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This study proposes a comprehensive framework for developing a multi-energy off-grid microgrid with the decoupled flow of thermal and electrical energies in a rural setting. A carbon-neutral microgrid with a hybrid generation system constituting a photovoltaic unit and a biofuel generator is proposed. In order to enhance the fuel utilisation efficiency, the biofuel generator is operated in combined cooling, heating, and power mode, and the recovered thermal energy forms the heat distribution network in the microgrid. The flexibility of system operation is improved by suitable multi-energy (electrical and thermal) storage. Firstly, an optimal sizing framework has been developed for the system as a mixed integer linear programming model. Secondly, a coordinated multi-energy management system (MEMS) has been developed for combined optimal dispatch of multiple generation and storage resources. The MEMS has been developed as a mixed integer non-linear programming model, which minimises system operational cost while considering minimum battery degradation to prolong its lifetime. Finally, a detailed economic analysis of the proposed system has been presented, highlighting the levellised cost of energy and net present value. Extensive case studies and simulation results depict the effectiveness and suitability of the proposed MEMS for the rural off-grid microgrid.

Abstract: The paper compares the thermodynamic performance of MS9001 gas turbine based cogeneration cycle having a two-pressure heat recovery steam generator (HRSG) for different blade cooling means. The HRSG has a steam drum generating steam to meet coolant requirement, and a second steam drum generates steam for process heating. Gas turbine stage cooling uses open loop cooling or closed loop cooling schemes. Internal convection cooling, film cooling and transpiration cooling techniques employing steam or air as coolants are considered for the performance evaluation of the cycle. Cogeneration cycle performance is evaluated using coolant flow requirements, plant specific work, fuel utilisation efficiency, power-to-heat-ratio, which are function of compressor pressure ratio and turbine inlet temperature, and process steam drum pressure. The maximum and minimum values of power-to-heat ratio are found with steam internal convection cooling and air internal convection cooling respectively whereas maximum and minimum values of fuel utilisation efficiency are found with steam internal convection cooling and closed loop steam cooling. The analysis is useful for power plant designers to select the optimum compressor pressure ratio, turbine inlet temperature, fuel utilisation efficiency, power-to-heat ratio, and appropriate cooling means for a specified value of plant specific work and process heating requirement. [Copyright &y& Elsevier]

Thermodynamic performance analysis of cogeneration cycle based on a state of the art gas turbine has been dealt with in this paper. A configuration has been conceptualised using the latest generation gas turbine MS9001H that uses either steam or air to cool the hot gas path components. Gas turbine performance is evaluated considering different blade cooling means. In this arrangement, the above conceptualised topping cycle, and the bottoming cycle comprising of a two pressure heat recovery steam generator (HRSG) in cogeneration configuration is selected for analysis. In HRSG, one of the steam drums generates steam for gas turbine stage cooling as per requirement and the other drum generates steam for process heating. The cycle performance is predicted based on parametric study carried out after modelling the various elements of cycle, such as compressor, combustor, cooled gas turbine, HRSG, etc. The performance is predicted based on parameters such as fuel utilisation efficiency (FUE), power to heat ratio (PHR) as a function of independent parameters like compressor pressure ratio rp,c and turbine inlet temperature (TIT), etc. The results of this study will be helpful for designers to select the optimum compressor pressure ratio, process steam pressure for cogeneration and TIT to achieve the target fuel utilisation efficiency, and PHR at the specified plant specific work. [ABSTRACT FROM AUTHOR]