Дисертації з теми "HYBRID SOLAR-BIOMASS"

This thesis examined solar thermal collectors for use in alternative hybrid solar-biomass power plant applications in Gujarat, India. Following a preliminary review, the cost-effective selection and design of the solar thermal field were identified as critical factors underlying the success of hybrid plants. Consequently, the existing solar thermal technologies were reviewed and ranked for use in India by means of a multi-criteria decision-making method, the Analytical Hierarchy Process (AHP). Informed by the outcome of the AHP, the thesis went on to pursue the Linear Fresnel Reflector (LFR), the design of which was optimised with the help of ray-tracing. To further enhance collector performance, LFR concepts incorporating novel mirror spacing and drive mechanisms were evaluated. Subsequently, a new variant, termed the Elevation Linear Fresnel Reflector (ELFR) was designed, constructed and tested at Aston University, UK, therefore allowing theoretical models for the performance of a solar thermal field to be verified. Based on the resulting characteristics of the LFR, and data gathered for the other hybrid system components, models of hybrid LFR- and ELFR-biomass power plants were developed and analysed in TRNSYS®. The techno-economic and environmental consequences of varying the size of the solar field in relation to the total plant capacity were modelled for a series of case studies to evaluate different applications: tri-generation (electricity, ice and heat), electricity-only generation, and process heat. The case studies also encompassed varying site locations, capacities, operational conditions and financial situations. In the case of a hybrid tri-generation plant in Gujarat, it was recommended to use an LFR solar thermal field of 14,000 m2 aperture with a 3 tonne biomass boiler, generating 815 MWh per annum of electricity for nearby villages and 12,450 tonnes of ice per annum for local fisheries and food industries. However, at the expense of a 0.3 ¢/kWh increase in levelised energy costs, the ELFR increased saving of biomass (100 t/a) and land (9 ha/a). For solar thermal applications in areas with high land cost, the ELFR reduced levelised energy costs. It was determined that off-grid hybrid plants for tri-generation were the most feasible application in India. Whereas biomass-only plants were found to be more economically viable, it was concluded that hybrid systems will soon become cost competitive and can considerably improve current energy security and biomass supply chain issues in India.

The serious energy supply problems along with the conventional resources depletion and the environmental conscience regarding global warming and climate change, have urged the need for a complete change in the energy production, supply and consumption patterns. Therefore, the switch towards renewable energy resources including solar, biomass, wind, hydro-power in addition to the development of energy efficient technologies are two key factors to attain a secure and reliable energy sector and to mitigate the global warming problem. Tri-generation is one of the most promising technologies allowing the efficient simultaneous production of heat, coolth and power with potential technical, economic and environmental benefits. [n this work, an innovative micro-scale hybrid solar-biomass tri-generation system was theoretically and experimentally investigated to provide cooling, heating and power generation in buildings. The proposed tri-generation system consists of an organic Rankinebased combined heat and power unit, a liquid desiccant dehumidification unit and a dew point evaporative cooling unit. To offset recent problems associated with small-scale ORC expanders including high cost, excessive fluid leakage and low isentropic efficiency, a novel compact and low-cost moditied scroll expander was employed in the organic Rankine unit for heat and power generation. In addition, an efficient and compact liquid-desiccant unit coupled with a dew point evaporative cooler was utilized to provide the additional cooling capacity through air dehumidification and cooling. Moreover, a novel hollow fibre-based core was proposed in this thesis to provide thermal comfort and humidity control lIsing a ho))ow fibre contactor with mUltiple bundles of micro-porous ho))ow fibres. The proposed core was developed and tested as a cooling core and dehumidification core in the Built Environment Laboratory. An extensive theoretical and experimental investigation of the micro-scale tri-generation system was carried out to model, design, develop and test the system different sub-units under various operational conditions. It was shown that using a heat input of about 19.6 kW, the micro-scale tri-generation system is capable of providing about 9.6 kW heating, 6.5 kW cooling and about 0.5 kW electric power. The overall efficiency of the combined cooling, heating and power system is about 84.4%.

The need for modern energy systems to embrace the requirements of energy security, sustainability and affordability in their designs has placed emphatic importance on exploitation of renewable resources, such as solar and wind energy, etc. However, these resources often lead to reduced reliability and dispatchability of energy systems; less-efficient conversion processes; high cost of power production; etc. One promising way to ameliorate these challenges is through hybridization of renewable energy resources, and by using organic Rankine cycle (ORC) for power generation. Thus, this PhD research project is aimed at conceptual design and techno-economic optimization of hybrid solar-biomass ORC power plants. The methodologies adopted are in four distinct phases: - First, novel hybrid concentrated solar power (CSP)-biomass scheme was conceived that could function as retrofit to existing CSP-ORC plants as well as in new hybrid plant designs. Thermodynamic models were developed for each plant sub-unit, and yearly techno-economic performance was assessed for the entire system. Specifically, the ORC was modelled based on characteristics of an existing CSP-ORC plant, which currently operates at Ottana, Italy. Off-design models of ORC components were integrated, and their performance was validated using experimental data obtained from the aforementioned real plant. - Second, detailed exergy and exergoeconomic analyses were performed on the proposed hybrid plant, in order to examine the system components with remarkable optimization potentials. The evaluation on optimization potentials considered intrinsic irreversibilities in the respective components, which are imposed by assumptions of systemic and economic constraints. This has been termed enhanced exergy and enhanced exergoeconomic analyses here. - Third, the techno-economic implications of using siloxane mixtures as ORC working fluid were investigated, with the aim of improving heat transfer processes in the ORC plant. The studied fluid pairs were actively selected to satisfy classical thermodynamic requirements, based on established criteria. - Fourth, the biomass retrofit system was optimized multi-objectively, to minimize biomass consumption rate (maximize exergetic efficiency) and to minimize exergy cost rate. Non-dominated Sorting Genetic Algorithm (NSGA-II) was adopted for multi-objective optimization. The conceptual scheme involves parallel hybridization of CSP and biomass systems, such that each is capable of feeding the ORC directly. Results showed that the proposed biomass hybridization concept would increase both thermodynamic efficiency and economic performance of CSP-ORC plants, thereby improving their market competitiveness. Total exergy destroyed and exergy efficiency were quantified for each component, and for the whole system. Overall system exergetic efficiency of about 7 % was obtained. Similarly, exergoeconomic factor was obtained for each system component, and their implications were analysed to identify system components with high potentials for optimization. Furthermore, it was observed that thermodynamic performance of the hybrid plant would be optimized by using siloxane mixtures as ORC working fluid. However, this would result in larger heat exchange surface area, with its attendant cost implications. Lastly, biomass combustion and furnace parameters were obtained, which would simultaneously optimize exergetic efficiency and exergy cost rate for the hybrid plant. In sum, a novel scheme has been developed for hybridizing solar and biomass energy for ORC plants, with huge potentials to improve techno-economic competitiveness of solar-ORC systems.

This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel. Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels.  When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.   This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.

This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel. Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels.  When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.   This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.

The use of solar thermal energy to drive both large and small scale power generation units is one of the prospective solutions to meet the dramatic increase in the global energy demand and tackle the environmental problems caused by fossil fuels. New energy conversion technologies need to be developed or improved in order to enhance their performance in conversion of renewable energy. The Organic Rankine Cycle (ORC) is considered as one of the most promising technologies in the field of small and medium scale combined heat and power (CHP) systems due to its ability to efficiently recover low-grade heat sources such as solar energy. This technology is especially in demand in isolated areas where connection to the grid is not a viable option. The present research provides thermodynamic performance evaluation and economic assessment for a small-scale (10 kW) hybrid solar/biomass ORC power system to operate in the UK climate conditions. This system consists of two circuits, namely organic fluid circuit and solar heating circuit in which thermal energy is provided by an array of solar evacuated tube collectors (ETCs) with heat pipes. A biomass boiler is also integrated to compensate for solar energy intermittence. A dynamic model for the hybrid ORC power system has been developed to simulate and predict the system behaviour over a day-long period for different annual seasons. In the thermodynamic investigation, an overall thermodynamic mathematical model of the proposed power system has been developed. The calculation model of the ORC plant consists of a number of control volumes and in each volume the mass and energy conservation equations are used to describe energy transfer processes. The set of equations were solved numerically using a toolbox called Thermolib which works in the MATLAB/Simulink® environment. The numerical results obtained on the performance of the ORC plant were validated against the theoretical and experimental data available in the open literature. The predicted results were in very good agreement with the data published in the literature. The comparison demonstrated that the developed simulation model of the ORC plant accurately predicts its performance with a maximum deviation of less than 7%. The developed mathematical model then has been used to carry out the parametric analysis to investigate the effect of different operating conditions on the system performance. The economic analysis has been performed with the use of equipment costing technique to estimate the system’s total capital investment cost. This approach is based on the individual costing correlation of each component in the system, considering all the direct and indirect costs of the proposed components. The system cost calculations have been conducted for a range of operating parameters and different working fluids for a fixed value of net power output. At the final stage of the research, a thermo-economic optimization procedure has been developed using Genetic Algorithm (GA) approach for selection of the rational set of design parameters and operating conditions for optimum system performance.

O presente trabalho tem por objetivo principal apresentar a avaliação térmica, energética e financeira para um sistema de aquecimento de ar de um secador solar híbrido de produtos agroalimentícios, o qual utiliza como fonte de energia a energia solar e uma fonte de energia auxiliar. Dois tipos de fonte de energia auxiliar são utilizados, uma fonte utiliza biomassa como combustível e a outra utiliza energia elétrica. O sistema é composto por um coletor solar térmico, tipo placa plana de exposição indireta, uma fonte de energia auxiliar. O software TRNSYS é utilizado como ferramenta para executar as simulações, tendo como meta alcançar a temperatura do ar de 70°C na entrada da câmara de secagem. Os resultados são apresentados em função das temperaturas da placa absorvedora, do ar de saída do coletor solar e do ar de entrada na câmara de secagem e em função da quantidade de energia, por hora, fornecida para o ar de secagem pelo coletor solar (ganho de energia útil) e pela fonte de energia auxiliar. Calcula-se o custo horário da energia considerando a utilização da biomassa e da energia elétrica, resultando no custo da biomassa equivalente a 42,5% do custo da energia elétrica.Embora os custos com insumos sejam mais baratos para a utilização do sistema com biomassa, a implementação desse sistema é mais cara, sendo viável apenas em longo prazo. O retorno do investimento para o sistema com biomassa ocorre no quarto ano, enquanto que o sistema com energia elétrica obtém retorno no primeiro ano.
This work aim to perform thermal, energy and financial analysis for an air heating system of a hybrid solar dryer for agricultural products, which uses as energy source a combination of solar energy and an auxiliary power source. Two types of external auxiliary power source for energy are used, biomass and electric power. The dryer is composed by an indirect flat plate flat plate collector, an external energy source and a drying chamber. The software TRNSYS is used to run the hybrid solar dryer simulations. The simulations goal is for the system to achieve 70°C air temperature at the drying chamber inlet. The results are showed as a function of the absorber flat plate temperature, the solar thermal collector outlet air temperature and the drying chamber inlet air temperature as a function of the energy amount per hour supplied to the drying air by the solar collector (useful energy gain) and by the external auxiliary power source. The energy cost per hour is calculated by assuming each one of the sources, biomass and electric power. It resulted that biomass costs 42.5% of the electrical power total costs. Although the source material costs are cheaper for biomass usage, it implies higher implementation costs, thus requiring long range usage analysis to prove practicable. The biomass system return of investment occurs at the fourth year while at the electrical power system return of investment occurs at the first year.

Master thesis deals with usage issues of autonomous, self-sufficient and decentralized systems. In the first part convectional and experimental sources for autonomous systems are disclosed. Second chapter deals with accumulation of electrical and thermal energy and possibilities of applications. 3rd part is focused on pilot project realized for autonomous and smart systems, which were built in last years. In the 4th chapter electrical and thermal energy consumption curves are made on daily and monthly basis for 4 type objects. In the fifth part issue of autonomy is explained, and for type buildings solutions are made with additional return on investment. The last chapter is focused on calculation of thermal accumulator and briefly discloses small district heating.

Proceeding from the sustainable development principle and the current energy issues, in the present work a small-scale fully renewable power plant was designed, modelled in a time-dependent environment and validated. The plant is design in order to produce both thermal and electric power either in on- or off-grid configuration. With respect to the state of the art, the power plant is composed by standard and well-known technologies. The novelties brought with the present study are entailed in the arrangement and size of the technologies themselves. Thus the selected parabolic trough solar field is a small size one, i.e. 1,2 MW, on the contrary of the usual multi-MW design. Moreover, the solar section is co-powered with a biomass furnace in place of the typical fossil fuel power generators. Finally, a steam engine is used in a saturated steam Rankine cycle substituting the most common configuration based on steam turbine and superheated steam cycle. In order to properly evaluate the plant performances, a time-dependent simulation tool was used, allowing to take into account the meteorological variations during a one year period, which has a direct influence on the solar field, affecting the whole system behaviour. Three different working configurations were proposed, with the aim to assess the plant flexibility to different working conditions, e.g. off-grid or grid-connected. In particular the proposed models are a baseline configuration with constant power outputs, an electric or thermal power tracking scenario coupled with end-users load, and a desalt scenario for electric power and desalted seawater production. The study shows the capability of the plant to follow different managements, demonstrating its suitability to work in several environments, thus it is effectively reproducible in different countries.

The global warming phenomenon as a significant sustainability issue is gaining worldwide support for development of renewable energy technologies. The term ‘polygeneration’ is referred to as “an energy supply system, which delivers more than one form of energy to the final user”, for example: electricity, cooling and desalination can be delivered from polygeneration process. The polygeneration process in hybrid solar thermal power plant can deliver electricity with lesser impact on environment compared to conventional fossil fuel based power generating system. It is the next generation energy production technique with a potential to overcome intermittence of renewable energy. In this study, the polygeneration process simultaneous production of power, vapor absorption refrigeration (VAR) cooling and multi-effect humidification and dehumidification (MEHD) desalination system from different heat sources in hybrid solar-biomass (HSB) system with higher energy efficiencies (energy and exergy), primary energy savings (PES) and payback period are investigated. There are several aspects associated with hybrid solar-biomass power generation installations such as state wise availability of biomass resources, solar direct normal irradiance (DNI) have been analyzed. Month wise solar and biomass heat utilization also has been analyzed for hybrid system in four regions of India (East: Guwahati, Assam; West: Udaipur, Rajasthan; North: Delhi, South: Madurai, Tamil Nadu). The month wise daily average solar radiation is also considered as 20%, 40%, 60% and 80% and remaining heat is taken from biomass resource in northern region (Delhi) in the proposed hybrid plant. The thermodynamic evaluation (energy and exergy) of HSB power plant has also been investigated. The total input energy of the proposed hybrid system is taken v from the heat transfer fluid through parabolic trough collector (PTC) as per availability of solar resource and remaining from biomass to maintain the steam at superheated state of 5000C and 60 bar and supplied to turbine at steam mass flow rate of 5 kg/sec. The energy and exergy analyses of 5 MW HSB system with series mode was carried out to identify the effects of various operating parameters like DNI, condenser pressure, turbine inlet temperatures, boiler pressure on net power output energy and exergy efficiencies. The VAR cooling system operates using the extracted heat taken from turbine and condenser heat of the VAR cooling system is used in MEHD system for production of drinking water as per demand requirement. Though the production of electricity decreases due to extraction of heat from turbine for VAR cooling and MEHD desalination, the complete system meets the energy requirements & increases the PES. The thermodynamic evaluation (energy and exergy), optimization and payback period of polygeneration process in HSB thermal power plant for combined power, cooling and desalination is investigated to identify the effects of various operating parameters. The system has achieved a maximum energy efficiency of 49.85% and exergy efficiency of 20.94%. The Primary energy savings of polygeneration process (PESPP) in HSB system is achieved at 50.5%. The electricity generation from polygeneration process increased to 78.12% as compared to simple thermal power plant. The payback period of polygeneration process in HSB thermal power plant is 1.5 years, which is less than solar thermal power plant, HSB thermal power plant, Cogeneration in HSB thermal power plant.

University of Technology, Sydney. Institute for Sustainable Futures.
After decades of stability the Australian electricity market is undergoing changes. Current government targets aim to reduce greenhouse gas emissions by 5% and raise renewable electricity production to 45 TWh by 2020. In addition, increases to natural gas prices, aging generation assets and falling electricity demand have had an impact in recent years. Uncertainties exist around current policies, including the carbon pricing mechanism and the renewable energy target, but in light of Australian and international ambitions to lower greenhouse gas emissions the deployment of renewable energy technologies is essential. In recent years wind and photovoltaic installations have shown the highest renewable energy growth rates while concentrating solar power has struggled, despite Australia having some of the best natural resources for concentrating solar power in the world and some selected government funding. Reasons for the slow uptake include the comparatively high cost and lack of financial incentives. While technology costs are expected to decrease by up to 40% by 2020 through deployment as well as research and development, other cost reduction options have to be identified to promote short-term implementation in electricity markets such as Australia where the wholesale cost is low. To overcome the cost problem and to address other relevant implementation barriers this research analyses the hybridisation of concentrating solar power with biomass and waste feedstocks. The results of this research include: ▪ a recommendation for a categorisation system for CSP hybrid plants based on the degree of interconnection of the plant components ▪ the availability of combined resources to generate up to 33.5 TWh per year and abate 27 million tonnes CO₂ annually ▪ an analysis of the most suitable CSP technologies for hybridisation ▪ a technology comparison showing CSP cost reductions through hybridisation of up to 40% ▪ the identification of cost differences of up to 31% between different hybrid concepts ▪ an analysis showing that the current economic and policy settings are the most significant implementation barriers ▪ two case studies with different biomass and waste feedstocks requiring power purchase agreements of AU$ 100-155/MWh. Based on the various benefits of concentrating solar power hybrid plants, this research analyses the potential role of this technological pairing in Australia’s transition to a low carbon energy future. The research concludes that concentrating solar power hybrid plants, not only hybridised with biomass and waste feedstocks, can immediately enable a lower cost deployment of concentrating solar power facilities in Australia. The technology, deployment and operation of the first hybrid installations would provide market participants with valuable lessons and would have the potential to reconfigure the electricity market towards more sustainable generation. This could help promote the development of future low-cost concentrating solar power plants in Australia.

Renewable energy-based power has gained significant global momentum—to minimize fossil-fuel use, combat climate change, and ensure energy security. While renewable energy (RE) is fast-growing, stand-alone single resource-based power plants (the most widespread RE plants) face challenges to generate stable power because of resource intermittency. Consequently, grid operators find it challenging to plan power supply relying on RE plants. Employing electrical storage, thermal energy storage, and hybridization in stand-alone plants could provide some solutions. However, electrical and thermal storage have limitations at megawatt scales, primarily in cost-effectiveness, greater installed capacities than nameplate ratings, and land requirements. This study identified that the hybridization of various renewable energy sources is a promising way to address intermittency challenges. The study involved techno-economic modeling and analysis of various RE systems along with hybridization. The plant capacities of the individual-resource and hybrid systems were chosen for the Indian context. Five hybrid configurations have been proposed while modeling and analyzing these hybrid-RE configurations. The resources and technologies considered for the hybrid system were solar energy (concentrated solar power and photovoltaic), biomass (combustion and gasification), and on-shore wind (horizontal-axis wind turbine). The specific details of the hybrid scenarios studied for the Indian context are provided below. 1. Synergetic-based hybrid option for grid-connected power: Concentrated Solar Power (CSP) and Biomass Combustion 2. Cost-effective hybrid option for grid-connected power: Photovoltaics (PV) and Biomass Combustion 3. Distributed hybrid option for off-grid power: Photovoltaics (PV) and Biomass Gasifier connected to a gas-engine 4. Multi-RE hybrid effective land-use option for grid-connected power: CSP, Biomass Combustion, and Horizontal Axis Wind Turbines 5. Hybrid opportunity to improve wind farms energy production: Horizontal Axis Wind Turbines and Biomass Combustion The study's techno-economic aspects provide insights on detailed modeling methods, the level of challenges on the single-resource-based RE plants, and improvement potential through hybrid plants. The results in all of these hybrid scenarios have been analyzed for the following: 1. Requirements of solar field area and biomass fuel requirements for a given plant capacity 2. Reduction possibilities of solar field area and biomass with an increase of plant capacities 3. Energy share from each source in the total energy mix, the extent of grid-friendly energy supply through hybrid systems 4. Plant load factors for various modes of plant operation (solar/wind-alone, hybrid with day-time, and hybrid with the day-night operation) and plant capacities 5. Levelized cost of electricity The suitable large hybrid capacities, for the Indian context, to generate firm power with biomass integrated solar plants are up to 20 MW. At higher capacities (up to 100 MW), the multi-renewable hybrid system (solar-biomass-wind) is a desirable option with increased solar and wind plant capacities. The results indicate that the stand-alone solar plants intermittently produce energy for about 2,700 hours of sufficient sunshine hours of 3,700 in a year. In the case of wind-alone plants, they produce intermittent energy for ~85% (7,500 hours) of the time in a year. Upon hybridization with the biomass system, it fulfills the required nameplate capacity in intermittent solar/wind periods by its flexible operation of a boiler with a ramp rate of 3%. Small-capacity solar-biomass hybrid plants (1 MW) require larger solar fields of 10,000 m2 and biomass of 3,300 tonnes per annum (day-only operation). Large-capacity plants show effectiveness in terms of these requirements. Solar-field area and biomass requirements for a 20 MW plant are 5,000 m2 and 1,600 tonnes per MW, respectively. The plant load factors (PLF) of solar-biomass hybrid plants from day-time operation results in 45–48% (against the single-resource plants with PLF of less than <18%) and day-night operation offers around 80%. Solar-biomass-wind hybrid systems offer similar PLFs when the plant capacities of CSP and biomass are equal (20 MW). At larger capacities (50 MW and 100 MW), the PLF are observed to be 40–50% with near firm power (better compared to highly intermittent power and lesser PLF of single resource solar/wind plants). From an economics perspective, the large scale solar-biomass hybrid plants result in an LCOE of ~ INR 5.0/ kWh. Small-capacity plants at distributed levels offer an LCOE of INR 6–9/ kWh. The wind integrated solar-biomass hybrid plants generate electricity at INR 3.4–4.6/ kWh.
The Center for Study of Science, Technology and Policy (CSTEP)

Impediments to investment in renewable energy resources arise in five areas, namely, infrastructure access, technological and resource uncertainty, competition from established fossil fuel alternatives, asset financing and public policy. Together these can lead to large capital cost penalties and poor resource productivity that reduce the viability of projects. Presented here are system-wide analyses of two novel pathways to generate new investment in concentrated solar thermal and in geothermal energy resources. The pathways are designed to reduce the minimum capital outlay required for the development of renewable energy resources, by identifying synergies with established energy and non-energy infrastructure and technologies. The endothermic, thermochemical processing of fossil, waste and biomass using concentrated solar energy has been demonstrated, at experimental scales between 3-500 kWth, to upgrade the calorific value of syngas relative to the feedstock by ~30%, depending on the reactor technology employed and the fuel that is processed. However, no process modeling analysis has previously been presented of the impacts of diurnal, seasonal and cloud-induced solar resource availability on the operational limits of commercially available Fischer-Tropsch (FT) liquids syngas processing infrastructure. Presented here, are process modeling analyses of the relative performance of two solar gasification reactor systems and the operational impacts of their integration with a coal-to-liquids polygeneration facility. The reactor designs assessed were the batch process, indirectly irradiated solar packed bed gasifier that operates with solar input alone and a hybridised configuration of the solar vortex reactor that is assumed to integrate combustion to account for solar resource transience and thus enable a continuous non-zero syngas throughput. To address the impacts of solar resource transience, the process modeling analyses showed that the packed bed solar reactor requires syngas storage equivalent to >30 days of gas flow to maintain feasible operation of unit operations downstream of the gasifier. In comparison, the hybrid solar vortex reactor was shown to require only ~8 hours of syngas storage. A dynamic process modeling study of integrating a hybrid solar vortex coal gasifier with a FT liquids polygeneration system was shown to improve the overall energetic productivity by 24% and to reduce mine-to-tank CO2 emissions by 28%. This is the first comprehensive system analysis of a solar hybridised coal-to-liquids process that has assessed all the impacts of solar resource transience on the unit operations that comprise a FT liquids polygeneration system. Geothermal resources can face barriers to investment arising from their remoteness—in particular, distance from established electricity transmission lines—uncertainty in the cost of establishing well infrastructure and uncertainty in the scale of the recoverable resource. To address these challenges, presented here is a comprehensive system evaluation of the potential of high-value energy load data-centres to reduce the cost of developing geothermal resources. This potential arises from the data-centres’ modularity, their stable load for both electricity and refrigeration, and because their energy demand can be scaled commensurate to geothermal resource availability. Moreover, they can be connected to market by fibre optic network infrastructure, which is at least two orders of magnitude less expensive than electricity transmission. System analyses of this concept showed that a hybrid energy system that integrates low-temperature geothermal resources to meet data-centres’ refrigeration load, and natural gas to meet the electrical load, could generate expected returns of 25% and reduce the cost of developing geothermal resources by >30 times. The systems modelled in this thesis have shown that, compared with stand-alone development, the hybridised development of renewable energy resources with fossil fuel energy technologies offers a lower cost pathway.
Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Mechanical Engineering, 2016