Electric Vehicles, Energy Storage, Executive Insight

The dichotomy of fast charging batteries for EVs in today’s infrastructure

Manufacturers and soon-to-be-owners of long-haul electric trucks want it all: long range; power delivered at any time; fast charging to maximize vehicle utilization rate; competitive price; and safety.

For electric trucks today, it is not possible to meet all these elements at the same time. Like the adage, “you can’t have it good, fast, and cheap; you need to choose two.” In this case, you may be able to choose three but not all.

Fast charging needs are primarily based on increasing vehicle utilization rate and to decrease ‘range anxiety.’

eTruck owners and manufacturers want to charge their large battery stacks quickly. This entails currently unavailable battery technology that could charge without heating up; without sacrificing longevity; and, without performance degradation.

They want to be able to do so anywhere. This implies a widely deployed, distributed fast charging network. For this to be feasible, high energy charging stations would have to be installed at the beginning of the route, along the various routes, and at various destinations. We need to also consider that each station will service multiple trucks or cars at the same time. As a result, fast charging stations will affect supply quality and grid capacity even at small penetration level.

Is this feasible? Of course! But, with lots of time, lots of planning and large capital investment. Also, truck owners should expect to pay a premium price per kW for the demand charges unless the available energy is locally produced or time-shifted using energy storage.

Today, a 500-kWh fast-charging energy pack powering a large truck for a long range (>300 miles) is an aspirational goal better suited for the next generation of trucks rather than current designs.

Needed: Flexibility

We are currently undergoing a (swift) transition from ICE towards electrified transportation. For trucks, current alternatives provide limitations that can be overcome provided some flexibility is involved.

Truck manufacturers will need to consider the suitability of current battery technologies to match the specific application.

First, charging infrastructure will be mostly centrally located at the beginning and end of the routes. To contain demand charges, these depots will have high capacity energy storage systems charging their batteries with low-cost energy during off-peak hours to be dispensed any time during the day or night when the truck arrives.

Second, when power is required resulting in batteries depleting faster, vehicle range will be more limited, and recharging will take place more often. Overcoming this requires oversizing the battery packs and increasing the vehicle weight, which limits payload size. For short term, last-mile applications, power and fast charging may be viable. However, battery life will be shorter and corresponding replacement and O&M cost needs to be accounted for.

Third, safety should continue to be a paramount concern even above power requirements. Quality battery selection is key to insure the important investment in the truck is preserved for a long time. Risking thermal runaway events (the possibility that a battery will catch fire due to short circuiting caused by manufacturing defects) on trucks with impact to human life and cargo should be minimized at all cost.

Existing solid-state battery technology offers a compromise: long range; consistent energy delivery; high degree of safety, performance and availability of energy; durability; and moderate power. Because of their chemistry, solid-state batteries will not catch fire, have full charge availability, and a wide range of operating temperatures without compromising their warranty.

We can see from the above that there is no one-size-fits-all solution for mobility storage. For the short and medium term, while some applications may benefit from fast-charging batteries, performance and economics seem to dictate that energy batteries provide a reasonable scenario for most truck applications not requiring power.

REFERENCES

  • Distribution Grid Impact of Plug-in Electric Vehicles Charging at Fast Charging Stations Using Stochastic Charging Model. Kalid Yunus, Hector Zelaya De La Parra, and Muhamad Reza.
  • Charging the Future: Challenges and Opportunities for Electric Vehicle Adoption. www.hks.harvard.edu. Henry Lee, and Alex Clark.
  • A tale of two grids: How California and Texas are preparing for the EV revolution – Todd Davidson, Dave Tuttle, Joshua D. Rhodes and Kazunori Nagasawa | www.greenbiz.com