The world\'s highest yielding crops are C4 plants due to their higher water use efficiency, nitrogen use efficiency, and productivity compared with C3 plants.  With an increasing demand for renewable resources as a result of the decreasing global supplies of fossil fuels, we need to improve our understanding of the limitations of biomass fuel feedstock to improve yields and better satisfy energy requirements.  The ability to attain the goal feedstock production in the US is limited by available arable land and cool temperatures.  This study investigates the effects of cool temperatures on the productivity and photosynthesis of the two species with the highest potential for feedstock production in the US: switchgrass (Panicum virgatum) cv. Alamo and miscanthus (Miscanthus × giganteus).  At 14/12"C and a 14/10 hour light/dark photoperiod, switchgrass showed lower productivity and light saturated photosynthetic rates (Amax=10.3 "mol m-2s-1) compared with 28/25"C and the same photoperiod (Amax=18.8 "mol m-2s-1).  Miscanthus has demonstrated cold tolerance in previous studies, and here showed no significant decrease in the productivity or photosynthetic rates in cool, compared with warm, growing conditions (Amax=8.2 "mol m-2s-1 and 7.0 "mol m-2s-1 for warm and cool conditions, respectively). Also, this study examines the potential limitations of C4 photosynthesis by the enzyme pyruvate phosphate dikinase (PPDK) under the same cool conditions, transgenic switchgrass cv. Alamo were created with the insertion of the miscanthus PPDK gene. Productivity and photosynthetic responses of the transgenic plants were evaluated in cool and warm growth temperatures.  Of the two transgenic events tested here, line S(1) displayed cold tolerance, as seen in no loss of both carboxylation efficiency and the ratio of CO2 assimilation to electron transport (Asat/Jmax).  These results indicate that PPDK may pose a significant limitation to C4 photosynthesis in cool conditions and there is a possibility that cold season photosynthesis of switchgrass cv. Alamo could be improved. / Master of Science

The main cause of spacecraft failures is due to the harsh space environment; therefore, rigorous testing of materials used in modern spacecraft is imperative to ensure proper operation during the life span of the mission. Enhancing the capabilities of ground-based test facilities allows for more accurate measurements to be taken as it better simulates the environment to which spacecraft will be exposed. The range of temperature measurements has been significantly extended for an existing space environment simulation test chamber used in the study of electron emission, sample charging and discharge, electrostatic discharge and arcing, electron transport, and luminescence of spacecraft materials. This was accomplished by incorporating a new two-stage, closed-cycle helium cryostat, which has an extended sample temperature range from 450 K, with long-term controlled stability of -7Pa) that can simulate diverse space environments. These existing capabilities include controllable vacuum and ambient neutral gases conditions (< 10-7 to 10-1 Pa), electron fluxes (5 eV to 30 KeV monoenergetic, focused, pulsed sources ranging from 10-4 to 1010 nA-cm-2), ion fluxes (<0.1 to 5keV monoenergetic sources for inert and reactive gases with pulsing capabilities), and photon irradiation (numerous continuous and pulsed monochromatic and broadband IR/VIS/UV [0.5 to 7 eV] sources). The original sample mount accommodates one to four samples of 1 cm to 2.5 cm diameter in a low-temperature carousel, which allows rapid sample exchange and controlled exposure of the individual samples. Multiple additional sample mounts have been added to allow for standalone use for constant voltage measurements, radiation induced and conductivity tests, as well as extended capabilities for electron-induced luminescent measurements to be conducted using various material sample thickness in the original existing space environment simulation test chamber.

The purpose of this study was to continue the assessment of low-temperature geothermal resources in Utah started . by the Utah Geological and Mineral Survey. The area of interest with in this report is north-central Box Elder County, Utah. Exploration techniques used included chemical analyses of water from wells and springs, temperature surveys, and temperature-depth measurements in unused wells within the study area. The highest water temperatures (31, 30, and 290c) recorded in this research were located in three separate geographic regions, suggesting that no single warm water occurrence dominates the study area. Total dissolved solid (T:DS) concentrations ranged from 294 to 11,590 mg/1. Areas of warm water occurrences generally had TDS values of greater than 1,100 mg/1. Three water types were distinguished using trilinear plots of common ion analyses of collected water samples. The warmest wells were of Type III water character, which has high (>75%) sodium and chloride concentrations. Reservoir temperatures were estimated using the water chemistry. Both the silica and the Na-K-Ca geothermometers were used to calculate reservoir temperatures, averaging between 500c and 1 ooo c. If mixing effects are taken into account, reservoir temperatures might be as high as 198°C. Temperature-depth measurements were logged in 16 unused wells. Thermal gradients calculated from the profiles ranged from isothermal to 267oC/km. The background gradient for the study area appears to be slightly above the average Basin and Range gradient of 35oC/km. The highest gradients were calculated for the area approximately 8 kilometers west of Snowville, Utah, which is also an area of warm water. Several areas of possible low-temperature geothermal interest have been identified in the study area by considering water temperatures, calculated reservoir temperatures, and temperature-depth data. However, additional work is needed to more accurately define the possible geothermal resource in these areas.

abstract: Micro/meso combustion has several advantages over regular combustion in terms of scale, efficiency, enhanced heat and mass transfer, quick startup and shutdown, fuel utilization and carbon footprint. This study aims to analyze the effect of temperature on critical sooting equivalence ratio and precursor formation in a micro-flow reactor. The effect of temperature on the critical sooting equivalence ratio of propane/air mixture at atmospheric pressure with temperatures ranging from 750-1250°C was investigated using a micro-flow reactor with a controlled temperature profile of diameter 2.3mm, equivalence ratios of 1-13 and inlet flow rates of 10 and 100sccm. The effect of inert gas dilution was studied by adding 90sccm of nitrogen to 10sccm of propane/air to make a total flow rate of 100sccm. The gas species were collected at the end of the reactor using a gas chromatograph for further analysis. Soot was indicated by visually examining the reactor before and after combustion for traces of soot particles on the inside of the reactor. At 1000-1250°C carbon deposition/soot formation was observed inside the reactor at critical sooting equivalence ratios. At 750-950°C, no soot formation was observed despite operating at much higher equivalence ratio, i.e., up to 100. Adding nitrogen resulted in an increase in the critical sooting equivalence ratio. The wall temperature profiles were obtained with the help of a K-type thermocouple, to get an idea of the difference between the wall temperature provided with the resistive heater and the wall temperature with combustion inside the reactor. The temperature profiles were very similar in the case of 10sccm but markedly different in the other two cases for all the temperatures. These results indicate a trend that is not well-known or understood for sooting flames, i.e., decreasing temperature decreases soot formation. The reactor capability to examine the effect of temperature on the critical sooting equivalence ratio at different flow rates was successfully demonstrated. / Dissertation/Thesis / Masters Thesis Aerospace Engineering 2019

京都大学 / 新制・論文博士 / 博士(農学) / 乙第13423号 / 論農博第2898号 / 新制||農||1086(附属図書館) / 学位論文||R3||N5346(農学部図書室) / (主査)教授 中嶋 洋, 教授 近藤 直, 教授 飯田 訓久 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20449号 / 農博第2234号 / 新制||農||1050(附属図書館) / 学位論文||H29||N5070(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 矢野 浩之, 教授 木村 恒久, 教授 髙野 俊幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20763号 / 工博第4415号 / 新制||工||1686(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 陰山 洋, 教授 阿部 竜, 教授 江口 浩一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21379号 / 農博第2303号 / 新制||農||1071(附属図書館) / 学位論文||H30||N5152(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 栗原 達夫, 教授 植田 充美, 教授 小川 順 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

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För att möta problem med ökande klimatförändringar kan fjärrvärmen ha en betydande roll ur både en svensk och en internationell kontext. Samtidigt står svenska fjärrvärmebolag inför betydande utmaningar då värmepumpar blir ett allt vanligare val för att möta uppvärmnings- och tappvarmvattenbehovet, tillgången till avfall och biomassa som bränsle förutspås bli mer begränsad och byggnaders uppvärmningsbehov blir allt lägre. För att fjärrvärme ska fortsätta vara ett konkurrenskraftigt och hållbart alternativ för att möta uppvärmnings- och tappvarmvattenbehovet har konceptet fjärde generationens fjärrvärme (4GDH) tagits fram. 4GDH karaktäriseras av lägre nättemperaturer, fler förnybara energikällor för fjärrvärmeproduktion samt ökad integrering med andra delar av energisystemet. I detta examensarbete har dels möjligheter med att arbeta mot 4GDH i Borlänge Energis fjärrvärmenät undersökts och dels har potentialen med att uppnå ett hållbart energisystem genom att konvertera existerande svenska fjärrvärmenät till 4GDH undersökts. Examensarbetets fokus har primärt legat på den aspekt av 4GDH som innebär lägre nättemperaturer.  Beräkningar på Borlänges fjärrvärmenät visar att det finns fördelar med att sänka nättemperaturen i form av (1) ökad elproduktion i kraftvärmeverk (KVV), (2) effektivare rökgaskondensering samt (3) mindre värmeförluster. Störst kostnadsbesparingar och undvikta CO2-utsläpp erhålls genom effektivare rökgaskondensering följt av minskade värmeförluster. Den ökade elproduktionen i KVV medförde små kostnadsbesparingar och undvikta CO2-utsläpp i förhållande till tidigare nämnda faktorer. Simulering av Borlänges fjärrvärmenät i dagsläget och med 4GDH visade på att 4GDH skulle kunna leda till att en stor mängd drifttimmar undviks i Borlänge Energis avfallseldade hetvattenpanna samtidigt som fjärrvärmesystemet blir oberoende av fossila bränslen. Detta innebär stora undvikta CO2-utsläpp men grundat i att avfallsförbränning är en tjänst som fjärrvärmebolag får betalt för i dagsläget leder det totalt sett till en ökade bränslekostnader för Borlänge Energi.   Vid analys av kunder i Borlänges fjärrvärmenät valdes fem fastigheter ut som till stor del uppfyllde framtagna kriterier för att en fastighet skulle lämpa sig väl för 4GDH. Av dessa var tre fastigheter planerade byggnationer och två befintliga fastigheter. Av de presenterade tekniska lösningarna fanns endast tydlig ekonomisk lönsamhet, miljönytta och teknisk möjlighet i ett av fallen, där majoriteten av fastighetens fjärrvärmebehov kunde täckas av returvärme tack vare låga temperaturkrav. I två andra fall kunde ekonomisk lönsamhet och miljönytta konstateras men dessa krävde investeringar av externa aktörer för att tekniskt möjliggöras. I de övriga två fallen begränsades den ekonomiska lönsamheten och tekniska möjligheten av ett begränsat flöde i närliggande returledningar som föreslogs användas som framledning för lösningarna.  De långsiktiga fördelarna med 4GDH indikerade att det är ett angreppssätt man på sikt bör jobba vidare med i Borlänge eftersom det kan bidra till att uppfylla kommunala miljömål. Samtidigt visade de studerade kundfallen att det finns tydliga hinder för implementering av 4GDH trots att fastigheter bedöms väl lämpade för att nyttja lågtempererad fjärrvärme. Således drogs slutsatsen att 4GDH främst bör implementeras i form av större sekundärnät vilket kräver samordning av ett flertal aktörer och långsiktig planering. För att stödja Borlänge Energis arbete mot 4GDH togs en handlingsplan fram med rekommenderade åtgärder i dagsläget, på fem till tio års sikt och på längre än tio års sikt.  För att avgöra potentialen med 4GDH i svenska fjärrvärmenät generellt nyttjades resultat från beräkningar och simuleringar av Borlänges fjärrvärmenät för att simulera fyra typiska svenska fjärrvärmenät med olika produktionsmixar. Simuleringarna visade på att 4GDH i samtliga fall ledde till kostnadsbesparingar och undvikta CO2-utsläpp samtidigt som tillförseltryggheten ökade. Simuleringarna indikerade på att fjärrvärmenät där restvärme eller biomassa är de primära energikällorna främst drar fördel med 4GDH i form av minskade bränslekostnader medan fjärrvärmenät där avfall eller fossila bränslen är primära energikällor drar större fördel i form av undvikta CO2-utsläpp.  Resultaten från detta examensarbete visade att potentialen för att uppnå ett hållbart energisystem genom att konvertera svenska fjärrvärmenät till 4GDH är god. Beroende på vilken typ av svenskt fjärrvärmenät det är bör policys och styrmedel anpassas för att gynna en utveckling mot 4GDH, extra betydande är detta i fjärrvärmenät där avfallsförbränning står för en betydande del av fjärrvärmetillförsel. Generellt kan arbete mot 4GDH påbörjas på ett förhållandevis likvärdigt vis i svenska fjärrvärmenät, därför presenteras en generell metodik för hur svenska fjärrvärmebolag kan initiera en omställning mot 4GDH. / To face the emerging climate crisis, district heating could play an important role both in Sweden and internationally. Meanwhile, Swedish district heating companies are facing major challenges as heat pumps become more common to meet the heating and domestic hot water demand in buildings, the availability of waste and biomass as fuel is predicted to be limited and the heating demand of buildings is reducing. In order for district heating to maintain a competitive and sustainable alternative to meet the heating and domestic hot water demand in buildings, the concept of the fourth generation of district heating (4GDH) has been created. 4GDH is characterized by lower temperatures in the district heating network, more renewable energy sources used for heat production and increased integration with other parts of the energy system. In this master thesis, the possibilities with working towards 4GDH in Borlänge Energi’s district heating network has been evaluated. Also, the potential of achieving a sustainable energy system by converting existing Swedish district heating networks to 4GDH has been examined. The focus of the master thesis has primarily been on the aspect of 4GDH considering lower network temperatures.  Calculations show benefits with lower temperatures in Borlänge Energi’s district heating network such as (1) increasing electricity production in the combined heat and power plant (CHP), (2) more efficient flue gas condensation and (3) decreased heat losses. The largest reductions of costs and CO2 emissions are obtained from more efficient flue gas condensation followed by decreased heat losses. The increased electricity production in the CHP plant resulted in smaller reductions of costs and CO2 emissions compared to the above-mentioned factors. Simulations of a scenario where 4GDH is fully implemented in Borlänge, shows that 4GDH could lead to a lot of operating hours being avoided in the waste-fuelled hot water boiler and the district heating network being independent of fossil fuels. This means significant reductions of CO2 emissions but due to that waste incineration is a service that district heating companies gets paid for the total costs of fuel are increased.   When analysing customers in Borlänge Energi’s district heating network, five buildings were selected that largely fulfilled presented criterions for a building to suit well in a 4GDH system. Of these five buildings, three were planned buildings and two were existing. Of the presented technical solutions, there were only economic and environmental benefits with few technical barriers in one case. In this case, the heating and domestic hot water demand could mainly be covered by return heat owing to low temperature requirements. In two other cases, the economic and environmental benefits depended heavily on investments by external actors to be technically feasible. In the remaining two cases, the economic benefits and the technical feasibility was limited due to a limited flow in nearby return pipes which were proposed to be used as supply pipe to the buildings.  The long-term benefits with 4GDH indicated that it is an approach that should be continued with in Borlänge in the long term as it can contribute to reaching municipal environmental targets. However, the studied customer cases showed significant barriers to implementing 4GDH, although the buildings were assessed to be suited well for using low-tempered district heating. Thus, it was concluded that 4GDH should mainly be implemented by building larger low-tempered secondary networks. This requires coordination of multiple actors and long-term planning. To support Borlänge Energi’s work towards 4GDH, an action plan was presented with recommended measures today, in five to ten years’ time and in more than ten years’ time.  To generalize the results from Borlänge on a national level, the results from calculations and simulations of Borlänge Energi’s district heating network were used to simulate four typical Swedish district heating networks with different production mixes. The simulations showed that 4GDH in all cases led to reductions of costs and CO2 emissions and increased security of supply. The simulations indicated that district heating networks where residual heat or biomass is predominantly used mainly benefits from 4GDH through cost reductions, while district heating networks where waste or fossil fuels are predominantly used mainly benefits from 4GDH through reduced CO2 emissions.  The results of this thesis shows that the potential of achieving sustainable energy systems by converting Swedish district heating networks to 4GDH is high. Depending on the characteristics of the district heating network, policies and instruments should be adjusted to support a development towards 4GDH. This is especially important in district heating networks where waste incineration is a major source of the district heating supply. However, work towards 4GDH could generally be initiated in a relatively similar way in Swedish district heating networks. Therefore, a general method for initiating a transition towards 4GDH was presented