Conventional Diesel Generator Research Articles

Enhancing energy control for a hybrid system comprising a wind turbine, diesel generator, and storage systems

The increase in demand for electrical energy has made renewable energy sources, such as wind power, increasingly attractive. However, intermittency and variability represent the major problems of these types of energies. The hybridization of several energy sources allows to have a reliable and efficient supply system. This paper was interested in the control of a hybrid energy system, which includes a wind turbine, storage systems (batteries and super-capacitors) and a conventional diesel generator, with the aim of generating constant power. A control strategy is developed taking into account the various constraints of the hybrid system. Both of storage systems as well as the diesel generator operate according to the modes presented in the supervision algorithm to absorb and compensate the fluctuation of the wind energy and reach to a constant energy flow. The super-capacitor operates before the battery to absorb the power peaks in both charge and discharge modes. The hybrid system is simulated using MATLAB/Simulink software, and the results are provided in order to show the effectiveness of this control strategy.

Environmental impact assessment of different power generation strategies in Oman: A comparative life-cycle analysis

This paper presents a comparative environmental impact assessment considering different power generation strategies in Oman. The Life-Cycle Assessment (LCA) methodology, and the OpenLCA tool, were employed in carrying out comprehensive analysis, and evaluation of the various environmental aspects in filling the research gap, by replacing conventional diesel generators with natural gas alternatives in Oman. The obtained results indicate that utilizing natural gas significantly reduces environmental impacts, including a decrease in global warming potential to 2.27 million kg CO2 eq, fossil fuel depletion to 34.5 million kg oil-eq, and ozone depletion to 0.13 kg CFC-11 eq. This study would help in policy decision-making to support a potential shift in power generation system, transitioning from the current use of diesel generator sets to flared produced Natural Gas across crude oil processing plants. Thus, mitigating operational cost, and improving efficiencies, for sustainable developments. Another salient part of this study is the implementation of more sustainable energy practices that supports the broader application of LCA in evaluating industrial environmental impacts. Furthermore, the results obtained in this work are in line with recent global climate change commitments and Oman's Vision 2040, in achieving cleaner energy sources to minimize environmental harm in the oil and gas sector.

Evaluation and Optimization of Hybrid Renewable Energy Systems for Sustainable Farm Machinery Operations in Northern Nigeria

This study aimed to assess and optimize hybrid renewable energy systems (HRES) integrating solar and wind energy for sustainable farm machinery operations in Northern Nigeria. A purposive sampling technique was used to select representative farms and agricultural sites within the Kaduna region. Qualitative data were collected through interviews and surveys with farm owners and operators to gain insights into energy use practices, challenges, and perceptions regarding renewable energy adoption. The comparative analysis of different HRES configurations revealed that Configuration C, with the highest solar (20 kW) and wind capacities (15 kW), achieved the highest renewable energy fraction of 90% and the lowest annual cost of $14,800. Configuration B, with increased capacities (15 kW solar and 10 kW wind) and a battery capacity of 200 kWh, achieved an 85% renewable fraction and reduced the annual cost to $16,200. The cost-benefit analysis confirmed that HRES are economically viable and offer significant environmental advantages compared to conventional diesel generators. These findings underscore the potential for optimizing energy resources to achieve higher renewable energy fractions and lower operational costs. The study provides practical recommendations for promoting HRES adoption, highlighting the necessity for financial support, technical training, and robust policy frameworks to facilitate the transition towards sustainable energy solutions in agriculture.

Improving the performance of PV/diesel microgrids via integration of a battery energy storage system: the case of Bilgo village in Burkina Faso

BackgroundPV/diesel microgrids are getting more popular in rural areas of sub-Saharan Africa, where the national grid is often unavailable. Most of the time, for economic purposes, these hybrid PV/diesel power plants in rural areas do not include any storage system. This is the case in the Bilgo village in Burkina Faso, where a PV/diesel microgrid without any battery storage system has been set up. This power plant is composed of three diesel generators operating in parallel (two of 16 kW and one of 24 kW), coupled with a photovoltaic field of 30 kWp. It was observed that for such power plants, the grid management is not always efficient due to constantly fluctuating solar output and loads. This inconsistency in energy output raises the question if integrating battery energy storage systems could improve the grid's performance. While many studies in the literature focus on hybrid energy systems, only a few of them have tackled the optimization of existing and operational systems.MethodsThis study investigated three scenarios based on the existing microgrid's characteristics: conventional standalone diesel generators, PV/diesel without battery storage and PV/diesel with a battery storage system which are the main technologies used for off-grid rural electrification in Burkina Faso. The levelized cost of electricity (LCOE) was used to assess the economic performance of each scenario, and the calculations were made using the HOMER software.ResultsIt was found that the best among the scenarios considered is the PV/diesel/battery configuration which has the lowest LCOE of US$ 0.524/kWh. The battery storage system for the optimal configuration has a capacity of 182 kWh with about 8 h of autonomy.ConclusionsIt can be inferred from this study that a storage unit is necessary for an optimal management of a PV/diesel microgrid. Indeed, the storage unit significantly reduces the operating and maintenance costs associated with running diesel generators, as well as the excess electricity. The storage system also allows for a greater reduction in CO2 emissions compared to systems without storage.

Improvement of an AC microgrid system’s stability by using a fuzzy logic-based PSS controller

This research article presents the low-frequency oscillation damping control of an AC Microgrid. It is integrated with four distributed generation units in which two DGs are renewable energy source based solar PV and wind energy using DFIG and the other two DGs are conventional synchronous generator-based hydro and diesel generators. There is insufficient generation through renewable-based DG then a diesel generator is employed as an emergency unit to fulfil the requirements and maintain and control the deviation of the frequency of the system. The use of renewable-based DG affected the system's dynamic stability and the characteristics of an integrated microgrid differ from conventional sources of generation. This investigation explores the impression of the deployment of multiple forms of the power oscillation damping (POD) controllers to distributed generation sources of grid forming AC Microgrid. The main various types of POD controllers are conventional lead-lag PSSs, MBPSS-4B, and proposed robust fuzzy logic PSS (FLPSS) controllers are implemented on distributed generation units of AC Microgrid for the elimination of low-frequency oscillation. Low oscillation frequencies between 0.1 and 2 Hz are the focus of this work. The system's damping ratios and stability margins because of MG integration are observed using eigenvalues analysis. The results of the simulation test demonstrate the accomplishment of the robust fuzzy logic PSS controller regarding conventional lead-lag PSSs and the MBPSS-4B controller during circumstances of fault.

Integration of very small modular reactors and renewable energy resources in the microgrid

Hybrid microgrids, integrating local energy resources, present a promising but challenging solution, especially in areas with limited or no access to the national grid. Reliable operation of off-grid energy systems necessitates sustainable energy sources, given the intermittent nature of renewables. While fossil fuel diesel generators mitigate risks, they increase carbon emissions. This study assesses the viability of integrating a very small modular renewable energy reactor into a microgrid for replacing conventional diesel generators, substantially curbing greenhouse gas emissions. A comprehensive analysis, including design and economic evaluation, was conducted for an off-grid community microgrid with an annual generation and load of 8.5 GWh and 7.8 GWh, respectively. The proposed microgrid configurations incorporate very small modular reactors, alongside solar, wind, and battery storage systems. MATLAB modeling and simulation across eight cases, accounting for seasonal variations, demonstrate the technical and economic feasibility of case 7. This configuration, integrating modular reactors, photovoltaics, wind turbines, and battery storage, satisfactorily meets load demands. Notably, it boasts a high internal rate of return up to ∼31% and a shorter payback period of around 4 years compared to alternative scenarios.

Multi-objective optimization of Hybrid Energy Systems based on Life Cycle Exergy and Economic criteria

The present study aims to develop a novel optimal design of hybrid energy systems based on exergy and lifecycle concepts using genetic algorithms. The model consists of both stand-alone and on-grid options with scenarios for exchanging energy with the grid. The objectives include cost minimization or benefit maximization primarily, and lifecycle exergy efficiency, i.e., cost as the sustainability index secondarily. This research considers renewable sources such as solar, wind, hydropower, and hydrogen production and storage in addition to conventional diesel generators. The optimization was performed subject to weather conditions and solar radiation profiles, demand, and environmental or economic aspects. Also, the model contains various modules such as water-heating, waste energy utilization, as well as the options of power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into the gas network. The application was demonstrated in a case study, where specific demands and the climate of Tehran were assumed. The case study considers four scenarios, including standalone, completely on-grid, on-grid with a non-backup generator, and on-grid without an energy sale option. The first optimal objective, the levelized unit cost of energy for the standalone system, is $0.22 per kWh. Moreover, the second optimal objective, the lifecycle exergy cost, ranges from 1.93 to 4.13 in different grid-connection states.

Effect of a Storage System in a Microgrid with EDR and Economic Dispatch Considering Renewable and Conventional Energy Sources

Due to the importance that organizations and governments have placed on environmental pollution and the policies that force organizations to comply with environmental standards, the use of renewable energy sources to meet energy requirements becomes important. The problem of the economic dispatch consists of satisfying the energy demand of the clients, establishing the most convenient source of supply at each moment, considering the established objective (minimize the operating cost of the microgrid) and satisfying the established restrictions. This paper addresses the problem of economic dispatch in a microgrid with a mathematical programming approach. The proposal to meet the energy demand considers: (a) interconnection to the main grid, (b) conventional diesel generators, (c) a photovoltaic system, (d) a hydroelectric turbine, (e) a wind system, (f) a battery-based storage system, (g) capacity to exchange energy with the main grid, (h) incentive for reducing electricity demand (EDR) by customers when an environmental contingency occurs and (i) regeneration of pollutants emitted by conventional generators. The proposal is implemented in the Lingo 17 software. The results show that by including a BESS and the EDR program, it is possible to save between 18% and 75% of the costs of the objective function and stop emitting a little more than 195 kg of pollutants into the environment.

Techno-economic assessment of fuel cell-based power backup system as an alternative to diesel generators in Nepal: A case study for hospital applications

A fuel cell-based combined heat and power (CHP) system holds significant potential to be a viable alternative to conventional diesel generators for providing backup power during disruptions. The system generates power with only water as a byproduct, thus promoting environmental sustainability through reduction in greenhouse gas emissions. This study provides a comprehensive techno-economic assessment for replacement of 488 kW diesel generator that powers a hospital in Nepal during power disruption. The counter power capacity of fuel cell is 500 kW. The scope of hydrogen generation has been considered both on-site and off-site. The economic analysis performed for the on-site hydrogen production resulted in a net present value of USD 42,717 with a corresponding internal rate of return of 8.40 % and a payback period of around 10 years, making it an economically viable option. The uncertainty and sensitivity analysis revealed the electricity tariff rate as the most significant cost factor. For off-site hydrogen production, the proposed system is economically feasible if the hydrogen can be purchased below 3.5 USD/kg.

Renewable Energy Sourcing to Enhance Sustainable Manufacturing by Using Madhab’s EEE Impact Analysis Model

The world's increasing energy demand, coupled with the depletion of finite energy resources, necessitates a shift towards sustainable energy solutions. This research explores the multifaceted benefits of substituting conventional fossil fuel-based energy sources with renewable energy in industrial settings, with a focus on sustainable manufacturing. A case study was conducted at a printing and packaging factory in Bhubaneswar, Odisha, to analyze economic, environmental, health, safety, and efficiency factors associated with various energy options based on the Madhab’s EEE (Environmental, Efficiency, Economic) impact analysis method. The study identified solar power generation as the optimal energy source, boasting the lowest EEE impact index of 1.90. Wind energy ranked second, followed by conventional GRID power and DG (Diesel Generator) power sources, which were found to be less favorable due to their higher EEE impact indices. Feasibility assessments revealed that the factory had ample rooftop and vacant land space for solar power plant installation, making it self-sufficient in power generation. The return on investment (ROI) for the solar power project was calculated to be 5.54 years, making it a viable option from a sustainability perspective. Moreover, the solar system could be integrated with the GRID through a reverse metering system, enabling excess energy to be sold back to the GRID. This research underscores the significance of transitioning to renewable energy sources in industries for environmental sustainability, energy security, and economic benefits. It emphasizes the need for similar studies in diverse industrial settings to identify the most suitable energy sources, considering all relevant factors.

Optimal sizing and techno-enviro-economic evaluation of a hybrid photovoltaic/wind/diesel system with battery and fuel cell storage devices under different climatic conditions in Cameroon

Due to advancements in renewable energy technology and their ability to mitigate the issue of global warming, solar and wind energy sources are becoming increasingly popular for power generation. However, the intermittent nature of these sources means that their availability does not always correlate with load fluctuations. Hence, to solve the unpredictability concerns associated with solar and wind energy sources, they may be integrated with storage technologies and conventional energy sources (diesel generators) in a hybrid energy system (HES) to continuously supply the load demand. This paper performs a techno-economic and environmental assessment of hybrid systems integrating photovoltaic (PV), wind turbine generator (WT), and diesel generator (DSL), considering fuel cell (FC) and battery (BAT) storage devices, to supply three non-domestic loads at different locations in Cameroon, namely, Fotokol, Idabato, Kousseri, and Figuil. The Cuckoo Search Algorithm (CSA) is introduced to optimally size the various components of the proposed systems in order to fulfill the load demands in the most cost-effective manner with excellent reliability. The results show that in the short term period, hybrid systems incorporating battery storage devices are more cost effective than fuel cell storage systems. Indeed, the most optimal system found was PV/WT/BAT/DSL at the city of Idabato, with a COE of 0.151$/kWh, 0.180$/kWh, and 0.220$/kWh for high, medium, and low consumers, with corresponding break-even distances of 0 km, 0.14 km, and 0.44 km, respectively. Traditionally, using diesel generator systems for power generation costs 0.469$/kWh, 0.618$/kWh, and 0.766$/kWh, with CO2 emissions of 13694.3 kg/year, 10351.4 kg/year, and 8978.1 kg/year for high, medium, and low consumers, respectively. However, using the PV/WT/BAT/DSL configuration at Idabato in comparison to the conventional diesel generator reduces CO2 emissions in this locality by 94.32%, 95.22%, and 93.79% for high, medium, and low consumers, respectively. On the other hand, the PV/WT/FC/DSL hybrid system at Idabato presents COE of 1.018$/kWh, 1.655$/kWh, and 2.289$/kWh, with saving CO2 emissions of 91.27%, 91.76%, and 94.63% for high, medium, and low consumers, respectively.

Modeling and optimization of a hybrid solar-battery-diesel power system for remote consumers.

Hybrid power systems can be affected by various uncertain parameters such as technical, economic, and environmental factors. These parameters may have both positive and negative impacts on the overall performance of the system. Therefore, in this study, an effective optimization method for modeling and optimization of a hybrid solar-battery-diesel power structure for remote consumers is proposed. The purpose of this method is to find the optimal configuration of the hybrid structure from the technical-economical-environmental point of view to cover the load demand requirements of remote consumers. To verify the performance of the hybrid microgrid, the results of the hybrid system based on the hourly meteorological data and load profile are compared with the results of the conventional diesel generator (DG). The optimization problem is solved using a harmony search optimization algorithm. The results show that the solar/battery/DG system is more suitable than the DG-only system in different uncertainty indexes based on economic and environmental aspects. Also, by the increase of the uncertainty index from 0.5 to 10%, the optimal total cost of the system decreases by 36.5%, while at the same time the unavailability value increases from 0.2259% to 9.9568%. Additionally, when the interest rate value increases from 1 to 7%, the total cost value increases around 17. 4%.

An effective quantum artificial rabbits optimizer for energy management in microgrid considering demand response

Solving the energy management (EM) problem in microgrids with the incorporation of demand response programs helps in achieving technical and economic advantages and enhancing the load curve characteristics. The EM problem, with its large number of constraints, is considered as a nonlinear optimization problem. Artificial rabbits optimization has an exceptional performance, however there is no single algorithm can solve all engineering problem. So, this paper proposes a modified version of artificial rabbits optimization algorithm, called QARO, by quantum mechanics based on Monte Carlo method to determine the optimal scheduling for MG resources effectively. The main objective is minimization of the daily operating cost with the maximization of MG operator (MGO) benefit. The operating cost includes the conventional diesel generator operating cost and the cost of power transactions with the grid. The performance of the proposed algorithm is assessed using different standard benchmark test functions. A ranking order for the test function based on the average value and Tied rank technique, Wilcoxon's rank test based on median value, and Anova Kruskal–Wallis test showed that QARO achieved best results on the most functions and outperforms all other compared technique. The obtained results of the proposed QARO are compared with those obtained by employing well-known and newly-developed algorithms. Moreover, the proposed QARO is used to solve two case studies of day-ahead EM problem in MG, then the obtained results are also compared with other well-known optimization techniques, the results demonstrate the effectiveness of QARO in reducing the operating cost and maximization the MGO benefit.

A Bottom-Up Approach to PV System Design for Rural Locality Electrification: A Case Study in Burkina Faso

This work evaluates the performance of optimal hybrid PV/battery and PV/diesel generator renewable energy systems for a remote village in Burkina Faso. Based on socioeconomic data and the household sample survey, a technoeconomic simulation and optimization model of electrical loading are presented. Ant colony optimization (ACO) and the loss of power supply probability (LPSP) algorithms were used for the search of the optimal hybrid power system. For the selected village location, the results have shown that the hybrid PV/battery system represents the best renewable energy solution due to abundant solar irradiation and carbon emission free compared to the conventional diesel generator (DG) or PV/DG system. To reach the estimated load power demand of 2150 kWh for the studied location, optimized PV/battery configuration sizing required 650 PV modules of 250 W and 715 batteries of 300 Ah. The economical evaluation reveals a cost investment of about 1,293 025.7 USD for a lifetime of 25 years in comparison of that of PV/DG and DG systems, which are 1,088 701.9 USD and 1,682 850.6 USD, respectively. However, environmental and atmospheric pollution is minimized with a saving of more than 17943 tons of CO2. Therefore, the production of electricity from the PV/battery system leads to better competitiveness reliability for a socioeconomic development of studied remote villages.

Economic dispatch in micro-grids with alternative energy sources and batteries

The problem of economic dispatch in a micro-grid interconnected to the conventional electrical system consists of optimizing the operating cost to satisfy the different operating requirements and the demand for electrical power required by the users. In the development of this proposal, there are challenges caused by the random nature of electricity generation systems based on renewable energy sources, for an adequate operation of the micro-grid, which can be solved through systems Energy Storage System (BESS). This paper addresses the problem of optimal economic dispatch in a microgrid that includes an energy storage system based on a battery bank and interconnected to the main grid through a mathematical programming approach, considering the benefits for customers by reducing their demand of electrical power and taking into account the costs of treatment pollutants produced by conventional energy sources. The generation systems used to satisfy the energy demand of the customers within the interconnected micro-grid are: a) conventional diesel generators, b) wind generation systems, c) photovoltaic systems, d) a hydroelectric turbine, and e) a storage system based on electric batteries. The results of the effectiveness of the proposed mathematical model show that the demand for electrical power to the main grid can be reduced and customers obtain economic benefits by integrating the incentive-based demand response program into the energy management problem when environmental contingency events occur. The results show that when there are peaks in energy demand, the operating costs of the micro-grid increase by up to 380%. In the same way, when there are failures in renewable energy sources, storage systems (BESS) and diesel generators work at 100% of their capacities. The proposal is implemented in Lingo 17.0 software and simulation results show the feasibility of the proposal through the optimization of the operation of the micro-grid.

Techno-economic comparison of standalone solar PV and hybrid power systems for remote outdoor telecommunication sites in northern Ghana

Telecommunication services have continued to evolve to meet the ever-changing bandwidth demand requirements. The electricity grid network of Ghana is faced with challenges, including low voltages, a lack of quick fault response teams, and the proximity to specific locations. Using diesel generators to address the shortfall in grid supply is expensive and has implications for greenhouse gas emissions. This study evaluated the technical and economic benefits of using a standalone solar photovoltaic (PV) system, hybrid (Solar PV/diesel), conventional diesel generators (DG), and grid extension to power an off-grid outdoor telecommunication site. Power solutions configurations were simulated using hybrid optimization of multiple electric renewables (HOMER). The study found the optimum design to be a standalone solar PV/battery system with 56.3 kW solar PV array and Sixty (60) pieces of 12 V SAGM batteries of 135 Ah. The optimum design had a net present cost (NPC) of US$ 88,176.00 and a cost of energy (COE) of US$ 0.321/kWh. The COE and the NPC of the optimum system were approximately 50% less than the design with DG only, which could significantly impact service tariff and improve access to digital connectivity. The COE from the solar PV/battery system is not competitive with the grid power supply (COE = US$0.12). However, considering the electric distance limit or breakeven distance of 4.51km for grid extension, the solar PV/battery is preferred. Therefore, the stakeholders in providing power solutions to off-grid locations should consider solar PV technology.

A practical solution for excess energy management in a diesel-backed microgrid with high renewable penetration

One of the limiting factors in adding high levels of rooftop solar photovoltaic (PV) resources to isolated hybrid microgrids is the ability to maintain the minimum operating point of must-run diesel generators. This research investigates a proposed inexpensive and practical solution to mitigate excess energy from renewables (mainly PVs) while maintaining a diesel-backed grid's acceptable minimum down reserve. It includes the innovative use of a resistive dynamic load bank (DLB) during peak PV periods. A control algorithm was developed to monitor the grid's total generation and control the DLB such that conventional diesel generators are not pushed below a setpoint equal to their minimum reliable operating level defined by the local utility. The setpoint is adjustable to allow for changes in grid conditions over time, such as the addition of more renewable resources or grid upgrades. This DLB system, as a practical and low-cost PV excess energy mitigation solution, has been connected to the grid in coordination with the local utility on the island of Molokai in the Hawaiian Islands. The DLB system addition has enabled the utility to significantly increase the allowed customer-sited PV on the power system without sacrificing grid reliability.

Techno-economic feasibility assessment model for integrating hybrid renewable energy systems into power systems of existing ships: A case study of a patrol boat

The shipping industry has set out to reduce CO2 emissions by 50% by 2050 compared to 2008, as op. cit. in the note by the International Maritime Organisation to the UNFCCC Talanoa Dialogue. In order to achieve this target, ship owners and operators are to consider replacing the conventional diesel generators and gas turbines with renewable energy and other cleaner power producing systems. In this paper, a techno-economic feasibility evaluation model for integrating hybrid renewable energy systems (HRES) into the power architecture of existing ships for greener and sustainable shipping is presented. For HRES to qualify as technically and economically feasible, a decision is made based on a ‘techno-economic measure’ which is estimated by combining space availability, load served and economic performance. The proposed model is applied to a patrol boat sailing along the Eastern Coast of Ghana with three different proposed HRES. The results from the applied case shows that the most technical and economically feasible HRES for the patrol boat that meets the key performance indicators and offers low GHG emission is a hybrid solar PV, wind turbine and diesel generator system. The results further shows that the proposed model is capable of assisting ship owners to integrate affordable and cleaner energy into the power architecture of ships.

A Brief Overview of Energy Efficiency Resources in Emerging Wireless Communication Systems

It is crucial to design new communication technologies to surmount the setbacks in RF communication systems. A suitable energy-efficiency scheme helps evade needless energy consumption in wireless communication. Appropriate choice of the most suitable energy-efficiency scheme aids in selecting the most energy-efficient equipment to minimize the expense of energy towards decreasing individual network element energy consumption without affecting their unique features. This review presents the energy efficiency challenges in wireless communication by employing different technologies. The emergence of visible light communication (VLC) provides an energy-efficient wireless communication system despite the various challenges inherent in its adoption that limit its physical realization. This work seeks to harness the potential of the transmission capabilities of VLC while providing an insight into novel practical implementation techniques. The work also addresses the energy consumption problem of low-active components and idle period of active components of base stations by using sleep modes for their systematic turning off and on. The high cost of power supply and the environmental emission of gases from base stations are also addressed by integrating a renewable energy resource into the conventional standalone diesel generators. Overall, the work provides an overview of information necessary for foundational research in energy-efficient resources applied to emerging wireless communication systems.

Variable Speed Diesel Generators: Performance and Characteristic Comparison

Diesel generators (DGs) are set to work as a backup during power outages or support the load in remote areas not connected to the national grid. These DGs are working at a constant speed to produce reliable AC power, while electrical energy demand fluctuates according to instantaneous needs. High electric loads occur only for a few hours a day in remote areas, resulting in oversizing DGs. During a low load operation, DGs face poor fuel efficiency and condensation of fuel residues on the walls of engine cylinders that increase friction and premature wear. One solution to increase combustion efficiency at low electric loads is to reduce diesel engine (DE) speed to its ideal regime according to the mechanical torque required by the electrical generator. Therefore, Variable Speed Diesel Generators (VSDGs) allow the operation of the diesel engine at an optimal speed according to the electrical load but require additional electrical equipment and control to maintain the power output to electrical standards. Variable speed technology has shown a significant reduction of up to 40% fuel consumption, resulting in low GHG emissions and operating costs compared to a conventional diesel generator. This technology also eliminates engine idle time during a low load regime to have a longer engine lifetime. The main objective of this survey paper is to present the state of the art of the VSDG technologies and compare their performance in terms of fuel savings, increased engine lifetime, and reduced greenhouse gases (GHG) emissions. Various concepts and the latest VSDG technologies have been evaluated in this paper based on their performance appraisal and degree of innovation.