by Larissa Affolabi
With the growing demand for environmentally friendly transportation options like electric vehicles (EVs), the need for reliable and efficient charging infrastructure has also increased. This has resulted in an increase in the deployment of EV charging stations alongside the concurrent rise in the deployment of distributed energy resources (DERs), such as solar photovoltaic (PV) systems and battery energy storage systems, which can complement EV charging stations. In the following discussion, we will explore the broader trend of transportation electrification and delve into the challenges and opportunities associated with charging infrastructure.
Sustainability Through Decarbonization
The pressing need to address climate change has led to a global consensus on reducing greenhouse gas (GHG) emissions across all sectors. This has prompted the widespread adoption of DERs such as PV and battery energy storage systems in the power sector. In this context, the transport sector has become the leading source of GHG emissions in the United States, surpassing the power sector as shown in Figure 1. These emissions primarily result from fossil fuel combustion in various transportation modes, including cars, buses, trucks, trains, and airplanes.
Figure 1: Total U.S. greenhouse gas emissions by economic sector in 2021 
EVs have emerged as an environmentally friendly and energy-efficient alternative to their internal combustion engine counterparts by significantly cutting GHG emissions as shown in Figure 2. As illustrated, emissions decrease further when EVs are charged with renewable energy. Though one may argue that emission estimates can increase due to manufacturing, the conclusion remains that EVs are effective in reducing GHG emissions, thus the ongoing emphasis on transportation electrification.
Figure 2: Vehicle emissions by fuel type 
As a result, EVs have gained tremendous popularity over the last decade with EV sales share skyrocketing from 0.2% in 2011 to 7.7%  in 2022 in the United States as illustrated in Figure 3. With battery EVs dominating most new EV sales (refer to Figure 4), EV charging stations are similarly experiencing rapid growth.
Figure 3: EV sales share in the United States 
Figure 4: Breakdown of EV sales in the United States 
Charging Station Deployment: The Backbone of EV Revolution
Transitioning to an electrified transport system poses challenges that ought to be dealt with. One key challenge lies in the balancing act required to manage the increased electricity demand from widespread EV adoption. From the power grid perspective, EVs and charging stations represent the introduction of a new load to satisfy; most of it if not all concentrated at the grid edge. High-power charging levels are practical (i.e., the higher the charging power, the lower the charging duration) for the user experience but would strain the grid in its current state especially during peak hours causing voltage instability and overloads, affecting transformers’ lifespan. The traditional approach to tackling these issues would be to extend the grid capacity, which is a capital-intensive and time-consuming solution. Given the urgency of the global problem at stake (i.e., climate change), non-wire alternatives like on-site PV and energy storage are promoted to avoid overburdening the existing grid while keeping capital expenditure and deployment timeframe low. The deployment of DERs at charging station premises would thus help in deferring and avoiding the need for distribution equipment upgrades.
Beyond technical challenges in deploying charging stations, economic hurdles also obstruct progress. Convenient and accessible charging infrastructure is essential to overcome the range anxiety often associated with EVs. Yet, a “chicken and egg” scenario emerges — infrastructure vs. EV demand. Collaboration is needed between public and private sector stakeholders for the establishment of wide charging networks spanning residential, commercial, and highway locations. However, charging network expansion is costly; subsidies alone are likely insufficient for the required scale. Thus, innovative and sound business models are needed to make charging stations a viable enterprise to appeal to private sector stakeholders to further accelerate EV adoption.
The deployment of charging stations with on-site DERs makes charging stations change from being regular electricity consumers to prosumers, entities consuming electricity but also capable of producing it. The main function of EV charging stations is that of charging service providers; thus, their main revenue stream stems from charging services. On-site DERs pave the way for a potential second revenue stream. Individual charging stations or aggregation of charging stations operating as one entity can provide additional grid services through either the wholesale electricity market (i.e., at the power transmission level) or a transactive energy market (i.e., at the power distribution level), although the latter is in theoretical stages and requires further study. Enabling charging stations to provide grid services by participating in electricity markets would greatly contribute to accelerating EV adoption by depicting EV charging stations as profitable entities while promoting the integration of renewable energy. FERC Order 2222 advances this goal by facilitating DER participation in wholesale markets.
Diversified Transportation Alternatives: Beyond EVs
While EVs and transportation electrification in general constitute a significant step towards sustainable and low-emission mobility, they alone will not solve the transportation sector conundrum. Solely switching to EVs curbs emissions but raises sustainability concerns due to finite materials. True sustainability demands a societal shift. No sole solution exists for reducing emissions. A more holistic approach would be to simultaneously promote other alternative solutions such as improving public transport that reduces reliance on personal vehicles, cutting down congestion and emissions.
In the journey to sustainable transportation, EVs have surged in popularity. With more EVs, charging infrastructure grows. Yet, for faster EV adoption, charging networks need to further expand. This poses techno-economic challenges, demanding innovation and public-private sector collaboration. Installing stations with on-site DERs would present benefits from environmental and grid operation perspectives. EVs are promising as a sustainability strategy, but a diverse approach beyond EVs is vital for a cleaner transport sector.
 U. S. Environmental Protection Agency. “Sources of greenhouse gas emissions,” https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions.
 Available. Online: https://www.flickr.com/photos/mpcaphotos/46652972941
 H. Ritchie. “Data explorer: Electric car sales, stocks, and charging points,” https://hannahritchie.com/ev-data-explorer/.
Larissa Affolabi is an upcoming Principal Software Engineer at OATI, a service provider to leading global energy industry organizations. She recently achieved her Ph.D. in Electrical Engineering with a dissertation entitled “Transactive Energy Market for Electric Vehicle Charging Stations in Constrained Power and Transportation Networks.” Her background covers topics related to power system planning and operation with expertise in mathematical optimization and its application to market clearing mechanisms and energy scheduling problems for distributed energy resources. As an IEEE PES member, Larissa is fervently dedicated to doing her part in navigating the transformative changes in the power system industry. Beyond her professional interests, she is a strong advocate for sustainable development goals for the betterment of society and our environment.