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A study of regularities associated with biochemical processes and renewable energy resourcesPatel, Snehal A January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
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Modelling and optimisation of energy systems with thermal energy storageRenaldi, Renaldi January 2018 (has links)
One of the main challenges in the implementation of renewable energy is the mismatch between supply and demand. Energy storage has been identified as one of the solutions to the mismatch problem. Among various storage technologies, thermal energy storage (TES) is foreseen to have a significant role to achieve a low carbon energy systems because of the large share of thermal energy demand and its relatively low cost. However, integrating TES into energy systems requires careful design and implementation since otherwise potential financial and environmental savings may not be achieved. Computational-based design tools are ubiquitous in the design process of modern energy systems and can be broadly categorised into two methodologies: optimisation and simulation. In both cases, designing an energy system with storage technology is significantly more complicated than those without, mainly due to the coupling of variables between time steps. This thesis is concerned with two facets of the application of TES in energy systems. First, the role of TES in improving the performance of renewable-based domestic heating systems. Second, the implementation of optimisation and simulation tools in the design of energy systems with integrated TES. They are addressed by examining two case studies that illustrate the spatial and temporal variance of energy systems: a single dwelling heat pump system with a hot water tank, and a solar district heating system with a borehole thermal energy storage. In the single dwelling case study, the technical and financial benefits of TES installation in a heat pump system are illustrated by the optimisation model. A simulation model which utilises the optimisation results is developed to assess the accuracy of the optimisation results and the potential interaction between the two methodologies. The solar district heating case study is utilised to highlight the potential of a time decomposition technique, the multiple time grids method, in reducing the computational time in the operational optimisation of the system. Furthermore, the case study is also employed to illustrate the potential of installing a similar system in the UK. The latter study was performed by developing a validated simulation model of the solar district heating system. The findings of the analyses reported in this thesis exemplify the potential of TES in a domestic and community-level heating system in the UK. They also provide a basis for recommendations on the improved use of optimisation and simulation tools in the design process of energy systems.
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Modeling and Analysis of a Photovoltaic System with a Distributed Energy Storage SystemMa, Anthony Winston 01 May 2012 (has links)
As California continues to integrate more renewable energy into its electrical system, the state has experienced a corresponding rise in photovoltaic system installations. PV arrays are a unique source of power generation in that they are affected by the location of the sun, shading, and temperature changes. These characteristics make solar one of the most highly variable forms of renewable energy. In order to improve solar power’s consistency, PV systems require a supplemental source of power. The primary focus of this paper is to determine if distributed energy storage systems can be used to reduce the effect of solar intermittency. This paper examines the test data and system specifications of an experimental DESS. The benefits of using a DESS in a PV system are further studied using computer simulation modeling. This paper also shows through computer simulations how a maximum power point tracker can increase a PV array’s power output. The results of this thesis demonstrate that DESS’s are capable of smoothing out highly variable load profiles caused by intermittent solar power.
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Corporate and city GHG inventories : Impact on global CO2 emissionswhen considering electricity and CHP-based district heatingNordenstam, Lena January 2018 (has links)
One initiative to reduce greenhouse gas (GHG) emissions involves developing standards for GHG inventories. Companies and cities (regions) can use GHG inventories to compile and report their GHG emissions. Standards for corporate and city GHG inventories often claim that GHG inventories can be used for identifying emissions opportunities, building reduction strategies and setting, measuring and reporting emissions targets. Attributional emissions factors are generally used in corporate and city GHG inventories. For purchased electricity, heat and steam, this means using average emission factors for regional or national production of each energy carrier. Also contractual emissions factors can be used. Changes in emissions from affected production elsewhere are not included. For purchased electricity and district heating (DH), a GHG inventory can be improved by lowered purchases or by purchasing a different energy carrier. Furthermore, combined heat and power (CHP) technology can help reduce global GHG emissions in the supply and conversion of energy, as CHP production is more efficient than conventional separate production of electricity and heat. In CHP production, excess heat from electricity production is utilised for heating buildings, hot water, industry processes etc., either directly or through DH systems. This thesis analyses how emissions reduction measures based on corporate or city GHG inventories, carried out using GHG Protocol standards, affect global CO2 emissions when electricity or CHP-based DH is affected. The incentive of a GHG inventory to a company purchasing electricity and DH, and to a city regarding purchases and production of electricity and DH in its region, is analysed. This is done for GHG inventories conducted in a nation where electricity produced within the nation is regarded as CO2-lean (Sweden) and in a nation where it is more CO2-rich (Germany). The indirect incentive to the DH company to change its production, in order to improve the GHG inventory of its customers and of the city where the DH system is located, is also analysed. Consequential analyses are used to assess how global CO2 emissions are affected by changes in purchases or production of electricity and DH that are incentivised by the GHG inventories studied. These consequential analyses include changes in emissions from affected electricity production elsewhere. The results show that the strength of incentive to reduce purchase of electricity or CHP-based DH by a company or in a city can differ between GHG inventories and consequential analysis. This is most clear when electricity produced within the nation is regarded as CO2-lean (Sweden) while affected electricity production elsewhere is CO2-rich. For replacing purchases of CHP-based DH with electricity, or vice versa, the incentive in a GHG inventory can be the reverse of that in a consequential analysis. Moreover, the incentive to lower the use of electricity is lost when contractual emissions factors with zero emissions, such as renewable electricity guarantees of origin (RE-GOs), are used. In addition, purchase of electricity RE-GOs, which have a large surplus and no requirement of additionality, is less likely to cause a corresponding increase in production of renewable electricity. Furthermore, when the highest emission reduction per Euro invested is sought (e.g. when investment resources are limited), the investment ranking of a heat-only boiler and a CHP plant can differ depending on whether the focus is on improving a city GHG inventory or lowering global CO2 emissions. Moreover, if the DH company improves (reduces) the average emissions factor for DH, it improves the GHG inventory of its customers and of the city where they are located. In a DH system based on bio-fuelled CHP production, the average emissions factor for DH improves when CHP electricity production is lowered to the extent that production of heat at the oil-fuelled heat-only boiler (used for peak heat production) is minimised. However, according to consequential analysis, this would lead to an increase in global CO2 emissions. Based on the results of this thesis, it is concluded that measures which include changes in purchases or production of electricity or CHP-based DH can increase global CO2 emissions when based on how corporate or city GHG inventories in general value CO2 emissions of electricity and DH. It is therefore unfortunate that GHG Protocol standards for corporate and city GHG inventories advocate basing emissions reduction decisions on GHG inventories. There is nonetheless an obvious risk of reported and communicated GHG inventories being used as a basis for emissions reductions decisions. If the aim is actual reduction of global CO2 emissions, average or purchased emissions factors should not be used for purchased electricity and CHP-based DH when assessing, reporting or communicating the impact of companies and cities (regions) on CO2 emissions. Instead, a consequential approach should be used for climate evaluation of purchased electricity and DH. / Ett av många initiativ för att minska utsläpp av klimatpåverkande gaser är framtagandet av regelverk för klimatredovisningar. Klimatredovisningarna kan användas av företag och städer (regioner) för att sammanställa och rapportera om företagets eller stadens utsläpp av klimatpåverkande gaser. I regelverken för framtagande av klimatredovisningarna betonas ofta att klimatredovisningen kan användas för att identifiera var utsläppsminskningar kan göras, att utveckla strategier för att minska klimatpåverkande utsläpp samt för att sätta, mäta och följa upp mål för klimatpåverkande utsläpp. En klimatredovisning innehåller vanligtvis bokföringsvärden, vilket innebär att lokala genomsnittliga utsläppsfaktorer används för köpt el och värme. Även köpta utsläppsfaktorer kan användas. Klimatredovisningen inkluderar inte ändringar i utsläpp från produktion som påverkas någon annanstans. En klimatredovisning kan förbättras t ex genom att mindre energi köps eller genom byte av energibärare. För el- och värmeförsörjning kan kraftvärmeteknik bidra till minskade globala utsläpp av koldioxid (CO2), eftersom kraftvärmeproduktion är mer effektivt än separat produktion av el och värme. Vid kraftvärmeproduktion tas överskottsvärmen från elproduktionen tillvara för att värma byggnader, varmvatten, industriprocesser mm, antingen direkt eller via fjärrvärmesystem. I denna avhandling analyseras hur globala utsläpp av CO2 påverkas av åtgärder som påverkar förbrukning eller produktion av el och fjärrvärme, när beslut om sådana åtgärder baseras på ett företags eller en stads klimatredovisning, gjorda enligt Greenhouse Gas Protocols regelverk. Incitamenten i ett el- och fjärrvärmeköpande företags klimatredovisning och i en stads klimatredovisning analyseras. Detta görs för klimatredovisningar utförda i ett land där elproduktionen inom landet är CO2-mager (Sverige) och ett land med mer CO2-rik elproduktion (Tyskland). Dessutom analyseras de indirekta incitament som dessa klimatredovisningar ger till det lokala fjärrvärmeföretaget att ändra sin produktion för att förbättra sina kunders klimatredovisningar och klimatredovisningen för staden där fjärrvärmeverksamheten finns. Konsekvensanalyser görs för att beräkna hur olika åtgärder som stödjs av klimatredovisningarna påverkar globala CO2-utsläpp. I konsekvensanalyserna inkluderas också förändringar i utsläpp från påverkad elproduktion, även om den förändringen sker någon annan stans. Resultaten visar att styrkan i incitamentet att minska ett företags eller en stads inköp av el eller fjärrvärme kan skilja sig mellan en klimatredovisning och en konsekvensanalys. Detta är särskilt tydligt när klimatredovisningen görs i ett land där elproduktionen inom landet är CO2-mager (Sverige) medan den påverkade elproduktionen är CO2-rik. När det gäller utbyte av fjärrvärme mot el eller tvärtom kan en klimatredovisning ge motsatta incitament jämfört med den ledningen en konsekvensanalys ger. När köpta emissionsfaktorer med nollutsläpp för el används, t ex förnybara ursprungsgarantier, försvinner incitamentet att minska elanvändningen. Det är dessutom mindre sannolikt att ett köp av förnybara ursprungsgarantier för el medför motsvarande ökning av produktion av förnybar el, då överskottet av förnybara ursprungsgarantier för el är stort och additionalitetskrav saknas. När investeringsresurser är begränsade kan det vara av intresse att utvärdera vilken investering som ger mest reduktion av klimatpåverkande gaser per investering. Avhandlingens resultat visar att investering i hetvattenproduktion och kraftvärmeproduktion då kan komma att sinsemellan rangordnas olika, beroende på om målet är att förbättra stadens klimatbokslut eller om målet är att minska globala utsläpp av CO2. Om fjärrvärmeföretaget förbättrar (minskar) genomsnittlig emissionsfaktor för sin fjärrvärme, förbättras klimatbokslutet för deras kunder och för staden där fjärrvärmesystemet är beläget. Resultaten visar också att i ett fjärrvärmesystem, som baseras på ett bioeldat kraftvärmeverk och där olja används för efterfrågetoppar när det är som allra kallast, förbättras fjärrvärmens emissionsfaktor när elproduktionen i kraftvärmeverket minskas. Dock visar konsekvensanalysen att ett sådant agerande kan medföra ökade globala utsläpp av CO2. Baserat på resultaten dras slutsatsen att beslut om åtgärder, som påverkar köp eller produktion av el eller kraftvärmebaserad fjärrvärme, kan orsaka ökning av globala CO2-utsläpp om de baseras på de incitament ett klimatbokslut ger. Det är därför olyckligt att GHG Protocols regelverk för företags och städers klimatbokslut rekommenderar att klimatboksluten används för beslut som avser att minska utsläpp av CO2. Även om de inte rekommenderade detta, finns ändå en uppenbar risk att rapporterade och kommunicerade klimatbokslut används som bas för beslut om åtgärder som syftar till minskade utsläpp av CO2. Om syftet är minskade globala CO2-utsläpp bör genomsnittliga och köpta emissionsfaktorer inte användas för klimatvärdering av köpt el och kraftvärmebaserad fjärrvärme när ett företags eller en stads (regions) klimatpåverkan beräknas, rapporteras eller kommuniceras. För klimatvärdering av köpt el och fjärrvärme bör i stället en konsekvensbaserad metod användas.
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Development of a new framework for a House Rating Scheme (HRS)Kordjamshidi, Maria, Built Environment, Faculty of Built Environment, UNSW January 2007 (has links)
There has long been concern that rating the thermal performance of buildings on the basis of predicted normalized energy requirement (MJ/m2) is inappropriate for achieving overall energy efficient design of houses, mainly due to the inability of such schemes to deal with the evaluation of passive architectural design in the form of free running buildings. This study, investigating the shortcomings in the current rating schemes, hypothesizes that the main reason for that inability is due to significant differences between efficient design for free running and conditioned houses. It also suggests that a multiple occupancy scenario, involving variable occupation times and zones, is an important parameter for improving the accuracy of any building evaluation system. The study aims to propose a new method for House Rating Schemes in which the efficiency of a house design will be evaluated with reference to its thermal performance in both free running and conditioned operation modes. By attributing more value to the performance of houses in the free running than the conditioned operation, it is assumed that policy objectives for reducing energy demand for space heating and cooling in the residential building sector are more likely to be achieved. Simulation was used to compare the predicted thermal performances of houses in free running and conditioned operation modes for the moderate climates of Sydney and Canberra. Parametric sensitivity analysis and multivariate regression analysis have been employed and point to the following results. The reliability of a free running rating scheme, in terms of addressing energy efficient aspects, as compared to the current energy based rating schemes, is demonstrated. The research illustrates significant differences between efficient design for conditioned houses and for free running houses. The findings strongly suggest the necessity of developing a new regulatory framework for reducing energy demand in the housing sector. Utilizing these findings, an aggregation of two rating systems for the purpose of creating a new house rating framework has been developed. It is assumed that this research approach is likely to deliver significant benefits in terms of reduction in energy demand and increased sustainability, if it is employed as a basis for House Ratings Schemes.
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Energy Accounting and Optimization for Mobile SystemsDong, Mian 16 September 2013 (has links)
Energy accounting determines how much a software process contributes
to the total system energy consumption. It is the foundation for
evaluating software and has been widely used by operating system based
energy management. While various energy accounting policies have been
tried, there is no known way to evaluate them directly simply because
it is hard to track every hardware use by software in a heterogeneous
multicore system like modern smartphones and tablets. This work
provides the ground truth for energy accounting based on multi-player
game theory and offers the first evaluation of existing energy
accounting policies, revealing their important flaws. The proposed
ground truth is based on Shapley value, a single value solution to
multi-player games of which four axiomatic properties are natural and
self-evident to energy accounting.
This work further provides a utility optimization formulation of
energy management and shows, surprisingly, that energy accounting does
not matter for existing energy management solutions that control the
energy use of a process by giving it an energy budget, or budget based
energy management (BEM). This work shows an optimal energy management
(OEM) framework can always outperform BEM. While OEM does not require
any form of energy accounting, it is related to Shapley value in that
both require the system energy consumption for all possible
combination of processes under question.
This work reports a prototype implementation of both Shapley
value-based energy accounting and OEM based scheduling. Using this
prototype and smartphone workload, this work experimentally
demonstrates how erroneous existing energy accounting policies can be,
show that existing BEM solutions are unnecessarily complicated yet
underperforming by 20% compared to OEM.
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Residual Energy Monitoring in WirelessSensor NetworksShenkutie, Daniel Kifetew, Shinde, Prashanth Kumar Patil January 2011 (has links)
Since wireless sensor networks are energy constrained, introducing a method that facilitates the efficient use of the available energy in each node is a fundamental design issue. In this work, a mechanism to monitor the residual energy of sensor networks is proposed. The information about the residual energy of each sensor node in the network is saved in a special node called monitoring node. This information can be used as input to other applications to prolong the network lifetime. Each sensor node in the network uses the proposed prediction-based model to forecast its energy consumption rate. The model's performance is measured based on the number of energy packets sent to the monitoring node for various thresholds (prediction errors). The simulation results showed that reducing the threshold will produce more accurate projection of the residual energy of each node in the monitoring node. However, as the threshold is further decreased the number of energy packets sent to the monitoring node grows significantly. This incurs higher energy map construction cost on the network in terms of energy and bandwidth. The simulation results also showed the tradeoff between increasing the accuracy of the prediction model and reducing the cost of energy map construction.
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Flywheel energy storage : a conceptucal studyÖstergård, Rickard January 2011 (has links)
This master thesis was provided by ABB Cooperate Research in Västerås. This study has two major purposes: (1) to identify the characteristics of a flywheel energy storage system (FESS), (2) take the first steps in the development of a simulation model of a FESS. For the first part of this master thesis a literature reviews was conducted with focus on energy storage technologies in general and FESS in particular. The model was developed in the simulation environment PSCAD/EMTDC; with the main purpose to provide working model for future studies of the electrical dynamics of a flywheel energy storage system. The main conclusion of the literature review was that FESS is a promising energy storage solution; up to multiple megawatt scale. However, few large scale installations have so far been built and it is not a mature technology. Therefore further research and development is needed in multiple areas, including high strength composite materials, magnetic bearings and electrical machines. The model was implemented with the necessary control system and tested in a simulation case showing the operational characteristics.
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Energy demand and indoor climate of a traditional low-energy building in a hot climateLi, Ang January 2009 (has links)
Energy demand in the built environment is quite important. China holds a large population and the energy use in the building sector is about 1/3. The rebuilding of old houses and building new low energy houses are becoming more and more popular in China. Low energy building not only consumes less energy, but also provides good indoor environment. An indoor climate software IDA is used in energy and indoor climate simulation. The traditional high isolated low energy house in a hot climate is analyzed, on a typical day in either summer or winter, or during the whole year. Energy consumptions under different parameters are presented. Results show that high isolated house may not always be suitable in a hot climate.
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EU¡¦s Policy on Energy SecurityChiu, Mei-Hsiang 29 June 2011 (has links)
The economic development, environmental sustainability and energy security stay on the top of government agenda, which guarantee the citizen¡¦s standards of living . EU's indigenous energy production is depleting, and each states has different priorities. The European Union push new European energy policies improving security of energy supply ,which are aiming at reducing the risks being dependent on external supply. Those new european energy policies transform Europe into a highly energy efficiency and low CO2 economy,creating an internal energy market and diversifying energy supplies. The EU¡¦s internal policies include enhancing powers and independence of regulatory authorities at Community level, improving the integrated and flexible energy networks,establishing adequate minimum security of gas supply standards and emergency measures and executing the Action Plan for energy efficiency. The EU¡¦s external policies include enhancing energy partnership and continuing energy dialogue with Russia, Central Asia and Mediterranean area, improving investment and growth, developing common trade,transit and environment rules, building the energy supply chain and diversifying energy supplies. In this thesis the security of EU¡¦s energy supply will be examined by the perspective of neo-functionalism.
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