Small-scale Distributed Power Generation Research Articles

Vortex-in-cell simulation of the flow and performance of a Savonius hydraulic turbine with S-shaped blades

The volume penalization vortex-in-cell (VP-VIC) method, which combines the vortex-in-cell and vortex penalization methods, is a kind of immersed boundary method that has the advantage of accurately calculating the vorticity field near the boundary. It is expected to be used as a design tool for shape optimization. In this study, the flow and performance of a small Savonius turbine rotor (rotor diameter DR = 245 mm) with S-shaped blades, which is used for small-scale distributed power generation with output less than 100 kW, were analyzed by numerical simulation. The results were compared with those of previous experimental studies to examine the usefulness of the VP-VIC method for fluid analysis around the Savonius turbine. The Reynolds number (Re=U0DR/ν) based on the streamwise velocity U0 is 1.32×105. The volume penalization vortex-in-cell (VP-VIC) method is applied for flow simulation, and the rotational motion of the rotor is analyzed using the calculation method previously proposed by the authors for the fluid force acting on the solid boundary (blade surface). As a result, the relationship between the rotational speed of the rotor and the output coefficient obtained in this simulation is similar in the experimental results of Golecha et al. [Appl. Energy 88, 3027–3217 (2011)] using S-shaped blades. In particular, with an increase in the load torque, the rotational speed of the rotor decreases, and the rotor stops momentarily. When the rotor stops, the positive torque of clockwise rotation acts on the advancing blade, while the negative torque of counterclockwise rotation acting on the returning blade decreases; hence, the rotor restarts immediately after stopping. In addition, it is established that the rotor output can be accurately predicted. Based on the above, it is reconfirmed that the VP-VIC method is beneficial for predicting the performance of a Savonius turbine.

Dual‐loop control of transfer delay based PLL for fast dynamics in single‐phase AC power systems

Phase-locked loop (PLL) is commonly utilised for AC power systems to detect phase and frequency. With the increasing use of small-scale distributed power generation, the technique becomes widely available for grid interconnection of renewable power source into single-phase AC distribution network. Through comprehensive analysis and design, this study proposed a new approach that includes dual independent control loops to enhance the transfer delay-based PLL capability in terms of speed and accuracy. The effectiveness and advantages of the proposed PLL structure are demonstrated by numerical simulation and verified by experimental test.

A Review of Technologies for Multistage Wood Biomass Gasification

Currently, small-scale distributed power generation is being intensively developed in Russia and abroad. Given the rise in the rates for the electric and thermal energy, the development of new territories, and the technical infeasible connection to the power supply system, one of the most promising variants of supplying isolated consumers with power is the application of wood biomass gasification technologies. Analysis of the studies in this sphere shows that considerable attention is paid to enhancing the gasification efficiency and ensuring the purity of the gas. These problems are solved using multistage gasification technology. This technology involves the pyrolysis and gasification in separated zones of the gasifier or individual interconnected reactors, which enables achieving the optimal conditions for the conversion of biomass at every separate stage. The major advantage of multistage gasifiers is the production of synthesis gas with a low content of tar. The article represents a review of technologies for multistage wood biomass gasification and comparison of the relevant gasifiers of various types; the basic single-stage and multistage wood biomass gasification technologies are examined and their technical characteristics and examples of their commercial implementation are provided. Analysis of the current situation shows that predominantly foreign multistage wood biomass gasification technologies/plants have found practical application. These technologies allow the produced syngas to be directly used in internal combustion engines and gas turbines without employing expensive auxiliary detarring plants.

Dynamic Economic Dispatch On Micro Grid Electrical Systems Using Quadratic Programming

Currently the needs of electric power increased rapidly along with the development of technology. The increase in power requirements is contrary to the availability of sources of energy depletion of oil and coal. This problem affects the national electrical resistance. To meet the needs of large electric power with wide area coverage is required small scale distributed power generation. This distributed generation (DG) of renewable energy sources sought to minimize the use of energy resources such as oil and coal and connected to the micro grid and use the battery as a power balance. Because of there are many DGs and the use of batteries, therefore it is important to determine the optimal power generation of each plant as well as the use of battery based on the optimal capacity so that requirement of electric power can be met with minimal cost each time. This optimization is known as Dynamic Economic Dispatch. In this study, the methods of Quadratic Programming is required to solve the optimization problem.

Small-scale Distributed Power Generation Development in the Siberian Regions: Evaluation of Efficiency

<p>It is shown that topical issue is the solution of problems of enhancement of structure electro and heat generations in regions of Russia, including through synchronization of schemes electro and heat supplies. It causes the necessity of integration to municipal level power engineering into development plans for big power industry that causes gain of a role of the distributed power engineering (including the cogeneration installations). The carried-out serial calculations for comparative assessment of a row of technologies of the small-scale distributed power generation in the Novosibirsk and Kemerovo regions allowed to select the perspective directions of diversification of energetic branch. </p>

Mathematical modeling of mini-CHP based on biomass

One of the promising directions of small-scale distributed power generation for Russia is the use of biomass. The present work is devoted to studies of an mini-CHP based on multi-stage biomass gasification. Mathematical models of elements and mini-CHP in general based on technological schemes were constructed. The mathematical models were constructed with the software developed at Melentiev Energy Systems Institute of Siberian Branch of the Russian Academy of Sciences. The calculations were made for two sizes of internal combustion engines. Thus, we obtained the values of flow rates, temperatures of heat carriers at various points of flow charts of the plants.

Technical, economic, and regulatory analysis of the implementation of micro-cogeneration technology in the Brazilian manufacturing sector

Small-scale distributed power generation offers environmental benefits through the improvement of global energy efficiency, in addition to increasing the reliability of the power supply. In this study, the technical and economic viability of the implementation of micro-cogeneration technology in the manufacturing sector was studied in light of the Brazilian regulatory situation. The thermal efficiency potential for the manufacturing sector is introduced for further exploration by decision-makers. This study also investigated the behavior of micro-cogeneration in distributed generation through the Brazilian Energy Compensation System. The technical viability was studied by simulating a Brayton cycle with the operation parameters of a 100 kW micro-turbine. This simulation allowed an estimation of the avoided cost of natural gas compared to an industrial process without cogeneration. Rate projections were performed by linear regression during the system’s depreciation period. The economic evaluation was performed using the following indicators: net present value (NPV), internal rate of return (IRR), and discounted payback. Finally, a sensitivity study was performed to project how the micro-cogeneration efficiency and the Brazilian regulations can address future variations of natural gas and electricity rates. Given the conditions of this study, the increase in energy prices favors micro-cogeneration; however, the economic viability is affected if the system operates below 70% of heat use in industrial processes, which reduces the effect of public policies toward the incentive to cogenerate.

Development of a 3 kW Microturbine for CHP Applications

Combined heat and power (CHP) concepts for small-scale distributed power generation offer significant potential for saving energy and reducing CO2 emissions. Microturbines are an interesting candidate for small CHP systems with advantages in terms of performance, size, noise, and costs. MTT is developing a 3 kW recuperated microturbine for micro CHP applications for large households and for truck combined APU-heating systems. To minimize costs, off-the-shelf automotive turbocharger technology has been used for the turbomachinery. During recent years, turbocharger turbomachinery performance and efficiencies have significantly increased, even for very small sizes. At the same time, efficient high-speed motor-generators have become available at relatively low prices. The development of a concept demonstrator started in May 2008. This program phase included a cycle analysis and component selection study around off-the-shelf turbomachinery, design of a custom combustor, recuperator and generator, and a test program. In this paper, results of the cycle definition, conceptual design and component matching study are presented. Next, the development of a detailed performance model is described and performance prediction results are given. Also, results of the test program and test analysis work are presented. Finally, from the conclusion of the demonstrator phase an outlook is given on the prototype design and performance, which will be the next phase of the development program.

D105 Development of an Efficient Small-scale Distributed Power Generation System Using Gasification of Woody Biomass(Biomass-2)

D105 Development of an Efficient Small-scale Distributed Power Generation System Using Gasification of Woody Biomass(Biomass-2)

442 バイオマス燃料により作動するマイクロガスタービン・燃料電池複合発電システムの性能解析(燃料電池,電力貯蔵,環境保全型エネルギー技術)

Solid oxide fuel cells (SOFC) are expected to become a primary power supply component in distributed energy systems. In addition, the fuel flexibility of SOFCs is attractive for the small-scale distributed power generation driven with biomass derived fuel. In this paper, the performance evaluation of a biogas fueled micro gas turbine (μGT)-solid oxide fuel cell (SOFC) combined power generation system is investigated by using thermodynamic cycle simulation. The power generation characteristics of methane and hydrogen fueled hybrid systems are performed as reference cases. At the SOFC operating temperature of 800℃ and the pressure ratio of 3.0, the efficiency values of the methane fueled system and the hydrogen fueled system are 59% and 51% (LHV), respectively. The data of biogas compositions are extracted from the previously reported work regarding the fuel cell operation with biogas from farming waste/sewage and a wood gasification process. Throughout the simulation, it is found that the fuel compositions significantly affect the system performance. Higher methane content in biogas causes the higher efficiency of a hybrid system, because an internal steam reforming of methane operates effectively upon the efficiency improvement of a hybrid system. In the case of hydrogen fuel, excess heat of a cell stack is solely used for fuel pre-heating. Consequently, much air is required for cell stack cooling, and the fractional power output of a μGT becomes larger. Higher ratio of μGT power to total power leads lower efficiency. This means that the utilization of hydrogen rich fuel degrades efficiency. The system optimization, which includes biomass fuel production processes, is essential for the development of much highly effective hybrid systems.