With the current state of automotive electrification, predicting which electrification pathway is likely to be the most economical over a 10- to 30-year outlook is wrought with uncertainty. The development of a range of technologies should continue, including statically charged battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), plug-in hybrid electric vehicles (PHEVs), and EVs designed for a combination of plug-in and electric road system (ERS) supply. The most significant uncertainties are for the costs related to hydrogen supply, electrical supply, and battery life. This greatly is dependent on electrolyzers, fuel-cell costs, life spans and efficiencies, distribution and storage, and the price of renewable electricity. Green hydrogen will also be required as an industrial feedstock for difficult-to-decarbonize areas such as aviation and steel production, and for seasonal energy buffering in the grid. For ERSs, it is critical to understand how battery life will be affected by frequent cycling and the extent to which battery technology from hybrid vehicles can be applied. Unsettled Issues in Electrical Demand for Automotive Electrification Pathways dives into the most critical issues the mobility industry is facing. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2021004

While direct electrification appears to provide the most cost-effective route to decarbonization of commercial vehicles, uptake may be constrained by critical metal supply. Additionally, it will be many years before hydrogen power becomes decarbonized or if it can ever compete economically with direct electrification. An electric road system (ERS) could offer a highly efficient and cost-effective route to direct electrification that would greatly reduce the volume of batteries required, but pilot schemes are urgently needed to provide concrete data on operating costs for different ERS technologies. Furthermore, if plug-in hybrid electric vehicles could obtain most of their power from an ERS, liquid biofuels and “electrofuels” may prove useful for occasional off-grid range extension. To achieve extremely long-range for operation in remote locations, liquid fuels remain the only viable option. Unsettled Issues Regarding Power Options for Decarbonized Commercial Vehicles discusses the analysis required to understand the lifecycle energy use for different power options for decarbonized commercial vehicles. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2021021

Sustainable first/last/only-mile (FLO-mile) transport is the key to sustainable travel. It could directly replace private car use for short urban journeys, which account for 1% of global greenhouse gas emissions. More importantly, it could enable public transport to be used for longer journeys, which account for 6% of emissions. Active travel, such as walking and cycling, has the lowest emissions and provides huge economic benefits that pay for the required infrastructure many times over. Unsettled Issues Regarding First- and Last-Mile Transport discusses the mass switch to more sustainable modes of transport and how to increase their perceived value to users. It also covers the prioritization of publicly owned cycles over rideshare options due to the latter’s higher lifecycle emissions, including manufacture, redistribution, and service operations and station construction. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2021024

Power options for off-road vehicles differ substantially from other commercial vehicles. Battery electrification is suitable for urban construction and light agriculture, but remote mining, forestry, and road building operations will require alternative fuels. Decarbonized Power Options for Non-road Mobile Machinery discusses these domains as well as the potential benefits and challenges of implementing fuels and energy sources such as bioenergy, e-fuels, and alcohol, as well as hydrogen, hydrocarbon, and direct methanol fuel cells. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2023002

Replacing fossil-fueled vehicles with battery-electric ones is a risky strategy. It is likely to be limited by the supply of metals critical to battery and solar cell production, and the investment required in decarbonized electricity. Using hydrogen to store renewable energy would greatly reduce efficiency, further increasing the investment required to decarbonize the electricity supply. The lowest technical risk and most economical pathway to decarbonization is reducing private car use. Shorter journeys would be made by walking and cycling – also known as “active travel” – with public transport used for most longer journeys. Realizing this cultural change in transport behavior will first require comprehensive networks for safe and enjoyable active travel, which separate walking and cycling. All locations should connect to either a fully segregated cycleway or traffic calmed roadways with a maximum speed of 30 kph. Active travel investment can save money due to improved public health, eliminate the 11% of carbon emissions caused by short car journeys, and facilitate public transport by empowering people to reach their final destination. Bicycle manufacturing is growing rapidly and further innovations in transport cycles and other lightweight vehicles compatible with an active travel infrastructure will boost this growth. Increased use of public transportation is vital to efficiently use the limited availability of decarbonized electricity. Autonomous vehicles in private use may increase vehicle miles, but autonomous operation within public transportation systems could be transformative. The remaining private cars, buses, and heavy goods vehicles could be electrified more cost effectively using electric road systems. These enable unlimited range and smaller batteries, with the lowest societal cost of any private car-based decarbonization pathway. Although users may pay higher road tax or tolls for the infrastructure, this is easily offset by greatly reduced vehicle costs and improved efficiency. Electrification needs to be brought initially to city bus networks and heavily used transport corridors. Wider use will require standardization and investment at the federal level or continental level. NOTE: SAE EDGE™ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies of interest to the mobility industry. The goal of SAE EDGE™ Research Reports is to stimulate discussion and work in the hope of promoting and speeding resolution of identified issues. SAE EDGE™ Research Reports are not intended to resolve the issues they identify or close any topic to further scrutiny. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2020014

Electric road systems (ERS) enable dynamic charging—the most energy efficient and economical way to decarbonize road vehicles. ERS draw electrical power directly from the grid and enable vehicles with small batteries to operate without the need to stop for charging. The three main technologies (i.e., overhead catenary lines, road-bound conductive tracks, and inductive wireless systems in the road surface) are all technically proven; however, no highway system has been commercialized. Electric Road Systems for Dynamic Charging discusses the technical and economic advantages of dynamic charging and questions the current investment in battery-powered and hydrogen-fueled vehicles. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2022007

Most heavy trucks should be fully electric, using a combination of batteries and catenary electrification, but heavy trucks requiring very long unsupported range will need chemical fuels. At the scale of heavy trucks, compressed hydrogen can match the specific energy of diesel, but its energy density is five times lower, limiting range to around 2,000 km. Scaling green hydrogen production and addressing leakage must be priorities. Hydrogen-derived electrofuels—or “e-fuels”—have the potential to scale, and while the economic comparison currently has unknowns, clean air considerations have gained new importance Decarbonized Power Options for Long-haul Commercial Vehicles discusses these energy sources as well as the caveats related to bioenergy usage, and reasons to prefer ethanol or methanol to diesel-type fuels. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2023005

To achieve decarbonization through means such as energy-efficient vehicles, active travel, and electrified road freight, solutions must reduce upstream demands on supply chains. However, even taking such a path, the energy transition will massively increase demand for raw materials such as cobalt, nickel, platinum group metals, and rare earth elements. Many of the metals can be largely substituted if required, so they are not truly critical to decarbonization. Critical Metals, Sourcing, and Long Supply Chains: Constraints on Transport Decarbonization discusses how lithium, silver, and copper are much more difficult to replace, and the energy transition is highly likely to depend on them. Greatly increased and more geographically dispersed investments in mineral extraction are vital. Governments must support this by giving investors clear signals about the rate of the transition, geological survey data, accelerated permits, and government backed finance. Public support for sustainable mining should be gained by raising awareness that mineral extraction is critical to combating climate change. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2022SE2

The transportation sector has an enormous demand for resources and energy, is a major contributor of emissions (i.e., greenhouse gases in particular), and it is defined largely by the kind of energy it uses—be it electric cars, biofuel trucks, or hydrogen aircraft. Given the size of this sector, it has a crucial role in combatting climate change and securing sustainability in its three forms: environmental, societal, and economic. Energy Options on the Path Toward a More Sustainable Transportation Sector examines the many questions concerning alternative energy options for mobility: Is hydrogen the fuel of the future? Is there is enough electricity to power a fully electric transportation sector? What happens when millions of electric vehicle batteries need to be decommissioned? Which regulatory measures are effective and appropriate for moving the sector in the right direction? What is the “right” direction? Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2022019

Variable renewable energy (VRE), such as photovoltaic solar and wind turbines, will require new approaches to buffering energy within the grid. This must include significant ancillary services and longer duration storage to buffer seasonal variations in supply and demand. Such services may be economically provided by leveraging the battery resources of electric vehicles (EVs) for frequency response and energy storage for durations of up to a few hours, together with baseload and dispatchable power for longer duration buffering. Impact of Electric Vehicle Charging on Grid Energy Buffering discusses the unsettled issues and requirements needed to realize the potential of EV batteries for demand response and grid services, such as improved battery management, control strategies, and enhanced cybersecurity. Hybrid and fuel cell EVs have significant potential to act as “peakers” for longer duration buffering, and this approach has the potential to provide all the long-term energy buffering required by a VRE-intensive grid. Click here to access the full SAE EDGETM Research Report portfolio. https://doi.org/10.4271/EPR2022022