Sarah Peeters, founder WEAR TO BE SAFE
In yacht building, inland navigation, and the offshore world, hybrid and all-electric concepts are now very common. Lithium-ion batteries are at the heart of many new designs. These offer enormous potential, but the risks are shifting from fuel and cable fire scenarios to battery fires, gas formation and complex electromagnetic interactions on board.
The fire risks of lithium-ion are now well described in guidelines from EMSA, DNV and others. The big problem: the so-called 'thermal runaway'. An overloaded, damaged or overheated battery can end up in a chain reaction where temperatures rise rapidly, flammable and toxic gases are released and flames spread to adjacent cells. In a compact battery compartment in an engine room, that means a combination of fire, smoke, pressure build-up and HF emission in a short time.
Onboard conditions present additional challenges. The spaces in which batteries are located are often small, irregularly shaped and surrounded by vital systems. Escape routes are limited, crews are small, and emergency services are far away. This makes design choices around compartmentalisation, ventilation and detection crucial. A battery room that is not designed for controlled gas venting can function as a pressure vessel in the event of an incident; a room without adequate detection does not raise the alarm until smoke already enters the ship elsewhere.
Fire fighting is fundamentally different from a 'normal' diesel fire. As a result, most tried-and-tested methods do not apply. Extinguishing with water or water mist is mainly a matter of cooling and limiting escalation. Gas-based systems can be effective for 'normal' electrical fires, but for lithium-ion the picture is very different. Research by Ineris and DNV, among others, shows that the battery itself generates oxygen during thermal runaway, gas extinguishers hardly cool at all and the chemical reaction in the cell therefore continues. Ineris shows that powder extinguishers have virtually no effect on a li-ion pack: the battery continues to burn or reignite. Foam and AVD (Aqueous Vermiculite Dispersion) cool the surface, but penetrate poorly between cells. Condensed aerosols (potassium salts) do block combustion reactions in space, but do not address the internal cell reaction.
Full immersion in a water tank (immersion container) is a widely used method for extinguishing Li-ion fires, but requires tens of cubic metres of water and large, heavy, leak-proof containers. However, this is anything but practical on a yacht or offshore installation.
In short: complete extinguishing does not happen as long as there is still significant energy in the pack. The issue of re-ignition, which we now know from EV fires ashore, plays out at least as strongly on board. This means that designers need to address not only the initial fire phase, but salvage and transport of damaged batteries.
Ordinary fire blankets are not designed for the temperatures and gas production of a li-ion fire. However, using a Li-Ion fire-resistant bag or blanket around a smoking or burning battery limits flames, flying particles and radiant heat, and prevents the fire from spreading to interiors, cable ducts or insulation. Li-Ion fire blankets are ideal precisely for this type of "thermal incident": controlled extinguishing or letting it burn out with minimal collateral damage. On board, you can then move the encapsulated battery to a pre-designated, ventilated "quarantine area" on open deck (e.g. a metal drip tray), under continuous surveillance and cooling if necessary. For large fixed ESS installations on board, blankets can temporarily encapsulate suspected or damaged modules. Battery modules can also be stored in a controlled and secure manner.
The conclusion, however, is not that lithium-ion would be "too dangerous" for marine applications. On the contrary: where EMSA regulations, DNV manuals and class rules have been consistently applied, hybrid and all-electric vessels can operate safely and reliably, with demonstrable fuel and emission reductions. The key lies in an integrated approach: battery selection, compartmentalisation, ventilation, sensing, DC architecture, Power Quality and operational procedures are designed and evaluated as a whole.
Want to know more about deploying Li-Guard products for lithium-ion fires as a fire suppression containment tool for li-ion sources?
Electrical fires are one of the most devastating incidents in industry and utilities. They can lead to prolonged downtime, huge financial losses and directly compromise the safety of employees.
The crucial question is: What can happen if an electrical fire breaks out? How do you protect your employees, your company and your site from this sudden and devastating risk?
Date: Thursday 26 February 2026 | 14:00 - 16:30
Location: Beemdstraat 3, Eindhoven
Costs: Free participation, registration required
Large li-ion packs are not passive consumers, but active sources on a mostly high-voltage DC grid. They can supply or absorb hundreds of kW in milliseconds. From energy saving and DP performance perspectives, this is positive: generator sets can run closer to their optimal load point, peaks are smoothed out, short-term power injections keep thrusters stable in wave conditions. But the same dynamics increase requirements for grid stability, protection selectivity and harmonic control.
Poorly damped harmonic currents or voltage fluctuations can trigger protective devices, allowing a single fault to develop into a blackout. Arcs also deserve explicit attention in this context. Large marine battery systems have extremely low internal resistance. The available short-circuit current on an 800 or 1000 V DC bus is substantial, while with DC the current has no zero crossing and an arc remains as long as voltage and power are present. In compact spaces, close to crew and critical equipment, an arc can lead to severe burns, mechanical damage from pressure waves and secondary fires. This puts the design of DC distribution - segmentation, fast detection and arc-resistant housing - in the same risk category as the battery itself. Simulations of grid dynamics, harmonic analyses, arc-flash studies, and correctly specified PPE are thus not a luxury.
Want to know more about Power Quality in relation to the marine world?
