Magnus Korpås, Aurora F. Flataker, Hanne Sæle, Bendik Nybakk Torsæter, Karen Byskov Lindberg, Shanshan Jiang, Åse Lekang Sørensen, Audun Botterud
Norway is at the forefront of the transition from fossil fuels to an electrified transport sector. In the first half of 2022, more than four out of five new passenger cars sold were fully electric and the share of electric vehicles (EVs) in the total car fleet was almost one out of five. There are several reasons for this successful development. Norway’s electricity supply sector is almost entirely made up of renewable energy in the form of hydropower, with the recent addition of wind power. As a result, Norwegian politicians and regulators had to consider other sectors than electric power to reduce domestic carbon emissions. In the early stages, Norway introduced several measures to reduce carbon emissions in the transport sector, which contributed to about one-third of domestic carbon emissions. Incentives were introduced in the form of benefits, like free parking and ferry rides, access to prioritized bus and taxi lanes, and free public charging. However, the most important factor for the transition to EVs was the exceptionally high taxes for conventional cars fueled by gasoline or diesel, from which EVs are exempt. For many drivers in Norway, these taxes alone have made EVs more favorable than their fossil fuel counterparts.
The history of modern EVs in Norway can be traced back to the 1990s with the launch of Think and Buddy, two small EV models that were produced domestically and served certain niche segments. However, it was not until the introduction of the Nissan Leaf in 2011 and Tesla Model S in 2013 that EV sales started to accelerate. As seen from Figure 1, the EV market share of new car sales has grown exceptionally in the last 10 years. EVs have already become the default car type in Norway, especially in urban areas. Plug-in hybrids are also popular, especially in more rural areas. But with bigger batteries and better charging infrastructure, EVs will probably soon be the preferred option in all parts of the country. With more EVs on the streets, carbon emissions from road transport have also started to decline. From the record year 2015 to 2021, carbon emissions from road transport have dropped about 15%, as tracked by the Norwegian government (https://www.environment.no/).
According to the Norwegian climate action plan from 2021, the official goal for the transport sector is to cut carbon emissions in half by 2030. This goal is expected to be reached by incentivizing the electrification of buses, trucks, heavy-duty vehicles, and ferries. Based on these expectations, parliament has made a resolution stating that the government must ensure sufficient grid infrastructure and establish economic incentives for realization of more low-carbon technologies within the whole transport sector.
Today, the annual electricity demand from EVs in Norway is less than 1% of the annual country-wide demand. With the expected growth in EV penetration levels in the coming years, many people are concerned about how EVs will impact the electricity supply and the grid. Historically, Norway has had abundant access to hydropower and is, therefore, already highly electrified, using electricity for heating of buildings and in power-intensive industry. Interestingly, due to the combination of efficient EV drivetrains and high baseline electricity use, EVs will contribute to less than 5% of the total electricity demand by 2030, even in the most ambitious climate-action scenarios, according to the Institute of Transport Economics. The Norwegian Energy and Water Directorate (NVE) has estimated that even if we electrify all passenger vehicles, buses, light-duty trucks, and commercial vehicles, the annual electricity demand will add up to some 12 to 14 TWh, which is still less than 10% of the total demand. However, the instantaneous impact on the grid from simultaneous EV charging may be much more significant.
The steady growth of EVs in the last years means that Norway already has gained valuable experience in how EVs impact the power system, as well as how to plan for charging infrastructure and utilization of EV flexibility for grid services. This article gives an overview of the knowledge gained from the Norwegian EV adoption so far, including key factors for successful grid integration of EVs, preferences revealed by EV owners, smart charging solutions, and the emerging infrastructure for high-power charging stations. Finally, we discuss the way forward for the full electrification of the Norwegian transport sector, and how grid planning and operations will need to be adapted to meet the new demands in a cost-effective and flexible way.
Since EVs are now becoming the primary car choice in most parts of Norway, many have been concerned about how the grid will cope with the new loads. In the early days of EV adoption, most owners did not have dedicated chargers at home and, therefore, charged their EVs using a regular power socket. Since then, dedicated chargers have become the standard solution for home charging, both due to safety regulations and user expectations for higher charging power and lower charging time.
A recent study for NVE by consultants from DNV and Pöyry Management Consulting investigated how the grid will be affected when all passenger cars become electric. They found that significant additional grid costs only occur in a worst-case scenario, when everyone using their car to commute to work would plug in immediately when they arrive home after work. Under this scenario, the daily peak load in a typical Norwegian distribution grid would shift from the morning (around 9 a.m.) to the evening (around 7 p.m.). The resulting additional grid investment costs nationally were estimated to be between 1.1 and 1.5 billion Euros. However, by limiting the evening charging to only those EVs that need to fill up their battery for the next morning, the grid expansion costs could be more than halved. Furthermore, under a complete shift to charging at night or other off-peak periods, possibly enabled though alternative tariff structures, the additional grid costs could become negligible since such charging patterns would be utilizing capacity that is already available in the existing grid.
The study done for NVE also revealed large differences in grid costs between cities and rural areas. Cities would only face marginal additional costs relative to their EV share because many people use public transport for their daily commute. Also, those who do use EVs often have short travel distances. Therefore, in Norwegian cities, there is plenty of opportunity to shift EV charging to off-peak hours. On the other hand, in rural areas, and especially in the popular tourist destinations in the mountains, there is often a need for long charging sessions due to longer travel distances. Moreover, people often need to use roadside fast chargers to boost up the battery state-of-charge (SOC) on the way to/from their home or cabin. In rural areas, the opportunity for flexible charging is therefore more limited than in urban areas, which gives rise to challenging situations in the distribution grids.
Slow chargers for EVs are connected to the low-voltage part of the distribution grid (400 V line-to-line and 230 V line-to-neutral). With flexible charging, including vehicle-to-grid (V2G), they can offer services at both distribution (e.g., congestion management, voltage support) and transmission (e.g., system balancing and congestion management) levels. (In this article, we refer to flexible charging as charging that is shifted in time and/or amplitude in response to varying electricity prices, grid fees, or grid capacity limits. Flexible charging can provide several services to the grid, such as frequency regulation, renewable energy balancing, and voltage support.)
Different market designs for grid services to enable the participation of distributed flexible resources have been widely discussed and tested out internationally. In Norway, the rapid increase in EVs has accelerated the need for real-life experiences based on practical and scalable solutions. In a pilot project carried out from 2019 to 2020, led by the Norwegian system operator and transmission grid owner, Statnett, flexible EV charging was used by the energy company Tibber to test the provision of reserves in the manual frequency restoration reserves (mFRR) market. The EV aggregator (Tibber) provided bids with 1 MW steps to the mFRR market according to its estimated aggregate flexibility. Figure 2 shows an example of aggregated EV charging power, where a 1 MW mFRR bid was activated at 1:05 a.m. The testing was successful in showing that it is possible to override the normal charging patterns if needed for grid services. However, the situation becomes more complex when the flexibility is needed both by Statnett and the distribution companies, illustrating the need for coordination between transmission and distribution system operators.
Detailed ac optimal power flow (ACOPF) studies carried out by the Norwegian University of Science and Technology for residential neighborhoods in the Trøndelag region suggest that EV charging based on energy market price optimization could violate grid limitations, such as transformer thermal ratings or voltage limits, when EV penetration levels approach 100% (every household owns an EV). Figure 3 demonstrates this issue showing charging dispatch of 35 EVs in one feeder with loading violations when operational limits are not accounted for. There is already a growing need in Norway to come up with practical solutions to activate flexible EV charging in response to constraints in the grid.
When charging at home, ac current is flowing through the charging cable and into the EV. The charger and the power electronics converting the power from ac to dc is located inside the car and is referred to as the on-board charger. The capacity of the on-board charger in the EV is limited by the amount of power the EV can draw from the grid when charging with ac power. For fast charging, the charger itself is located outside the EV (so-called off-board charger) and the current going through the charging cable is dc, allowing for charging at higher power. The standard IEC 61851-1 “Electric Vehicle Conductive Charging System” is the European standard for charging systems for EVs. It defines four charging modes, of which the first three are for ac charging and used for home charging:
Modes 1, 2, and 3 have been used for home charging in Norway. The wall connectors used for home chargers can be simple or include functionality for the smart control of the charging. With new regulations from July 2022, all new electric installations for EV charging must have a charging box (a normal socket is not sufficient). Dimensioning the home charger for charging currents at 16 or 32 A are common when using Mode 3, whereas 10 A is common for household power sockets (Mode 2). In a 230 V system with single-phase Mode 3 charging, the maximum charging power becomes 3.7 kW with 16 A charging current. The highest power capacity used for home charging is 22 kW, which is doable for 400 V systems with 32 A charging current and three-phase charging. However, most EVs have on-board ac chargers limited to 11 kW.
To get a better understanding about EV charging and driving behavior, the Norwegian EV Association performs a large survey among its members each year. The annual EV surveys give an indication of how the charging capacities have increased over time. The results of the survey have been studied among others as part of the research project FuChar (Grid and Charging Infrastructure of the Future) and the research center CINELDI (Center for Intelligent Electricity Distribution).
In 2016 (3,653 respondents), 64% of the respondents were using ordinary power sockets (Mode 1 or 2) for home charging and only 27% Mode 3 chargers (19% with 16 A and 8% with 32 A). In 2020 (14,169 respondents), the figures were flipped: 69% were using Mode 3 charging and only 27% ordinary power sockets. In 2021 (15,467 respondents), the share of Mode 3 chargers increased even more, up to 77%.
As many as 90% of the EV owners participating in the 2021 survey reported that they charged at home either daily, two to three times a week, or weekly. Only 5% reported to never charge at home. However, home charging behavior highly depends on the residential building types. More than half of the residents in single- and double-family houses charge their EV daily at home, according to the annual EV survey from 2016. But less than 10% of residents in apartments and housing cooperatives did so. Nonetheless, since 2016 it has become easier for EV owners in housing cooperatives to charge at home. In the beginning of the EV era, several housing cooperatives did not allow EV owners to install EV chargers, even when they had a private parking spot. For many years, there has been a discussion about how to share the charging infrastructure costs between EV owners and others. Since 2020, the right to install an EV charger at the parking spot for members in housing cooperatives was established by law. It is becoming common to have good charging opportunities also in housing cooperatives, which makes home charging an option for more EV owners independently of where they live.
Many housing cooperatives choose to sign a contract with a charging operator who is installing chargers, operating them, and providing a payment/subscription solution for the users. Often, the housing cooperatives choose to dimension the electrical installation to allow for installation of EV chargers at all parking spots, even if not all members of the housing cooperative have EVs yet. Those who already have an EV can make a subscription for charging, including installation of the wall connector on their parking spot. The subscription often involves a monthly fixed cost for having the charger available and maintained, as well as a variable cost to cover the electricity use (kilowatt hours) and grid tariffs for the actual charging.
To use the overall charging capacity efficiently, some charging operators have implemented a load balancing system for sharing the capacity among the EVs that are charging simultaneously. The simplest way to share is to distribute the capacity to the EVs equally. Other schemes are “queueing systems” allocating a higher power consumption for the latest EVs to plug in. In this way, the EVs increase their SOC faster in the beginning of the charging period to be ready for the next trip. EVs that are plugged in for a long time get reduced charging power if there are more recently plugged-in EVs that need the charging power more. Similar charging solutions to those used in housing cooperatives are also used at workplaces, hotels, malls, or other destinations with many parking spots.
As the EVs are parked and plugged in for a much longer duration than what is necessary to recharge the battery, flexible charging depending on electricity prices, grid tariffs, or to respond to grid needs (e.g., through a flexibility market) are studied in research and tested in demo projects. To some extent, it is already being done in practice. In the EV survey from 2021, respondents estimated in which time slots during the day the EV was actively being charged when plugged in at home. Most of the respondents were charging during the evening and night, whereas very few charged the EV during the day, as seen from Figure 4. The respondents who charged at nighttime were asked why they did so:
In 2021, 58% of the EV owners reported controlling their charging actively either through the wall connector, the designated EV app, or a third-party charging app. The remaining 42% charge their car passively, i.e., at a fixed charging rate while plugged in. It is likely that flexible charging will grow because of both the new grid tariffs introduced in July 2022 (with the purpose of leveling out demand and shift EV charging away from peak hours) and the electricity price awareness that rose among the public after the 2022 European energy crisis.
In Oslo, the capital of Norway, transportation is responsible for about 50% of the city’s carbon emissions. Therefore, electric mobility is seen as one of the major remedies for emission reduction. However, scaling up EV adoption in urban areas faces many challenges. And among those is the well-known “chicken and egg” problem: i.e., what comes first, the charging point or the EV? Currently, the municipality of Oslo is focusing on providing cost-efficient home charging facilities for people living in apartment blocks.
The Røverkollen Housing Cooperative (Figure 5), located in the eastern suburb of Oslo, is a real-life demonstrator for charging with smart energy management. It was implemented and tested as part of the European Union GreenCharge project. Røverkollen has 246 apartments in five building blocks and a common four-floor garage in a separate building with 230 private parking spots dedicated to each apartment. The GreenCharge project invested in the electric infrastructure within the garage, such that it would be possible to charge 230 EVs. However, apartment owners would need to invest in their own EV chargers to connect to the common charging infrastructure. Currently, there are 65 EV chargers installed in the garage. It is becoming the norm in Norway that residents in apartment buildings who have their own parking spot also have their own EV charger, as in Røverkollen. The EV infrastructure-related challenges at Røverkollen are thus representative of the scaling requirements for EVs in urban areas with limited capacity of the power grid infrastructure. The GreenCharge demonstration revealed that the private charger increases the EV flexibility potential, since the EVs are parked and plugged into the charger longer, compared with EVs using a shared charger.
In another project, involving an apartment building with 97 EV users in the city of Trondheim, it was found that the average connection time was 6.5 h for shared chargers while twice as high for private chargers. Residential charging habits were investigated, based on data from EV charging reports from the charging operator and hourly electricity metering. Figure 6 illustrates average daily load profiles for the EV charging, with different estimated load curves for 3.6 kW or 7.2 kW charging power, under the condition that the EV charging starts directly after the car is plugged in. The estimates were compared with the electricity metering for EV charging, showing how the real values occurred between the two charging power assumptions. Many residents connect their EV to the charger when coming home after work and the EVs often finish charging around midnight, while still being connected to the charger until the morning. In most situations it is therefore possible to delay the EV charging until the nighttime, when electricity consumption is much lower in the building. If the residential building has solar photovoltaic (PV) systems, the use of PV production should also be considered in the charging strategy. The challenge is to provide simple and practical solutions to communicate with the users.
The current regulatory framework in Norway does not allow for common metering of several buildings. For the GreenCharge demonstration project at Røverkollen, this means that the flexibility that the EV charging is offering in the garage cannot be utilized for balancing load fluctuations in the nearby separate apartment blocks.
The experience and lessons learned from the GreenCharge Oslo pilot tell us that:
In 2022, for the first time in Norway, the number of kilometers driven by EVs exceeded gasoline cars. In total, 23% of all kilometers driven by cars were battery-electric. Diesel cars still cover most kilometers (40%) but have declined steadily the last five years, as can be seen from Figure 7, which suggests EVs were not only used to cover short distances, but to a much larger extent all types of trips. In addition, electric vans, trucks, and buses are becoming real alternatives to their conventional counterparts. So far in 2023, 32% of new long-distance buses sold and as much as 91% of new city buses sold are EVs.
New vehicles will also have a need for alternative locations to recharge their batteries fast and in a user-friendly way, both at the depots and along their transport routes. It is therefore an urgent and increasing need for a well-developed network of high-power charging stations, both in cities and along highways. The number of fast charging stations (FCS) in Norway is increasing rapidly, as shown in Figure 8. The first 50-kW charger for electric cars was installed in 2012. Since then, the number of public fast chargers has increased to 7,307 in June 2022. The charging capacity of the fast chargers has also increased. While the first fast chargers only could deliver up to 50 kW, charging capacities between 150 and 350 kW are the standards when new FCSs are built today. So far, FCSs have mainly been built for private cars. However, the first FCS dedicated to electric trucks was built in 2022.
Although home charging is the most common, charging at FCSs represents an important option for reducing EV owners’ range anxiety on longer trips. In the 2021 edition of the annual EV survey from the Norwegian EV Association, the vast majority (87%) responded that they use fast charging for longer trips outside of their own municipality or county. In total, 79% of the respondents reported that they only use fast charging monthly or more rarely. Hence, charging at FCSs is, for most EV owners, something that is done in conjunction with weekends, vacations, or other occasions when there is a need to drive longer distances than normal.
In the FuChar project, the researchers are investigating the charging pattern of EVs at FCSs to understand impacts on the power system. So far, charging stations are rarely utilized to their maximum-rated capacity when it comes to both grid capacity and available charging capacity. This situation is beneficial from a grid-planning perspective, as it enables more flexible grid connections. Currently, the grid is normally dimensioned to handle the worst-case scenario, where the FCS draws maximum power at the same time as the load in the rest of the grid is at its peak. However, at many locations, the peaks of charging stations occur during weekends and summer holidays, whereas the general peak load occurs on cold winter days with high demand for electric heating. By considering the coincidence factors of load from FCSs and other loads in the network, it is possible to reduce the need for grid reinforcements or connect more charging infrastructure while waiting for grid upgrades.
At the FCSs, EV owners typically want to charge as fast as possible, in contrast to charging at home or at the workplace. However, even at FCSs there is flexibility potential that can be exploited to reduce the need of grid investments and help to balance the power system. Short reductions of charging power to quickly respond to short duration needs on the balancing market is likely to be acceptable for EV owners, as it will not affect the charging duration to a large extent. With the high-charging powers and long range of many EVs today, it also happens that the EV user needs more time for breaks than the EV needs to recharge. If charging operators have installed load-balancing systems that distribute available capacity among the individual charging points in an intelligent way, they can also control the aggregated power to the FCS, responding to power system needs without negatively affecting the user experience of EV drivers.
FCSs can also be equipped with converters that support the grid by injecting reactive power to improve the voltage quality in distribution grids. Grid support could be even more valuable in grid operation if several stations in the same area are providing coordinated reactive power support simultaneously.
Price signals can be designed to redirect EV owners toward the stations that are less loaded or where the grid capacity is higher, exploiting the EVs’ mobile nature to offer both temporal and spatial flexibility. One example that was tested at some Tesla superchargers in 2021 was to decrease the charging price on Saturdays. The aim was to incentivize people to charge on Saturdays instead of Fridays and Sundays, which are the typical peak days when many people are driving longer distances for weekend trips.
So far in Norway, the flexibility from FCS (as well as for home and workplace charging) that has been tested is what is referred to as unidirectional smart charging or V1G. The reason for not testing bidirectional charging (V2G) to a large extent is partly because most of the EVs and chargers that are deployed so far do not allow V2G, and partly because the benefits one can get from unidirectional smart charging is already significant.
When electrification of transport moves beyond cars, the demand for charging infrastructure increases. However, since different types of transport have different driving characteristics and charging patterns, new types of flexibility arise. An example is the potential for co-using charging infrastructure for different transport types. As an example, charging of city buses (at depots) takes place during nighttime, while delivery trucks typically need to charge during work hours.
In the last couple of years, the number of connection requests to Norwegian distribution and transmission companies has skyrocketed due to projects related to EV charging stations, electrification of ferries, and other new electricity demands. Therefore, many projects are still waiting for grid connection or response from the distribution companies on when and at what cost they can connect to the grid. When there is scarcity of transmission capacity at the at high voltage levels, the grid reinforcement is not only a question of cost and environmental impact, but also a question of long construction lead times. This situation may render connection of many new projects to the grid impossible within the next decade in areas with high demands. To enable rapid and efficient electrification of transport, better methods for understanding and modeling the future load demand from EVs must be developed and implemented by the grid planners. Methods for modeling load demand from high-power charging stations are being developed in the FuChar project and CINELDI, which is one of the Norwegian Research Centres for Environmentally Friendly Energy (FME CINELDI). Figure 9 shows aggregated load profiles for high-power public truck charging, which have been developed based on traffic data. New load models with high resolution in both time and space are needed for grid planning as more of the transport sector is being electrified with high-power charging infrastructure.
Grid operators can apply different connection agreements and strategies that can reduce the operational risk when connecting new customers to constrained grids. An example for efficient use of existing grid infrastructure can be seen with electric ferries. The challenge of obtaining sufficient grid capacity is even bigger for electrification of ferries than for road transport, as ferries require very large amounts of power regularly over the day. Currently, about 80 ferry routes in Norway have been electrified, and from 2023 all new contracts for ferries must contain requirements for low-emission solutions. For most ferry connections, this requirement means battery-electric drivetrains. Many of the ferries crosses the so-called fjords (a fjord is a deep and narrow inlet of the sea between steep slopes formed by a glacier). As these ferries only have about 10 min to recharge, they need several megawatts for charging. Many of the ferry ports are in remote areas connected by long distribution feeders. Therefore, battery banks already have been installed at the shore several places to even out the power demand and reduce the grid impact. In other places, the ferries have so-called conditional grid-connection agreements. These agreements are made to reduce the need for redundancy in the grid connection for the ferry and thereby reduce need for grid expansions, which the ferry company must partly cover. In case of a fault in the nearby network, the grid operator can temporarily disconnect the charger to maintain power supply for other, more critical consumers. Charging stations for other types of transport, from passenger cars to shore power and charging power for vessels, are also sometimes connected using such contracts, as it can speed up the connection process and reduce connection costs since fewer grid reinforcements are needed. Further development of alternative connection agreements and strategies could make it possible to allow more grid connections that leads to operation closer to the grid’s limits, without increasing the operational risk of the power system.
EVs are already the preferred choice for Norwegians buying a new car. This success in EV deployment is a result of a combination of factors: better EVs, privileges for EV owners, and fossil fueled car taxation. The Norwegian power system has been able to tackle the EV charging demands so far, since there is a surplus of renewable power generation and a relatively strong grid infrastructure due to the traditional use of electricity for heating of buildings in a cold climate. The share of energy demands for EVs is still low compared to other electricity uses, but grids will need to be expanded significantly if the flexibility potential of EV charging is not utilized effectively. Extensive EV owner surveys have shown that charging capacities have increased, which may lead to grid problems if many users charge at the same time. However, there is generally a willingness among EV owners to move charging away from peaking hours and even to provide grid services by using simple app solutions and retailer agreements.
Results from real-life pilots have shown that there is significant potential in utilizing flexible EV charging as part of smart building and neighborhood energy management systems. The flexibility of EV charging has proven to be one of the most available end-user flexibility potentials in residential buildings in Norway. However, current regulations are still a barrier for facilitating full use of flexible charging to alleviate problems in the power grid. For other countries, regulatory barriers with regards to electricity sharing and local trade or coordination should therefore be addressed at an early stage. Implementing smart charging solutions in practice requires an interdisciplinary approach to achieve common understanding of the goals and concepts.
In Norway, the range anxiety for long-distance EV travel has been overcome by a combination of several key factors:
The “first movers” have done their job. Now, driving long distances with an EV has become as normal as other ways of travel.
For a country to build up a large EV fleet, it is necessary to both support EV ownership and charging infrastructure at the same time. In Norway, the first FCSs were subsidized. However, already when EVs made up just 3% of the car fleet, building these stations without public support started to become profitable. To reach climate goals in Norway, the challenge is now to develop grid infrastructure, grid operational practices, and flexibility incentives that facilitate full transport electrification beyond passenger cars.
Although Norway currently is an outlier in the global landscape, with its high electricity consumption and strong governmental support for EV adoption, its experiences are still highly relevant for other countries as they embark on deep decarbonization efforts, which typically include substantial electrification of transport. Moreover, as battery and EV prices continue to decline, rapid EV adoption will not necessarily require the same level of incentives in other regions.
“Results from the eFleks pilot in the mFRR-market 2019/2020,” Statnett, Oslo, Norway, Tech. Rep., Feb. 2021. [Online] . Available: https://www.statnett.no/en/about-statnett/news-and-press-releases/news-archive-2021/safeguarding-the-power-supply-with-help-from-electric-cars-panel-heaters-and-ventilation-systems/
P. B. Wangsness and A. H. Halse, “The impact of electric vehicle density on local grid costs: Empirical evidence from Norway,” Energy J., vol. 42, no. 5, pp. 149–167, 2021, doi: 10.5547/01956574.42.5.pwan.
S. Jiang, M. Natvig, S. Hallsteinsen, and K. B. Lindberg, “Lessons learned from demonstrating smart and green charging in an urban living lab,” in Advanced Information Networking and Applications, L. Barolli, F. Hussain, and T. Enokido, Eds. Cham, Switzerland: Springer International Publishing, 2022, pp. 624–636.
E. Figenbaum and S. Nordbakke, “Battery electric vehicle user experiences in Norway’s maturing market,” Institute of Transport Economics, Oslo, Norway, 2019. [Online] . Available: https://www.toi.no/publications/battery-electric-vehicle-user-experiences-in-norway-s-maturing-market-article35709-29.html
E. Lorentzen, P. Haugneland, C. Bu, and E. Hauge, “Charging infrastructure experiences in Norway – The worlds most advanced EV market,” in Proc. EVS30 Symp., Stuttgart, Germany, Oct. 2017. [Online] . Available: https://elbil.no/wp-content/uploads/2016/08/EVS30-Charging-infrastrucure-experiences-in-Norway-paper.pdf
Magnus Korpås is with Norwegian University of Science and Technology, 7491 Trondheim, Norway.
Aurora F. Flataker is with Norwegian University of Science and Technology, 7491 Trondheim, Norway.
Hanne Sæle is with SINTEF Energy Research, 7465 Trondheim, Norway.
Bendik Nybakk Torsæter is with SINTEF Energy Research, 7465 Trondheim, Norway.
Karen Byskov Lindberg is with Norwegian University of Science and Technology, 7491 Trondheim, Norway.
Shanshan Jiang is with SINTEF Digital, 7465 Trondheim, Norway.
Åse Lekang Sørensen is with Norwegian University of Science and Technology, 7491 Trondheim, Norway and SINTEF Community, 0373 Oslo, Norway.
Audun Botterud is with the Massachusetts Institute of Technology, Cambridge, MA 02139 USA and Argonne National Laboratory, Lemont, IL 60439 USA.
Digital Object Identifier 10.1109/MPE.2023.3308246
Date of current version: 19 October 2023
1540-7977/23©2023IEEE