Power Generation &
BESS

Power generation used to mean fuel, turbines and switchrooms. It still does, and now it also means battery storage, hydrogen and the detection problems both bring with them.

Most of what follows comes from work our Technical Consultants have done on Australian sites, including a battery room specification where the certification requirement turned out to be the hard part.

Lithium-Ion Off-Gas, And Which Gas Actually Matters

Battery energy storage and battery rooms share a failure sequence, and the detection opportunity sits early in it.

Recharging lithium-ion cells can cause overheating, breakdown, cracking and fracture, and the risk rises as cells age. Well before anything catches fire, cycling cells release gas, and which gas depends on which electrode.

Experimental work shows cathodes releasing carbon dioxide and carbon monoxide, while anodes release ethylene, carbon monoxide and hydrogen. Hydrogen also comes from electrochemical decomposition of the carbonate electrolyte. When a cell actually vents, the release is mainly carbon dioxide, along with vaporised electrolyte containing hydrogen fluoride at 20 to 200 milligrams per watt hour and phosphoryl fluoride at 15 to 22 milligrams per watt hour.

Ethylene is the useful marker. It comes from the anode during cycling, which means it appears before venting, before smoke and well before thermal runaway. That is why off-gas detection buys time that smoke and heat detection cannot, and it is what the Li-ion Tamer is built around.

Sensor placement matters as much as sensor choice. Detectors go near ground level, at a distance from forced ventilation and exhaust ducting, and clear of positive supply ventilation. A detector in the path of a supply fan is being fed clean air regardless of what is happening in the room.

The Certification Question Nobody Expects

On one Australian data centre battery room project the technical specification was straightforward and the certification was not.

The client was a United States company operating in Australia, and their engineering standard required FM approved sensors complying with US standards rather than IECEx. Target gases were ethylene at 0 to 100 percent LEL and carbon monoxide at 0 to 500 ppm, with triple redundancy. Hydrogen, hydrogen fluoride and carbon dioxide were considered and not included.

The lesson generalises. On battery and data centre projects the standard being applied is often the parent company’s rather than the Australian one, and FM approval and IECEx are not interchangeable. Establishing which certification the specification actually requires, before equipment is ordered, avoids an expensive discovery at commissioning.

Why Lithium Fires Need UV/IR Rather Than Infrared

This is the technical point that decides flame detector selection for battery installations, and it runs opposite to the usual answer.

Lithium burns with a red flame in the visible spectrum. More importantly, the combination of chemicals in a lithium-ion battery generates most of its light in the ultraviolet range, with some infrared from other materials burning alongside it. So a multi-spectrum infrared detector, which is the right choice for a hydrocarbon fire, is looking in the wrong part of the spectrum.

The optimum detector for lithium-ion fires is UV/IR.

There is a second reason. Thermal runaway generates an intense explosion very quickly rather than a developing fire, so response time matters more than detection distance. The F-Guard UV/IR responds to an explosive fireball in 5 milliseconds.

And a third, which is uncomfortable but worth stating. There are currently no established fully effective suppression methods for lithium-ion battery fires. That changes what detection is for. If suppression cannot be relied on to put the fire out, the value of the system shifts toward giving people accurate information early, which is why the HD variant with live video is specified on these installations. Attending fire and emergency services can see the situation before entering the site.

Detectors should be high mounted with a 45 degree downward angle. Applicable standards include EN 54-10, AS 1670.1 Section 7 for flame detection, and internationally NFPA 855 and Chapter 12 of the International Fire Code.

After The Fire Is Out

A lithium-ion battery incident does not end when the flames stop, and this is where portable detection comes in.

In a significant thermal event, and the three day Megapack fire in Victoria in 2021 is the Australian reference case, a lithium-ion battery system can release hydrogen, methane, carbon monoxide, hydrogen fluoride, hydrogen chloride and hydrogen cyanide.

During a fire or explosion the perimeter should be entered only by trained firefighters in self contained breathing apparatus. The part that gets missed is afterwards. Once the fire is extinguished, full protective equipment including portable gas detectors should continue in use until flammable and toxic gases are measured at safe levels. The atmosphere does not clear because the fire has.

The measurement set is demanding: methane to 100 percent LEL, carbon monoxide to 1,000 ppm, hydrogen to 1,000 ppm, hydrogen fluoride to 20 ppm, hydrogen cyanide to 100 ppm and hydrogen chloride to 15 ppm. Instruments such as the iBrid MX6 and the POLI MP400 cover the multi-gas requirement, with single gas instruments for hydrogen fluoride, hydrogen cyanide and hydrogen chloride.

Two practical constraints apply. Cross sensitivity across a mixed toxic atmosphere affects readings, and ambient temperature is high, both of which need allowing for rather than assuming away.

Thermal And Gas Fired Generation

In a conventional power station the burner is at the heart of the plant, producing thermal energy delivered to a gas turbine or to water for thermal and combined cycle operation.

Boilers and gas turbine combustion chambers run above 1,000 degrees Celsius, which rules out ordinary gas analysis in those spaces. Flame detection has a specific safety function alongside fire detection, since detecting flame failure allows inlet fuel to be cut before unburned fuel accumulates to an explosive quantity.

Areas needing coverage across a station are fuel storage and supply, whether coal, gas or diesel, turbine areas, high voltage facilities, cooling and waste water collectors, HVAC plant, corridors and lifts in process areas, and control rooms.

Detector selection turns on false alarm immunity and on the fuel present, since fuel type, chemical compatibility and airflow all affect which technology suits. Flame detection with response times around 40 milliseconds reduces the exposure window on volatile fuel. In large turbine halls, open path detection covers volumes that would need impractical numbers of point detectors.

Diesel Generation And Combustion Tuning

Diesel power stations run remote sites without mains access and back up mains supply elsewhere, and their efficiency is more sensitive to tuning than most operators expect.

Air surplus, fuel pressure, ambient temperature and humidity all significantly affect how a generator runs and what it emits, and all four have to be accounted for when optimising it. A correctly tuned generator delivers better fuel efficiency, lower emissions, longer engine life and improved reliability. Adjusted wrongly it misfires, runs hotter, wears faster and costs more to service.

The method is straightforward. Establish a baseline with an emissions test and a record of current set points. Analyse the combustion data to find where performance can improve. Adjust the operational settings. Then measure again to confirm the change did what was intended.

That last step is the one most often skipped, and it is the reason combustion analysis belongs in a maintenance programme rather than being hired once.

Wind

Wind turbines are not usually thought of as a gas detection application, and the reason they are is confined space.

Several parts of a turbine structure meet the definition, including the basement, the generator, access towers, the hub and the blades. In basements, workers can become oxygen deficient where gases heavier than air displace oxygen, with asphyxiation the risk rather than toxicity.

Carbon dioxide released from a fire suppression system is a specific hazard worth designing for, since the system intended to protect the space can make it unbreathable. Nacelles carry fire risk from electrical and mechanical faults. And hot work inside a hub generates fumes, with additional vapour from cleaning materials, paints and solvents used during maintenance.

Detection is portable multi-gas covering oxygen, LEL, carbon monoxide, carbon dioxide and volatile organics by photoionisation, which is a wider set than a standard four gas instrument provides.

Hydrogen

Hydrogen generation, electrolyser halls and storage bring a detection problem that most equipment cannot address.

Hydrogen contains no carbon, so it burns to water vapour rather than carbon dioxide. A multi-spectrum infrared flame detector watching the carbon dioxide band will register nothing at all while a hydrogen fire burns in front of it. That is not a sensitivity limit, the detector is blind to it. The F-Guard IR3-H2 is built for hydrogen specifically.

Hydrogen accumulation is a separate matter from hydrogen fire. Lead acid battery rooms generate hydrogen during charging through electrolysis, which is an accumulation problem solved with fixed detection tied to room ventilation.

Who Regulates It

Power generation sits under general work health and safety law rather than a sector specific regime, so the WHS regulator is WorkSafe WA, SafeWork NSW or Workplace Health and Safety Queensland depending on location.

Electrical safety is regulated separately from work health and safety. In Western Australia, Building and Energy, within the Department of Energy, Mines, Industry Regulation and Safety, is responsible for the technical and safety regulation of the electrical industry and most of the gas industry.

For battery installations the relevant standard in Australia is AS/NZS 5139 covering the safety of battery systems for use with power conversion equipment, with NFPA 855 and UL 9540A the internationally referenced documents, and UL 9540A the test method behind most published off-gas and thermal runaway data. Flame detection follows AS 1670.1 and EN 54-10. Confined space entry in turbine structures follows AS 2865:2009.

Requirements for a specific installation depend on its size, enclosure type, location and the authority having jurisdiction, which for a grid scale battery may include the network operator as well as the WHS regulator.

What Gastech Supplies

BESS and off-gas detection for battery energy storage and battery rooms, detecting electrolyte off-gas before thermal runaway begins.

Flame detection including UV/IR for lithium-ion installations, hydrogen capable variants, and HD video options where responders need to see the scene before entering.

Fixed gas detection for hydrogen accumulation, fuel supply areas, turbine enclosures and switchrooms, with open path detection for turbine halls and large volumes.

Portable multi-gas and single gas instruments for maintenance, confined space entry in turbine structures, and post incident atmospheric clearance.

Controllers with the relay capacity to drive ventilation, isolation and alarm rather than only reporting a reading.

Behind them sit project engineering, NATA calibration and service, field service, fleet management and hire, from WA, NSW and QLD.

If you are specifying detection for a battery installation, or working out which certification your client’s engineering standard actually requires, talk to our Technical Consultants.