We're not here to sell you a battery. We're here to help you solve whatever's actually driving your electrification project. A CARB compliance deadline bearing down on the fleet? A newbuild spec still open on the propulsion package? A hybrid retrofit already underway that needs a safer buffer than the pack you spec'd two years ago? Tell us the vessel and where you are in the build, and we'll tell you honestly whether a non-flammable VSB buffer is part of the answer, not assume it is before we've heard your specifics.
CARB's Commercial Harbor Craft rule (with EPA Clean Air Act authorization granted January 6, 2025) requires harbor tugs to meet Tier 3/4+ standards or go zero-emission on a schedule running to 2032, pulling the ports of LA, Long Beach, San Diego, and San Francisco toward electric-assist tugs now, not later. Washington State Ferries has committed $3.98B to electrify up to 16 vessels and the terminals behind them. The hybrid/electric marine-propulsion market is on a similar trajectory: roughly $1.3-1.8B today, tracking toward $2.2-2.9B in the early 2030s. The propulsion decision is being made now; the buffer chemistry inside it isn't settled yet.
Sources: EPA (CARB waiver, Jan. 2025) · Washington State Ferries electrification program
It removes the power-sizing wall lithium hits on short, hard bursts. A tug assist, a DP station-keeping event, or a CTV approach is a 3-5 minute high-power event, not a multi-hour discharge, and a battery sized for power, not energy, doesn't need to be oversized just to deliver current safely. At up to 60C, VSB doesn't hit that sizing wall the way a 0.5-3C lithium cell does: for a representative 1,000 kW / 3-minute assist duty, a VSB pack comes in at roughly a third the weight of the NMC pack sized for the same job, freeing up deck space and hull weight for the vessel's actual work, not its battery room.
It removes the pack-replacement cycle across the vessel's hull life.Lithium packs in peaky assist duty typically run 3,000-5,000 cycles over 8-10 years, meaning a tug or OSV with a 20-year hull life goes through the battery-replacement yard period roughly three or four times. At 15,000+ cycles and a 20+ year design life, VSB is sized to run closer to two pack-replacement events across that same hull life instead of eight: fewer dry-dock periods dedicated to the battery room specifically, on a vessel whose whole economics depend on days in service, not days in the yard.
It removes a documented fire-risk category from the battery room. The marine incident record on lithium is real and recent: the container ship Genius Star XI (Dec. 2023, cargo-shift thermal runaway, $3.8M in damage), Höegh Xiamen (June 2020, 8-day lithium fire, total loss, $40M), and Morning Midas (June 2025, three-week fire, vessel lost) all involved cargo lithium batteries, not propulsion packs, but the same underlying chemistry risk a hybrid retrofit brings on board. Closer to the passenger side, Norled's ferry MF Ytterøyningen suffered a battery-room fire and overnight gas explosion in October 2019 that hospitalized 12 firefighters, traced to a coolant-circuit failure: the kind of active-cooling dependency VSB's −40°C to +100°C range doesn't need at all.
This isn't the whole story, and we won't pretend it is: on long-crossing, energy-dominant duty (ocean-going ferries, cruise ships, anything where the discharge is hours long rather than minutes), a sustained-energy pack sized for that duty is the right call, and VSB is not the right buffer for that duty cycle. VSB is TRL 5-6, field-proven in grid stabilization deployments (Sweden, Poland) and fleet trials, not yet type-approved or fielded on any tug, ferry, OSV, or CTV. This is a first-pass positioning page, not a sized deployment or case study. Tell us your vessel and duty cycle and we'll listen before we pitch anything back.
Scored on duty-cycle fit, cycle frequency, and safety/space unlock against the incumbent lithium pack. If your vessel isn't on this list, that doesn't rule VSB out. It just means we size the fit case-by-case rather than assume it.
Assist bursts, CARB-driven electrification timeline
Station-keeping power spikes on a hybrid refit
Dynamic-positioning duty, long service life
High-frequency, short-hop crew transfer
High-frequency short crossings, frequent dock charging
Sized for onboard hybrid propulsion or power-buffer duty: here's how the chemistry stacks up.
| What matters on board | Lithium-ion (NMC / LiPo) | LFP (LiFePO₄) | VSB (Vanadium Solid-State) |
|---|---|---|---|
| Fire / thermal runaway | Propagating; needs suppression, vents, setbacks | Reduced but real: runaway above ~270 °C | None: non-flammable, no off-gas, no propagation |
| Cycle life (deep) | 500-2,000 | 3,000-6,000 | 15,000+ |
| Service life / hull-life pack count | 8-10 yrs; ~3-4 pack changes over a 20-yr hull | 10-12 yrs; ~2 pack changes over a 20-yr hull | 20+ yrs; ~2 pack changes by design |
| Power response / fast-charge | 0.5C-3C | 0.5C-3C (EV-class cells) | Up to 60C |
| Operating temperature | 0 to +45 °C (active cooling required) | −20 to +60 °C (still wants cooling) | −40 to +100 °C, no active cooling |
| Freight / DG class | UN 3480 / 3481, Class 9; ≤30% SoC on aircraft | UN 3480 / 3481, Class 9; same DG burden | Dead-safe at 0 V; UN number pending, no blanket DG exemption claimed. |
| Recyclability | ~50% recoverable | ~50% recoverable | ≈85% of cell material recovered |
Specifications indicative; final ratings confirmed per project. VSB has not yet completed marine type-approval (DNV/ABS/class society) or a fielded tug, ferry, OSV, or CTV installation.
Whatever it is, a CARB compliance clock, a newbuild spec still open, a retrofit already underway, or an insurer asking harder questions about the battery room, you're not wrong to want a straight answer instead of a sales pitch. Tell us what's going on and we'll connect it directly to whether VSB actually fits.