Intentions to Charge Electric Vehicles Using Vehicle-to-Grid Technology among People with Different Motivations to Save Energy

Abstract

This article presents the results of a quantitative survey conducted on 4000 electric energy consumers in Spain, France, Italy, and Denmark. The results demonstrate differences in the effects of additional remuneration for using vehicle-to-grid (V2G) stations, depending on users’ reasons for saving electricity. Individuals with extrinsic financial motivations are sensitive to such incentives; the higher the remuneration is, the more willingness they demonstrate to use V2G. Although individuals with intrinsic (the desire to control spending) and ecological (caring for the environment) motivations are also interested in using V2G, no relationship can be observed between the sizes of the rewards and individuals’ desire to use the technology. Users are similarly encouraged by low (an extra 2.5% of energy for free) and high (an extra 20%) rewards. In contrast, individuals who display intrinsic general modesty (willingness to not waste things) motivations may even be discouraged: the higher the reward, the less interest they demonstrate in V2G. The article illustrates how different types of motivation can affect users’ interest in the innovative V2G concept, as well as underlining the importance of constructing intrinsic and altruistic motivations in the process of education.

1. Introduction

Most countries, except for a few in the Middle East, signed the Paris Agreement in 2015, which set the goal of limiting global temperature rises to 2.0 °C above the preindustrial era. The European Union has declared an ambitious plan to transform its energy mix to one based entirely on low-carbon sources [1]; China has announced that it will become a carbon-neutral economy by 2060 [2,3]. Therefore, there is a growing global effort to decarbonize energy and reduce its negative impact on the climate. A report by the Intergovernmental Panel on Climate Change on possible actions to mitigate climate change shows that renewable energy from the sun and wind has the greatest potential to reduce greenhouse gas emissions [4]. The transformation of the energy system is most often realized by increasing the share of renewable energy in the energy mix [5]. However, renewable energy sources, particularly wind and solar energy, deliver energy with variable intensity. On sunny and windy days, there can be an excess of energy on the grid; on cloudy and windless days, there can be a shortage. Thus, such a change creates major challenges for the energy system and radically alters its operating pattern. It is a move away from energy produced in large power stations with controlled intensity to a distributed model in which energy is produced at different locations—and the intensity of generation is variable and largely unpredictable.

Fluctuation of production levels from renewable sources cause significant stress on energy suppliers, who must stabilize the intermittency in the power system [6,7]. One renewable source of energy that is used to stabilize the power grid is hydropower [8], though its potential is limited due to geographic conditions (availability of rivers, altitude differences), and in most countries, the availability of this type of energy is too low to effectively stabilize the fluctuating levels of energy production from wind and solar. Assuming that the share of variable energy sources will grow in the future, maintaining the balance between the amount of energy produced and consumed will require adjustments not only on the part of energy suppliers but also on consumers [9]. To address this challenge, the elasticity of demand for energy among consumers, both commercial and residential [10,11], must increase. Various innovative ideas are emerging that serve to increase energy flexibility among individual users to more efficiently use low-carbon energy when it is available. One method involves shifting demand and mitigating ‘demand peaks’. An example of how technology can be used in this way can be found in the use of smart appliances, which automatically control the consumption of energy from the grid according to the availability of low-carbon energy [12].

The electrification of road transportation is also potentially widening imbalances in the energy system. According to the International Energy Agency, the global electric car market is expected to grow from 11 million to 145–230 million vehicles by 2030 [13]. The energy demand of the growing number of electric cars could lead to a 20% increase in global electricity consumption and create new imbalances in the energy system through the development of new demand peaks driven by EV charging patterns [14]. The solution involves integrating electric cars into the power grid so that power consumption for charging the cars is matched to the availability of renewable energy on the grid, and electric car batteries come to serve as energy storage to balance the imbalances in the system [15,16]. Utilization of the battery potential of electric cars by the power grid requires the use of vehicle-to-grid (V2G) technology, which enables a two-way flow of energy from and to the electric car, and allows the car’s charging time and intensity to be matched to current energy availability and grid load [17,18]. In this case, a distribution or transmission system operator can draw energy from car batteries in certain situations (e.g., peak energy demand during windless days, cloudy weather) and either pay for it or return energy to the user when renewable energy becomes available. An analysis of the potential costs and benefits of such integration of electric car battery potential into the power grid indicates that it is a favorable solution that effectively increases the efficiency of intermittent renewable energy [19].

However, to successfully implement V2G technology, astute recognition of social factors is also required. Users’ motivations for using technological solutions to reduce energy consumption are complex and go beyond the intuitively obvious need to reduce spending and be environmentally responsible. A study by Bohdanowicz et al. (2021) conducted in four European countries concludes that factors such as openness to technology, attachment to consumption and comfort, and the influence of the social environment also play significant roles [20]. Thus, to successfully implement new technologies, it is important to ensure that they are understood, convenient, and desired by users [21]. In the case of electricity, changing the way we use it requires users to change the way they think about it. Adapting to V2G technology can be a major challenge, first because it is a change in the principle that energy is always available, and second, in certain situations, it is the user who is expected to supply energy to the grid rather than receive it. Moreover, a study by Geske and Schumann (2018) suggests that a key concern of electric car users is range; this is an important barrier that serves to limit interest in V2G technology [22].

Users are accustomed to using electric energy in any amount and at any time; its constant, unlimited availability is taken for granted, and its use is typically nonreflective [23]. The flexible demand paradigm changes the situation. To shift demand, consumers must actively participate in usage; for example, they must decide to do the laundry later than they would like due to the expected lower price of energy in the future. Doing laundry or setting the dishwasher is no longer a spontaneous, unreflective decision but a conscious one. Shifting demand, granting autonomy to smart appliances, or feeding electricity from one’s car into the grid may be exotic ideas for some consumers; this, in turn, may cause barriers to their adoption [24]. The concept that a charging station can draw electricity, i.e., discharging the battery, contradicts common thinking and even the name of the device; it is unexpected that something called a ‘charging station’ can work in reverse. Noel et al. conducted an extensive qualitative study in 2019 with transportation and energy experts, which addressed barriers to V2G technology development [25]. In summarizing the range of barriers, they highlighted that innovative solutions must not only be well developed technologically and economically but must also overcome users’ cognitive and perceptual barriers.

Motivating factors are necessary to convince users to use new solutions. Some studies [26] suggest that in the case of financial motivation, users expect higher rewards than such systems can offer. Moreover, money is an extrinsic motivation and utilizing it carries risks. If the price of energy is perceived as relatively low, feedback that focuses on the value of that energy may even work to increase consumption [27]. Users operate in a market paradigm: a specific price is set for electricity, which the users are able to pay, so they pay and fail to reflect on the implications of energy consumption. Individuals can also be motivated intrinsically. For example, consumers may believe that energy should be saved because it is good not to waste resources. Another example of intrinsic motivation is a concern for ecology and the environment [28]. Some psychological studies indicate that intrinsic social motivations are more durable and effective than extrinsic financial ones [29].

The primary goal of our study was to discover whether motivations to save electricity translated into sensitivity to material rewards for using V2G charging. We were interested to discover how individuals with different motivations for saving energy would respond to the incentive mechanism implemented at a car charging station with V2G technology. In this concept, the user, in exchange for transferring electricity from his car to the grid, could recover that energy with an additional bonus when charging later. We tested this by conducting a quantitative exploratory survey.

2. Materials and Methods

The quantitative survey was part of a research package conducted within the Horizon 2020 project, ebalance-plus: energy balancing and resilience solutions to unlock flexibility and increase market options for the distribution grid. The survey was conducted in December 2021 on a sample of 4000 individuals in four countries: France, Italy, Denmark and Spain (1000 in each). The survey was conducted by an external research agency, IQS Poland, which coordinated data collection in the four countries. The data were subjected to quality control and weighed so that their structure reflected that of the populations of the surveyed countries, based on census data. The sample was gender balanced and stratified by gender, age, city size, region, and education level. The survey was conducted in the form of a self-completed online questionnaire (computer-assisted web interview) and covered topics related to household electricity use, as well as an evaluation of the user interfaces of energy management devices and electric vehicle charging systems, of messages that build energy literacy, and of the V2G charging concept. The study sample comprised adults (mean age: 43) who were responsible for paying electric bills or purchasing electrical appliances for their homes and who use smartphones daily.

The following research hypotheses were formulated:

H1. 

The sizes of rewards for providing power to the grid will correlate positively with interest in using V2G charging stations.

H2. 

Individuals who display different motivations to save energy will differ in their interest in using V2G car charging stations.

H3. 

The sizes of the rewards will affect interest in using car charging stations differently among individuals who display different motivations to save energy.

In this article, we examine the relationship between interest in using electric car charging stations with V2G technology and the degree of gratification for providing electricity from cars to the grid, as well as the types of motivation individuals display to save energy. For this purpose, we analyzed the following variables:

• Type of motivation to save energy. In a single-choice question, respondents selected the most important reason why they saved energy of the four listed. Their responses classified the respondents into four groups with different motivations to save energy. The question stated: ‘Which of the following best describes your reasons for saving energy in your home?’

  -

  (Financial) I have more money for other expenses because of this.

  -

  (Control) I feel that it gives me more control over my spending.

  -

  (Modesty) I believe that we should try to live frugally and not waste the things we use, like energy, even if we can afford them.

  -

  (Ecology) I am concerned about the state of the environment and the climate, so by reducing my electricity consumption, I try to limit my negative impact.

• Degree of interest in using electric car charging stations by the degree of gratification for providing electricity to the grid. Each respondent viewed the question with one randomly-selected size of bonus for energy provided to the grid. This provided us with results for five different price thresholds, each of which was shown to an equal number of respondents. The question stated: ‘Suppose you own an electric car. There is a charging station in the parking lot of your workplace. Now, suppose that the charging station can discharge your battery to some extent (but never below half of its capacity). Over the following days, you would be able to get this “borrowed” energy back for free + an additional (2.5/5/10/15/20)% free. Would you like to plug your car in there’?

3. Results

Those who participated in the study were divided into four groups, depending on their stated motivation to save energy. The size of each group allows us to conduct analyses. Members of the smallest group save energy purely for financial reasons (16%); members of the largest group save energy as a result of modesty motivations (36%). The structure of the study sample by the variables analyzed is shown in

Table 1. Descriptive statistics for the study variables.

Variables	Values	Frequency (Total Sample N = 4000)	Percentage of the Total Sample
Motivation to save energy	Financial	657	16.4%
	Control	782	19.5%
	Modesty	1438	35.9%
	Ecology	1123	28.1%
Intention to use V2G charging stations	Definitely no	354	8.9%
	Rather no	488	12.2%
	Hard to say	962	24.0%
	Rather yes	1504	37.6%
	Definitely yes	692	17.3%
Reward level, calculated as the percentage of energy transferred to the electricity grid	2.5%	801	20.0%
	5.0%	790	19.8%
	10.0%	793	19.8%
	15.0%	828	20.7%
	20.0%	788	19.7%

.

Each participant stated their degree of interest in using charging stations for cars with V2G technology, with a randomly selected reward level for providing energy from their cars to the grid. Over half of the respondents expressed preferences for using such charging stations (55% answered ‘yes’ or ‘definitely yes’; 21% answered ‘no’ or ‘definitely no’). Reward levels were randomly generated for each respondent; each level was presented to 20% of the sample.

The results of the study on intentions to use V2G chargers for different levels of reward among people with different motivations to save energy are presented in Figure 1. The size of the reward does not seem to affect intentions to use V2G chargers among respondents who save energy due to environmental motivation and respondents who need to control energy spending. Among those with a financial motivation, the degree of intention seems to increase as the size of the reward increases; among those with a modesty motivation, the relationship seems to be inverted.

To test whether intentions to use V2G stations differed between groups with distinct motivations for saving energy and the size of the premium for energy delivered to the grid, we conducted a one-factor analysis of variance with ‘Motivation to save energy’ and ‘Reward level’ as factors. The results, in

Table 2. Univariate analysis of variance. Dependent variable: intention to use V2G charging stations; factors: reward level, motivation to save energy.

Source	df	Mean Square	F	Sig.
Corrected Model	19	3.98	2.944	0.000
Intercept	1	48,067.05	35,560.131	0.000
Reward level	4	1.203	0.890	0.469
Motivation to save energy	3	15.108	11.177	0.000
Interaction: reward level and motivation to save energy	12	2.354	1.742	0.052
Error	4559	1.352
Total	4579

, demonstrate that the intention to use V2G charging stations differs among groups with diverse motivations to save energy, F(3, 4579) = 15.108, p = 0.000, but does not among groups with varied sizes of bonus, F(4, 4579) = 1.203, p = 0.890. The analysis also demonstrates that the interaction effect between ‘Reward level’ and ‘Motivation to save energy’ is insignificant: F(12, 4579) = 2.354, p = 0.52.

Next, we examined which groups of people with different motivations for saving energy differed in their intentions to use V2G charging stations. The Tukey posthoc test (results in

Table 3. Tukey posthoc test results (intention to use charging stations in groups that displayed different motivations to save energy).

(I) Motivation Category	(J) Motivation Category	Mean Difference (I–J)	Std. Error	Sig.	95% Confidence Interval
					Lower Bound	Upper Bound
Financial	Control	0.00336	0.057825	1	−0.14525	0.15197
	Modesty	−0.09801	0.051438	0.226	−0.2302	0.03418
	Ecology	−0.24827 *	0.053554	0	−0.3859	−0.11064
Control	Financial	−0.00336	0.057825	1	−0.15197	0.14525
	Modesty	−0.10137	0.048335	0.154	−0.22559	0.02285
	Ecology	−0.25163 *	0.050581	0	−0.38162	−0.12164
Modesty	Financial	0.09801	0.051438	0.226	−0.03418	0.2302
	Control	0.10137	0.048335	0.154	−0.02285	0.22559
	Ecology	−0.15026 *	0.043135	0.003	−0.26112	−0.03941
Ecology	Financial	0.24827 *	0.053554	0	0.11064	0.3859
	Control	0.25163 *	0.050581	0	0.12164	0.38162
	Modesty	0.15026 *	0.043135	0.003	0.03941	0.26112

Note: * Statistically significant results, p < 0.05.

) revealed that support for the concept among users who displayed ecological motivations (mean = 3.58) was significantly higher than among those who displayed each of the other motivations to save energy (financial, mean = 3.33, mean difference 0.25, p = 0.000; control, mean = 3.33, mean difference 0.25, p = 0.000; modesty, mean = 3.43, mean difference 0.15, p = 0.003).

The univariate analysis of variance suggested that the interaction effect between the ‘Reward level’ and ‘Motivation to save energy’ lies close to the significance boundary; therefore, to more closely examine the relationship between these variables and ‘Intention to use V2G charging stations’, we conducted a series of correlation analyses, with results shown in

Table 4. Pearson correlation results for intention to use charging stations and size of reward for energy delivered to the grid (2.5%; 5.0%; 10.0%; 15.0%; 20.0%) across groups that displayed different motivations (finance, control, modesty, ecology).

		Intention to Use V2G Charging Stations
		N	Pearson Correlation	Sig. (2-Tailed)
‘Reward level’ among:	Financial motivation group	657	0.076	0.049 *
	Control motivation group	782	0.042	0.241
	Modesty motivation group	1438	−0.057	0.032 *
	Ecology motivation group	1123	0.016	0.593
	Total sample	4000	0.005	0.743

Note: * Statistically significant results, p < 0.05.

. We performed the analyses on five groups of subjects: one on the entire study sample and four on the subgroups that displayed specific motivations for saving energy.

Correlation analysis reveals that among those who displayed financial motivations, a positive correlation can be observed between the ‘Reward level’ and ‘Intention to use V2G charging stations’: r(657) = 0.076, p = 0.049. The opposite relationship can be observed among those who save energy for reasons of modesty; the correlation between the ‘Reward level’ and ‘Intention to use V2G charging stations’ is negative: r(1438) = −0.057, p = 0.032.

4. Discussion

A major challenge in introducing innovations to manage energy consumption is motivating users to adopt them. Using these solutions often requires users to make an extra effort, learn how to use new devices, change their habits, and accept the fact that energy cannot be consumed at any time and in any amount. In many cases, the potential financial benefits are small compared to total energy costs. This means that motivating users with such incentives can prove ineffective. Moreover, with such incentives, the motivation to act fades when the financial benefits cease.

In the case of V2G technology, it requires users to accept that it may take longer to charge their cars. It also demands that the battery in the car be used by the grid to balance energy demand and supply. Users may be concerned that such charging could shorten the life of their car batteries—an effect that is difficult to estimate and value. Using V2G chargers also requires a modification of thinking about the use of electricity, which, until now, has only been drawn from the grid. The model of energy use that V2G technology represents assumes that users understand and accept that on the power grid, energy supply and demand must be balanced and that with a high share of intermittent energy sources, periodic use of energy storage may be required.

Our study produced a result that is inconsistent with intuitive thinking about motivating users. We identified no significant relationship between the size of the reward in the form of additional electricity for sharing the energy stored in a car’s battery and the degree of interest in using V2G charging stations. Contrarily, we discovered that the type of motivation to save energy impacts intentions to use V2G chargers significantly. Thus, the tangible benefit of additional energy available as compensation for sharing a car’s battery proved to be a nonsignificant incentive, although the values manifested in different motivations for saving energy significantly differentiated openness to using V2G technology. People who save energy for environmental reasons are more likely to use solutions that reduce the load on the power grid, even when they are not rewarded for doing so. This illustrates how important it is for education to incorporate the construction of pro-environmental values based on an inner conviction that we should care about the state of the world that our descendants will inherit. It is worth investigating whether similar results can be obtained for other interventions that reduce the negative impact of energy consumption on the state of the climate and nature.

The data reveal compelling interaction effects between the type of motivation and responsiveness to the size of the reward for providing access to car batteries while charging. Among those who display financial motivations, larger energy bonuses correlate positively with interest in the concept; among those who display modest motivations, the opposite is true. This can be interpreted in terms of intrinsic and extrinsic motivation. Financial motivation is extrinsic, so it is stronger when accompanied by higher financial incentives. We can observe this in the data, in which higher compensation in the financial incentive group is linked to greater intention to use V2G chargers.

The relationship between reward level and intention to use V2G charging stations is less clear among those who save energy to avoid unnecessary consumption of resources (modesty motivation). Among these individuals, larger energy bonuses are paired with decreases in interest in using V2G charging stations. This can be explained by the conflict between financial compensation and the values of individuals who save energy to reduce their resource consumption. We can hypothesize that, in this case, valuing behavior undertaken due to intrinsic motives weakened those individuals’ motivation to act prosocially. This group exhibits a similar effect to that described by Gneezy and Rustichini [29,30]. They demonstrated that the introduction of a punitive fee for parents who collected their children from kindergarten too late caused the parents to be late more often. Paying for lateness somehow relieved the parents of the obligation to treat lateness as something undesirable; the introduction of the fee shifted this behavior from the social relations category to the financial category. Parents began to apply the rule of the market instead of the rule of social norms. Interestingly, such a negative correlation appears not to exist among the other respondents who save energy for environmental reasons or because they want to control expenses. These respondents’ intentions to use V2G charging stations and ‘lend’ energy from their own batteries were independent of the size of the rewards for doing so. This means that they were open to doing this even for low rewards.

Our survey reveals that material rewards are of little importance when it comes to intentions to use V2G car charging stations. Such rewards are an incentive for those who are financially motivated but are simultaneously a disincentive for those who want to save energy so as not to waste resources unnecessarily rather than to benefit financially. In the latter case, the introduction of small financial rewards moves the act of saving energy from the category of principles and values to that of the market, where it is profitability rather than intrinsic beliefs that matters. The overall impact of the material incentive on the entire sample of respondents was found to be neutral.

5. Conclusions and Limitations

Our study indicates that motivating users to adopt new solutions for the flexible use of the electricity grid requires a deep understanding of their needs and the matching of motivating instruments to those needs. In the case of the concept tested, it transpired that the intuitively compelling method of motivating users with additional benefits has questionable effectiveness and is limited to users who are motivated by a financial stimulus.

Users’ values proved to be a much greater influencer of intentions to use the solution under test than the size of the rewards did. Those with pro-environmental values demonstrated high degrees of intention to use V2G car chargers, regardless of the size of the reward for sharing energy from their own cars. These results allow us to draw several conclusions for those who will design electric car charging stations in the future, as well as solutions to increase the flexibility of energy demand. First, the study points to the high importance of environmental values, which translate into high user engagement that is independent of tangible benefits. Thus, in the context of motivating users, activities that strengthen ecological values in the broadest sense can be effective. Second, certain incentives that are intended to increase engagement might serve, in fact, to demotivate certain groups of users; this pertains in our study to users who displayed the modesty motivation. Therefore, it is advisable that user motivation mechanisms be tested before their introduction and, if possible, that motivational incentives be tailored to the specific needs of user groups.

This study has also incurred a number of limitations. Because two-way car charging remains in the testing phase, it is impossible to conduct a quantitative survey among those who use the technology in real life. Moreover, the penetration of electric cars remains very low, so limiting the sample to current electric vehicle users would not allow us to draw conclusions about the attitudes of all car users. Our survey was conducted among users of all types of cars under the assumption that their opinions are important for the success of the planned electrification of automobile transportation in the European Union, according to which the sale of cars with internal combustion engines will be banned as early as 2035. However, the evaluation of the solution concepts that we conducted in this study offers only approximate information about actual user behavior. In addition, our study evaluated only one of a number of possible incentives for using V2G technology. It is likely that other incentives could be offered to users that are better tailored to their expectations; this would more effectively motivate a broader group of users. Given the great importance of transport electrification for achieving climate and energy goals, it is advisable that further research projects be conducted that evaluate V2G technology from users’ perspectives in real-life situations. When implementing a survey on a lower number of users, however, it must be remembered that users’ professional qualifications and experience may affect the results, so a sample that reflects that diversity must be selected.