costs are and what techniquesare most profitable and efficient to use. The survey was conducted through field visits,interviews and contact by phone and internet with active companies and peoplefamiliar with the modern production of biogas.The survey was compiled and the various techniques and concepts were presented,evaluated and discussed to give the client a good basis for further development ofsmall-scale biogas plants.The investigation revealed that there are no barriers for biogas production in smallerfacilities, given that the same conditions in terms of temperature, acidity and nutrientis created just like in the larger facilities. It also showed that active heating and stirringof the substrate in the digester is of utmost importance to have a functioning processand maximum gas exchange.</p>

Due to historically low prices for electricity in Sweden, many small-scale hydropowerplants were closed down. A small-scale power plant has more or less the samemaintenance costs as larger plants, but doesn’t generate as much income. Today’sincreasing price for electricity in combination with a desire for renewable energysources makes small-scale hydropower interesting again. The sawmill in Venås is afacility of that kind. During the 1920´s two Francis turbines were installed as powersource for the machinery and a small private DC-grid. In 1966 the dam collapsed andthe facility was therefore retired. There is a possibility that the station can once againbe used as a power station to feed electricity to the grid. This will demand a largeamount of work and economic investment. Therefore is both technical andeconomical calculations needed in order to get the facility profitable. This reportincludes such calculations for the Venås station.

Biogas mainly consists of methane and carbon dioxide, where methane is theenergy-rich gas, and is naturally created when organic matter breaks down in absenceof oxygen, also known as anaerobic digestion. A biogas plant re-creates the anaerobicconditions inside a digester where the organic substrate is fed into and digests toproduce biogas. The gas is then used to produce energy by combustion and can beseen as a completely renewable fuel.Today, energy from biogas is used primarily by major stakeholders such asmunicipalities and thus the plants become very large with high investment- andconstruction costs. There are currently few small plants in Sweden, even though thepotential for agriculture and medium-sized to smaller farms to become self-sufficientin terms of electricity and heat is great. Farms have a natural stock of digestibleorganic material in form of manure or crops for example, which are constantlyavailable. A reason that only a few small plants exists are the large investment costs.A study focusing on the actors who supply these smaller plants today was made withthe intention to find out where the large investment costs are and what techniquesare most profitable and efficient to use. The survey was conducted through field visits,interviews and contact by phone and internet with active companies and peoplefamiliar with the modern production of biogas.The survey was compiled and the various techniques and concepts were presented,evaluated and discussed to give the client a good basis for further development ofsmall-scale biogas plants.The investigation revealed that there are no barriers for biogas production in smallerfacilities, given that the same conditions in terms of temperature, acidity and nutrientis created just like in the larger facilities. It also showed that active heating and stirringof the substrate in the digester is of utmost importance to have a functioning processand maximum gas exchange.

Växjö har ett intresse att förbättra sin miljöfråga om koldioxid utsläpp genom att öka mängden av förnybara energier resurser i samhället. Detta examensarbete bär med sig detta intresse och studerar om urbana vindkraftverk på tak. Syftet med arbetet är att öka kunskap om småskaliga vindkraftverk på tak i urban miljö som vidare kan bidra till utvecklingen med förnybar vindkrafts energi i staden. Rapporten studerar de faktorer som rör energiproduktions fråga från småskaliga vindkraftverk på tak i urbana miljöer som vindresurser, lämpliga vindkraftverk och förhållande mellan dem med dem medförande påverkningar samt problem. Resultatet av undersökningen visar energi beteende från småskaliga vindkraftverk på en befintlig offentlig byggnad i Växjö stad. Undersökningen visar en låg energiproduktion som bara täcker en liten del av bygg-nadens energianvändning. Urban vindkraft behöver mer insatser och studier för en fungerande marknad som kan konkurrera ut koldioxiden.

This thesis aims to propose a recommended upgrade for the generator protectionsystems in small hydropower stations. The hydropower stations examined areBrantafors, Djupafors, Horkoneryd, Kallinge ,Karlsnäs, Ronneby and Verperyd. Therecommended generator protection systems are developed from regulations basedon constitutions from Svenska Kraftnät and Elsäkerhetsverket. The recommendationpresented in this thesis is a lowest recommendation for the generator protectionsystems of small hydropower stations and in some cases the owner of the powerplant may request above this lowest level of protection. The overall documentation of the stations has been inadequate and many parametersare unknown in the stations and therefore assumptions have been made. Theassumptions have a big influence on the short circuit calculations which affects therecommended settings for short circuit protection and therefore a conservativeapproach has been used. The result of this thesis is that the hydro power station Ronneby can’t manage therequirements specified from Svenska Kraftnät, and therefore the protection system inthe hydro power station need to be adjusted. The hydropower stations Brantaforsand Verperyd can with minor adjustments meet the recommended generatorprotection. On the stations Djupafors, Horkoneryd, Kallinge and Karlsnäs largerupgrades of the generator protection systems need to be done to fulfill therecommended protection system.

Syftet med denna studie var att undersöka förutsättningar och möjligheter att producera biogas på Utö. Förhoppningen var att på detta vis kunna utnyttja främst slammet ifrån det lokala reningsverket som en resurs. Examensarbetet utfördes som en del av EU-projektet Green Islands där Skärgårdsstiftelsen i Stockholms Län är Lead Partner. Utöver reningsverkets slam undersöktes andra möjliga substrat, där matavfall ifrån Utö Värdshus och slakteriavfall ifrån ett mindre slakteri valdes ut som bäst lämpade. En uppskattning av substratsmängderna gav att en lämplig storlek på biogasreaktorn skulle vara ca 50 m3. Lokala användningsområden för producerad gas och rötrest utreddes och ett antal olika typer av små biogasverk har undersökts. De reaktorer som granskats djupast är forskningsreaktorn Renowaste på Henriksdalsberget, MR120 som tas fram av Energiutvecklarna och en ordinär reaktor uppbyggd av betongelement. Biogasprocessens mikrobiologi har också studerats och potentiella svårigheter analyseras. Praktiska, ekonomiska och miljömässiga aspekter undersöktes. Vid kraftvärmeproduktion skulle producerad elektricitet och värme kunna utnyttjas i sin helhet internt i reningsverket, men ingen avsättning för den näringsrika rötresten hittades eftersom det närbelägna jordbruket drivs ekologiskt vilket gör att humanslam inte får spridas på odlingsmarken. Rapporten visar på att uppförandet av ett biogasverk i Gruvbyn på Utö inte kan motiveras ekonomiskt. Ett flertal praktiska problem uppmärksammas också, där främst småskaligheten och substratens ojämna flöden förväntas bidra. De medtagna substratens sammanlagt låga kol/kvävekvot på ca 8 skulle också kunna innebära svårigheter att få en stabil process. Miljö- och klimatvinsterna bedöms relativt små, främst på grund av att en uppgradering av biogasen till fordonsgas, för att ersätta fossila drivmedel, inte kan ses som en realistisk möjlighet. Ett antal förbättringsmöjligheter som anses mer realistiskt genomförbara föreslås, som lokalt omhändertagande av slam i form av en vassbädd, effektivisering av reningsverkets uppvärmningssystem och lokal kompostering av Värdshusets matavfall. / The purpose of this study was to investigate the conditions and opportunities to produce biogas at Utö, an island in the Stockholm archipelago. The intention was that the sludge from the local sewage treatment plant could be used as a resource. The Master Thesis was conducted as part of the EU-funded project Green Islands, where the Archipelago Foundation in Stockholm County is Lead Partner. In addition to the sludge, other possible substrates were investigated. Food waste from Utö Inn and slaughterhouse waste from a small slaughterhouse were determined best suited. An estimate of the amounts of substrate gave that a suitable size of a biogas reactor would be about 50 m3. Local uses of produced gas and the digestate were investigated. Several small scale biogas digesters were investigated. The closest examined digesters are the research reactor Renowaste at Henriksdalsberget, MR120 which is developed by Energiutvecklarna and an ordinary, small scale digester constructed by concrete segments. The microbiology of the biogas process has also been studied and potential difficulties were analyzed. Practical, economic and environmental aspects were examined. If CHP were to be applied, electricity and heat could be utilized at the waste water treatment plant. No suitable usage of the nutrient-rich digestate was found. The nearby organic farm could not use the digestate since human sludge cannot be spread on organic farming land. The report states that the construction of a biogas plant in Gruvbyn on Utö cannot be economically justified. Several practical problems were also noted, where mainly the small scale and the uneven flows of substrates are expected to contribute. The low carbon/nitrogen ratio of the substrates, about 8, could also pose difficulties in obtaining a stable process.Environmental and climatic benefits deemed relatively small, mainly due to that upgrading of biogas to vehicle fuel, thus replacing fossil fuels, cannot be seen as a realistic possibility. A number of possible improvements that are considered more realistically feasible are suggested, like local treatment of sludge in a bed of reed, making the heating system of the waste water plant more efficient and local composting of the inn’s food waste.

Small scale biogas plants (max digester volume 1000 m3) in Sweden produced in average 1.26 GWh per plant in 2014. Most of the biogas was used for combined heat and power production. The relatively cheap electricity in Sweden makes this a low profit business. If the biogas is upgraded to vehicle fuel its value will increase. However, upgrading biogas with conventional methods is costly, and for small scale biogas plants this cost cannot be justified. Development of alternative upgrading methods is an option to decrease the cost of upgrading and making small scale vehicle fuel production a reality. In this master thesis the upgrading method known as in-situ methane enrichment was investigated. This method involves desorption of carbon dioxide in the sludge using a desorption chamber separated from the digester. Air is blown through the sludge for desorption of carbon dioxide. Subsequently, the sludge is pumped back to the digester. The aim was to perform an energy mapping on the enrichment facility installed at the biogas plant (260 m3) at Sötåsens naturbruksgymnasium. In addition, the possibility to absorb ammonium-nitrogen in the off-gas from the process using a scrubber was also investigated in laboratory-scale. The results showed that the upgrading facility lost large quantities of heat during operation. During the coldest circumstances using an air flow of 260 m3/h through the sludge, the heat loss was 495 kWh/day. The corresponding efficiency of carbon dioxide removal was 7.6 kWh/m3 removed carbon dioxide. With proper insulation and heat recovery, the facility has the potential to decrease the heat demand to ca 139 kWh/day, giving an efficiency of 2.3 kWh/m3 removed carbon dioxide. The electric efficiency was 1 kWh/m3 removedcarbon dioxide. The laboratory test of ammonium-nitrogen absorption indicated that the plant has a potential to absorb 59 – 275 kg nitrogen/year by installing a scrubber with a volume of 122 l. The economic benefits are small, but other values such as reduced ammonia pollution or heat recovery solutions using a scrubber should be considered. / Biogas 2020

I rapportens första del behandlas vad som orsakar omfattande driftstörningar och krav från nätägare som ställs på mindre vattenkraftsstationer med asynkrongeneratorer. Det gjordes med hjälp av en enkätundersökning som skickades ut till ett antal medlemmar i Svensk vattenkraftsförening (SVAF). Rapporten tar upp allmänt om småskalig vattenkraft i Sverige, olika typer av vattenkraftverk och dess uppbyggnad. Resultatet från undersökningen visar att de som drabbas av kortare driftstopp på upp till en vecka oftast beror på nätbortfall medan längre driftstopp beror på mekaniska problem inne i vattenkraftverket. De elektriska felen som beror på t.ex. kondensatorbatterier eller generatorer har bara i några få fall inneburit längre driftstopp. Undersökningen har visat att kraven hos olika vattenkraftägare varierar i stor utsträckning. Majoriteten av de som svarade på enkäten uppger att de faskompenserar sin asynkrongenerator men ytterst få ligger inom AMP:ens rekommendationer gällande effektfaktor. Rapportens andra del behandlar ett mindre vattenkraftverk i Östebyn där en asynkrongenerator som förbrukar mer reaktiv effekt än vad avtalet med nätägaren tillåter är installerad. Avsikten är att ta fram ett lösningsförslag för att minska den reaktiva förbrukningen genom installation av ett kondensatorbatteri. Vattenkraftverket har för tillfället ingen faskompenseringsutrustning och ägaren behöver välja mellan att faskompensera sin asynkrongenerator eller bli debiterad för överuttaget. Rapporten behandlar även problem och vad man bör ta hänsyn till vid installation av ett kondensatorbatteri. Vid tomgångskompensering med kondensatorbatteri kan den reaktiva förbrukningen minskas så att inget överuttag sker. Ett intervall på storleken beräknades fram med hjälp av mätdata till 21,2 – 26,1 kVAr. Priset på ett kondensatorbatteri och kostnaden för debiteringen har lett fram till en payback-tid för investeringen på ungefär sex år. / The first part of this thesis includes what causes disruptions in small hydropower stations with asynchronous generators and what requirements the power grid owners have. This was made through a survey that was sent to a group of members in Svensk vattenkraftförening (SVAF). The thesis includes general information about small hydropower stations and how they are constructed. The survey shows that the ones that are affected by short disruptions in production is often caused by grid loss while longer disruptions, over a week, is often caused by mechanical failure. The electrical failures that are caused by problems in capacitor banks or generators have only in a few cases caused disruption for a longer period of time. The survey shows that the requirements from the power grid owners towards the owners of the hydropower station vary. The majority of the responders claim that they have reactive power compensation installed but only a few of them are within the recommended interval that is set by the AMP. In the second part of the report a small hydropower station where an asynchronous generator consumes more reactive power than the agreement with the power grid owner allows. Therefore the owner needs to reduce the reactive power usage from the grid or pay a fee. The purpose is to find a solution on how to reduce the required reactive power from the grid. The thesis also includes different aspects to consider when installing a capacitor bank. To reach an accepted level of reactive power usage from the grid, an idle current compensation is recommended. The conclusion of this thesis is that a capacitor bank within the size interval of 21,2 - 26,1 kVAr is required and the payback time of this investment will be approximately six years.

På elmarknaden har man utvecklat fenomenet mikroproduktion av elenergi vilket innbär att slutkunden själv ska producera sin el främst genom att utnyttja sol och vind kraft. I Sverige finns det ett växande  intresset för mikroproduktion. De flesta som producerar sin egen el gör det främst genom solpaneler och mindre vindkraftverk som sätts upp vid deras egendom. I den här studien har vi gjort en djupare analys kring olika typer av anläggningar för att producera småskalig elkraft. Men även tittat på den ekonomiska aspekten genom att beskriva ekonomisk vinning och kostnader samt ställt upp en kostnadskalkyl för att beskriva detta i siffror. Slutligen gjordes en teknisk analys för att se ifall en mikroproduktionsanläggning ger några störningar på elnätet. Utifrån våra mätningar ute på fältet kan vi konstatera att anläggningen inte bidrog till någon störning.