With the current state of battery technology, electric trucks face a trade-off. For every additional kWh of storage capacity – and therefore every additional unit of range – the weight of the battery must increase, and therefore the weight of the truck’s payload must decrease. Due to this trade-off, current trucks on the market attempt to find a balance: maximizing the amount of payload that the truck can carry, while also including a battery large enough to accommodate a reasonable range. However, after this balance has been found, most electric trucks still have ranges between 200 and 600 miles – less than half of that of diesel trucks, which average between 1000 and 1500 miles.[1]Davis, Ben. “How Many Miles Can a Semi Truck Go on One Tank of Diesel?” MVOrganizing, February 1, 2021. https://www.mvorganizing.org/how-many-miles-can-a-semi-truck-go-on-one-tank-of-diesel.[2]Tesla Semi. “Tesla Semi.” Accessed November 19, 2021. https://www.tesla.com/semi.
Source: Inside EVs, 2018[3]InsideEVs. “Siemens EHighway in California | InsideEVs Photos.” Accessed November 18, 2021. https://insideevs.com/photo/3983283/first-us-ehighway-launched-in-california-by-siemens/.
For this reason, one of the most pressing problems with the widespread implementation of electric trucks is the limited range. In order to help accommodate for this, a catenary system, similar to systems under study in California and Germany, could be installed along the densest trucking routes in the US.[4]Kane, Mark. “First U.S. EHighway Launched In California By Siemens.” InsideEVs, January 31, 2018. https://insideevs.com/news/336589/first-us-ehighway-launched-in-california-by-siemens/.[5]Kane, Mark. “Germany: A5 Autobahn Gets Catenary Overhead Lines For XEV Trucks.” InsideEVs, August 22, 2020. https://insideevs.com/news/440388/germany-a5-autobahn-catenary-overhead-lines-trucks/.
Definition
A catenary system consists of overhead wires that run along the road, which trucks can connect to using a pantograph – essentially a mechanical arm, mounted on the roof of the truck, with the ability to clip to and unclip from the overhead wire. While trucks are connected to the wire, they can use the electricity to simultaneously power their motors and recharge their batteries. This reduces the frequency with which they have to stop to charge their batteries. It would be primarily useful for long-haul trucking, where drivers need to travel further than the range of their truck without stopping to load, unload, or take a break. Therefore, it’s specifically intended for long, continuous routes – in most other situations, trucks would be able to use a charging station instead.
Installation Plans and Economics
For maximum economic feasibility, catenary should be installed first on the routes with the greatest density of trucks. This ensures that all lines installed get as much use as possible, maximizing the return on the investment. As of 2015, there were about 6,000 miles of highway in the US considered “high-volume truck routes” – defined as routes that carried more than 8,500 trucks per day (see Figure 2).[6]U.S. Department of Transportation, Bureau of Transportation Statistics. “Freight Transportation System Extent & Use,” 2020. … Continue reading This number is predicted to approximately double by 2045. Nonetheless, it would make sense to first install catenary along the routes currently considered high-volume, since they will likely continue to be the highest volume routes, and then consider possible expansions after that.
Source: BTS 2017 Freight Facts and Figures[7]United States. Department Of Transportation. Bureau Of Transportation Statistics. “Freight Facts and Figures 2017,” 2018. https://doi.org/10.21949/1501488.
The cost per mile is estimated at $1,800,000, making the total cost to install catenary along 6000 miles of road about $10.8 billion.[8]Zhao, Hengbing, Qian Wang, Lewis Fulton, Miguel Jaller, and Andrew Burke. “A Comparison of Zero-Emission Highway Trucking Technologies,” October 18, 2018. https://doi.org/10.7922/G2FQ9TS7. Like the other parts of the Trucks plan, this cost would be distributed over the entire timeline, costing about $470 million per year for 23 years.
In addition to the catenary lines, this system would require trucks to have pantographs installed, compatible with the catenary lines. This problem is currently being worked on by Siemens and Continental, two railway companies with experience building pantographs for trains.[9]Sustainable Truck&Van. “Pantographs for Trucks? Siemens Mobility and Continental Will Work on the so-Called EHighway Technology.” Sustainable Truck&Van, July 29, 2021. … Continue reading However, costs of existing pantographs are quite high, estimated at $42,000 per truck.[10]Mareev, Ivan, and Dirk Uwe Sauer. “Energy Consumption and Life Cycle Costs of Overhead Catenary Heavy-Duty Trucks for Long-Haul Transportation.” Energies 11, no. 12 (December 2018): 3446. … Continue reading These prices are expected to come down with economies of scale and improvement of the technology, but until this happens, this will be a trade-off decided by trucking companies – a high cost, but with the benefit of a significantly improved range. During the early adoption period, the subsidies provided for electric truck purchases will help to cover this cost.
Political Considerations
In addition to economic concerns, the installation of catenary lines across the country is something that may also pose political concerns. States may oppose the installation of catenary along highways within their borders. This could be due to concerns around noise or aesthetics, or it could simply be due to the cost. These are valid considerations, though like with any construction project, they are most likely costs that must be taken. However, there are also a number of incentives for states to support catenary installation:
- Reduced air pollution, since trucks will be electric instead of diesel or gasoline
- Attracts companies with electric trucks; for example, if a major retail chain electrifies its fleet, it may prefer to build stores in states with catenary installed
- Helps manage traffic flow on highways – if trucks are confined to a specific lane, this could help reduce congestion
The cost of catenary is also something that could pose political conflict, due to budgeting concerns and lack of public funds. It is possible that industry would be willing to take over catenary installation: for example, Siemens and Continental, as previously mentioned, are currently working together on developing scalable catenary infrastructure. However, in order to ensure that the private sector does step up, an incentive program would be important. To determine the amounts and timeline of this program, it would be necessary to gain a better understanding of the cost and the willingness of the private sector to make the needed investments. In addition to incentives, federal intervention might be useful to ensure that all necessary permits are acquired, since the project involves building over many state lines.
Untested Technology
Since catenary is still a relatively untested technology, there are still many unanswered questions about its cost, feasibility, and potential issues. For this reason, it should be closely studied as it is implemented. Relative to the other components of this plan, catenary is still fairly low-cost, so the first few hundred miles could be used as a test case to determine its feasibility on a more widespread scale. In particular, the rapid development of battery technology could render catenary obsolete, if batteries become light and cheap enough to significantly extend electric truck ranges. In light of this, a discussion should be had with trucking companies and government entities to determine whether catenary is truly an important part of this proposal. If it is required to ensure the rapid adoption of electric vehicles, then the cost may be worth it. If battery technology improves quickly over enough the timescale of this plan, or if the current ranges of electric trucks are deemed sufficient, then catenary may not be necessary. Regardless, it is presented here as the best solution to range concerns that makes use of currently available technology.
Take-Aways
- Catenary is considered as a potential solution to range concerns with electric vehicles
- The plan accounts for about 6,000 miles of catenary, with an estimated cost of $10.8 billion
- This solution remains fairly untested, and should be carefully studied during early stages of its implementation
References
