Bergen B36:45V20
11,280 kW at 60 Hz at 48.9% electrical efficiency, and over 630 MW of named US data center orders, from a Langley Holdings company
Bergen B36:45V20 is one of 23 gas engines tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.
Bergen B36:45V20 lean-burn gas engine: 11,280 kW at 60 Hz, 48.9% electrical, 500 mg/Nm3 NOx, Langley Holdings ownership and the US SCR requirement.
The Bergen B36:45V20 is a 20-cylinder, 360 mm bore, 450 mm stroke lean-burn gas engine rated 11,280 kW at 60 Hz and 11,785 kW at 50 Hz. Bergen quotes nominal electrical efficiency of 48.9% at maximum continuous rating and power factor 1.0, against a reference fuel of natural gas at methane number 80 and lower heating value 36 MJ/nm3. It runs at 720 r/min at 60 Hz and 750 r/min at 50 Hz. Ownership first, because it is easy to get wrong. Bergen Engines AS is owned by Langley Holdings plc, not Rolls-Royce. Rolls-Royce signed the sale on 3 August 2021 at a stated enterprise value of EUR 63 million with sale proceeds of EUR 70 million; Langley completed on 31 December 2021 and states a consideration of EUR 91 million. The two figures are published as they stand, since neither party explains the difference. Bergen publishes no heat rate. From the published 48.9% efficiency, 3,600 divided by 0.489 is 7,362 kJ/kWh, or 6,978 BTU/kWh on a lower-heating-value basis. That is a computed figure, not a Bergen number. The engine weighs 155,000 kg dry and measures 14,200 by 3,750 by 4,750 mm.
Why it matters
This is the most-ordered large-bore gas engine for US data centers by named orders, and its press releases count discrete gensets rather than describing a plant. It also carries the class constraint: 500 mg/Nm3 at 5% O2 engine-out is 90.4 ppmvd at 15% O2, above the 82 ppmvd federal ceiling.
Who buys it
US data center developers building behind-the-meter generation. Two named projects account for over 630 MW: 45 gensets for Liberty Energy and twelve for E-Finity Distributed Generation. Also independent power producers and industrial sites, particularly where a single-group supply of engine, alternator and power conditioning has procurement value.
Role in the data center
Bergen sells this as a generator set and its releases count them. Liberty Energy ordered 45 B36:45V20 AG1 Bergen-Marelli sets at 11.2 MWe each for over 500 MW, with deliveries from the second half of 2027. E-Finity took twelve for over 130 MW initial capacity. The E-Finity plant is configured n+3, which is a redundancy scheme rather than an exercise regime. Power Engineering describes deployment in modular 12 MW blocks scalable beyond 500 MW.
Key specifications
| Electrical output, 60 Hz | 11,280 kW continuous |
|---|---|
| Electrical output, 50 Hz | 11,785 kW continuous |
| Nominal electrical efficiency | 48.9 % at MCR, pf 1.0 |
| Heat rate, computed | 7,362 kJ/kWh (computed, not published) |
| Bore x stroke | 360 x 450 mm |
| Cylinder configuration | 20 cylinders, V |
| Speed | 720 (60 Hz) / 750 (50 Hz) r/min |
| Dimensions L x W x H | 14,200 x 3,750 x 4,750 mm |
| Dry weight | 155,000 kg |
| NOx, engine-out | 500 mg/Nm3 at 5% O2 |
| Reference fuel methane number | 80 MN at 36 MJ/nm3 |
| Genset rating in US data center orders | 11.2 MWe with Marelli alternator |
Technical summary
Electrical output: 11,280 kW at 60 Hz, 11,785 kW at 50 Hz, maximum continuous at power factor 1.0. Nominal electrical efficiency: 48.9%. Configuration: 20-cylinder V, bore 360 mm, stroke 450 mm. Speed: 720 r/min at 60 Hz, 750 r/min at 50 Hz. Dimensions: 14,200 x 3,750 x 4,750 mm; dry weight 155,000 kg. NOx: 500 mg/Nm3 at 5% O2, engine-out, equal to 90.4 ppmvd at 15% O2. Reference fuel: natural gas, methane number 80, lower heating value 36 MJ/nm3. Genset rating in US orders: 11.2 MWe with a Marelli Motori alternator. Fuel flexibility: hydrogen blends to 25% without modification, 30% demonstrated at full load.
Major variations
The B36:45V platform ships in 12V, 16V and 20V, rating 6,750 kW, 9,015 kW and 11,280 kW at 60 Hz. No inline gas variant is offered. Two Bergen revisions disagree slightly. The 2021 Rev D document gives 11,770 kW at 50 Hz for the V20 against 11,785 kW on the 2024 fact sheet, a 0.13% difference. The 2024 fact sheet figure is used here.
Pricing and availability
Comparable secondary-market band: 2000–3150 $ per kW installed. Trend: stable The hour meter sets the price in this category, not the year. An engine three years from a major overhaul is worth materially less than an older unit fresh out of one. No used engine at this size is publicly listed, so there is no used price band. Lead time, new: No published lead time. Derived from dated Langley announcements: the Liberty order was announced 8 May 2026 with deliveries commencing in the second half of 2027, roughly 14 to 18 months. The E-Finity order was announced 4 June 2025 with first deliveries later that year. Both are observed durations from press releases, not quotations.. Lead time, used or refurbished: No used engine at this size class is publicly listed, so no used lead time applies..
Lifecycle and maintenance
Bergen publishes no time-between-overhaul on any product page or fact sheet. As with Wartsila, maintenance is priced inside a service agreement rather than stated as a catalog number, so total cost of ownership cannot be built from the nameplate alone. One availability figure exists at plant level. The E-Finity project is configured n+3 across twelve gensets, and Langley markets 99.999% uptime for the Bergen and Piller combination. That is a vendor claim about a plant with power conditioning, not an engine mean time between failures, and it should be quoted that way.
Thermal and emissions profile
Bergen publishes NOx at 500 mg/Nm3 at 5% O2, engine-out, against a reference fuel of methane number 80. Wartsila publishes 90 ppm at 15% O2 for the same class. They are the same number: 500 x 22.414/46 = 243.6 ppmv at 5% O2, then x (20.9-15)/(20.9-5) = 0.3711 gives 90.4 ppmvd at 15% O2. 40 CFR 60 Subpart JJJJ caps non-emergency spark-ignition natural gas engines of 500 HP or more, built on or after 1 July 2010, at 82 ppmvd at 15% O2. At 90.4 ppmvd the engine is above the federal ceiling, so selective catalytic reduction is required to sell it in the United States at all. Budget SCR as a capital line item, not an accessory. Ozone non-attainment areas push BACT or LAER far below the NSPS floor and add urea storage.
Common failure points
- Gas quality against the reference fuel — Retard and derate when delivered gas falls below methane number 80 or 36 MJ/nm3
- SCR catalyst and urea dosing system — Stack NOx climbs toward the 90.4 ppmvd engine-out equivalent and the permit limit is exceeded
- Cylinder heads and exhaust valves — Widening exhaust temperature spread across the 20 cylinders and falling compression on one bank
- Alternator and power conditioning interface — Voltage or frequency transients on block load that the engine alone did not cause
- Charge air cooler fouling — Rising charge air temperature and progressive output derate below the nominal rating
- Lubricating oil condition — Rising iron, chromium and viscosity in oil analysis between changes
Inspection checklist
Hours since major overhaul: Bergen publishes no interval, so demand the service agreement schedule and the hour meter reading. Hours since top-end and head change-out: record per-bank hours across all 20 cylinders. Oil analysis trend across the last 12 samples: rising iron and chromium indicate liner and ring wear. Cylinder liner wear at top ring reversal: measure against the 360 mm nominal bore. Turbocharger shaft play and compressor wheel erosion: record the reading as a trend across at least 2 outages. Charge air cooler fouling: rising charge air temperature costs output against the nominal 11,280 kW at 60 Hz. Spark plug and ignition coil hours: log the current set across all 20 cylinders. Cylinder head hours and change-out history: 20 heads per engine is a material parts bill on a life-limited component.
Procurement channels
Direct from Bergen Engines AS. The facilities page lists twelve sales and service subsidiaries including the USA and Mexico, with all engines built at the Hordvik factory north of Bergen, Norway. In practice the US channel currently runs through developer partners rather than a Bergen-branded dealer network. E-Finity Distributed Generation and Liberty Power Innovations are the named counterparties on the two US data center projects. A buyer should establish the service and parts arrangement explicitly, because Bergen does not document a US dealer footprint by city or function.
Regional notes
Rated at both frequencies, 11,280 kW at 60 Hz and 11,785 kW at 50 Hz. North American channel is confirmed: USA and Mexico subsidiaries, two named US data center projects totalling over 630 MW, and sister companies Marelli Motori and Piller Power Systems already in the US market.