Key takeaways
- Gabriel Collins argues that an electric pickup able to tow like a Ford F-250 would need a battery weighing as much as a Ford F-150 Raptor.
- Collins describes electric vehicles as having the power-to-weight ratio of an aircraft but the onboard fuel of a subcompact car.
- Collins says his two electric vehicle presentations are each about 3.5 years old, yet the underlying physics-based challenges still largely hold true.
- Collins republished the presentations to give a brand- and vehicle-agnostic perspective on the emerging electric truck competition among automakers.
I’m embedding two presentations here that are relevant to ongoing electric vehicle discussions–especially with the emerging electric truck competition between various OEMs. They are each about 3.5 years old, but the fundamental underlying physics-based challenges still largely hold true as far as I can tell. As such, wanted to refloat them in the hope they contribute to ongoing debates by providing broader, brand and vehicle-agnostic perspective.
Presentation 1: Want an Electric Pickup to Tow Like a Ford F-250? You’ll
Need a Battery That Weighs As Much As an F-150 Raptor
Presentation 2: EVs = Power-to-Weight Ratio of an Aircraft, Onboard Fuel of a Subcompact Car
Summary
Two January 2020 Baker Institute research presentations by Gabriel Collins test whether electric pickups and SUVs can match gasoline and diesel trucks at towing and hauling. High-end EVs have power-to-weight ratios like turboprop aircraft but carry little onboard energy: even after adjusting for efficiency, gasoline and diesel vehicles hold about twice the usable onboard energy, and usable jet fuel stores about 23 times more energy per kilogram than a lithium-ion pack. Modeling Tesla’s Cybertruck, Collins finds that a pickup able to tow like a Ford F-250 would need a battery weighing about as much as a Ford F-150 Raptor (5,500 lb curb weight). A 10% cut in trailer drag reduces energy use per mile by about 5.3%, cold weather can cut EV range by 41% according to AAA, and trailer owners’ sunk costs and pack energy densities of 0.09–0.21 kWh/kg remain key constraints.
Full text of both presentations (from the PDFs)
Want an Electric Pickup to Tow Like a Ford F-250? (28 January 2020)
Slide 1. Gabriel Collins, J.D.
Baker Botts Fellow for Energy & Environmental Regulatory Affairs
Baker Institute for Public Policy, Rice University
Please cite as: Gabriel Collins, “Want an Electric Pickup to Tow Like a Ford F-250? You’ll Need a Battery That Weighs As Much As An F-150 Raptor,” Baker Institute Research Presentation, 28 January 2020, Houston, TX
Want an Electric Pickup to Tow Like a Ford F-250? You’ll
Need a Battery That Weighs As Much As an F-150 Raptor
*Note: These are working research findings and are subject to change. In the event of material developments, the author will post an updated version.*
Slide 2. Disclaimer
This analysis reflects my personal opinions and assessments only. It is designed solely to be illustrative and stimulate broader thought, with the objective of elevating the conversation in the energy and water space. It IS NOT an investment analysis or investment advice. It is also NOT offering any legal opinions or advice and does not create an attorney-client relationship with any reader or consumer of the information presented herein. Readers rely on the information in this analysis at their own risk. Neither the author nor the Baker Institute for Public Policy are liable for any loss or damage caused by a reader’s reliance on information contained in any of the charts, data series, opinions, or other information presented herein. I am not a hydrologist, geologist, or engineer and am not offering advice on technical aspects of any assets which may be discussed in this analysis, including, but not limited to geological factors and engineering challenges that may arise in an oilfield water development project, vehicle powertrain design, and other subject matter areas. The information and opinions contained in, and expressed by this analysis, are based on sources deemed reliable. However, there is no warranty, assurance, or guarantee, express or implied, about the completeness, reliability, or accuracy of this content. The views expressed herein are my interpretations as of the date the report is published and are subject to change without notice.
Slide 3. Why Engage The Electric Pickup and SUV Question Now?
• SUVs and trucks are what most consumers actually want, whether in the U.S., China, or other major global auto markets.
• Consumers are unlikely to “trade down” for an EV. In other words, someone who drives an ICE pickup or SUV now will likely want an EV of similar size and capability, not a small electric sedan. Manufacturers will seek to facilitate lateral trades within popular, high profit margin vehicle classes.
• 2020 marks the beginning of a critical period for determining how well EVs will be able to scale across key consumer segments, particularly SUVs and pickup trucks.
Multiple Manufacturers Aim to Bring New Electric Pickups and SUVs to Market in Next 2 Years
2H2015 1H2016 2H2016 1H2017 2H2017 1H2018 2H2018 1H2019 2H2019 1H2020 2H2020 1H2021 2H2021 1H2022 2H2022 1H2023 2H2023 MSRP
Tesla Model $125,000
Jaguar I-Pace $72,000
Hyundai Kona EV $41,400
Audi E-Tron (Premium Plus) $74,800
Ford Mach-E (extended range) $50,000
Lordstown Motors Endurance $52,500
Rivian R1T $69,000
Rivian R1S $72,500
Tesla Model Y (Long Range Dual Motor All-Wheel Drive $52,000
General Motors pickup Unknown
Ford Electric F-150 Unknown
Bollinger Motors B1 $125,000
Bollinger Motors B2 $125,000
Tesla Cybertruck (tri-motor AWD) $79,000
Ford Lincoln electric SUV 1 1 1 1 Unknown
Source: Company Reports, Kelly Blue Book, InsideEVs, Reuters
• Tesla’s Model X has been the dominant electric SUV to date, but likely sells less than 40k vehicles per year. Tesla reported a total of 66,672 S and X vehicles delivered in 2019. Will the market have greater demand for SUVs and trucks below Tesla’s six-figure Model X price point? 2020 is likely to begin shedding light on the scale of true consumer demand as more electric SUVs and trucks become available.
Slide 4. Estimated Cybertruck Battery Pack Weight-to-Range Assuming
Energy Density of Current Tesla Batteries (0.17 kWh/kg) Cybertruck Battery Pack Weight @ 25% Higher Energy Density
Electric Full-Size/HD Pickups or SUVs Will Need Large, Heavy Battery Packs to Approach
ICE Vehicle Tow/Haul Capabilities
2020 Tacoma TRD Pro:
4,425 lb curb weight
• Battery mass exacerbates the EV towing/hauling disadvantage because a battery which does not get lighter even as the engines drain it of energy. This battery burden thus constantly counts against a vehicle’s load carrying capacity and may also worsen efficiency as more of it becomes dead weight upon discharging electrons during a journey.
Source: CarMax, CleanTecnica, Ford, Author’s Analysis
202020 F-150 Raptor:
5,500 lbs’ curb weight
Slide 5. Estimated CyberTruck Towing Energy Consumption
• More weight and/or drag = more energy use is a physical reality that applies to all vehicles regardless of fuel type. But with batteries, the weight/energy ratio gives much less leeway than a gasoline or diesel-powered vehicle enjoys.
• The drag coefficient is very important, as a 10% reduction reduces energy use (and the battery capacity required) by about 5%, all else held equal.
So it is possible to at least partially engineer around the EV range problem insofar as some future trailer buyers are concerned.
Estimated Energy Use of Tesla CyberTruck, kWh/mile, Towing and Naked
Source: CleanTecnica (Bower), Author’s Estimates
Slide 6. CyberTruck Energy Use Model
Slide 7. CyberTruck Model Methodology
• My model draws very heavily from the style and parameters of a model published on the insideevs.com website in December 2019 by an engineer named George Bower in collaboration with, Keith Ritter, another engineer. The article is titled “Detailed Modeling: Tesla Cybertruck 500-Mile Tri-Motor Battery & HP,” was published on 10 December 2019, and was accessed at https://insideevs.com/news/387046/tesla-cybertruckanalysis-battery-horsepower/.
• To the extent possible, I have sought to triangulate and cross-check the information and assumption Messrs.
Bower and Ritter used. I’ve also made some adjustments of my own, since this model aims to assess likely energy needs of a CyberTruck for towing. That said, I am an attorney and commodity analyst attempting a trek into the engineers’ domain and any errors in assumptions and/or calculations are mine alone.
• The biggest area of additions came from the assumptions I made regarding the mass and drag coefficient of trailers that a CyberTruck might tow. A tractor trailer likely has a drag efficient in the range of 0.96 and a bus would be 0.6 to 0.8 (https://www.engineeringtoolbox.com/drag-coefficient-d_627.html). My model assumes the trailer pulled by the truck would have a Cd of 0.5 and a net frontal area (I.e. the portion not drafting in the towing vehicle’s slipstream) of 35 square feet, yielding a total surface area of 67 square feet and a weighted average Cd of 0.42 based on the CyberTruck’s estimated Cd of 0.33.
• The drag assumption is perhaps the single most significant source of potential error in the model. If the CyberTruck turns out to be more aerodynamic and manufacturers develop a more streamlined set of trailers optimized for EV towing, energy use per mile could be reduced significantly. For instance, my model suggests a 10% reduction in the trailer’s Cd would reduce electricity use per mile by about 5.3%, on par with the drag sensitivity Bower and Ritter obtained in their modelling.
Slide 8. Key Factors Influencing Battery Range and “Right-Sizing” For an Application
• The rolling resistance of tires and battery capacity loss due to unfavorable external temperatures will also influence tow/haul range and how large a battery may be to build in sufficient margins to satisfy drivers.
• A 2019 AAA study found that at temperatures of 20 degrees Fahrenheit, electric vehicles that used their HVAC system on average suffered a 41% decline in driving range.
• Models tested were 2018 BMW i3s, 2018 Chevrolet Bolt, 2018 Nissan Leaf, 2017 Tesla Model S 75D, and 2017 Volkswagen e-Golf. Report can be downloaded at: https://newsroom.aaa.com/2019/02/cold-weather-reduceselectric-vehicle-range/
• The legacy challenge posed by trailer owners’ sunk costs also matters. Trailers are a capital asset that in some instances cost as much or more than the trucks that tow them. Consider, for instance, Airstream travel trailers that in their most basic form cost around $40,000 and for larger versions, can exceed
$115,000 per unit. Buying a new trailer or retrofitting older ones is possible, but poses an expensive barrier to becoming more aerodynamic and is likely one that many users will be unwilling or simply unable to cross. Even utility trailers often cost $5k to $10k per unit new, and for more aerodynamic versions, could cost substantially more due to additional material needs and design inputs.
• Accordingly, for the existing fleet of trailers in the US and beyond, immediate capital asset turnover will likely be not economically feasible.
Source: AAA, Quadratec
Slide 9. Battery + Pack Energy Density Data
Vehicle Battery Type Total Battery + Pack
Mass, Kg Battery Capacity (kWh) kWh/kg Kg/kWh eDumper dump truck li-ion NMC 8,000 700 0.09 11.43
Caterpillar/Pon excavator li-ion 3,400 300 0.09 11.33
Tesla Power Wall li-ion 114 14 0.12 8.44
Tesla P100D li-ion 619 100 0.16 6.19
Tesla Model 3 LR li-ion 478 80 0.17 5.95
Alta Motors Redshift
MX Motocross Bike li-ion 32 6 0.18 5.48
Tesla Semi (estimated) li-ion 4,809 1,000 0.21 4.81
Source: Cycleworld, Elektrek, InsideEVs, Tesla
Source: https://www.cyclenews.com/2018/08/article/2019-alta-redshift-exr-first-impression/ The Highest Existing EV Battery + Pack Energy Density I Could Find: Alta Motors
Slide 10. Developments That Could Influence Our Thinking
1. The first Tesla Cybertruck owners use their trucks to tow/haul and share the resulting energy use and range data.
2. Tinkerers tear down a Rivian R1T battery pack and give the public a first look at what an e-pickup battery looks like in terms of weight, cooling, housing, etc. This could conceivably happen within the next 12 months (i.e. by January 2021)
3. Trailer manufacturers choose to invest serious money and effort into developing lower-drag trailers optimized for EV towing.
There could be a sizeable market because low-drag trailers would also be beneficial to people using traditional ICE pickups and SUVs.
4. Truck owners capable of affording two vehicles decide to keep an ICE truck for tow/haul applications and use their electric steeds as daily drivers. This would already mirror a pattern among many Tesla car owners who maintain a multiple vehicle household mixing ICE and electric propulsion.
5. Advances in tire technology reduce rolling resistance and increase range for a given battery size.
Cybertruck’s Shape Suggests a “Skateboard”
Type Battery Pack Configuration
Source: Tesla, Rivian
Slide 11. Baker Institute Electric Vehicle and Transportation Research Bibliography
1) Gabriel Collins, “The EV Conundrum: High Power Density and Low Energy Density,” Baker Institute Research
Presentation, 8 January 2020, Houston, TX, https://www.bakerinstitute.org/research/high-end-electricvehicles-power-weight-ratio-aircraft-onboard-fuel-subcompact-car/ 2) Gabriel Collins, “Low-Speed Electric Vehicles: An Underappreciated Threat to Gasoline Demand in China and Global Oil Prices?,” Issue Brief, 15 May 2019, Baker Institute for Public Policy, Houston, Texas, https://www.bakerinstitute.org/research/low-speed-electric-vehicles-china/ 3) Gabriel Collins, “China’s Gasoline Demand Growth: Is Recent Deceleration Near-Term Noise or Early Stages of a Structural Shift?,” Baker Institute Research Presentation, March 2019, https://www.bakerinstitute.org/media/files/files/147628cc/ces-collins-china-gasoline-demand-032819.pdf
4) Gabriel Collins, “Addressing the Impacts of Oil & Gas Development on Texas Roads,” 20 April 2018, written testimony submitted to the Texas House of Representatives Transportation Committee. https://www.bakerinstitute.org/media/files/files/04c6f77b/collins-testimony-042018.pdf
The EV Conundrum: High Power Density and Low Energy Density (8 January 2020)
Gabriel Collins, J.D. Baker Botts Fellow for Energy & Environmental Regulatory Affairs Baker Institute for Public Policy, Rice University
EVs = Power-to-Weight Ratio of an Aircraft, Onboard Fuel of a Subcompact Car
• Electric vehicles’ instant torque and high horsepower make the higher-end editions true performance monsters. Their power-to-weight ratios are often on par with turboprop aircraft and many helicopters.
• The fly in the ointment comes from the fact that batteries remain heavy and relative to hydrocarbons and simply cannot store energy nearly as efficiently per unit of mass.
• The power-to-weight/onboard energy density relationship of the Rivian R1T electric truck and A-29 Super Tucano attack aircraft is such that “Rivianizing” the Tucano would mean making its onboard jet fuel stores retain their current energy content, but weigh more per liter than lead metal. Needless to say, the plane’s flight endurance and carrying capacity would fall dramatically.
• This estimate assumes the A-29’s PT-6 turboprop has a thermal efficiency of about 35%–less than half the R1T’s likely capacity to convert fuel into actual propulsive energy.
Source: Beechcraft, Car & Driver, EIA, EV Database, GE, Global Security, Man, Nikola, Peterbuilt, Rivian, SNC, Trucks.com, USAF, US Navy
Please cite as: Gabriel Collins, “The EV Conundrum: High Power Density and Low Energy Density,” Baker Institute Research Presentation, 8 January 2020, Houston, TX
Super Tucano (17) and Rivian R1T (14)
Big, long-range platforms
Gabriel Collins, J.D. Baker Botts Fellow for Energy & Environmental Regulatory Affairs Baker Institute for Public Policy, Rice University
Please cite as: Gabriel Collins, “The EV Conundrum: High Power Density and Low Energy Density,” Baker Institute Research Presentation, 8 January 2020, Houston, TX
Electric Vehicles’ Onboard Energy Still Significantly Trails ICE Vehicles On an Efficiency-Adjusted Basis
• To make the energy density comparison a bit more fair, we adjust the onboard fuel based on the fact that EVs convert nearly 80% of their battery energy into tractive power at the wheels, while IC vehicles feature efficiencies closer to 20%. (US DOE)
• But even with the adjustment, vehicles running on gasoline or diesel fuel still have about twice the onboard energy density of an EV.
• Battery energy densities have improved in recent years, but a near-term doubling of energy density is unlikely.
• IC vehicles also recharge much more quickly, needing around 5 minutes to fill up even a large pickup truck tank, whereas a state of the art Tesla V3 Supercharger still likely needs about 20 minutes to completely charge a 100 kWh battery pack. In real life, few drivers wait until their tank is nearly empty to fill up and EV drivers will also likely top up in a somewhat similar fashion, but the significant filling speed differential still endures as a matter of electrochemistry. (https://www.tesla.com/blog/introducing-v3-supercharging)
Source: Carmudi Phillippines, Car & Driver, Chevrolet, EIA, EV Database, fueleconomy.gov, Rivian
Efficiency-Adjusted Comparison
Supercar power to weight ratios, but tiny “gas tanks.”
Jet Fuel Density Adjustment Calculations
• JP-5 jet fuel contains a minimum energy content of 18,300 BTU/lb, or 40,333 BTU/kg. This equates to 11.8 kWh of energy per kg (40,333 BTU ÷ 3,412 BTU/kWh) (Source 1)
• A turboprop engine like that of the A-29 Super Tucano likely operates with a thermodynamic efficiency of approximately 35% (Source 2)
• This in turn yields a “usable” JP-5 energy content of 3.5 kWh/kg (11.8 kWh * 35% thermo efficiency * 0.85 fuel tank weight penalty) and 2.7 kWh/liter (3.5 kWh/kg * 0.778 kg/liter JP-5 density).
• The Panasonic 2170 battery cells used in Tesla’s Model 3 have a volume of 24.25 cm^3, weigh 0.07 kg apiece, and contain 0.0173 kWh of energy apiece (Source 3). As such, they have a density of 2.9 g/cm^3 and a weight-based energy density of 0.25 kWh/kg, which after imposing a 25% weight penalty for battery pack housing, cooling systems, and other components, yields an energy density of 0.19 kWh/kg. Assuming an EV is 80% efficient in transferring fuel energy into motive force, the “usable” energy density of the pack would thus be 0.15 kWh/kg.
• As such, the JP-5 fuel’s “usable” energy density in mass terms is 23 times higher than the lithium-ion battery’s (3.5 kWh/kg ÷ 0.15 kWh/kg). Taking the JP-5’s actual density of 0.778 g/cm^3 and multiplying it by 23 to impose the energy density weight penalty would yield 17.9 g/cm^3, nearly 60% higher than the density of lead metal (11.3 g/cm^3).
• Source 1: (National Research Council (US) Subcommittee on Permissible Exposure Levels for Military Fuels. Washington (DC): National Academies Press (US); 1996. 2, Physical and Chemical Properties of Military Fuels, https://www.ncbi.nlm.nih.gov/books/NBK231234/
• Source 2: National Academies of Sciences, Engineering, and Medicine. 2016. Commercial Aircraft Propulsion and Energy Systems Research: Reducing Global Carbon Emissions. Washington, DC: The National Academies Press. https://doi.org/10.17226/23490.
• Source 3: Kyle Field, Tesla Model 3 Battery Pack & Battery Cell Teardown Highlights Performance Improvements, CleanTecnica, 28 January 2019, https://cleantechnica.com/2019/01/28/tesla-model-3-battery-pack-cell-teardown-highlights-performance-improvements/
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