Gas Engine Generator Research Articles

Study on the Application of a Multi-Energy Complementary Distributed Energy System Integrating Waste Heat and Surplus Electricity for Hydrogen Production

To improve the recovery of waste heat and avoid the problem of abandoning wind and solar energy, a multi-energy complementary distributed energy system (MECDES) is proposed, integrating waste heat and surplus electricity for hydrogen storage. The system comprises a combined cooling, heating, and power (CCHP) system with a gas engine (GE), solar and wind power generation, and miniaturized natural gas hydrogen production equipment (MNGHPE). In this novel system, the GE’s waste heat is recycled as water vapor for hydrogen production in the waste heat boiler, while surplus electricity from renewable sources powers the MNGHPE. A mathematical model was developed to simulate hydrogen production in three building types: offices, hotels, and hospitals. Simulation results demonstrate the system’s ability to store waste heat and surplus electricity as hydrogen, thereby providing economic benefit, energy savings, and carbon reduction. Compared with traditional energy supply methods, the integrated system achieves maximum energy savings and carbon emission reduction in office buildings, with an annual primary energy reduction rate of 49.42–85.10% and an annual carbon emission reduction rate of 34.88–47.00%. The hydrogen production’s profit rate is approximately 70%. If the produced hydrogen is supplied to building through a hydrogen fuel cell, the primary energy reduction rate is further decreased by 2.86–3.04%, and the carbon emission reduction rate is further decreased by 12.67–14.26%. This research solves the problem of waste heat and surplus energy in MECDESs by the method of hydrogen storage and system integration. The economic benefits, energy savings, and carbon reduction effects of different building types and different energy allocation scenarios were compared, as well as the profitability of hydrogen production and the factors affecting it. This has a positive technical guidance role for the practical application of MECDESs.

Gas Quality Impact on Gas Engine Performance: Case of an Indonesia Natural Gas Station

This research was conducted to find a correlation between changes in the variable composition of the natural gas fuel in gas engine generators, and the occurrence of a unit shutdown at a natural gas distribution facility in South Sumatra-Indonesia. The analysis is carried out by investigating the trend of changes in gas composition parameters, and simulation using the Methane Number Calculator application. The results obtained from the research results, in Changes in the composition of fuel gas cause changes in the methane number, Low Heating Value (LHV), High Heating Value (HHV), and Wobbe index (WI), which may indicate engine trouble and cause a unit shutdown. Several options of solutions can be carried out as discussions to solve problems that occur in the gas engine generator at the natural gas distribution facility

Dynamic simulation of hydrogen-based zero energy buildings with hydrogen energy storage for various climate conditions

Solar energy systems are an effective way to meet the needs of zone heating, cooling, electricity, and domestic hot water. However, to reach sustainability, and energy storage unit should be considered for installation. In this study, two combined cooling, heating and power (CCHP) systems are simulated and studied using TRNSYS software; both using natural gas engine generators and photovoltaics as prime movers and a hydrogen fuel cell/electrolyzer storage unit, one with absorption chiller and another with compression chiller cooling. For the study, a residential building is modeled for three major populated climate zones of the United States of America, namely, Hot-humid, mixed-humid and cold using DesignBuilder and EnergyPlus software. The energy demand for its HVAC operation and domestic electricity is obtained and used for system simulation in TRNSYS software. Due to choosing actual equipment for the CCHP arrangement, precise economic and environmental models are designed to further evaluate the possibility of execution of the system. The results show that absorption chiller-equipped CCHP has better performance both environmentally and economically. In addition, the outcome shows that the suggested systems show less favorability to be utilized in hot humid climate zones.

A Power Balance Simulator to Examine Business Continuity in Hospital Facilities Due to Power Outages in a Disaster

Abstract In hospitals, the energy supply is the key to ensuring modern medical care even during power outages due to a disaster. This study qualitatively examined whether the supply–demand balance can be stabilized by the private generator prepared by the hospital building during stand-alone operations under disaster conditions. In the nanogrid of the hospital building, the power quality was examined based on the AC frequency, which characterizes the supply–demand balance. Gas engine generators, emergency diesel generators, photovoltaic panels, and storage batteries were presumed to be the private generators in the hospital building. The output reference values for the emergency diesel and gas engine generators were set using droop control, and the C/D controller-enabled synchronized operation. In addition, to keep the AC frequency fluctuation minor, the photovoltaic panels were designed to suppress the output fluctuation using storage batteries. As a result of case studies, the simulator predicts that the frequency fluctuation varies greatly depending on the weather conditions and the fluctuation suppression parameters, even for the same configuration with the same power generation capacity. Therefore, it is preferable to increase the moving average time of the output and reduce the feedback gain of the storage battery to suppress the output fluctuation from the photovoltaics. However, there is a trade-off between suppressing the output fluctuation and the minimum required storage capacity. Furthermore, since the photovoltaics’ output varies with the weather, other private generators’ capacity and control parameters significantly impact power quality. The simulator proposed in this study makes it possible to study each hospital's desirable private generator configuration.

Improving the reliability of the energy supply to the district boiler house

Currently, measures are being worked out at generation facilities, in particular at district boiler houses, the implementation of which will increase the reliability of both individual elements of the system and the entire energy supply system as a whole, improve its technical and economic indicators, and achieve the target financial indices of the enterprise. As one of such measures, the article considers the ways of organizing a mini-TPP (thermal power plant) on the example of a large district boiler house for the purpose of energy supply for their own needs. This solution will increase the energy independence of the boiler house from the external network, reduce the cost of electricity consumption. The paper presents the results of a technical and economic analysis of options for organizing own generation, taking into account the actual operating conditions of the boiler house, linking the mini-TPP to the existing communications of boiler house, the impact of the joint operation of the mini-TPP and the boiler house on the sanitary zone. Based on the analysis of the loading graphs of the electric equipment of the boiler house, the required capacity of the gas engine generator plant and the place of its installation on the production site are determined. The operation of the gas engine generator plant involves the production of electric energy only for its own needs without issuing it to an external electrical network, in connection with which an automation system is provided that does not allow electricity to be issued to an external network. This restriction is related to the requirements of the technical specifications of the electric grid company.

PERFORMANCE MEASUREMENT TOOLS (PMT) FOR GAS ENGINE GENERATOR (GEG) POWER PLANTS: A CASE STUDY AT LEADING MEDIUM ENERGY COMPANY IN INDONESIA

Gas Engine Generator (GEG) Power plants as electricity producers need to be maintained using monitoring performance and continuously improvements. Company management of power plant is difficult to make decision for continuous improvement, requires Performance Measurement Tools (PMT) to determine the performance of a GEG power plant. PMT developed using Key Performance Indicator (KPI) that was defined through Forum Group Discussion (FGD) with different field of expertise in company and based on references and the weighting of KPI criterion that was developed by Analytic Hierarchy Process (AHP). This study was a case study at leading medium energy company in Indonesia. PMT is a tool to calculate Performance Score (PS) from the calculation of actual data, contracts and KPI (Power Output/PO, Heat Rate/HR, Operation Ratio/OR, Capacity Factor/CF) weights. If there is a gap in the PS then it can indicate penalty from customer especially PO and HR. Case study was conducted on three power plants that have different capacity and number of engines. The sum of the PS from the KPI will get a Total Performance Score (TPS). The highest TPS value will get a Performance Benchmark (PB) for each power plant.

Holistic Approach for Creating Environmentally Friendly Campus

To achieve an environmentally friendly campus, UMN operates gas engine generator with co-generation system. Waste heat from generator powers absorption chiller for air conditioning. UMN benefits clean energy sources, reduced pollution, and energy saving. The next phases rely on energy consumption reduction by applying passive design. Two towers were designed with double-skin facade. The perforated aluminum panel reduces solar heat gain on the building wall while still allows sunlight into the room for natural lighting. Lower room temperature will reduce cooling load, which will save energy. Combined with energyefficient appliances and natural air ventilation for corridors and open space, this concept saves more than half of energy consumption. Both towers were awarded the first and second winners of ASEAN Energy Award in 2014 and 2019. Various trees have been planted and produce oxygen to supply fresh air to create comfortable studying environment without air conditioning. To reduce carbon footprint, UMN provides shuttle bus and bike-sharing service. A holistic approach is implemented by recycling and conserving water with sewage water treatment and infiltration wells surrounding the campus. As part of the sustainability program, UMN has also utilized solar energy.

Technical and Economic Assessment of Local Power Supply Systems for Agro-Industrial Production in the Digital Economy

Energy and energy supply development determines the rate of production intensification, including agricultural production. The current state of rural power supply is characterized by a high degree of deterioration of electrical equipment, long distance overhead power lines, low reliability of low-voltage electrical networks, and a higher accident rate. With an aim of ensuring food security and export orientation of the industry for the next 5 years, it is necessary to implement a set of measures to improve the efficiency of energy supply to agricultural production. This task will be hampered by a constant rise in prices and tariffs for energy resources. Thus, over the last 20 years, energy costs have increased from 3-5 % to 30-40 % in agricultural production. The specific capital investment (per 1 kW of power) and the cost of 1 kWh of electricity were reported to depend on a type of local energy source and its capacity. The paper proposes a method for marking out the economic boundaries of the effective use of local power supply arrangements to replace a standard central station. A power gen-set supplying energy to an agricultural holding is capable of operating in two modes subsequent upon utility (central station) electricity – autonomous and parallel. The authors compared the cost of electrical and thermal energy produced by the power gen-set and tariffs for these types of energy. Calculations have shown that it is advisable for an agricultural holding to have a local power supply system being a power gen-set based on gas engine-generators.

Investigation of performance measures of power generating unit of sewage treatment plant

The main objective of present study to investigate the availability and profit of power generation systems established in sewage treatment plants. The sewage treatment plant is an industry in which waste sewage water has been treated and waste is used to generate power. For this purpose, a mathematical model has been proposed by considering constant failure and repair rates. The power generating unit in sewage treatment plant comprises six subsystems as sludge digester, gas holding tank, gas burner, gas scrubber, gas engine and power generation. By using appropriate redundancy technique in model development Chapman-Kolmogorov differential equations has been drawn with the help of the Markov birth death process. Availability and profit have been analysed based on making variation in the failure and repair rates. The numerical and graphical results have been depicted for a particular case. The derived results have been discussed with system designers and found useful.

Electrical energy storage systems for increasing technical and economical characteristics of gas engine power plants

Developing of new technologies such as electrical energy storage systems (EESS) opens new ways to increasing efficiency, decreasing exhaust waste and fuel consumption in traditional fossil fuels power station. This paper contains actual testing results of electrical energy storage system based on lithium-ion technology working with gas engine generator and altering load power. EESS parameters: rated power 100 kVA, rated capacity 153 kWh. As is known, gas generators are sensitive to changes in load power, obtained results show the effectiveness of the usage EESS to supply sustainability of generators in high amplitude and frequency altering load power environment. These results achieved through the ability of the developed converter and control strategy to compensate rapid deviations of the load power. In additional, in control system realized others common functionality: active power limitation, voltage and frequency control, reactive power control, power factor control and others. With the usage EESS, the nominal power of plane station should be lower than without EESS.

PMSG Control for a Stand-Alone Gas Engine Generator Using Active Rectifier and VSG-Controlled Inverter

The engine generator system with a diode rectifier causes harmonic currents in the generator which can affect generator efficiency and may produce torque oscillations. Using an active rectifier instead of a diode rectifier helps us to improve the current waveforms. In this paper, an active rectifier is used for a stand-alone gas engine generation system with a permanent magnet synchronous generator (PMSG). The generator side converter and the load side converter can be controlled separately to achieve high performance and reliability of the system. In the proposed control framework, the generator side converter is controlled by means of a current vector control method in a cascade structure with the synchronous reference frame (dq- frame). In the proposed control scheme, the dc link voltage is controlled by the generator side converter. For load side converter control, the concept of virtual synchronous generator control method is adopted to support a smooth power transient during the load changes. To verify the usefulness of the proposed control structure, using PSCAD software (version 4.2.1), the system transient responses with both a diode rectifier and an active rectifier are investigated under loading and load removal cases. Moreover, for the system with an active rectifier, the transient response of the system with different vector control strategies of PMSG is also investigated.

An experimental study of combined operation of energy storage system and gas engine power plant in off-grid power system

Test results of the main industrial prototype of energy storage system (ESS-10-1200-400) of nominal power 1200 kVA, energy capacity 400 kWh and voltage 10 kV based on lithium-ion batteries when operating in combination with gas engine generators (GEG) as a part of experimental power system with active abrupt variable load are given. Its structure, components and parameters, as well as the components and parameters of ESS are described. Tests have shown high operation capacity of the prototype tested, high efficiency of the implemented algorithms and confirmed the expediency of the use of ESS for smoothing power surges/sheddings in the GEG, thus preventing their emergency shutdown resulted from the power surge.

Characteristics of gas from the fluidized bed gasification of refuse paper and plastic fuel (RPF) and wood biomass

Energy recovery from small and medium scale waste thermal treatment facilities in the municipalities of Japan is challenging, owing to low power generation efficiency and high economic demands. Gas Engine (GE) generation is considered an efficient resource utilization method in these facilities. In this study, new and consistent feedstock, Refuse Paper and Plastic Fuel (RPF), and wood pellets were tested in an air-blown Fluidized Bed Gasifier (FBG) for syngas utilization in a GE. With temperatures ranging from 700 to 940 °C and varying Equivalence Ratios (ER) of 0.3–0.5, some of the most important product gas characteristics were analyzed, including the Lower Heating Value (LHV) and tar concentration levels. Gas composition results revealed that the concentration tendencies varied for the product gases CO, H2, and hydrocarbons, depending on the feedstock type, whereas the same tendencies were observed for CH4 and tar concentrations. Through the ER range, the LHV of product gas for RPF and wood pellets was 3.4–5.9 MJ/Nm3. Tar concentrations decreased to 2.5–14.0 g/Nm3-dry as the ER was raised. The optimal ER for LHV performance in GE generation was approximately 0.4 for RPF and wood pellets, and remaining tar concentrations were about 5.0 g/Nm3-dry at the gasifier exit.

Multi-objective optimization to determine installation capacity of distributed power generation equipment considering energy-resilience against disasters

Abstract In 2017, the Mistry of Health, Labor, and Welfare in Japan added a requirement for domestic disaster base hospitals to install electric power generation equipment with a generation capacity at least 60% of usual demand for securing business continuity. In this study, we developed a multi-objective optimization tool for assisting the determination of the capacity of distributed generation equipment and contract plans considering energy-resiliency after a disaster. The selected objective functions are a total cost representing economy and environment, and an expected value of power shortage ratio after the catastrophe representing energy-resiliency. As a result, our developed tool could obtain the Pareto-optimal solutions for various size hospitals on the parameter plane of the two objective functions. As well as total costs, for all optimal solutions, the expected value of power shortage ratio under disaster situation resulted in less than 40% suggesting that the national requirement standard is satisfied. Then, the cluster analysis was carried out to grasp the tendency of optimal solutions. From the analysis of average value for each cluster, it is shown that the optimal introductory capacities of gas engine generators and storage batteries couple through the outage probabilities of gas supply. Furthermore, the optimal capacity of photovoltaic is much larger than the one assumed to install on the estimated rooftop area of the hospital building, which suggests that hospital can take an option to introduce more photovoltaics to an adjacent area if possible.

Enhanced Performance of a Stand-Alone Gas-Engine Generator Using Virtual Synchronous Generator and Energy Storage System

Gas engine generators have been recognized as a set of beneficial generating units for producing electric power owing to their high efficiency, low emissions and appropriate fuel price. However, the major drawback of gas engine generators is the weak transient performance during sudden load change. The reason is that the engine's mechanical system cannot quickly respond to the demanded torque. Therefore, a change in load causes a large engine speed deviation, especially in stand-alone mode. If the engine speed deviation exceeds the allowable limits, the system operation will be shut down. To fix this drawback, this paper introduces the virtual synchronous generator control method combined with an additional energy storage system to the stand-alone gas engine generator. In this paper, the applied virtual synchronous generator control scheme is presented. Compared to the constant-voltage constant-frequency control method, the benefit of virtual synchronous generator control method for the gas engine generator is evaluated by simulation study in PSCAD software. The energy-variables-based feedback control structure is adopted for the control of energy storage system. The required capacity of energy storage system is estimated. To verify the effectiveness of proposed control structure, simulation is conducted under load connection and load removal cases. Finally, an experimental study is carried out for the same configuration of simulation model using a real gas-engine generator set up.

Emissions and performance of a spark-ignition gas engine generator operating with hydrogen-rich syngas, methane and biogas blends for application in southern Brazilian rice industries

Brazil is one of the world's largest rice producers with more than 50 industries in this field. During the processing of the grain, high amounts of husk are generated, with a capacity to produce synthesis gas with high hydrogen content. On the other hand, in the process of parboiling, the final result is considerable volumes of effluent rich in organic matter, generating high amounts of methane. Therefore, spark ignition engine (SI) can operate with biogas, syngas or biogas-syngas mixtures, taking advantage of the bioenergy potential of the rice industries in Brazil. Accordingly, in this work, it was used the spark-ignition engine test operating with typical biogas and syngas compositions generated in the rice industries, named Bio70, syngas1 and syngas2, respectively. An important result could be observed. For both methane and biogas fuel the increase in excess ratio (λ) value from 1 to 1.25 lead to lower CO and NOx emissions as well as an increase in indicated efficiency. Using fuel mix, even at low concentration, such as 10% by vol., Bio70 provided increases in the calorific value of air-fuel mixture (edv) equal to 5.4 and 13.2% for syngas 1 and 2, respectively.

Development of secondary chamber for tar cracking–improvement of wood pyrolysis performance in pre-vacuum chamber

Energy crisis and global warming, in other words, climate change are critical topics discussed in various parts of the world. Global warming primarily result from too much emission of carbon dioxide (CO2) in the atmosphere. To mitigate global warming, or climate change and improve electrification in rural areas, wood pyrolysis technology is developed in a laboratory scale, of which gases are directly applicable to the gas engine generator. Our laboratory has developed a prototype of wood pyrolysis plant with a pre-vacuum chamber. However, tar yield was around 40 wt% of feedstock. This research aims to reduce tar yield by secondary tar cracking. For the secondary tar cracking, a secondary pre-vacuum chamber is installed after primary pre-vacuum chamber. Gases generated in the primary pre-vacuum chamber are lead into the secondary chamber that is heated up to 1000 K. This paper reports performance of the secondary chamber for secondary tar cracking in homogeneous mode and heterogeneous mode with char.

An anaerobic-aerobic sequential batch process with simultaneous methanogenesis and short-cut denitrification for the treatment of marine biofoulings

Although combination of denitritation and methanogenesis for wastewater treatment has been widely investigated, an application of this technology to solid waste treatment has been rarely studied. This study investigated an anaerobic-aerobic batch system with simultaneous denitritation-methanogenesis as an effective treatment for marine biofoulings, which is a major source of intermittently discharged organic solid wastes. Preliminary NO2−-exposed sludge was inoculated to achieve stable methanogenesis process without NO2− inhibition. Both high NH4+-N removal of 99.5% and high NO2−-N accumulation of 96.4% were achieved on average during the nitritation step. Sufficient CH4 recovery of 101 L-CH4 kg-COD−1 was achieved, indicating that the use of NO2−-exposed sludge is effective to avoid NO2− inhibition on methanogenesis. Methanogenesis was the main COD utilization pathway when the substrate solubilization occurred actively, while denitritation was the main when solubilization was limited because of substrate shortage. The results showed a high COD removal efficiency of 96.0% and a relatively low nitrogen removal efficiency of 64.4%. Fitting equations were developed to optimize the effluent exchange ratio. The estimated results showed that the increase of effluent exchange ratio during the active solubilization period increased the nitrogen removal efficiency but decreased CH4 content in biogas. An appropriate effluent exchange ratio with high anaerobic effluent quality below approximately 120 mg-N L−1 as well as sufficient CH4 gas quality which can be used as fuel for gas engine generator was achieved by daily effluent exchange of 80% during the first week and 5% during the subsequent 8 days.

Experimental Verification of Robust Controller for Electronic Governor of Small Gas Engine Generator

In this paper, a novel application of a robust controller for an electronic governor of a small gas engine generator is presented. There are a few studies regarding the fluctuations in the concentration of bio-methane fuel and load fluctuation of a generator using an approximately 1-kW small gas engine generator. For a relatively small-scale local-production-type energy circulation system, such as the gas energy from a Tambo (GET) system, it is necessary to develop a small gas engine generator that can use the generated unpurified bio-methane gas to accommodate the load fluctuation. The GET system is a bio-methane gas production system, utilizing the sustainable resources from a paddy field, without requiring any distinct auxiliary facilities. We have examined the bio-methane gas produced from the GET system as the fuel of a small gas engine generator, which can supply electric energy and thermal energy to a greenhouse. We have studied the application of a robust engine controller by combining a model matching controller and an optimal observer (MM_OBSV controller) with the electronic governor of the small gas engine generator. The results indicate that the control system is adapted for the input disturbance (load fluctuation and modeling error), with the MM_OBSV controller embedded in the electronic governor of the small gas engine generator.

Biogas-based electricity generation in swine farm in Thailand: Economic and CO2 reduction aspects

Biogas-based electricity generation is one of the challenging in organic waste management in the developing countries. This paper investigates the existing electricity generation technology in swine farm with the supporting of feed-in tariffs and incentive of investment under Clean Development Mechanism (CDM) in Thailand. In swine farm the rearing capacity of 70,000 swines has potential for generating a minimum of 2,736,000 m3 of biogas per year from swine’s manure. This amount represents the contribution of biogas derived from swine farm to climate change mitigation if biogas is used for electricity generation. Since Thailand provides incentive investment of electric power generated from renewable sources and other biological wastes in terms of feed-in tariffs and feed-in premium, these incentives can motivate private enterprises to invest and supply electricity to the national grid. To generate electricity from biogas in swine farm it also contributes in CO2 reduction and creates potential jobs. The increased capacity of its two gas engine generators with total capacity of 870 kW can generate electricity of 6,144 MWh per year and can increase the average carbon credits of 32,750 ton CO2 per year. This electricity production cost is the lowest when compares to other biogas-based electricity generations such as in palm oil plants, in cassava plants, and in landfill-based plants. Results of this study show that the feed-in tariffs of $0.1074 per unit of electricity, and the supporting mechanisms under CDM scheme for 10 years can shorten payback periods and increase the return of investment to the renewable energy investors.