Trainsmission
18.8 MWh
Usable AC energy
per Gen.1 railcar
92 %
Round-trip
efficiency
2.1 GWh
Delivered by a
10,000 ft train
429,000 lb
Gross rail load, against 286,000
for a standard four-axle car
Energy distribution by rail
We move energy
by rail. Not by wire.
Transmission lines take a decade to permit and build. The freight rail network is already there — 140,000 route-miles of it, reaching nearly every generator and every load in North America. We use it as an energy distribution network, and we can energize a site in as little as twelve months from financing.
See the railcars Talk to us
The model
01 / Origin
Contracted generation
Railcars charge at a dedicated interconnection at the generation site under a long-term offtake agreement. The origin is fixed for the term of the contract, not selected week to week.
Interface · 1,500 VDC
Charge rate · 0.25C
Containers · (4) 20′ ISO
02 / Corridor
Existing track
The consist runs a scheduled route in ordinary interchange service on Class I rail. No new right-of-way, no permitting cycle, no interconnection queue — the corridor is already built and already maintained.
Car type · 89′ articulated flatcar
Axles · 6
Network · ~140,000 mi
03 / Delivery
Contracted load
Energy is delivered into the offtaker’s interconnection under a long-term PPA, or into the wholesale market at the delivery point. Revenue is contracted, not merchant.
Max AC discharge · 9 MW / car
Usable AC · 18.8 MWh
Duration · 2 hours
A Trainsmission project is a fixed corridor, not a roving asset. One contracted generator at the origin, one contracted load at the delivery point, and a dedicated consist cycling between them for the life of the agreement.
An alternative energy distribution network.
The corridor
The network is already built.
Roughly 140,000 route-miles of Class I and regional track, reaching nearly every major generator and every major load in North America. Nothing here needs permitting, right-of-way, or a place in an interconnection queue.
The queue
Generation isn’t the constraint.
Getting it to the load is.
Interconnection queues run for years, and the wire behind them takes a decade to build. The power already exists — it is curtailed at the generator for want of a path to the customer. We were moving energy by rail before AI load was the reason everyone wanted it. The queue was already full.
Rail gives a site a path in twelve months instead of ten years. That matters to anyone holding a position in the queue.
Who we deliver to
Utilities
Wholesale energy markets
Ports
Mines
Data centers and similar
energy-intensive heavy industry
Energy transfer
Charge and discharge run through an automated interface rather than hand-cabled connections made car by car. The interface is selected per site — two DC, one AC.
Three ways to make the connection.
PREFERRED · DC
Third rail
Contactors fold down from the railcar and meet a ground-level conductor rail once the consist is in position. They fold up in transit and are never laterally exposed. The same principle as a subway third rail, at far higher power.
PREFERRED · AC
Overhead pantograph
The consist parks beneath a pavilion structure on industry track. An overhead crane drops to meet the top of each battery railcar, discharging to AC with no track-level equipment. Sited on private track, the structure never fouls a railroad’s overhead clearance.
AVAILABLE · DC
Quick-connect coupler
An automated plug-type coupler that slides forward on a conveyor drive once the railcar is in place. Its leading edge does not encroach on the right-of-way, and nothing overhangs the car.
Interface · Stäubli QCC
Voltage · To 1,500 V DC
Current · 670 A cont.
In the field
Already on real track, behind real power.
Our test consist runs at a working rail yard in San Francisco, California, interchanged with Union Pacific power and charged from an on-site solar array. Five deployments to date:
San Francisco, CA · Test yard — UP interchange, on-site solar
Port of Oakland, CA · Demonstration
Port of Long Beach, CA · Demonstration
MHX · Demonstration — EV charging from railcar
Colorado · WATT pilot — Xcel Energy & NREL
UL 1741 UL 1973 UL 9540 UN 38.3 IEC 61373 IEC 62982
CBS News
Nine minutes, from someone who doesn’t work here.
CBS News covered the battery railcar program for its Behind The Story strand — the technology, the rail operations and the people building it.
The fleet
Two railcars. One in manufacturing, one in development.
Gen.1 is a containerized battery on an 89′ articulated flatcar, manufacturing now. Gen.2 moves the pack inside a purpose-built Plate F boxcar. Gen.2 is the shorter car — 58′-2″ over the couplers against 89′ — so a train of the same length carries about 1.6× the energy. About 2.1 GWh today on a 10,000-foot train, and up to 4 GWh as consist length and priority grow with the railroads.
Specification
Energy per railcar
Max AC discharge
DC bus
Round-trip efficiency
Form factor
Gen.1 — Manufacturing now
18.8 MWh
Up to 9 MW
1,500 VDC
92 %
89′ articulated flatcar
Gen.2 — In development
20+ MWh
Up to 10 MW
1,500 VDC
92 %
Plate F boxcar
Engineering
Everything but the cell.
Working with our manufacturing partners we build the entire BESS framework — BMS and EMS, wiring harnesses, inverter and transformer, racking, safety and monitoring systems, and the mechanical systems that let a battery survive freight service: shock absorption, vibration damping, fire suppression. The cell itself is commercially available LFP, and deliberately so — proven chemistry, multiple sources, no single point of failure in the supply chain. Everything around it is ours, built on an articulated six-axle platform so axle loading stays within interchange limits. A stationary battery never has to survive being switched in a yard. That mechanical work is what makes this a railcar and not a container on wheels.
In the news
Anthropocene Magazine
Shipping solar power at the speed of a freight train
April 2025 — on whether railroads could break the clean-energy transmission logjam.
The Economist
Solar power is going to be huge
“Instead of a multi-decade planning battle to build a high-voltage transmission line, SunTrain could meet the utility’s power-import needs with a couple of trains a day.”
Financial Times
How to ship sunlight and deliver green energy
“One battery train could meet the daily energy needs of 120,000 homes.”
Series A
The grid needs more capacity than wire can deliver.
We are raising to build the first commercial fleet. If you invest in energy infrastructure, we should talk.