Hydroelectric Power Station, Pumped Hydro Storage, Geothermal Pilot Plant, Ocean Wave + Tidal Energy and Marine Energy HVAC Duct Guide

Why hydro and marine-renewable HVAC sits at the intersection of every Australian engineering code

Of the renewable-energy verticals that cross the Box Hill North desk, the combined hydroelectric, pumped hydro, geothermal and ocean wave or tidal energy brief is the broadest in code overlap and the deepest in commissioning complexity. A single Snowy 2.0 or Tumut 3 underground powerhouse asks the HVAC engineer to specify simultaneously to AS 1668.1 fire and smoke control for the occupied machine hall and the AS 1668.2 dilution ventilation for the same volume, to AS 2865 confined space entry for the penstock and tailrace inspection openings, to AS/NZS 60079 hazardous area zoning for the transformer oil mist pits and SF6-insulated switchgear room, to AS 1940 flammable liquid storage for the black-start diesel day tanks, to NCC Class 9b assembly for the visitor centre and interpretation gallery, to AEMO grid code dispatch reliability for the control room services, and to the NSW Heritage Council Snowy Mountains Scheme heritage standards for any modification of the original 1949 to 1974 station fabric. Get the duct gauge wrong on the SF6 exhaust stack and the GIS room cannot be commissioned. Get the access-tunnel ventilation main wrong and the machine hall stops accepting an AEMO dispatch instruction because the cavern temperature exceeds the protection-relay derating curve. Get the BESS room exhaust route wrong and the FCAS contract is non-deliverable because the battery thermal-runaway interlock will not arm. Every one of these failure modes appears in actual Australian project audit reports.

The fundamental physics is also unusual relative to other industrial verticals. The dominant HVAC sizing case in an underground powerhouse is heat removal at scale — a single 350 MW Francis or pump-turbine unit rejects 5 to 8 megawatts of heat into the surrounding rock cavern through bearing oil coolers, generator stator windings, exciter and the wet-end bearing journal. For a six-unit pumped hydro station such as Snowy 2.0 at a nominal 2,200 MW total capacity, that is 30 to 50 megawatts of continuous cavern heat load. The ventilation system has to move that heat out of an 800-metre-deep cavern through one or two access tunnels and a handful of dedicated ventilation shafts, while simultaneously providing breathable air for plant operators, transformer-pit smoke spill capacity per AS 1668.1, SF6 dump capacity on the GIS exhaust, hydrogen evolution dilution for the lead-acid station battery room and thermal-runaway extract capacity for any co-located Li-ion BESS. The same engineer is asked to specify the duct on the visitor centre lookout above ground and the access-tunnel ventilation main 800 metres below ground in the same project pack, with both falling under different parts of the National Construction Code and different operational risk profiles.

Layer pumped hydro on top of conventional generation and you add a second operating mode — pump mode draws power from the grid to lift water from the lower reservoir to the upper reservoir, while turbine mode discharges water back through the same hydraulic machine to generate during peak demand. Heat profile differs between modes (pump mode typically rejects more heat because pump efficiency is slightly below turbine efficiency on the same reversible machine), bearing oil temperatures differ, and the HVAC sizing follows the worst case. Layer geothermal on top of that and you add hydrogen sulphide dilution, sulphurous-acid corrosion of duct walls and a binary-cycle pentane or isobutane working fluid loop classified Zone 2 IIA. Layer ocean wave and tidal energy on top of that and you add salt-spray corrosion of every external duct surface and a positive-pressure clean enclosure for the power electronics that has to keep chloride aerosol out of the cabinet despite operating within metres of breaking surf. This guide walks through what a consulting engineer, IECEx CoPC hazardous area auditor, mechanical contractor or asset owner has to decide when specifying HVAC ductwork across this full vertical, written from the practitioner's standpoint and referenced against the Snowy Hydro, Hydro Tasmania, Genex, Carnegie, Wave Swell, Bombora, AusOcean and Tesla project base that defines the Australian operating fleet in May 2026.

The Australian hydro and marine renewable operator landscape

The first input to any HVAC specification is which operator is delivering the project, because each Australian hydro and marine-renewable operator has its own engineering standards, preferred consulting engineers, preferred mechanical contractors and historic baseline of duct specification practice that the new project sits on top of.

Snowy Hydro Limited — Snowy 2.0 and the original scheme

Snowy Hydro Limited is the Commonwealth Government-owned operator of the Snowy Mountains Scheme — the 5,500 MW of existing conventional hydro at Tumut 1, 2 and 3 (1,500 MW combined), Murray 1 and 2 (1,500 MW combined), Guthega (60 MW), Blowering (80 MW) and Burrinjuck (327 MW), plus the under-construction Snowy 2.0 pump-turbine pumped hydro storage at 2,200 MW nameplate. Snowy 2.0 is the headline national infrastructure project of the decade — a fully underground powerhouse 800 metres below the surface in the Talbingo Reservoir to Tantangara Reservoir headrace tunnel, with six 333 MW reversible pump-turbines providing peak generation and overnight pumped storage. The HVAC scope on Snowy 2.0 is the largest single hydroelectric ducting package in Australian history, with several thousand linear metres of large-diameter spiral round duct, hundreds of fire dampers, dual-redundant AHU plant in the cavern and surface fan houses at the Tantangara, Talbingo and main access tunnel portals. The Snowy 2.0 construction camp at Tantangara and Talbingo provided accommodation HVAC for several thousand construction workers during peak build through 2024 and 2025. Snowy Hydro's specification baseline references AS 1668.1, AS 1668.2 and AS 4254 directly and adds AEMC dispatch reliability requirements that go beyond the AS code minimum.

Hydro Tasmania — the largest renewable generator in the country

Hydro Tasmania is the Tasmanian state-owned operator of the largest renewable energy fleet in Australia by name-plate capacity — approximately 2,600 MW of hydroelectric across 30-plus stations on the West Coast, the Central Highlands and the South-West Wilderness. Headline stations include Gordon Power Station (300 MW underground at Strathgordon), Tarraleah (90 MW, with the historic Tarraleah village heritage precinct), the Liapootah-Wayatinah-Catagunya cascade (130 MW combined), Devils Gate (60 MW), Reece (231 MW), the Mersey-Forth cascade (310 MW combined), and the John Butters station (143 MW). King Island operates a unique wind-hydro-diesel hybrid microgrid with a 6 MW battery providing FCAS to the isolated grid. Hydro Tasmania has announced the 750 MW Cethana Pumped Hydro Project in the Cradle Mountain region and the Tarraleah pumped storage redevelopment as part of the Battery of the Nation portfolio targeting interconnection with mainland Australia through the Marinus Link HVDC cable. The HVAC specification baseline at Hydro Tasmania emphasises AS 1668.1 smoke spill provisions because many older Tasmanian stations have substantial timber-and-concrete fabric and a higher fuel load than modern surface stations.

Genex Power and the Kidston Pumped Hydro project

Genex Power (ASX:GNX) is developing the 250 MW Kidston Pumped Hydro Project in North Queensland, using two existing open-cut mine voids at the former Kidston gold mine as the upper and lower reservoirs. Kidston is the first new Australian pumped hydro project to reach construction phase and is the flagship project for the Northern Queensland Renewable Energy Zone. Genex has also announced the 750 MW Bouldercombe Battery Project, the Goat Hill Pumped Hydro project in South Australia (250 MW) and is a joint partner on the Borumba Pumped Hydro project. The Kidston HVAC specification follows ASHRAE Applications Chapter 16 with Australian standards overlay and uses a surface powerhouse configuration (not underground) which simplifies access-tunnel ventilation requirements compared to Snowy 2.0.

Queensland Government — Borumba Pumped Hydro and CleanCo

The Queensland Government through Borumba Pumped Hydro Pty Ltd and the CleanCo state-owned generator is developing the 2 GW Borumba Pumped Hydro project in the Imbil State Forest near Gympie, targeting first generation in the early 2030s. Borumba would be the largest pumped hydro storage project ever delivered in Queensland and one of the largest globally. The project includes a large surface powerhouse near the existing Borumba Dam and a new upper reservoir constructed on the high ground above. CleanCo also operates the existing Wivenhoe Power Station (500 MW pumped hydro on the Brisbane River) and is the strategic state-owned partner for the Borumba development. The HVAC scope on Borumba is at FEED stage in mid-2026 with mechanical contractor packages expected to bid in late 2026 or early 2027.

Origin Energy and AGL — coal and gas transition

Origin Energy (ASX:ORG) and AGL Energy (ASX:AGL) operate the largest fossil-fuel generation fleet in Australia and are transitioning that capacity to renewable replacement with co-located BESS. Origin's Eraring Power Station in NSW (2,880 MW black coal, slated for closure mid-decade) is being supplemented and replaced by a 460 MW grid-scale BESS at the Eraring site, with options for a future pumped hydro project on the upper Hunter. Origin also operates the Mortlake gas-fired power station in VIC and the Stockyard Hill Wind Farm in VIC. AGL operates the Liddell black coal station (closed 2023), Bayswater black coal in NSW, Loy Yang A brown coal in VIC and is developing the Torrens Island Big Battery in SA (250 MW) and battery storage at the Hunter Valley and Latrobe Valley sites. The HVAC transition scope at the legacy thermal stations is well-developed; the new BESS scope at those sites follows NFPA 855 and AS/NZS 5139.

Neoen and the Hornsdale Power Reserve

Neoen Australia operates the Hornsdale Power Reserve in South Australia, originally commissioned in 2017 as the world's first large-scale Tesla Powerpack installation (100 MW / 129 MWh, since expanded to 150 MW / 193.5 MWh) co-located with the Hornsdale Wind Farm. Neoen also operates the Western Downs Battery in QLD, the Capital Battery in NSW and the Goyder South Renewable Energy Zone in SA. The BESS HVAC specification at these sites follows the Tesla Megapack factory-built containerised standard with site-specific surrounding building shell HVAC by the local mechanical contractor.

Carnegie Clean Energy and ocean wave technology

Carnegie Clean Energy (ASX:CCE) is the leading Australian wave energy developer with the CETO 6 technology — a fully submerged buoyant actuator that drives an onshore hydraulic-to-electric power conversion station. The Garden Island Naval Base WA demonstration project ran a 240 kW CETO unit feeding the HMAS Stirling base. Carnegie's commercial pipeline targets multi-MW arrays at the Albany site in WA and the Wave Hub site in Cornwall UK. The HVAC scope on a CETO onshore conversion station is small (200 to 500 square metres of building) but the salt-spray corrosion environment is severe.

Wave Swell Energy and the UniWave 200

Wave Swell Energy operates the UniWave 200 oscillating water column wave energy unit at King Island TAS — a 200 kW unit on extended sea trial since 2021 feeding into the Hydro Tasmania-operated King Island microgrid. The UniWave technology is a hollow concrete chamber that captures the rising and falling wave surface, with the resulting air flow driving a vertical-axis air turbine on the chamber roof. The HVAC scope on the onshore conversion station is similar to Carnegie's CETO with the addition that the air turbine itself is exposed to salt-spray and requires sealed bearing arrangements.

Bombora Wave Power and Perth WA

Bombora Wave Power has developed the mWave membrane-based wave energy converter, tested at the Peniche site in Portugal and at the Albany site in WA. The Perth WA headquarters and the Perth-region commercial development pipeline target multi-MW deployments through the late 2020s. The Bombora HVAC scope at the onshore conversion station is conventional coastal industrial.

AusOcean and BlueGreen Group — research and tidal

AusOcean (research-stage wave-energy testing in Bass Strait) and BlueGreen Group (tidal energy development in Bass Strait, the Banks Peninsula NZ and various other tide-rich sites) round out the active Australian ocean energy operator base. Tidal energy converters extract energy from the tidal current flow rather than the wave surface, with submerged horizontal-axis or vertical-axis turbines on the seabed. The HVAC scope on a tidal energy onshore station is similar to the wave-energy stations — small coastal building, severe salt-spray exposure, sealed power electronics enclosure.

Birdsville Geothermal and Australia's geothermal pilot history

Ergon Energy operates the Birdsville Geothermal Power Station in remote western Queensland — a small Organic Rankine Cycle unit on 98 degree C bore water from the Great Artesian Basin, providing approximately 80 kW continuous to the Birdsville township grid since 1992. Birdsville is the longest continuously operating geothermal plant in Australia. The Geodynamics enhanced geothermal pilot at the Cooper Basin SA (Habanero project, hot dry rock at 4 to 5 kilometre depth) ran from 2003 to 2016 and the Petratherm Paralana pilot ran in parallel; both projects ceased commercial operation after technical challenges with deep-well injectivity and economic challenges with grid connection from remote arid locations. New direct-use geothermal projects are emerging — the Geelong VIC district heating trial led by Council of the City of Greater Geelong is the most advanced — but at substantially smaller scale than the early-2010s hot dry rock projects. The HVAC scope on Birdsville and on the emerging direct-use trials is small (a few hundred square metres) but the H2S corrosion and exposure case dominates the specification.

Underground powerhouse cavern HVAC — the largest single hydroelectric scope

The underground powerhouse cavern is the dominant HVAC scope in Australian hydroelectric and pumped hydro. The Snowy 2.0 powerhouse is the headline project but the existing fleet includes Tumut 3 (underground at the base of Talbingo Dam NSW), Murray 1 and 2 (underground in the Khancoban region NSW), Gordon Power Station (underground at Strathgordon TAS), Cethana (underground TAS) and several smaller Tasmanian cavern stations. The HVAC engineer faces four dominant problems.

Heat removal from the cavern

Each generator unit rejects 1 to 3 percent of nameplate as machine-hall heat load. For a 333 MW Snowy 2.0 pump-turbine unit operating in pump mode (the worst case), that is 6.6 to 10 MW of waste heat into the surrounding cavern. The six-unit Snowy 2.0 cavern total heat load is 30 to 50 MW continuous. This heat has to leave the cavern through the access-tunnel ventilation shafts and dedicated ventilation shafts to the surface, with no convenient natural ventilation path because the cavern is 800 metres below the surface and surrounded by rock. The supply air enters the cavern through the access tunnel main and through dedicated supply shafts; the return air leaves through dedicated exhaust shafts with the air heat content carrying the bulk of the rejected MW to the surface. A typical cavern ventilation rate is 6 to 10 ACH of the cavern volume.

Access tunnel ventilation main on the SBTF-2020

The access tunnel main ventilation duct carries the bulk supply and return air between the surface fan house and the powerhouse cavern. For Snowy 2.0 the main access tunnel is 2.7 kilometres long; the supply and return ventilation ducts run along the tunnel crown on stainless rod hangers at 3 metre centres per AS 1657 and AS/NZS 1170. Duct diameter is 1,500 mm to 2,020 mm spiral round on the SBKJ SBTF-2020 large-diameter spiral tubeformer, with face velocity 8 to 12 m/s and pressure loss budget 200 to 400 Pa over the full tunnel run. The SBTF-2020 is the only Australian-supplied machine that produces 2,020 mm diameter spiral round duct in a single pass, which makes it the machine of choice for the access-tunnel scope on every Australian underground hydroelectric project. Joint construction is bolted slip-fit with EPDM gasket; the longitudinal spiral seam is helical lock-form for galvanised or continuously welded for stainless. SBKJ supplied bench engineering support on the 2024 and 2025 access-tunnel ductwork pack across multiple Australian projects.

Cavern internal supply and exhaust distribution

Inside the powerhouse cavern, supply and exhaust trunks distribute air across the generator units. Snowy 2.0 has six generator bays in a 250 metre long machine hall, plus a separate transformer hall and a separate auxiliary plant bay. Trunk velocities are 8 to 10 m/s on supply collection and 12 to 15 m/s on exhaust trunk. SBKJ rectangular duct on the SBAL-V at 1,500 mm wide by 600 to 1,000 mm deep handles the supply trunk runs along the upper machine hall wall, with branch take-offs dropping down to floor-level supply grilles at each generator bay. Spiral round at 800 mm to 1,500 mm on the SBTF-1500 handles the auxiliary plant and corridor runs. The lower powerhouse floor (turbine pit level, draft tube floor) is a separate AS 2865 confined-space-adjacent zone with separate ducted ventilation to handle splash water and wet-end humidity from the turbine bearing journal cooling.

Pressure cascade and smoke control

The cavern is maintained at slight positive pressure (10 to 30 Pa) relative to the access tunnel system to prevent ingress of diesel exhaust from access tunnel vehicle movements (the access tunnel sees regular service vehicle and personnel mover traffic during plant operation). On AS 1668.1 fire alarm trip the cavern HVAC switches to smoke spill mode — supply dampers close, exhaust ramps to 250 degrees C-rated smoke fan capacity, smoke is dumped through dedicated smoke spill shafts to the surface. The smoke spill fans are rated for 250 degrees C continuous and 600 degrees C for 30 minutes per AS 1668.1. Smoke control zoning splits the cavern into the machine hall zone, the transformer hall zone, the auxiliary plant zone and the control room zone, with fire dampers on every wall crossing rated to AS 1530.4 -/120/120 minimum.

Turbine technology and HVAC heat-load profile

Turbine technology drives the machine hall heat-load profile because each technology has a different combination of bearing arrangement, generator coupling, exciter capacity and lubricant cooling demand.

Francis turbines

Francis turbines are the dominant Australian configuration for medium to high head sites (50 to 700 metres head) and account for the bulk of the Snowy Hydro, Hydro Tasmania and CleanCo fleet capacity. Tumut 3 at the base of Talbingo Dam NSW uses six 250 MW Francis units; Murray 1 uses ten 100 MW Francis units; Gordon Power Station TAS uses three 144 MW Francis units. Heat rejection profile is 1 to 3 percent of nameplate to the machine hall through bearing oil coolers and generator stator windings. Bearing oil temperatures run 50 to 75 degrees C continuous with hot-spot up to 95 degrees C; generator stator windings run up to 130 degrees C. HVAC sizing follows the worst-case full-load summer condition with all units running.

Pelton turbines

Pelton turbines are used at very high head sites (300 metres plus) and dominate the Tasmanian West Coast and Central Highlands schemes. Tarraleah, Liapootah-Wayatinah-Catagunya, the Mersey-Forth cascade and John Butters all use Pelton wheels at heads from 200 metres to 800 metres. Heat rejection profile is slightly lower than Francis (1 to 2 percent of nameplate to the machine hall) because the Pelton runner is unshrouded and a higher fraction of the residual hydraulic energy goes to the tailrace water rather than to the surrounding air. HVAC sizing is correspondingly slightly relaxed compared to Francis.

Kaplan turbines

Kaplan turbines are used at low head sites (5 to 70 metres head) and are present at Burrinjuck NSW and Hume Power Station VIC. Heat rejection profile is similar to Francis but bearing oil temperatures run slightly cooler because the runner speed is lower. Kaplan units are less common in the modern Australian fleet because most new pumped hydro and conventional hydro target medium-to-high head sites where Francis or pump-turbine reversible technology is more efficient.

Pump-turbine reversible units

Pump-turbine reversible units operate in two distinct modes — turbine mode generating power when discharging from upper reservoir to lower, and pump mode consuming power when pumping water from lower to upper for storage. Snowy 2.0 uses six 333 MW reversible Francis-type pump-turbines. Tumut 3 has been operated in pumped-storage mode since the 1970s using a separate pump unit beside each turbine. Wivenhoe Power Station QLD uses two reversible 250 MW pump-turbines. Kidston uses two reversible 125 MW units. Borumba Pumped Hydro will use multiple 250 MW reversible units. Heat rejection differs between modes — pump mode rejects 2 to 3 percent of nameplate against 1 to 2 percent in turbine mode because pump efficiency is slightly below turbine efficiency on the same hydraulic machine. HVAC sizing follows pump mode as the worst case. Mode transitions occur on AEMO dispatch signal and typically take 5 to 8 minutes; the HVAC system tracks the mode transition by ramping cooling capacity over the same window.

Penstock and tailrace tunnel confined space ventilation under AS 2865

Penstocks (the high-pressure water conduits feeding each turbine inlet) and tailrace tunnels (the dewatered discharge tunnels downstream of each draft tube) are AS 2865 confined spaces during inspection and maintenance outages. Each generating unit typically gets a 10-yearly or 15-yearly major inspection where the penstock is dewatered, the runner and shaft seal are inspected, and any defect repair is carried out inside the dewatered space. The HVAC engineer specifies the permanent installation that supports this work plus the portable ventilation system that extends into the tunnel during occupied entry.

Confined space entry permit and atmospheric testing

AS 2865 confined space entry requires a written permit-to-enter issued by an authorised permit issuer (typically the asset manager or a senior maintenance engineer). The permit requires pre-entry atmospheric testing for oxygen content (between 19.5 and 23.5 percent volume), flammable gas (below 5 percent of LEL where any hydrocarbon source is credible — turbine oil leakage from the wet-end bearing journal is a credible source), toxic gas (below the Safe Work Australia WES TWA for any credible toxic), and (where biological growth is suspected in older tunnels with extended dewatering or standing-water pools) hydrogen sulphide at below 10 ppm 8-hour TWA. Continuous atmospheric monitoring throughout occupied entry is mandatory using AS 2865-compliant 4-gas portable detectors. Ventilation must be running and proven before entry permit issue.

Permanent surface fan house and portal ductwork

Each penstock and tailrace entry portal at the surface or upper-elevation entry point has a permanent surface fan house and a fixed ductwork run from the fan house to the entry portal flange. SBKJ duct on these projects is 1,200 mm to 2,020 mm diameter spiral round on the SBTF-2020 in galvanised configuration for inland projects or 316L stainless for the marine and brackish environments. Joint construction is bolted slip-fit with EPDM gasket. The fan house is a small portal building of 50 to 200 square metres with two redundant fans (N+1 redundancy per AS 2865 minimum), variable speed drive control to set the flow rate at the inspection requirement, atmospheric monitoring on the fresh air intake to confirm clean source, and a discharge to the tunnel proper through the entry portal flange.

Portable tunnel-internal ventilation duct

Inside the dewatered tunnel proper, ventilation continues on portable PVC-coated polyester fabric duct in 600 mm to 1,200 mm diameter, rolled to length and hung from the tunnel crown on inspection-day rigging. Typical tunnel ventilation rate is 6 to 8 air changes per hour of the dewatered tunnel volume. Discharge is to the entry portal back out through the fan house, with the supply continuing inward to the active inspection face. For very long tunnels (over 1 kilometre) a parallel supply-and-return fabric duct pair is required to maintain ventilation rate throughout the tunnel length. SBKJ supplies the permanent installation; the portable fabric duct is sourced separately from specialist tunnel ventilation equipment suppliers and is rented or owned by the asset manager.

Permanent low-rate purge ventilation during extended outages

During extended dewatered outages (typically 4 to 12 weeks for a major inspection), permanent low-rate purge ventilation at 2 ACH of tunnel volume runs continuously to prevent condensation accumulation and biological growth. The purge ventilation uses the permanent surface fan house equipment at reduced flow rate, with the fabric duct removed during non-occupied periods. SBKJ ductwork at the portal handles the continuous purge as well as the inspection-day full-flow duty.

Transformer hall HVAC and oil-mist extract

Each main generating unit in a hydroelectric or pumped hydro station has at least one large step-up transformer (typically 400 to 600 MVA at 330 or 500 kV for Snowy Hydro and major Hydro Tasmania stations, or 132 kV for smaller regional and Tasmanian sites) plus auxiliary transformers for station service and excitation. The transformer hall is a separate fire-rated room or cavern bay from the machine hall, with the transformers sitting in bunded oil-containment pits per AS 1940 industrial flammable liquid and IEC 61936 high-voltage installation.

Oil-mist emission and dilution ventilation

Transformer mineral insulating oil under normal load runs at 65 to 80 degrees C bulk temperature with up to 95 degrees C hot-spot temperature in the winding hot spot. The oil expands and contracts through the breather as load and ambient cycle, with continuous emission of a fine oil mist from the breather, the conservator tank vent and the bushing turret seals. Safe Work Australia WES for mineral oil mist is 5 mg/m3 8-hour TWA. Hall ventilation runs at 8 to 15 ACH continuous to dilute the oil mist below the WES at the breathing zone, with supply air filtered to G4 minimum (to keep airborne dust out of the transformer bushings) and exhaust passing through an oil-mist eliminator (chevron-style stainless mesh or fibre-bed coalescer) before discharge to a surface stack.

Material specification and corrosion

Hall material specification is 316L stainless on the exhaust trunks downstream of the mist eliminator because oil aerosol attacks galvanised over a 5 to 8 year horizon, with chloride contribution from any coastal exposure accelerating the failure. The supply side is aluminium-clad insulated 304L because the supply is filtered clean air with no direct oil contact. The SBKJ SBAL-V stainless configuration handles the 316L rectangular trunk runs at 1,500 mm wide by 600 to 800 mm deep, the SBTF-2020 handles the surface-stack discharge run in 1,500 mm to 2,020 mm diameter spiral round, and the SBSF-1525 stitchwelder handles the continuous longitudinal seam welding required on the 316L exhaust trunks under AS/NZS 60079.14 for any Zone 1 or Zone 2 service.

Transformer fire suppression and HVAC interlock

Transformer fire suppression is water deluge per IEC 62271-301 and AS 2118 — a fixed deluge spray covers the transformer body at 10 L/min per square metre for a minimum of 30 minutes from a dedicated water tank or pressurised mains supply. Deluge actuation on transformer fire alarm interlocks with HVAC to close the normal exhaust dampers (containing the fire and the deluge water vapour within the transformer hall), open the high-volume dump damper to a dedicated deluge dump duct, and ramp the dump exhaust fan to full speed. The dump duct is 1,200 mm to 1,500 mm diameter spiral round on the SBTF-2020 in 316L stainless, sized for the post-deluge water vapour volume plus combustion products from any oil that ignites before deluge suppression. Dump duct discharge is to the surface stack at sufficient elevation and separation from any fresh air intake.

Oil pit drainage and bund containment

Each transformer bund pit contains the full oil inventory plus deluge water capacity in a fire scenario. Bund drainage is to a dedicated oil-water separator with skimmer for the floating oil layer and discharge of the cleaned water to the tailrace. The bund pit itself is unclassified outside HVAC scope but the pit-level air space is monitored for hydrocarbon vapour with a portable detector during routine inspection. No HVAC ductwork runs through the bund pit volume.

GIS switchroom HVAC and SF6 detection

Modern Australian hydroelectric and pumped hydro stations almost universally use SF6-insulated gas-insulated switchgear at 132, 220, 330 or 500 kV because of the compact footprint compared to air-insulated switchgear. Snowy 2.0 uses 500 kV GIS for grid connection; Tumut 3, Murray and Gordon use 330 kV GIS; smaller regional stations use 132 kV GIS. The GIS switchroom is a separate fire-rated room from the machine hall, typically located adjacent to the transformer hall on the high-voltage side.

SF6 hazard profile and global warming potential

SF6 is an asphyxiant rather than a toxic gas — there is no formal Safe Work Australia WES — but the rapid-asphyxiation risk on a major bus leak is severe because SF6 is approximately five times denser than air and pools at floor level in enclosed switchrooms. SF6 also has a global warming potential of 23,500 times CO2 over a 100-year horizon, which makes leak quantification and reporting under the National Greenhouse and Energy Reporting NGER scheme mandatory for any utility-scale operator. Trace decomposition products of SF6 arcing during normal switch operation include SO2, HF, SOF2 and a small fraction of S2F10; these decomposition products are toxic and corrosive even at very low concentrations.

SF6 detection grid

SF6 detection uses non-dispersive infrared (NDIR) or photoacoustic spectroscopy sensors at floor level (within 300 mm of slab) on a maximum 5 metre by 5 metre grid. First alarm setpoint at 1,000 ppm SF6 by volume triggers ventilation boost to 20 to 30 ACH, audible-visual alarm and operator notification. Second alarm at 10,000 ppm triggers full plant evacuation, ventilation maximum, grid-side isolation of the affected GIS bay and emergency response activation. Detector calibration is on a 6-month cycle with full functional testing on each calibration.

Ventilation strategy and ductwork material

Switchroom ventilation runs at 4 to 6 ACH baseline rising to 20 to 30 ACH on SF6 detection trip. Exhaust grilles are at floor level (not ceiling) because of SF6 density, with a separate ceiling exhaust path for normal-mode ventilation. The trunk routes to a dedicated surface stack discharging well clear of any HVAC fresh air intake — typical 20 metre horizontal and 10 metre vertical separation. Ductwork is 316L stainless on the SBSF-1525 stitchwelder line with continuous longitudinal seam closure because trace SF6 arcing products (SO2, HF, SOF2) attack galvanised within 12 to 24 months. The supply side is aluminium-clad insulated 304L because supply air is clean.

Spark-resistant fan housing

Although SF6 itself is not flammable, the GIS switchroom often shares ventilation envelope with adjacent rooms classified Zone 2 IIA (transformer oil mist) or contains arc-fault credible events that generate brief but intense hot ignition sources. Spark-resistant fan housings in aluminium or non-sparking stainless are specified across the entire GIS switchroom exhaust to remove any credible ignition source from the duct. SBKJ supplies SBAL-V-fabricated duct paired with spark-resistant fan housings from approved suppliers as a packaged delivery.

Battery room HVAC — lead-acid and Li-ion

Battery rooms at hydroelectric and pumped hydro stations come in two distinct technologies with different HVAC requirements.

Lead-acid station batteries — 110 V DC and 24 V DC control supply

Lead-acid station batteries for the 110 V DC and 24 V DC control supply are present at every Australian hydroelectric and pumped hydro station. They provide UPS-backed protection relay supply, breaker tripping power, control panel auxiliary supply and emergency lighting. Battery rooms are AS/NZS 60079 Zone 2 IIB+H2 because hydrogen evolves during float charge (typical 0.42 ml/Ah/cell) and especially during equalisation charge (typical 4.2 ml/Ah/cell). Sulphuric acid mist also evolves from cell vents under heavy charge. The applicable standards are AS/NZS 4509 stand-alone power systems and AS 3011 secondary batteries installations.

Continuous mechanical ventilation maintains H2 concentration below 25 percent of LEL (1 percent H2 by volume in air) under worst-case credible equalisation charge release; typical battery room ventilation is 4 to 8 ACH baseline. H2 detectors are catalytic-bead or electrochemical sensors at ceiling level (because hydrogen rises rapidly, relative density 0.0695). The room is held at slight negative pressure relative to surrounding spaces to contain hydrogen and acid mist. Ductwork is 316L stainless because sulphuric acid mist attacks galvanised within months; SBKJ duct on the battery room exhaust uses welded 316L on the SBAL-V stainless configuration with the SBSF-1525 seam closure.

Battery cabinets themselves are typically pre-engineered packaged units with integral ventilation; the SBKJ scope is limited to the room shell HVAC and the room-to-stack exhaust connection.

Li-ion BESS rooms — grid-scale FCAS storage

Li-ion BESS installations co-located with pumped hydro and hydroelectric stations are increasingly common — the Hornsdale Power Reserve at Hornsdale Wind Farm SA, the Western Downs Battery in QLD, the Torrens Island Big Battery in SA, the Capital Battery in NSW and the Goyder South project in SA are operating examples. Hornsdale itself is the prototype installation for FCAS market participation, and the technology and HVAC specification developed at Hornsdale flows into every subsequent Australian grid-scale BESS.

Li-ion BESS HVAC follows NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems), AS/NZS 5139 (Electrical installations — Safety of battery systems) and AS/NZS 3000 wiring rules. The dominant hazard is thermal runaway of an individual cell propagating to an entire module or rack, releasing electrolyte vapour (DMC, EMC, EC and other organic carbonate solvents) and a mixed off-gas of CO, H2, methane, ethane, ethylene and HF (from PF6 electrolyte salt decomposition). Vapour density is mixed — HF is denser than air, hydrogen is much lighter — so detection grids run at both ceiling and floor levels with combined heat, smoke and combustible gas detection.

Building ventilation is 4 to 8 ACH baseline rising to 20 to 30 ACH on thermal-runaway detection trip. Ductwork is 316L stainless throughout because HF and organic carbonate vapour attack galvanised within hours during an off-gas event. Spark-resistant fan impellers in aluminium or non-sparking stainless are mandatory per AS/NZS 60079 Zone 2 IIB+H2 classification during a thermal event. SBKJ supplies welded stainless duct from the SBAL-V stainless configuration paired with spark-resistant fan housings.

Tesla Megapack and similar grid-scale BESS products are typically supplied as factory-built containerised units with integral HVAC and detection inside the container envelope. SBKJ's scope at the surrounding building shell level includes the supply and exhaust ducting between the BESS container and the building shell, the building-shell ventilation plant and the discharge stack to atmosphere.

Control room HVAC — positive-pressure refuge with AEMO grid code reliability

The plant control room is the operational heart of the station and houses SCADA workstations, protection relays, communication equipment, AEMO dispatch interface and operator amenity. Control room HVAC is specified as a positive-pressure refuge at 50 to 100 Pa above the surrounding plant, with separate filtered fresh air supply and no air return path from the machine hall, transformer hall or switchroom back to the control room.

Air intake placement and filtration

The supply intake is located on the side of the control room facing away from any transformer vent stack, SF6 exhaust stack or BESS exhaust stack, with the standard 20 metre horizontal and 10 metre vertical separation from any process exhaust point. Intake filtration is F7 minimum per ISO 16890 for fine particulate, with optional activated carbon filter if the site is near a coal-handling or other dusty operation. Filter pressure differential is monitored at the AHU and the filter is changed on differential pressure rather than time.

AEMO grid code reliability — N+1 redundancy

AEMO grid code requirements drive the control room HVAC redundancy specification. Typical configuration is dual N+1 AHUs with automatic changeover, dual chilled water plants with independent power supply, and a UPS-backed control panel allowing continued HVAC operation through a station blackout for at least 4 hours. The control room must remain habitable through any plant operational scenario including total grid blackout because operators are required to remain in the control room to support grid restoration. AEMC dispatch reliability requirements are reflected in the Network Operating Plan for each station and the HVAC engineer reviews the Network Operating Plan during FEED.

Internal cooling load

The control room internal cooling load is dominated by SCADA cabinets, protection relay cabinets and operator workstations — typically 500 to 1,500 W per square metre of floor area, much higher than commercial office. Chilled water supply at 6 to 12 degrees C feeds the fan-coil units serving the control room with secondary backup from a packaged DX cooling unit on independent power supply. Operator workstations have task lighting and standard commercial fit-out; the AS 1668.2 outdoor air rate of 10 L/s per person plus the cooling-driven supply rate gives a typical control room rate of 4 to 6 ACH.

Smoke detection and clean agent fire suppression

The control room is protected by clean-agent fire suppression (FM-200, Novec 1230 or inert-gas IG-541) per AS 4214 gaseous fire-extinguishing systems and AS 1670 fire detection. Smoke detection is at very early warning level (VESDA aspirating smoke detection per AS 1670.4) to allow operator action before clean-agent discharge. Clean-agent discharge interlocks with control room HVAC to close all fresh air dampers and isolate the control room volume to maintain agent concentration for the design hold time. SBKJ ductwork on the control room is conventional galvanised with mechanical isolation dampers rated for the clean-agent discharge pressure.

Diesel black-start generator and day tank HVAC

Black-start diesel generators are mandatory at every Australian hydroelectric and pumped hydro station per AEMO grid code requirements — the plant must be able to self-start without grid supply to support grid restoration after a system black event. Diesel generators are typically 2 to 5 MW per unit with 1 to 2 units per station depending on the station auxiliary load profile.

Generator room ventilation

Diesel generator rooms host engine cooling air supply, combustion air supply and combustion exhaust extraction at substantial volumes. Engine cooling air is typically 30 to 50 m3/s per MW of generator capacity, drawn through engine-room louvres and exhausted through radiator-driven roof discharge. Combustion air is approximately 6 m3/s per MW, drawn through a separate filtered intake. The diesel exhaust routes through a separate fire-rated trunk to a surface stack discharge with appropriate noise attenuation per the local LGA noise envelope, typically 75 dB(A) at 7 metres from the stack base.

Day tank room hazardous area

The day tank room is AS 1940 flammable liquid storage with bunded containment per AS 1940 Section 4 and Zone 2 IIA hazardous classification within 1 metre of any fuel transfer point. The day tank is sized for 8 to 24 hours of continuous diesel operation at full load (typically 5,000 to 50,000 litres) and is fed from a main fuel storage tank elsewhere on site. Transfer pumps are AS/NZS 60079-rated for Zone 2 IIA. Ventilation is 6 to 8 ACH continuous with the supply at low level and exhaust at high level, discharging through a separate stack from the engine combustion exhaust.

Material specification

Ductwork is galvanised on the engine cooling supply and the combustion air supply. The engine combustion exhaust is 316L stainless because high-temperature flue gas plus condensate forms sulphurous acid which attacks galvanised rapidly. The day tank room exhaust is 316L because diesel vapour plus condensate condenses on duct internal surfaces over time. SBKJ duct on diesel scope is typically split — SBAL-V galvanised for the supply runs, SBAL-V stainless for the combustion exhaust and day tank exhaust, with SBTF-2020 spiral round on the surface stack discharge run.

Geothermal pilot plant HVAC and H2S extract

Geothermal capacity in Australia is modest but the HVAC specification is distinctive because of the hydrogen sulphide content of the geothermal brines and the binary-cycle working fluid hazard.

Birdsville geothermal plant — Ergon Energy

The Birdsville Geothermal Power Station in remote western Queensland is the longest continuously operating geothermal plant in Australia. Bore water at 98 degrees C from the Great Artesian Basin feeds a small Organic Rankine Cycle unit with pentane working fluid, providing approximately 80 kW continuous to the Birdsville township grid via Ergon Energy distribution since 1992. The HVAC scope is a small 100 to 200 square metre plant building housing the brine separator, ORC turbine-generator, heat rejection cooling tower interface and the pentane condenser. Building ventilation runs at 6 to 10 ACH continuous, with H2S detection at floor level on 5 metre grid (electrochemical sensors, first alarm 5 ppm, second alarm 10 ppm interlocked to plant trip and increased ventilation). Pentane working fluid loop area is Zone 2 IIA per AS/NZS 60079.

Pressure relief vent stack and H2S scrubber

Pressure relief vent stacks on the brine separator and any auxiliary pressure relief on the ORC working fluid loop discharge through a caustic scrubber (a packed-bed sodium hydroxide spray tower) before atmospheric vent. The scrubber neutralises any H2S in the vent gas to soluble sodium sulphide and sulphur, preventing odour and environmental impact at the township boundary. The scrubber stack itself is 316L stainless from the inlet to the demister and FRP (vinyl ester resin) downstream of the demister where the caustic-saturated gas contact is dominant.

Ductwork material — 316L throughout

Ductwork is 316L stainless throughout the geothermal plant because trace H2S plus condensate forms sulphurous acid which attacks galvanised within months. The supply side, normally clean filtered air, is also 316L because cross-contamination on shutdown and startup can deposit acid on supply duct internals. The SBKJ SBAL-V stainless configuration handles the rectangular trunk runs and the SBTF-1500 handles the round duct on the brine separator vent line.

Geelong VIC district heating trial and emerging direct-use

The Geelong VIC district heating trial led by the Council of the City of Greater Geelong is the most advanced of the emerging Australian direct-use geothermal projects. Direct-use takes geothermal bore water (at lower temperature than electricity-generating geothermal, typically 50 to 80 degrees C) directly into a district heating network for building heating without an intermediate Organic Rankine Cycle. HVAC scope at the geothermal heat pump plant is small — a few hundred square metres of building — with the bore water heat exchanger as the primary mechanical equipment. H2S content of the geothermal water is the dominant HVAC sizing case as at Birdsville. The Geelong trial is approximately a 10-year horizon and is at proof-of-concept stage in 2026.

Historic enhanced geothermal pilots — Geodynamics and Petratherm

The Geodynamics Cooper Basin enhanced geothermal pilot (Habanero project, hot dry rock at 4 to 5 kilometre depth in remote SA) ran from 2003 to 2016 with a 1 MW pilot ORC plant. The Petratherm Paralana pilot in the same region ran in parallel. Both projects ceased commercial operation after technical challenges with deep-well injectivity and economic challenges with grid connection from remote arid locations. The HVAC reference design from these projects informs the materials specification on any future Australian enhanced geothermal venture, although no commercial-scale follow-on is currently in development.

Ocean wave and tidal energy onshore station HVAC

Australian ocean wave and tidal energy developers operate a small number of pilot and demonstration installations along the southern and western coasts. Each technology routes the captured wave or tidal energy to an onshore power conversion station — a small coastal building of 200 to 1,000 square metres housing the hydraulic accumulator, generator, power electronics, transformer and grid interconnect.

Carnegie Clean Energy — CETO wave

Carnegie Clean Energy (ASX:CCE) operates the CETO 6 wave energy technology — a fully submerged buoyant actuator connected to the seabed by a tether, with onshore conversion. The Garden Island Naval Base WA demonstration project ran a 240 kW unit feeding the HMAS Stirling base from 2014 until decommissioning in 2019; Carnegie's commercial pipeline targets multi-MW arrays at Albany WA and at Wave Hub Cornwall UK. The onshore conversion station for a CETO array is a small coastal building of 200 to 500 square metres housing the hydraulic accumulator, the hydraulic-to-electric power unit, the transformer, the power electronics and the grid interconnect.

Wave Swell Energy — UniWave 200 at King Island TAS

Wave Swell Energy operates the UniWave 200 oscillating water column wave energy unit at King Island TAS — a 200 kW unit on extended sea trial since 2021 feeding into the Hydro Tasmania-operated King Island microgrid. The UniWave technology is a hollow concrete chamber on the seabed close to shore that captures the rising and falling wave surface, with the resulting air flow driving a vertical-axis air turbine on the chamber roof. The onshore conversion station for UniWave is co-located with the King Island microgrid main station and houses the generator, power electronics and grid interconnect; air turbine itself is exposed to salt-spray and requires sealed bearing arrangements.

Bombora Wave Power — mWave

Bombora Wave Power has developed the mWave membrane-based wave energy converter, with development testing at Peniche Portugal and Albany WA. The Perth WA headquarters and the Perth-region commercial development pipeline target multi-MW deployments through the late 2020s. The onshore conversion station for mWave is conventional coastal industrial scope.

BlueGreen Group and tidal energy

BlueGreen Group is developing tidal energy in Bass Strait between Tasmania and mainland Australia and at the Banks Peninsula NZ. Tidal energy converters extract energy from the tidal current flow rather than the wave surface, with submerged horizontal-axis or vertical-axis turbines on the seabed. The HVAC scope on a tidal energy onshore station is similar to wave energy.

AusOcean and research-stage

AusOcean is a research-stage wave-energy testing organisation operating in Bass Strait. The research-stage installations are typically smaller than commercial-stage and the HVAC scope is correspondingly smaller, often limited to a temporary or trailer-mounted onshore conversion package.

Coastal HVAC engineering — salt-spray corrosion

The dominant HVAC concern at every ocean wave or tidal onshore station is salt-spray corrosion from continuous coastal exposure. Every duct material specification is at least 316L stainless or aluminium-clad galvanised on the exterior; internal supply duct is 316L because cross-contamination on opening of intake louvres can deposit chloride on the duct internal surfaces. Building ventilation is 4 to 8 ACH for personnel comfort and dust control, with the fresh air intake side of the building facing inland (away from the prevailing onshore wind) and through a salt-spray pre-filter (typically a coalescing demister followed by a G4 panel filter).

Power electronics cooling

Heat rejection from the power electronics is typically 50 to 200 kW for a 1 to 5 MW wave or tidal unit. Direct air cooling is not used because direct salt-spray air would accumulate chloride deposits on the power electronics within weeks. Instead, power electronics cooling is through a sealed liquid-cooled heat exchanger with a closed-loop refrigerant or dielectric coolant, then a fan-coil rejection heat exchanger to outside air. The power electronics cabinets are held at slight positive pressure (clean dry instrument air) and rated IP66 minimum to keep chloride aerosol out of the cabinet during routine maintenance access.

SBKJ ductwork on coastal energy projects

SBKJ duct on these projects uses 316L throughout, fabricated on the SBAL-V stainless configuration with welded longitudinal seams on the SBSF-1525 stitchwelder for any duct in the salt-spray exposure envelope. SBTF-1500 spiral round handles any large-diameter exhaust and discharge stacks. The SBPC1500 plasma cutter handles the 316L sheet penetrations.

OTEC Ocean Thermal Energy Conversion — pilot stage

Ocean Thermal Energy Conversion (OTEC) extracts energy from the temperature gradient between warm surface seawater (25 to 30 degrees C in tropical Australian waters) and cold deep seawater (5 to 7 degrees C at 1,000 metre depth). OTEC plants use a closed-cycle ORC similar to geothermal but with seawater instead of geothermal brine. Australian OTEC is at pilot-evaluation stage only; no commercial installations are currently in development. If an Australian OTEC pilot proceeds, the HVAC specification will follow the geothermal binary-cycle pattern with substitution of seawater hazards (chloride corrosion, biofouling) for H2S hazards. SBKJ duct specification would be 316L stainless throughout with super-duplex or 6Mo upgrade on any duct in direct seawater contact.

Hydrogen co-located with renewables — cross-reference

Hydrogen production co-located with renewables — solar farms feeding electrolysers, wind farms feeding electrolysers, pumped hydro feeding electrolysers during off-peak — is increasingly common in the Australian project pipeline. The HVAC scope for the electrolyser hall is covered in detail in the SBKJ Green Hydrogen Production, Electrolyser Plant, Ammonia Synthesis, H2 Refuelling and Renewable Hydrogen Export Terminal HVAC Duct Guide and is not repeated here. For renewable-paired electrolyser projects co-located with hydroelectric and pumped hydro, the typical scope is a small electrolyser plant building (a few hundred kilowatts to a few MW of electrolyser capacity) adjacent to the hydroelectric switchyard, with hydrogen production used for vehicle refuelling, industrial process heat or grid balancing.

Snowy 2.0 underground construction worker accommodation — a unique HVAC scope

The Snowy 2.0 construction phase (mid-2020s) is one of the largest single Australian construction workforces ever assembled — several thousand workers on extended camp deployment at the Tantangara and Talbingo construction lodges, plus the Cabramurra construction support town and the in-tunnel temporary works ventilation. The construction worker accommodation HVAC is a temporary scope built to NCC Class 3 hostel-style standards with conventional commercial HVAC at 4 to 6 ACH, galvanised supply duct on the SBAL-V, and standard commercial cooling and heating plant. The temporary accommodation is decommissioned after construction completion and is not part of the permanent station operating scope.

In-tunnel temporary works ventilation during construction is a separate scope from the permanent station ventilation — typical underground civil tunnelling ventilation rates (50 to 100 m3/s per kilometre of tunnel) are 5 to 10 times the eventual permanent ventilation rate because of the diesel construction plant load. The temporary ventilation system is installed in 1,500 mm to 2,020 mm diameter ducting on the SBKJ SBTF-2020 in galvanised configuration, removed and replaced with the permanent stainless ductwork once construction completes. SBKJ supplied bench engineering support on Snowy 2.0 temporary tunnel ventilation through the construction phase.

Visitor centre, interpretation gallery and heritage HVAC

Many Australian hydroelectric and pumped hydro sites host a public-facing visitor centre or interpretation gallery — the Snowy Hydro Discovery Centre at Cooma NSW, the Tumut 3 Lookout NSW, the Cabramurra Visitors Centre (Australia's highest town, formerly), the Hydro Tasmania visitor experiences at Strathgordon and Tarraleah TAS, the Wivenhoe Dam Visitor Information Centre QLD, and the new Snowy 2.0 visitor facility under construction at Tantangara.

NCC Class 9b assembly

Visitor centres are NCC Class 9b assembly buildings with mechanical ventilation per AS 1668.2 at 10 L/s/person plus the thermal load from interactive displays and lighting, smoke control per AS 1668.1 with smoke spill to roof discharge, and accessible egress per NCC Part D. Ductwork is conventional galvanised on the SBAL-V at 4 to 6 ACH plus a dedicated kitchen exhaust trunk to AS 1668.2 Section 4.11 if a cafe is included. The visitor centre is physically and acoustically separated from the active machine hall by fire-rated walls and AS 1668.1 smoke control zones.

Heritage-sensitive HVAC at original Snowy Scheme stations

The original Snowy Mountains Scheme stations constructed between 1949 and 1974 — Guthega, Murray 1 and 2, Tumut 1 and 2, Blowering, Burrinjuck — fall under the NSW Heritage Council Snowy Mountains Scheme heritage standards. Any HVAC modification to the original station fabric (the structural concrete, original stainless and brass fittings, original control panels, original lighting and any externally visible building element) requires Heritage Council approval and must preserve the original visual character. New ductwork in heritage stations is typically routed through service voids and false ceilings rather than surface-mounted, with duct grilles and access panels matched to the original brass and stainless finishes.

The SBKJ project office at Box Hill North supports heritage-sensitive specifications by providing custom finish options on SBAL-V output including matched brass-and-stainless trim and bespoke grille profiles to match the original 1950s and 1960s aesthetic. The Snowy 2.0 new powerhouse is contemporary scope and does not fall under heritage standards because it is a new underground cavern, but the surface portals at Tantangara and Talbingo are subject to a Heritage Council overview because they sit in the alpine environment adjacent to Kosciuszko National Park.

Hydro Tasmania heritage precincts — Tarraleah and Waddamana

The Tarraleah village in Tasmania (built in the 1930s and 1940s alongside the original Tarraleah Power Station) and the Waddamana Power Museum (the original 1916 Hydro Tasmania installation, now decommissioned as an operating asset and operated as a public museum) are both heritage-listed under the Tasmanian Heritage Council. Any HVAC modification at these sites is subject to Heritage Council review with the same preservation-of-original-character requirements as the Snowy heritage scope.

Murray-Darling Basin Authority water release protocols

Hydroelectric stations on the Murray-Darling system (Hume Power Station VIC, Dartmouth Power Station VIC, the upper Murray stations operated by Snowy Hydro) are subject to Murray-Darling Basin Authority MDBA water release protocols. Water release for environmental flow and irrigation purposes is coordinated through the MDBA Basin Plan rather than dictated solely by power dispatch economics. This influences the HVAC operational profile because units cycle on environmental-flow schedule that does not align with the AEMO peak-and-trough dispatch curve, with higher overall annual operating hours than a peak-only pumped hydro unit and a longer cumulative operating envelope for HVAC equipment.

Materials selection — when 316L and when galvanised

The duct steel grade decision on hydroelectric and pumped hydro projects splits cleanly between unclassified scope (galvanised acceptable) and hazardous or corrosive scope (316L mandatory).

Galvanised carbon steel sheet to AS 1397

Galvanised carbon steel sheet to AS 1397 is acceptable for unclassified scope across the project — surface station office, amenity, workshop, control room supply, machine hall supply trunks above the transformer pit envelope, access tunnel ventilation supply, visitor centre, training room and break room. Galvanised handles the dominant volume of HVAC ductwork on most projects because the bulk of building services is unclassified industrial. Coil thickness typically 0.5 to 1.2 mm on the SBAL-V; G275 zinc coating standard for inland projects and G350 for marine-exposed projects.

316L austenitic stainless steel UNS S31603

316L austenitic stainless steel is mandatory for transformer hall oil-mist extract, GIS switchroom SF6 exhaust, Li-ion BESS room thermal-runaway extract, lead-acid battery room acid mist extract, geothermal H2S extract, penstock portal humid-air return, tailrace tunnel inspection ventilation, diesel combustion exhaust and any duct on a coastal ocean-energy station. 316L offers low carbon content (below 0.03 percent) which suppresses chromium carbide precipitation in the heat-affected zone during welding, preventing inter-granular corrosion at the weld joint. The 2 to 3 percent molybdenum content gives 316L substantially higher chloride tolerance than 304, which is the dominant rationale on coastal sites.

304L for inland non-corrosive scope

304L stainless is acceptable for control room supply duct, switchroom supply duct, geothermal supply duct (where the supply air is clean and pre-filtered) and any unclassified scope that needs the visual or hygienic premium of stainless but does not face direct corrosive exposure. The cost saving over 316L is 20 to 30 percent on coil price but the chloride tolerance is significantly lower — service life on a coastal site is under 10 years against 25 years plus for 316L.

Aluminium-clad insulated duct

Aluminium-clad insulated duct is used for supply trunks where condensation control is the dominant requirement — for instance the supply trunks into a transformer hall (where the inside surface stays close to room temperature but the outside is colder cavern wall) or the supply trunks into a GIS switchroom (similar profile). The aluminium cladding handles the external surface and the insulation handles the thermal break. The substrate is typically 304L stainless or galvanised carbon steel.

FRP vinyl ester resin for caustic scrubber service

For geothermal H2S scrubber discharge and for any caustic mist or scrubber-saturated airstream, FRP vinyl ester resin duct is used in place of stainless because the FRP is fully corrosion-resistant in caustic service and avoids the cost premium of upgraded stainless grades. SBKJ does not manufacture FRP duct directly but supplies the transition pieces between FRP and stainless on the discharge stack arrangement.

Acoustic and vibration considerations

Hydroelectric and pumped hydro stations are large generators of low-frequency mechanical noise (turbine and generator at 60 to 150 RPM, gearbox-coupled units at 1,500 RPM, transformer hum at 100 Hz mains frequency) that propagates through the cavern envelope and through the access-tunnel ventilation duct. AS 1055 acoustic noise emission limits apply at the site boundary and AS/NZS 2107 internal noise levels apply inside occupied spaces.

Duct acoustic lining

Acoustic lining inside the supply and exhaust trunks is mandatory for any duct passing within 50 metres of an occupied space. Lining is typically 50 mm rockwool slab faced with perforated metal liner per AS 4859 thermal insulation materials and AS 4254 ductwork. The SBKJ SBAL-V handles double-skin construction with internal acoustic lining at the standard duct sizes. For the control room HVAC supply, attenuator silencers are added at the AHU discharge and at the control room intake to bring noise breakout below NR-30.

Vibration isolation on fan and AHU mountings

Fan and AHU mountings use spring-and-rubber vibration isolators sized for the rotating mass and the dominant frequency. Flexible duct connectors at every fan and AHU connection break the structural path from the fan vibration into the duct. SBKJ supplies the flexible duct connectors as standard accessory on the SBAL-V output.

Pressure relief and emergency blowdown ductwork

While hydroelectric and pumped hydro stations are not gas-pressure plants in the same sense as a hydrogen facility, certain pressure relief paths exist that route through duct rather than hard pipe.

Penstock pressure surge relief — surge shaft

Each penstock has a surge shaft for hydraulic pressure relief during load transients. The surge shaft is a hard-pipe arrangement, not HVAC duct, and is outside SBKJ scope. The HVAC engineer is aware of the surge shaft location and routes ductwork to avoid the surge shaft head pressure envelope.

Transformer pressure relief vent

Each transformer has a sudden pressure relief valve that vents excess pressure on internal fault. Vent discharge is to atmosphere through a short stack on the transformer roof — outside HVAC scope but informs HVAC duct routing.

GIS bus pressure relief

SF6 GIS bus has pressure relief discs for over-pressure on internal arc fault. Disc rupture releases SF6 directly into the switchroom which is then captured by the SF6 detection and exhaust system described above.

Refrigeration and chilled water plant HVAC

Underground powerhouses and large surface stations typically use chilled water cooling for the control room and switchroom temperature control, supplied from a central chilled water plant in the auxiliary plant bay. Chilled water plant scope includes the chiller package (typically water-cooled centrifugal chillers at 1 to 5 MW per unit), the chilled water pumps, the condenser water pumps and the cooling tower or heat rejection arrangement.

Chiller machinery room

The chiller machinery room is unclassified scope outside any hazardous area envelope. Building ventilation is 6 to 8 ACH for personnel comfort and refrigerant leak dilution. ASHRAE 15 (Safety Standard for Refrigeration Systems) and AS/NZS 5149 (Refrigerating systems and heat pumps) apply. For HFC refrigerant (R134a, R513A, R1234ze and similar) the dilution ventilation case is straightforward; for ammonia refrigerant (R717, used in some larger chiller installations) the toxic-gas detection and exposure case is similar to a green-ammonia synthesis plant — Safe Work Australia WES 25 ppm 8-hour TWA, 35 ppm STEL, electrochemical detectors at breathing height.

Cooling tower and heat rejection

Cooling tower heat rejection is typically a counterflow or crossflow cooling tower on the surface or a fluid cooler on the surface for closed-loop applications. The cooling tower itself is outside SBKJ scope; the duct between the chiller condenser water heat exchanger and the cooling tower is hard pipe rather than HVAC duct. The HVAC engineer is aware of the cooling tower location for noise breakout and Legionella considerations under the relevant state public health legislation.

Fire damper and AS 1851 maintenance regime

Every fire-rated wall crossing carries a fire damper per AS 1530.4 with thermal release at 70 degrees C. The fire damper register is the master document for AS 1851 maintenance — every fire damper is tested annually with the actuator dropped and the blade verified to close fully and to seal against the duct frame.

Fire damper inventory

A typical underground powerhouse has 100 to 300 fire dampers across the cavern envelope and the access tunnel duct system. Each damper is identified in the AS 1851 fire damper register with its location, type, manufacturer, installation date and test date. SBKJ supplies the fire damper frames as part of the SBAL-V output, with the damper itself sourced from approved fire damper manufacturers.

Annual drop test under AS 1851

Annual drop testing is performed by a qualified AS 1851 inspector — the inspector accesses each damper through an access panel in the duct, manually releases the actuator, verifies the blade closes fully, verifies the blade seals against the frame, and records the test in the fire damper register. Any failure triggers a repair and re-test cycle. The SBKJ duct design provides access panels at every fire damper location with hinged or removable covers.

SBKJ machinery for hydroelectric, pumped hydro, geothermal and ocean energy projects

SBKJ supplies HVAC ductwork fabrication machinery to Australian and international hydroelectric, pumped hydro, geothermal, ocean wave, tidal and grid-scale BESS project fabricators from the Box Hill North VIC office. The standard machine specifications on these projects are:

SBAL-V auto duct line — galvanised configuration for unclassified scope

The SBAL-V auto duct production line in galvanised configuration accepts 0.5 to 1.2 mm galvanised coil and produces TDF flange rectangular ductwork from 200 mm wide up to 1,500 mm wide at line speeds up to 25 metres per minute on 1 mm galvanised. This is the workhorse machine for the surface station office, amenity, workshop, control room supply, machine hall supply trunks above the transformer pit envelope and access tunnel ventilation supply. SBKJ delivers the SBAL-V with TDF flange tooling standard, integrated Pittsburgh seam closer (for unclassified scope) and the option of a stitchwelder for stainless seam service. For full specification see the SBAL-V versus SBAL-III comparison guide.

SBAL-V auto duct line — 316L stainless configuration for hazardous and corrosive scope

The SBAL-V in 316L stainless configuration handles the transformer hall oil-mist extract, GIS switchroom SF6 exhaust, BESS thermal-runaway extract, geothermal H2S extract and ocean energy coastal-station ductwork. Line speed on 1 mm 316L is 8 to 12 metres per minute. The stainless configuration includes hardened tooling, stainless-compatible coolant and lubricant systems, and brushed stainless rolls to minimise surface marking on the finished product. The continuously welded longitudinal seam (via SBSF-1525 stitchwelder or GTAW seam welder option) is mandatory for any Zone 1 or Zone 2 service under AS/NZS 60079.14.

SBTF-2020 large-diameter spiral tubeformer

The SBTF-2020 large-diameter spiral tubeformer produces spiral round ductwork up to 2,020 mm diameter in galvanised or stainless coil, in continuous lengths up to the available coil width. The SBTF-2020 is the machine of choice for the access tunnel ventilation main on an underground powerhouse, the powerhouse machine hall return air riser, the penstock and tailrace portal purge duct, the diesel exhaust surface stack and the transformer hall deluge dump duct. Forming speed on 1 mm galvanised coil is 12 to 18 metres per minute; on 1 mm 316L stainless is 6 to 10 metres per minute. The SBTF-2020 is the only Australian-supplied machine that produces 2,020 mm diameter spiral round duct in a single pass.

SBTF-1500 and SBTF-1602 mid-diameter spiral tubeformers

The SBTF-1500 and SBTF-1602 produce spiral round duct up to 1,500 mm and 1,602 mm diameter respectively. These mid-diameter machines handle the bulk of the branch duct, the auxiliary plant duct and the smaller-bore exhaust stack runs that do not require the full SBTF-2020 capacity. Forming speed on 1 mm galvanised coil is 15 to 22 metres per minute.

SBSF-1525 stitchwelder for stainless seam closure

The SBSF-1525 stitchwelder handles longitudinal seam welding on stainless rectangular duct that is mandatory for any Zone 1 or Zone 2 service under AS/NZS 60079.14 — the transformer hall extract, GIS switchroom exhaust, BESS exhaust, lead-acid battery room exhaust, geothermal H2S extract, diesel combustion exhaust and any duct on a salt-spray coastal exposure. Pittsburgh seams are not permitted in Zone 1 because the seam can lift under hydrogen overpressure or chemical mist accumulation and create a localised release path. The SBSF-1525 produces a continuously welded longitudinal seam at line speed compatible with the SBAL-V stainless output.

Spark-resistant fan housing for hazardous area exhaust

For any duct in AS/NZS 60079 Zone 2 IIB or IIC classification — the SF6 GIS switchroom, the Li-ion BESS room during thermal event, the lead-acid station battery room, the geothermal binary-cycle area — spark-resistant fan housing is mandatory. SBKJ supplies the duct and pairs with approved spark-resistant fan housings from specialist hazardous area fan manufacturers as a packaged delivery, with FAT and on-site commissioning support from the Box Hill North project office.

SBPC1500 plasma cutter for 316L sheet

The SBPC1500 plasma cutter handles 316L sheet penetrations for branch take-offs, access panel cutouts and damper frame openings. Plasma cutting is preferred over oxy-fuel for stainless because it produces a cleaner cut with minimal heat-affected-zone discolouration and no surface contamination. Post-cut grinding and pickle-and-passivate restores the chromium oxide passive layer.

Quality and traceability

Hydroelectric, pumped hydro and BESS plant fabricators normally require mill certificates on every coil and weld procedure qualification records (WPQR) on every welder per AS/NZS 1554.6 and ISO 15614. SBKJ machines support material traceability through coil tag readers and weld parameter logging at the PLC. The standard SBKJ Factory Acceptance Test (FAT) procedure (see the HVAC duct machine buyer's checklist) is extended to include stainless-specific qualification on hazardous-area-adjacent projects, with witness inspection by the buyer's QA representative at the SBKJ project office before the machine ships. For the full SBKJ machine fleet see the machines page; for product detail on the SBAL-V specifically, see the SBAL-V product page.

Cost benchmarks and lead time

Hydroelectric and pumped hydro HVAC ductwork costs are dominated by the project scale rather than the unit duct rate. A Snowy 2.0-scale underground powerhouse may require 5,000 to 8,000 linear metres of duct across the cavern, access tunnel, surface station portals and ancillary buildings; a small wave-energy onshore station may require 200 to 500 metres total.

Material cost benchmarks (May 2026)

Galvanised carbon steel coil at 1 mm thickness costs approximately AUD 1.40 to 1.80 per kilogram delivered from an Australian coil supplier (BlueScope Steel for AS 1397 G275 standard). 316L stainless coil at 1 mm thickness costs approximately AUD 8 to 12 per kilogram delivered from Australian, European or Asian mills. Total finished duct cost (material plus fabrication labour plus welding plus surface finishing) typically runs AUD 180 to 280 per linear metre for 1,200 mm wide rectangular galvanised and AUD 700 to 1,000 per linear metre for the equivalent 316L stainless. Spiral round on the SBTF-2020 at 2,020 mm diameter lands at AUD 400 to 600 per linear metre galvanised and AUD 1,200 to 1,800 per linear metre 316L stainless, installed.

Lead time benchmarks

Galvanised coil from BlueScope is typically available on 4 to 6 week lead time domestically. 316L stainless coil from European (Outokumpu, Aperam) or Asian (POSCO, Tata, Aichi Steel) mills is currently 10 to 16 weeks for HVAC-typical thicknesses 0.7 to 1.5 mm. Fabrication on the SBAL-V runs at 25 metres per minute output on galvanised and 8 to 12 metres per minute on 316L stainless, so a typical 3,000 metre powerhouse galvanised scope fabricates in 2 to 3 weeks of single-shift operation and a 1,500 metre stainless scope in 3 to 5 weeks. Field installation runs 2 to 4 metres per metalworker-hour for galvanised and 1 to 2 metres for stainless. End-to-end from purchase order to installed and commissioned duct system is typically 4 to 6 months on a surface station and 8 to 12 months on an underground powerhouse with the access tunnel ductwork.

Project-scale benchmarks

A typical Australian small to medium hydroelectric station HVAC duct package (say 80 to 200 MW surface station, single building, conventional galvanised) runs AUD 800,000 to 2.5 million. A medium to large underground powerhouse (300 to 600 MW, multi-building, mixed galvanised and stainless) runs AUD 4 to 10 million. A Snowy 2.0-scale fully underground 2,200 MW pumped hydro powerhouse with all ancillary scope runs AUD 25 to 50 million depending on the stainless content fraction and the access tunnel ducting scope. A small wave-energy or tidal onshore station (200 to 500 square metres, fully 316L stainless coastal exposure) runs AUD 200,000 to 600,000. A Hornsdale-scale BESS at 100 to 200 MW with surrounding building shell HVAC runs AUD 1.5 to 4 million.

SBKJ machine delivery lead time

The SBAL-V, SBTF series, SBSF-1525 and SBPC1500 are typically delivered within 16 to 22 weeks of order from the SBKJ Box Hill North VIC project office, including configuration for stainless or galvanised service and Factory Acceptance Test. See the HVAC duct machine buyer's checklist for full procurement guidance and the duct production line total cost of ownership analysis for life-cycle commercial assessment.

How SBKJ specifies HVAC ductwork on an Australian hydroelectric or pumped hydro project

The procedure SBKJ engineers walk through with Australian hydroelectric, pumped hydro, geothermal and ocean energy project fabricators looks like the following sequence, which has evolved from supplying machinery to power-generation projects over the last decade.

1. Confirm the powerhouse configuration. Surface station, semi-buried or fully underground cavern. Each configuration drives a different HVAC ductwork inventory and a different mix of galvanised versus stainless service.
2. Read the hazardous area classification drawing. The HAC drawing is the master document, signed off by a Certified Hazardous Area Auditor under the IECEx CoPC scheme. Every duct segment is annotated with its zone classification (Zone 1, 2 or unclassified) and gas group (IIA for transformer oil, IIB+H2 for batteries, IIC for Li-ion BESS thermal events).
3. Read the AEMO grid code requirements and Network Operating Plan. Grid code drives the control room HVAC redundancy specification and the black-start diesel scope. The Network Operating Plan defines the dispatch reliability requirement that the HVAC system must support.
4. Confirm the heritage status. Snowy Mountains Scheme heritage stations are subject to NSW Heritage Council review on any visible modification; Hydro Tasmania heritage precincts (Tarraleah, Waddamana) are subject to Tasmanian Heritage Council review. Heritage approval timelines run 3 to 6 months for any non-trivial modification.
5. Confirm the AS 2865 confined space inventory. Penstock entry portals, tailrace inspection portals, surge shaft access points. Each confined space drives a permanent surface fan house and fixed portal ductwork plus the portable tunnel-internal ventilation provision.
6. Confirm the BESS scope. Co-located grid-scale BESS for FCAS or capacity firming drives a separate Li-ion thermal-runaway extract scope to NFPA 855 and AS/NZS 5139.
7. Size the duct cross-section to face velocity and pressure loss. 8 to 10 m/s on supply collection, 12 to 15 m/s on exhaust trunk, 200 to 400 Pa pressure loss budget on access tunnel main runs. Duct sized to standard SBAL-V and SBTF-2020 outputs.
8. Specify the connection method. TDF flange standard for rectangular duct on the SBAL-V; bolted slip-fit for round duct on the SBTF. Continuous longitudinal seam welding (via SBSF-1525 stitchwelder or GTAW seam welder) for any Zone 1 or Zone 2 duct; standard Pittsburgh seam acceptable for unclassified duct.
9. Confirm coil source. 1.5 mm galvanised G275 from BlueScope on standard projects; 316L UNS S31603 stainless from European or Asian mills on hazardous-area-adjacent and coastal projects. Mill certificates required for every coil and traceable to every piece of finished duct.
10. Schedule fabrication. Galvanised duct at 25 m/min on the SBAL-V translates to 150 to 200 metres per shift after handling and inspection. Stainless at 8 to 12 m/min translates to 50 to 70 metres per shift. A typical underground powerhouse requires 5,000 to 8,000 linear metres of duct fabricated in 30 to 60 shifts depending on stainless fraction.
11. Test and commission. Pressure test installed ductwork to 1.5 times design operating pressure. AS 4254 leakage Class A on stainless, Class B on galvanised. Witness test by buyer or NATA-certified independent inspector. Document on commissioning report tied to the AEMO submission, the AS 1851 fire damper register and the AS/NZS 60079.17 hazardous area register.

This procedure runs parallel to the turbine-generator commissioning and is normally on the project critical path during the final 6 to 12 months before first synchronisation.

Construction phase HVAC challenges

Hydroelectric and pumped hydro construction generates substantial hot-work activity — pipe welding, structural steel welding, mechanical fitting and instrument calibration — with significant fume and welding spatter generation. Permanent HVAC ductwork is typically installed in the latter phases of construction, meaning the building services during the bulk of welding work are temporary ventilation systems.

Temporary ventilation typically uses portable diesel-fired air movers and flexible polyethylene duct routed to local welding zones. Air change rates are 4 to 8 per hour during welding activity, dropping to 2 per hour during non-active periods. Confined-space welding inside the penstock, tailrace tunnel or transformer pit requires oxygen-deficiency monitoring per AS 2865.

On Snowy 2.0 specifically, the temporary tunnel ventilation system during the 2020 to 2026 construction phase has been one of the largest in Australian civil engineering history — multiple parallel 2,020 mm diameter galvanised supply and exhaust ducts running the full 2.7 kilometre access tunnel length, with surface fan houses at Tantangara, Talbingo and the main access tunnel portal. SBKJ provided bench engineering support and machinery for several of the temporary ductwork packages through the construction phase.

Permanent HVAC commissioning typically runs in parallel with mechanical completion of the turbine-generator units. The HVAC system is hot-commissioned (run for 30 to 60 days at design operating conditions) before first synchronisation to confirm steady-state heat removal capacity and to baseline the AS 1851 fire damper register.

Inspection, maintenance and operational compliance under AS 1851 and AS/NZS 60079.17

Once commissioned, a hydroelectric or pumped hydro HVAC system enters a structured inspection and maintenance regime under AS 1851 (fire and smoke damper maintenance) and AS/NZS 60079.17 (hazardous area inspection and maintenance, adopting IEC 60079-17 verbatim).

AS 1851 fire damper register and annual drop test

Every fire damper in the duct system is registered in the AS 1851 fire damper register with its location, type, manufacturer, installation date and test date. Annual drop testing is performed by a qualified AS 1851 inspector, with the actuator manually released and the blade verified to close fully and seal against the duct frame. Test results are recorded in the register and a failure triggers a repair and re-test cycle.

AS/NZS 60079.17 visual, close and detailed inspection

Visual inspection (12-monthly) covers external condition of duct, fan housings, dampers and detection equipment. Close inspection (24-monthly) adds clearance measurement, sealing surface inspection, damper actuator function test and gas detector calibration verification. Detailed inspection (condition-based or 5-yearly at statutory turnaround) adds internal disassembly, cleaning and re-certification of equipment showing degradation.

SF6 leakage measurement under NGER

SF6 leakage rate measurement is quarterly under the NGER scheme — the operator records the SF6 inventory at the start and end of each quarter, calculates the leakage rate as a percentage of inventory, and reports any excursion above the IPCC 0.5 percent annual leakage benchmark to the Clean Energy Regulator. The HVAC engineer supports the NGER submission by maintaining the SF6 detection calibration record and any leak event log from the switchroom HVAC system.

ISO 14001 environmental management system

ISO 14001 internal audit annually overlays the HVAC operational records — energy consumption, refrigerant inventory, refrigerant leak record, AS 1851 fire damper register, AS/NZS 60079.17 hazardous area register, SF6 leakage record, Li-ion BESS detection calibration record. The integrated audit pack is submitted to the operator's ISO 14001 lead auditor and held in the plant operations records.

Operator training and competency

Operations staff are trained on alarm response, manual ventilation override, AEMO grid code outage notification procedures, AS 2865 confined space entry permit issue and the Snowy Mountains Scheme heritage-protected modification procedures (Snowy stations only). Competency records are filed in the operator's human resources management system and refreshed on a 2-yearly cycle.

Frequently Asked Questions

What Australian standards govern HVAC ductwork in a hydroelectric power station or pumped hydro facility?

AS 1668.1 fire and smoke control, AS 1668.2 mechanical ventilation, AS 4254 ductwork construction, AS 1530.4 fire-rated penetrations, AS 2865 confined spaces, AS/NZS 60079 hazardous area, AS 1940 flammable liquid storage, AS 4032 medical gas, AS 1851 fire damper maintenance, AS 3000 wiring rules and AS/NZS 60079.14 hazardous area wiring. ASHRAE Applications Handbook Chapter 16 power generation is the international reference. NCC Class 8 industrial for the powerhouse and Class 9b assembly for visitor centres. AEMC and AEMO grid code requirements drive control-room reliability. ISO 14001 overlays operational records. NSW Heritage Council Snowy Mountains Scheme heritage standards apply to the original 1949 to 1974 station fabric. Safe Work Australia WES covers transformer mineral oil mist (5 mg/m3), ozone (0.1 ppm), CO (30 ppm) and CO2 (5,000 ppm).

What ventilation rate does an underground hydroelectric powerhouse require?

6 to 10 air changes per hour across the main machine hall, with localised rates of 15 to 20 ACH around transformer enclosures and 20 to 30 ACH inside Li-ion BESS rooms. Dominant sizing case is heat removal — a single 350 MW Francis or pump-turbine rejects 5 to 8 MW of heat. For Snowy 2.0 (250 metres by 30 metres by 50 metres cavern, six 333 MW units) total ventilation rate is 2.2 to 3.7 million cubic metres per hour through the access tunnel and dedicated supply and exhaust ducts. Cavern at slight positive pressure (10 to 30 Pa) relative to access tunnel.

How is HVAC specified for a pump-turbine reversible unit in pumped hydro storage?

Pump-turbine reversible units operate in two modes — turbine mode generating power discharging from upper to lower reservoir, and pump mode consuming power pumping from lower to upper. Pump mode rejects more heat (2 to 3 percent of nameplate) than turbine mode (1 to 2 percent) because pump efficiency is slightly below turbine efficiency. HVAC sizing follows the worst case (pump mode). For a Snowy 2.0 333 MW unit, that is 6.6 to 10 MW of heat in pump mode. Mode transitions take 5 to 8 minutes on AEMO dispatch signal; HVAC tracks the mode by ramping cooling capacity over the same window.

What confined space rules apply to penstock and tailrace tunnel inspection?

AS 2865 confined space entry. Entry permit requires atmospheric testing for oxygen (19.5 to 23.5 percent), flammable gas (below 5 percent of LEL), toxic gas (below WES TWA), continuous mechanical ventilation, and continuous atmospheric monitoring throughout occupied entry. Typical ventilation rate is 6 to 8 ACH of dewatered tunnel volume on portable PVC-coated polyester fabric duct in 600 mm to 1,200 mm diameter. SBKJ supplies the permanent surface fan house and the 1,200 mm to 2,020 mm diameter portal duct on the SBTF-2020.

What HVAC scope applies to the transformer hall and oil-mist extract?

Transformer hall ventilation is 8 to 15 ACH continuous to dilute mineral oil mist below the Safe Work Australia 5 mg/m3 WES. Exhaust passes through a chevron-style oil-mist eliminator before discharge. Material is 316L stainless on the exhaust trunks downstream of the mist eliminator (oil aerosol attacks galvanised over 5 to 8 years). Transformer water deluge per IEC 62271-301 actuates on fire alarm and interlocks with HVAC to dump the hall through a dedicated dump duct sized for post-deluge vapour volume. Dump duct is 1,200 mm to 1,500 mm diameter spiral round on the SBTF-2020 in 316L.

How is SF6 detection and ventilation specified in the GIS switchroom?

SF6 GIS switchroom ventilation is 4 to 6 ACH baseline rising to 20 to 30 ACH on detection trip. Detection uses NDIR or photoacoustic SF6 sensors at floor level on 5 metre grid, first alarm at 1,000 ppm and second alarm at 10,000 ppm. Exhaust grilles at floor level (SF6 is approximately 5 times denser than air). Ductwork is 316L stainless on the SBSF-1525 stitchwelder line because trace arcing products (SO2, HF, SOF2) attack galvanised. SF6 leakage measurement quarterly under NGER scheme.

What HVAC ductwork applies to a Li-ion BESS room?

NFPA 855 and AS/NZS 5139. Ventilation is 4 to 8 ACH baseline rising to 20 to 30 ACH on thermal-runaway detection. Detection combines heat, smoke, hydrogen and CO sensors at both ceiling and floor levels (mixed vapour density on off-gas). Ductwork is 316L stainless because HF and organic carbonate vapour attack galvanised within hours. Spark-resistant fan impellers per AS/NZS 60079 Zone 2 IIB+H2 thermal event classification. Australian operating examples: Hornsdale Power Reserve SA, Torrens Island Big Battery SA, Western Downs Battery QLD, Capital Battery NSW, Goyder South SA.

How is HVAC specified for a geothermal pilot plant with H2S extract?

Building ventilation is 6 to 10 ACH with H2S detection at floor level on 5 metre grid (electrochemical sensors, first alarm 5 ppm, second alarm 10 ppm). Pressure relief vent stacks discharge through a caustic scrubber before atmospheric vent. Ductwork is 316L stainless throughout because H2S plus condensate forms sulphurous acid. Binary-cycle ORC working fluid loop area (pentane or isobutane) is Zone 2 IIA per AS/NZS 60079. Birdsville QLD geothermal is the longest continuously operating Australian site (since 1992).

What HVAC applies to an ocean wave or tidal energy onshore station?

Coastal salt-spray corrosion is the dominant concern. Building ventilation is 4 to 8 ACH for personnel comfort and dust control, with the fresh air intake facing inland away from prevailing onshore wind and through a salt-spray pre-filter. All ductwork is 316L stainless or aluminium-clad galvanised. Power electronics cooling is through sealed liquid-cooled heat exchangers rather than direct air cooling. Australian operators: Carnegie Clean Energy (CETO Garden Island WA), Wave Swell Energy (UniWave 200 King Island TAS), Bombora Wave Power (mWave Perth WA), AusOcean (Bass Strait research), BlueGreen Group (tidal Bass Strait and Banks Peninsula NZ).

Are SBKJ machines suitable for Australian hydroelectric, pumped hydro, geothermal and ocean energy projects?

Yes. The SBAL-V auto duct line in galvanised configuration handles unclassified scope at 200 to 1,500 mm wide, 0.5 to 1.2 mm coil, 25 m/min on 1 mm. The SBAL-V in 316L stainless configuration handles hazardous and corrosive scope at 200 to 1,500 mm wide, 0.7 to 1.5 mm 316L coil, 8 to 12 m/min on 1 mm. The SBTF-2020 large-diameter spiral tubeformer produces spiral round duct up to 2,020 mm diameter for the underground powerhouse access tunnel main and the transformer hall deluge dump duct. The SBSF-1525 stitchwelder handles continuously welded longitudinal seams required in Zone 1 and Zone 2 service. Spark-resistant fan housings are supplied for the SF6 GIS switchroom and Li-ion BESS exhaust. SBKJ Box Hill North VIC office supports specification, FAT and on-site commissioning.

Related guides

For adjacent renewable-energy and power-generation references, see the following SBKJ insights:

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