The Robotaxi Rollout #2: The Charging Hub Hurdle

The Robotaxi Rollout #2: The Charging Hub Hurdle

In our previous article, we discussed many of the unseen challenges required to support a sizeable AV fleet and how manual charging can significantly drive-up operating costs due to the large amount of people required to keep a fleet on the road. Now let’s look at some other parts of the equation.

Maximizing Dollars per Charge

If you’re a robotaxi company, there’s one guiding principal that you live by:

Money is Earned on the Road

Which means charging = NOT being on the road, earning money!

An Uber driver can generate $50 - $70 in revenue in an hour, so not being on the road is expensive for a robotaxi service. Charging should require as little time as possible with fast charging being a critical component of the operation.

But wait, there’s more: when a robotaxi needs to charge, it needs to navigate back to a charging hub. This is called transit time. Transit time results in dead miles – driving without earning money, as a vehicle making it’s way back to a charging hub can’t carry passengers. If a vehicle takes several hours to travel across town or in rush hour traffic (both a very real possibility in cities like LA) that’s a long time for it to be out of operation and not earning money!

So if we accept: 

• Money is earned on the road
• Charging = NOT being on the road
• Transit time to charging station = dead miles and therefore effectively also not being “on the road”

The location of these charging sites is critical to the efficiency and profitability of a robotaxi fleet.

The Large Hub Model

Most robotaxi fleets will be supported by 2 – 3 charging hubs located around the city. Given the footprint of many cities in the US, they could be as much as 15 miles apart. This distance plus the below average speed that robotaxis must travel in traffic means that those 2 – 3 hubs are introducing a large number of dead miles. So how do you reduce dead miles and increase money earned on the road? Ideally, you want charging hubs on every street corner, allowing robotaxis to easily charge between fares thus decreasing transit time and dead miles.

Easier than it sounds, unfortunately. Building a charging hub is an extremely lengthy and expensive process:

• A large hub (50+ stalls) would require a 5 - 7 megawatt electricity connection.
• A local utility could take 3 - 4 years to deliver that much power to your site, if it’s possible at all.
• Plus, there’s the cost of installation, construction and permitting, which could run into the millions.

So, it can be very difficult to find suitable locations for a hub.

In addition, finding large sites that can accommodate a fleet of vehicles is not that easy in most urban areas, and obtaining permits for large sites is also a very lengthy (and costly) process. So, building more hubs starts to sound like a very daunting project with a lot of complexities. The landscape looks something like this:

Utilizing Local Charging

So, what’s the solution? Building smaller hubs or utilizing charging stations in residential areas may be a lower barrier to entry. Creating a business model that allows robotaxis to utilize available chargers at residential or commercial properties would both reduce dead miles and provide more convenient transportation options for people at those locations. The charge speed would vary depending on the type of charger, but this could be offset by allowing them to charge more often and in more locations. You would also need to automate the charging process, either through robotics or, since the power level is low, induction charging. At a high volume, both options may be suitable solutions, however robotics would be the more cost-effective option and would not require significant modification to vehicles, charging equipment, or infrastructure.

The main aspect is to figure out a business model where people would allow robotaxis to charge at their residential or commercial property. Maybe this can be solved with some kind of revenue share model or a co-ownership model where people partially own the vehicle, as Tesla is suggesting.

Either way, at these locations you are charging at a slower rate (4-8 hours roughly). For a dedicated robotaxi service this means lost revenue. So, this model might be best utilized to support existing charging routines – supplementing existing hubs during non-peak hours.

Hands-Free Micro Hubs with Fast Charging

With robotic attendants as introduced in the previous blogpost, you can build a smaller robotaxi charging hub almost anywhere. For example, by creating smaller charging hubs, which can automatically charge 2 - 4 vehicles in parallel through a robotic attendant, the power requirements stay in the few hundreds of kilowatts. This kind of power is available at many commercial properties such office buildings, parking garages industrial sites, etc. and the space requirement for the station would be much smaller, opening up more potential locations. This formula could potentially be scaled very quickly!

Let’s call this concept an AV micro hub. This concept could cover a city quickly and provide a very flexible charging backbone for a robotaxi fleet. It has fast charging capability (30-60 mins.), is easy to implement at many locations, and, as it is served by a robotic attendant, could be operated in numerous locations with a suitable grid connection, which at this power level is not too difficult to find. A denser network of automated AV micro hubs with fast charging capability could be a big opportunity in eliminating transit time to charge, and therefore optimize the ROI for a robotaxi operator. We will explore this concept further in a next post.

While there are numerous challenges to charging a robotaxi fleet, as this industry continues to evolve, new solutions come to the forefront. In this series we’ll continue to explore robotaxis and the charging methods that will keep this industry in motion. 

More about Hands-Free Charging for Robotaxis >