What impacts can large-scale fleets of electric vehicles (EVs) have on the power delivery system? That question has generated a great deal of interest, but it’s a tricky subject to concentrate on adequately. For this discussion let’s limit the focus to the electrification of the medium- and heavy-duty vehicles (MHDVs) used for the last-mile delivery fleet. Everyday fleets of trucks and vans burn a great deal of fossil-fuels making deliveries to homes and businesses, which seems ripe for electrification.
According to the World Economic Forum approximately one-third of the total shipping costs are attributed to local deliveries, which means there is a lot of incentive to find cost saving methods to achieve this last-mile task. There have been a lot of studies and reports focused on this sector. The findings make a great deal of sense business-wise, and that hasn’t been missed by Amazon, DHL, FedEx, Sysco, UPS, and others as they accelerate their efforts for electrification of their commercial vehicles.
Converting the MHDV transportation segment into an EV fleet will not be easy, but it has a lot going for it. It’s not hard to see why electrifying the MHDV fleet is getting so much attention. EV technology has matured to the extent that costs are declining while efficiencies are improving, and fossil-fuels are climbing. Also the daily operational characteristics of MHDV fleets needed for local delivery services are ideal for EVs to perform effectively.
It's Happening
Think about it, the typical delivery vehicle follows well defined routes day in and day out. They make frequent starts and stops, which would work well with EV regenerative breaking. They travel less than 200 miles (322 km) per-day, which is a sweet spot for EVs. At the end of the day they return to a central depot, and that is ideal for EV’s battery charging. These qualities are very important when it comes to the benefit-cost ratio, but there are other considerations.
Corporations are finding that announcing they are rolling out an EV delivery fleet is good for their business image because their customers are concerned with environment. There are many studies that show the benefits of MHDV fleets converting from internal combustion engines to EVs is good for the environment. One such study came from the EPA (US Environmental Protection Agency). It stated fossil-fueled MHDVs contributed 26% of greenhouse gas (GHG) emissions for the transportation sector, which is now the number one sector for overall GHG emissions.
Several states have been doing their own studies and have provided some interesting statistics. The Connecticut Department of Energy and Environmental Protection published a report in March 2022. The report said that MHDVs in Connecticut accounted for about 37% of the GHGs despite being only 6% of the on-road vehicle fleet. Several other states in the area also reported similar statics. In 2020, Massachusetts reported that MHDVs make up 3% of their on-road vehicles, but are responsible for 29% of the on-road CO2 emissions.
New York reported that trucks and buses make up 4% of their on-road vehicles, but those vehicles product 25% of their total transportation sector emissions. Interestingly, in May of 2022 six customer and conservation groups asked the New York Public Service Commission to address the issues surrounding the electrification of MHDVs. This should prove to be interesting as regulators get involved.
Low-Hanging Fruit
It seems like most authorities agree that electrification of the large-scale MHDV fleets roaming the streets of our cities and towns is a no brainer in the battle against GHG emissions and reducing the corporate carbon footprint. Some experts have even gone so far as to say it’s the low-hanging fruit, but what about the impact these MHDV fleets represent to the local power grid?
Don’t forget they require an enormous fleet charging infrastructure along with potential upgrades in specific portions of the transmission grid and the distribution network to support these fleet charging centers. There are, however, problems with this scenario. The operating characteristics of MHDV fleets vary as much as their locations do. The use patterns vary by fleet along with the fleet sizes and there is a good probability that the best location for these fleets is the worst case location on the power delivery system.
This is such a new phenomenon there hasn’t been a great deal of real-world study work performed, but that is changing. Last year, a joint investigation by National Grid and Hitachi Energy took place and the companies published the results of their study. It’s titled “The Road to Transportation Decarbonization: Understanding Grid Impacts of Electric Fleets,” and is available online. This report describes itself as, “A “bottom-up” analysis of what the long-term impacts of fleet electrification might look like on specific parts of the electric distribution system.” The paper has some remarkable insights into this timely subject and the issues affecting the electrification of the MHDV fleet.
Real-World Experience
Recently Charging Ahead had a chance to speak with Gary Rackliffe, vice president North America Market Development and Innovation and Bart Gaskey, senior vice president of Strategic Marketing and Business Development. These two gentlemen are Hitachi Energy’s experts on key emerging innovations in the utility landscape. The discussion brought up some interesting perspectives when it comes to large-scale EV fleet charging and the technology’s impact on utilities and the grid.
Gaskey led off the discussion saying, “There has been a tremendous amount of work done on the residential EV charging, but it’s happening in small incremental amounts. What is missing is the large-scale commercial and industrial MHDV EV fleet. To correct that situation, National Grid and Hitachi Energy performed field studies in one of the metropolitan cities in National Grid’s service territory. The city had more than 50 MHDV EV fleets operating in its metro area. These installations were mapped in respect to the actual electric distribution lines and substations serving them.”
Rackliffe added, “We found these MHDV fleets tended to be clustered in warehouse districts, and in many cases more than one fleet was on the same distribution circuit. That can add megawatts (MW) of additional demand to the circuit’s nightly off-peak load. The best way to describe it is to say it’s similar to a flock of birds coming home to roost at night, but in this case it’s a fleet MHDV EVs returning to the warehouse parking lot. When these vehicles are plugged into charging systems existing simple heating and lighting load become massive MW industrial spot loads.”
At this point, Rackliffe explained, “In one case the study found that a distribution circuit’s load was increased 60% above the circuit’s rated capability because of the EV charging cycle. That charging created a new peak demand in the middle of the night, which worsened when multiple fleets plugged in at the same time. Suddenly these circuits feeding commercial and industrial loads experienced a shift in peak demand that was not on anyone’s planning models.”
He pointed out, “As businesses continue to increase their EV fleets, the planning models for these impacted circuits will have to be modified. Substations and distribution circuits will have to be upgraded to meet the needs. There are, however, digital technologies available to lessen this impact on the power delivery system. One of those is an advanced energy management system that takes advantage of machine learning and modern communications technology to charge more EVs with less infrastructure.”
Rackliffe resumed, “It does this by utilizing intelligent charger hardware with sophisticated software. The system allows the operator to replace the traditional practice of charging every vehicle as soon as they return to the depot, at the distribution center, and are plugged into the charging infrastructure. Instead, the system spreads the charging load over the entire timeframe the vehicle is at the distribution center.”
He continued, “This intelligent software knows the charging characteristics of the vehicles, along with the capabilities of the charging infrastructure, and the distribution feeder it’s connected to, plus the amount of time available for each of the vehicles to be charged. By communicating with the grid and matching the load to the available circuit capacity the energy management system lets operators charge their large-scale fleets minimizing the additional load on the feeders.”
EV fleet sales are expected to continue to grow. Bloomberg New Energy Finance (BNEF 2021) projected that “EVs will grow to make up to more than 10% of commercial MHDV sales by 2030 and almost 30% by 2040.” So it is reasonable to expect operating issues will also grow proportionally. At the top of the EV MHDV problem list is charging. Fleet managers are concerned with demand charges, time-of-day rates, and charges for overconsumption of electricity resources.
It’s going to require a change of mindset by everyone involved, utilities, regulators, fleet owners, etc. Intelligent charging systems analyzing real-time big-data may be what’s needed to tame this latest onslaught to the electric grid. Can’t wait to see where this is going!
