Fuel cell glossary

Plain-language definitions of the terms used across fuel cell technology.

Anode

The fuel-side electrode of a fuel cell, where the fuel is oxidised and electrons are released to do electrical work.

Balance of plant (BoP)

The supporting components around the stack — pumps, valves, sensors, controls and cooling — needed to run a fuel cell as a complete system.

Catalyst

A material (often a platinum-group metal) that speeds up the electrochemical reactions at the electrodes without being consumed.

Cathode

The air-side electrode of a fuel cell, where oxygen combines with electrons and protons to form water.

DEFC (Direct Ethanol Fuel Cell)

A fuel cell that runs directly on ethanol. Fully oxidising ethanol requires breaking a carbon–carbon bond, which is part of what makes multi-fuel operation hard.

DMFC (Direct Methanol Fuel Cell)

A fuel cell that runs directly on liquid methanol, without first reforming it into hydrogen.

Dual-use

Technology with both civilian and military applications. In the EU it is governed by the dual-use regulation (Regulation (EU) 2021/821), which shapes how it can be exported.

Electrolyte

The medium that conducts ions between the electrodes while blocking electrons. In a PEM fuel cell, the electrolyte is the proton-exchange membrane.

Energy density

How much usable energy you carry per unit of weight (gravimetric, Wh/kg) or volume (volumetric, Wh/L). For long missions, a multi-fuel fuel cell offers up to ~15× the system-level energy density of lithium-ion.

Ethanol

A liquid alcohol fuel that is energy-dense and easy to store and transport. It is one of the three fuels LEC's multi-fuel platform runs on (via DEFC).

Fuel cell

A device that converts a fuel and oxygen directly into electricity, heat and water through an electrochemical reaction — not combustion. Unlike a battery, it generates power as long as it is supplied with fuel.

Hybrid (fuel cell + battery)

Pairing a fuel cell for endurance with a battery for peak power, so each handles what it does best. Common in long-duration portable and unmanned systems.

Hydrogen

The cleanest fuel for a PEM fuel cell: it reacts with oxygen to produce only water and heat, with zero local emissions.

Lithium-ion battery

A rechargeable energy store. It delivers high instantaneous power but is heavy when sized for long-duration energy and loses capacity in the cold.

MEA (Membrane Electrode Assembly)

The heart of a PEM fuel cell — the membrane plus the catalyst layers where the reaction happens. LEC's patent-pending single-piece MEA is what lets one platform run on hydrogen, methanol or ethanol.

Methanol

A liquid alcohol fuel that is easy to store and transport, with a mature supply chain. One of the three fuels LEC's multi-fuel platform runs on (via DMFC).

Microgrid

A local energy system that can operate independently of the main grid, often combining renewable generation, storage and dispatchable power such as a fuel cell.

MIL-STD

United States military standards specifying equipment performance and environmental durability. They are common requirements in defense procurement.

Multi-fuel

The ability to run on more than one fuel — hydrogen, methanol or ethanol — on the same hardware. It is LEC's core differentiator, enabled by a single-piece MEA.

PEM (Proton Exchange Membrane)

The thin polymer membrane at the core of the cell that conducts protons while blocking electrons. It also names the cell type — a PEM fuel cell.

Power density

The power output per unit of mass or volume (for example, kW/kg). It describes how much power a system delivers for its size, distinct from energy density.

Specific energy

Energy per unit of mass, usually in Wh/kg. It is the metric that matters most for anything carried or flown, where every kilogram counts.

Stack

Multiple fuel cells connected in series to reach a useful voltage and power output. Stacking modules is how a platform scales from watts to megawatts.

STANAG

NATO Standardization Agreements — specifications that ensure equipment and procedures are interoperable across allied forces.

SWaP (Size, Weight and Power)

The core design trade-off for portable and airborne systems. Lower size and weight for a given power — better SWaP — directly improves endurance and payload.

Thermal signature

The heat a system emits, which infrared sensors can detect. A low thermal signature — like that of a fuel cell versus a combustion generator — aids survivability.