Criteria to consider when siting EV charging infrastructure for medium- and heavy-duty vehicles

By Sam Pournazeri

Apr 28, 2022

6 MIN. READ

There are currently more than 13 million medium- and heavy-duty (MD/HD) vehicles operating across the U.S., consuming more than 50 billion gallons of diesel annually. While these vehicles only account for 5% of all vehicles on the road, they are responsible for almost one-third of the total greenhouse gas (GHG) emissions from on-road transportation in the country. Aside from their GHG emission, MD/HD vehicles are one of the major sources of air pollution—especially in low-income and underserved communities near major freight facilities—due to their high levels of nitrogen oxides (a precursor to ozone) as well as their exhaust of toxic diesel particulate matter. As such, the rapid transition of this sector to zero-emission technology is critical for the U.S. to achieve its climate goals and address long-standing environmental justice issues—the two top environmental priorities of the Biden administration.

Despite the fact that light-duty electric vehicles have been sold on the U.S. market for more than a decade, the zero-emission technology for MD/HD vehicles is lagging. However, over the past three years, major truck manufacturers announced their development and production of zero-emission MD/HD vehicles (i.e., battery-electric and fuel cell trucks). According to our EV Library—a regularly updated database of EV makes, models, specifications, and commercial availability—there are approximately 170 models of electric MD/HD vehicles that are either available today or planned to be available in the next two years. These models feature varying battery capacities and electric ranges making them suitable for various trucking vocations.

In addition to technology providers, there is also significant activity at the state and federal levels focused on transitioning this sector to zero emissions. In 2020, California adopted the Advanced Clean Truck (ACT) regulation, which sets the first-in-the-nation sales requirements for MD/HD vehicle manufacturers to sell zero-emission trucks starting with model year 2024. Upon the adoption of the ACT regulation in California, 15 states and the District of Columbia announced a joint memorandum of understanding to work collaboratively to advance and accelerate the market. The goal is to reach 100% of all new MD/HD vehicle sales as zero-emission vehicles by 2050 with an interim target of 30% sales by 2030.

California is also pursuing a new policy, Advanced Clean Fleets (ACF), and a Zero-Emission Drayage Truck regulation that requires fleets operating in the state to transition to zero-emission technology between 2024 through 2042. According to these policies, two-thirds of the trucks operating in California should be zero-emission by 2050. We expect other states to follow in California's footsteps and adopt similar requirements for their fleets. Meanwhile, the EPA recently announced new GHG emissions standards for HD vehicles as soon as model year 2030, which will more comprehensively address the long-term trend towards zero-emission vehicles across the HD sector.

This rapid transition is driven by a number of key factors: manufacturers shifting their products to electric; local, state, and federal governments pushing for aggressive policies transitioning the U.S. freight sector to zero-emission; and, most importantly, fleets demanding these vehicles due to lower operational and maintenance costs compared to their diesel counterparts. That’s why it is more important than ever to consider the charging infrastructure needed to power these vehicles. According to the Department of Energy’s Alternative Fuels Data Center station locator, there are currently over 114,000 publicly accessible EV charging ports in the U.S., of which almost 22,000 are DC fast-charging (DCFC) ports and the remaining are Level 2. Of the 22,000 DCFC ports, almost 13,000 of them are Tesla superchargers. In terms of location and power availability, most of these charging stations are built for light-duty vehicles, although some might be suitable for the overnight charging of MD vehicles.

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However, due to the high-energy demands of HD vehicles—often power charging of >50 kW—the existing charging infrastructure may not be sufficient. Today, an average Class 8 electric truck consumes about 2 kWh per mile, meaning that for an electric line haul truck to operate similarly to its diesel counterpart, it will need approximately 660 kWh of electricity a day. Even if overnight charging (~8 hours) is feasible, charging power of more than 80 kW is needed. This significantly exceeds the existing charging capacities for light-duty vehicles. Therefore, unlike the traditional gas station business models that work for both light- and heavy-duty vehicles, charging infrastructure models for MD/HD vehicles may vary from those that serve light-duty vehicles.

MD/HD electric vehicles use two primary charging models: depot charging and on-route charging. Base-duty cycles (e.g., delivery vehicles) often utilize depot charging, whereas more intensive interregional freight trucks that go longer distances require on-route charging. Depending on the type of MD/HD vehicle, chargers are either located at a central home base such as a warehouse, distribution center, or a headquarter where trucks start from and return to each day; at the customer’s site, which allow return-to-base vehicles with long routes to charge while unloading; or on major freight corridors using public charging infrastructure. Of course, there are only limited options for depot charging locations and the utilization of these chargers could vary significantly depending on the duty cycle and dwelling time of vehicles within that fleet. However, this is not necessarily the case for public charging infrastructure. Therefore, proper siting of these chargers plays a very important role in the economics of such stations.

Factors to consider when siting public charging infrastructure for MD/HD vehicles

Utilization

First and foremost, it is crucial to optimize charging infrastructure locations for maximum utility. Here, utility means how often charging stations are being used. To maximize the utilization, one needs to know where vehicles are most likely traveling, at what point in their route they need charging, and how much time they can allocate to recharge. Luckily, with the advent of transportation data analytics, also known as big data, we can answer most of these questions using origin-destination, dwelling time, and trip length information. For example, one can use data to highlight areas with high traffic of MD/HD vehicles that originated from locations more than 100 miles away that are likely going to have more than a couple of hours of dwelling time (e.g., truck stops). Using a scoring algorithm, one can rank locations based on their likely utility and consider those likely to have the highest utilization for building EV MD/HD charging infrastructure.

Grid interconnection and capacity

As noted earlier, MD/HD vehicles have higher energy needs, and high-power charging stations (often greater than 50 kW) are needed to support these vehicles. Determining the proper location of charging stations for MD/HD vehicles is often limited by the availability of grid interconnection and capacity. Currently, there are various programs offered by utilities to help MD/HD fleets to install charging infrastructure at their depots. For example, the San Diego Gas & Electric Power Your Drive for Fleets and Pacific Gas & Electric (PG&E) EV fleet programs are designed to help MD/HD fleets operating in their service territory to install make-ready charging infrastructure. However, if significant improvement to the grid system is needed, or if the grid does not have the capacity to provide the power needed for a public charging infrastructure, the process to make a site ready could take a much longer and become more costly. Therefore, when siting a public charging infrastructure, it is critical to have a thorough assessment of the grid capacity. Integration Capacity Analyses and supporting distribution system maps are often one of the most useful tools to assess the appropriateness of a location with respect to grid capacity and interconnection availability. These maps provide a snapshot of the conditions on a utility’s distribution grid that reflect its ability to host additional distributed energy resources, such as electric vehicle charging stations, at specific locations on the grid.

Vehicle mileage and battery charging range

In deciding the optimal locations of public charging infrastructure, it is critical to have a good grasp of the mileage range of existing and potential future technologies operating in the region. Unlike gasoline and diesel vehicles, it is often recommended to operate electric vehicles within a state-of-charge range that does not go too low in discharge nor too high when recharging. Considering that the battery-electric technology for MD/HD vehicles is rapidly evolving—and future models are expected to have much longer ranges—it is critical to consider the expected future electric ranges to determine the maximum possible distance between charging stations. This could certainly serve as a key factor when determining how densely populated this network of chargers should be.

Equity

When siting charging infrastructure for MD/HD vehicles, we need to ensure that the deployment of this infrastructure will have direct benefits in low-income and disadvantaged communities. As discussed earlier, these communities often bear the burden of air pollution from freight transportation. Prioritizing equity does not always translate to placing chargers within disadvantaged communities, but the focus should be on how to maximize zero-emission operation within these communities. Similar to the approaches for maximizing utilization of charging infrastructure, big data can be instrumental in determining the strategic placement of charging infrastructure to attract a higher fraction of zero-emission vehicles in underserved communities

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Other factors such as space constraints, permitting requirements, and system resiliency should also be considered when siting EV charging infrastructure for MD/HD vehicles. As noted in our recent article on the cost of EV charging infrastructure, building a network of DCFCs could be very costly. In California alone, which has 15% of the U.S. MD/HD vehicle market, there will be a need for more than 157,000 DCFCs by 2030 to support the upcoming wave of electric MD/HD vehicles. According to our estimates, such a network of charging infrastructure could cost more than $15 billion over the next 10 years. That is twice the amount of funding the federal government allocated through the Infrastructure Investment and Jobs Act.

This is not to say that that building such a network is impossible. But we emphasize how critical it is to properly site EV charging infrastructure for facilitating the much-needed transition to zero-emission transportation in this decade and ensure that the economics will work for both fleets and charging infrastructure providers. We provide commercial fleets and local, state, and federal agencies with robust methodologies and tools, as well as sophisticated data analytics, to help them optimize charging infrastructure deployment efforts. With the use of big data, our capabilities expand and further our mission of helping clients to get the biggest bang for their buck when it comes to charging infrastructure deployment.

Meet the author

Sam Pournazeri, Director, Clean Transportation and Energy

Sam is a nationally recognized transportation and energy expert with more than 10 years of experience in air quality and climate change planning and policy development. View bio

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