The manuscript deals with an interesting research topic, having a solid methodological background, but a rather weak theoretical coverage and poor discussion of the research outcomes. In this respect the following review comments can be addressed, prior to the acceptance of the manuscript for publication at the “World Electric Vehicle Journal”.

1) The technological side of the reviewed analysis: “Therefore,............. are evaluated” it can be accompanied by one or two extra sentences in the Abstract section stating the technical specifications and conditions related to them in numerical data-quantitative terms. Besides, the methodological approach of “four different EVs” can succinctly specify what are the characteristics of each EV type studied (However, no brand names of EVs to be given here). Two or three extra sentences in the Abstract section are adequate.

Since the pricing of “These V2G TCO range from euro ............to euro ........”, as all monetary goods-products-services are always place- and time- dependent, it is recommended authors to:

-round up the values into integer numbers, since it does not make sense a 2-decimal digits precision in a thousands’ scale. -provide the exact (calendar/economic) year and country-region (....... Belgium) in which these values are referred to.

2) The text content of the Introduction section it is better matching to expand the short-typed Abstract section. Then, a more pluralistic theoretical coverage of the examined topic it is highly recommended. To this end, I made a fresher literature search by using relevant key-words, the outcome of which it is presented at the end of my review comments. Therefore, authors are recommended to solidify the theoretical background of their analysis while considering those relevant citations at their revised manuscript, accordingly. It is anticipated the revised Introduction section to be extended to one full and cross-cited text page.

3) The information contained at Table 1 can be accompanied by:

-relevant citations’ recalled from. -relevant pricing values per cost type, possibly from more than one citation recalled, in the form of pricing-range values (along with the monetary units calculated/estimated).

4) In lines 74-75 the following statement “Electricity prices are identified according to the three charging cases, namely ...............” can be succinctly expanding by describing the situations and the conditions of each one of these three cases investigated. Two or three text paragraphs are adequate.

5) In case that Figure 1 information have been recalled or adapted from other published studies, then, the source citations have to be added in its legend. Otherwise the notation of “Authors’ own study” can be denoted.

6) All narrative of subsection 4.2 V2G TCO results it cannot be overly devoted in transferring Figures or Tables data in plenary text but, based on them, a creative discussion of synthesising them in a descriptive manner, it is highly recommended. Therefore, one or two argumentative paragraphs can be also developed. Otherwise, the per each one of the three charging cases’ discussion should be collectively denoted in relevant subsections in the main section 6. Discussion. The section 6. Discussion section can be expanded accordingly.

7) The reliability and the verification of the research outcomes could be fully conveyed in the section 6. Discussion. In particular:

-Each one of the four limitations-preconditions of future development being noted in the first part of section 6 they can be cross-cited and verified by at least one extra citation referred to. I am not full convinced that for all these diversified, and interestingly proposed, constraints the proper way of addressing them is the “.............. is required”. For example each one of the four limitations-preconditions-constraints proposed are not all finance-affected, but they can be approached in a more explicit and exclusive basis of proposals needed, no merely the tariffing or the monetary proposal.

-The following statement of section 6 “Furthermore, little is known about the EV owners’ expectations to actively participate in a V2G market, …………, further research would increase the reliability on the evaluated results”, it can be creatively expanded in an holistic approach containing the a) governmental motives and regulations, b) technological synergies, c) driving performance, d) operational conditions and e) decommissioning prospects and materials recovery in terms of circular economy and financial appreciation, adding value to depreciated-used car-machinery and EV batteries under the logic of recovering and reusing at a second round of use. Again indicate literature citations on circular economy studies are presented at the end of my review comments.

8) The numerical data of section 7. Conclusions it cannot be placed as concluding remarks, since conclusions are not a summary of the outcomes but a space of briefly revisiting the main constraints, limitations, challenging issues and future prospects of the conducted analysis, offering feasible proposals of technological scalability, commercial marketing, and spatial (through land uses in urban contexts) changes’ abiding towards the applicability of the outcomes in real world conditions.

.............................

Falkoni, A., Pfeifer, A., Krajačić, G. Vehicle-to-grid in standard and fast electric vehicle charging: Comparison of renewable energy source utilization and charging costs (2020) Energies, 13 (6), art. no. 1510, . Cited 5 times. DOI: 10.3390/en13061510

ABSTRACT: Croatia aims to achieve 10% of its energy production from the renewable energy sources in the total energy consumption in the transport sector. One of the ways to achieve this goal is by the use of electric vehicles. This work comparatively analyses the financial and social aspects of vehicle-to-grid charging in standard and fast charging mode, their impact on the renewable electricity production and the total electricity consumption regulated through variable electricity prices. Data were taken for the wider urban area of the Dubrovnik region. The assumption is that the Dubrovnik region will be self-sufficient by the year 2050 with 100% renewable electricity production and that all conventional vehicles will be replaced by electric vehicles. This work aims to show that the fast charging based on 10 min time steps offers more opportunities for flexibility and utilization of renewable generation in the energy system than the standard charging based on hourly time step. The results of this work showed the opposite, where in most of the scenarios standard charging provided better results. Replacement of the existing two tariff model in electricity prices with variable electricity prices contributes to the stability of the energy system, providing better regulation of charging and higher opportunities for renewable electricity utilization in standard and fast charging and reduction of charging costs. According to the financial aspects, fast charging is shown to be more expensive, but for the social aspects, it provides electric vehicles with more opportunities for better competition in the market. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Su, X., Yue, H., Chen, X. Cost minimization control for electric vehicle car parks with vehicle to grid technology (2020) Systems Science and Control Engineering, 8 (1), pp. 422-433. DOI: 10.1080/21642583.2020.1789898

ABSTRACT: With coordinated charging and discharging, electric vehicles (EVs) in smart car parks can be used as energy storage systems and a reserve against unexpected outrage. In this work, a modeling and control framework for EVs in a smart car park has been built up, which includes key factors such as the charging and discharging costs, the battery degradation cost, the driving probability, the feed-in tariff (FIT), and the vehicle-to-grid (V2G) rebates. Each EVs' charging and discharging activities are scheduled through an optimization route with the purpose to minimize the car park electricity cost. Results from comprehensive simulation studies demonstrate the potential benefits of V2G for car park systems with multiple EVs subject to vehicle and battery characteristics, FIT and policy support. © 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

Amamra, S.-A., Marco, J. Vehicle-to-Grid Aggregator to Support Power Grid and Reduce Electric Vehicle Charging Cost (2019) IEEE Access, 7, art. no. 8930487, pp. 178528-178538. Cited 27 times. DOI: 10.1109/ACCESS.2019.2958664

ABSTRACT: This paper presents an optimised bidirectional Vehicle-to-Grid (V2G) operation, based on a fleet of Electric Vehicles (EVs) connected to a distributed power system, through a network of charging stations. The system is able to perform day-ahead scheduling of EV charging/discharging to reduce EV ownership charging cost through participating in frequency and voltage regulation services. The proposed system is able to respond to real-time EV usage data and identify the required changes that must be made to the day-ahead energy prediction, further optimising the use of EVs to support both voltage and frequency regulation. An optimisation strategy is established for V2G scheduling, addressing the initial battery State Of Charge (SOC), EV plug-in time, regulation prices, desired EV departure time, battery degradation cost and vehicle charging requirements. The effectiveness of the proposed system is demonstrated using a standardized IEEE 33-node distribution network integrating five EV charging stations. Two case studies have been undertaken to verify the contribution of this advanced energy supervision approach. Comprehensive simulation results clearly show an opportunity to provide frequency and voltage support while concurrently reducing EV charging costs, through the integration of V2G technology, especially during on-peak periods when the need for active and reactive power is high. © 2013 IEEE.

Turker, H., Bacha, S. Optimal Minimization of Plug-In Electric Vehicle Charging Cost with Vehicle-to-Home and Vehicle-to-Grid Concepts (2018) IEEE Transactions on Vehicular Technology, 67 (11), art. no. 8449109, pp. 10281-10292. Cited 56 times. DOI: 10.1109/TVT.2018.2867428

ABSTRACT: This paper deals with the problems of the Plug-in Electric Vehicles charging costs in housing sector. A review of the optimal strategies is proposed and as such six algorithms are presented: three smart unidirectional and three smart bidirectional charging algorithms where the Vehicle-to-Grid (V2G) and the Vehicle-to-Home (V2H) concepts were exploited. In addition an innovative V2G algorithm named Optimal Logical Control (V2G-OLC) is introduced in this paper. This latter is dedicated to the French energy billing system within the peak/base hour's contract. All the algorithms are tested over a set of 1000 data composed of real elements with four different daily energy price profiles. The results show a great efficiency of the V2G-OLC algorithm compared to the traditional optimal charging strategies. Indeed, the results show a reduction of 47.94% of the average charging cost with a unitary selling/buying price ratio in comparison to the simple charging at 230V-32A. © 1967-2012 IEEE.

Bishop, J.D.K., Axon, C.J., Bonilla, D., Banister, D. Estimating the grid payments necessary to compensate additional costs to prospective electric vehicle owners who provide vehicle-to-grid ancillary services (2016) Energy, 94, pp. 715-727. Cited 21 times. DOI: 10.1016/j.energy.2015.11.029

ABSTRACT: The provision of ancillary services in the smart grid by electric vehicles is attractive to grid operators. Vehicles must be aggregated to meet the minimum power requirements of providing ancillary services to the grid. Likely aggregator revenues are insufficient to cover the additional battery degradation costs which would be borne by an existing electric vehicle owner. Moreover, aggregator revenues are insufficient to make electric vehicles competitive with conventional vehicles and encourage uptake by prospective consumers. Net annual costs and hourly compensation payments to electric vehicle owners were most sensitive to battery cost. The fleet provided firm fast reserve from 1900 h for 0.42 h, up to 2.7 h in the best cases. At best, likely aggregator revenue was 20 times less than the compensation required, up to 27,500 times at worst. The electric vehicle fleet may not be large enough to meet the firm fast reserve power and duration requirements until 2020. However, it may not be until 2030 that enough vehicles have been sold to provide this service cost-effectively. Even then, many more electric vehicles will be needed to meet the power level and duration requirements, both more often and for longer to enable participation in an all-day, everyday ancillary services market. © 2015 Elsevier Ltd.

KIAEE, M., CRUDEN, A., SHARKH, S. Estimation of cost savings from participation of electric vehicles in vehicle to grid (V2G) schemes (2015) Journal of Modern Power Systems and Clean Energy, 3 (2), pp. 249-258. Cited 21 times. DOI: 10.1007/s40565-015-0130-2

ABSTRACT: The storage capacity of the batteries in an electric vehicle (EV) could be utilised to store electrical energy and give it back to the grid when needed by participating in vehicle to grid (V2G) schemes. This participation could be a source of revenue for vehicle owners thus reducing the total charging cost of their EVs. A V2G simulator has been developed using MATLAB to find out the potential cost saving from participation of EVs in V2G schemes. A standard IEEE30 network has been modelled in the simulator which uses the MATPOWER engine to undertake power flow analysis. A novel control algorithm has been developed to take advantage of the difference between the selling and buying electricity prices by charging and discharging EVs at the appropriate time. Two scenarios are simulated to compare the total charging cost of EVs with or without the utilisation of V2G technology within the power system assuming a total of 5000 EVs. The results of the simulation show that the applied control strategy with V2G is able to reduce the charging cost of EVs by 13.6 % while satisfying the minimum requirement for state of charge (SoC) of the EV batteries to complete their next journey. © 2015, The Author(s).