Pioneering Railroad, Oceanic and Plane ELectrification with 1K energy storage systems

ARPA-E PROPEL-1K Program Graphic

Release Date:
Project Count:

Program Description:

PROPEL-1K aims to develop emission-free, high-energy, and high-power energy storage solutions to electrify domestic aircraft, railroad, and ships. Projects must achieve energy density targets of so-called “1K” technologies that equal or exceed 1,000 watt-hours per kilogram and 1,000 watt-hours per liter at the end of life and at the net energy storage system level. Electrochemical and chemical solutions developed in the PROPEL-1K program must be distinct from traditional energy storage and battery solution strategies to achieve the ambitious high energy density targets.

The program will have two categories: A and B. Projects in Category A will target energy storage for electrifying regional flights by achieving greater peak power and continuous power capability with a higher cost base. Projects in Category B will aim for energy storage solutions for railroad and ship transit that require lower peak power and continuous power capability with a reduced levelized cost.

If successful, PROPEL-1K technologies will electrify regional flights traveling as far as 1,000 miles with up to 100 people, all North American railroads, and all vessels operating exclusively in U.S. territorial waters. PROPEL-1K energy storage technologies will achieve greater than 4 times energy density improvement compared to incumbent technologies.

Innovation Need:

The transportation sector is the largest contributor to the country’s greenhouse gas emissions, and aircraft, trains, and ships generate approximately 13% of the sector’s annual emissions. Energy consumption may increase as much as 50% globally between now and 2050, and electrifying transportation will be an essential part of achieving our net zero carbon goal.

While existing battery chemistries have been sufficient to make widespread electrification of passenger vehicles possible, technologies for electrifying domestic aircraft, railroad, and ships remain elusive. Energy storage for these heavy-duty vehicles and vessels must charge rapidly, achieve exceptional longevity and safety even in harsh conditions, and operate continuously over long periods. The extraordinary challenges posed by electrifying aircraft, railroad, and ships means the traditional energy storage device “playbook” must be discarded.

Historically, energy storage devices have developed and commercialized over extended timelines. While the fundamental mechanisms for lithium-ion batteries were discovered in the 1970s, the first commercial lithium-ion product did not emerge until 1991. An additional 20 years was needed for lithium-ion batteries to achieve the energy and cost required to become a leading option for electric vehicles. Assuming that “1K” technologies are possible, development needs to begin now to realize meaningful impact toward the 2050 net zero climate goal.

Potential Impact:

Developing zero-emission energy storage solutions for domestic aircraft, railroad, and ships would have the following impacts:


Domestic electricity generation will power heavy-duty vehicles and vessels instead of fuels, increasing energy independence and security.


"All-electric” aircraft, railroads, and ships will promote the country’s net-zero goal and reduce the transportation sector’s share of U.S. greenhouse gas emissions.


Energy storage at lower costs than incumbent solutions will encourage widespread adoption for all commercial transportation.