Bloom Energy Energy Server 5 (ES5-EAXAAC), 250 kW

Bloom's 250 kW Energy Server 5, superseded by the ES6 platform after its natural gas certification lapsed in March 2026

Bloom Energy Energy Server 5 (ES5-EAXAAC), 250 kW is one of 12 fuel cells tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.

Bloom Energy Server 5 dossier: 250 kW solid oxide, 65 to 53% efficiency band, lapsed CARB certification, transfer risk and a used-unit inspection checklist.

The ES5-EAXAAC is a 250 kW net AC solid oxide server, documented as DOC-1013935 Rev A and filed with the Connecticut Siting Council. The slug rating is correct, which is not true of every entry in this category. Electrical efficiency is published as a 65% to 53% LHV cumulative band with a heat rate of 5,811 to 7,127 Btu/kWh, and the unit weighs 13.6 tons in a 14 ft 4 in by 8 ft 8 in footprint or a 28 ft 8 in linear arrangement. Production status is superseded. The natural gas CARB certification for the ES-5 family, Executive Order DG-044, expired on 27 March 2026, and the digester gas and landfill gas certifications DG-050 and DG-051 expire on 7 September 2026. The current equivalent at this rating is ES6-2500 on the Energy Server 6.5 platform. Note that CARB certifies the family at its 300 kW maximum, which is why the CARB record reads 300 kW ES-5 while Bloom's own spec sheets document 200 kW and 250 kW builds. For a California siting decision that lapsed certification matters more than the hardware condition. A used ES5 cannot be sited under a certification that has expired, and the certification belongs to Bloom rather than to the owner, so the buyer cannot renew it. That is a category-specific transfer risk with no analogue in generators or switchgear.

Why it matters

This entry is where the category's regulatory transfer risk becomes concrete. A certification issued to a manufacturer, expiring on a published schedule, is a condition of siting that travels with neither the equipment nor the owner. DG-044 lapsed on 27 March 2026, so any California listing for an ES-5 has to be checked against the live executive order list before a price is agreed.

Who buys it

Owners of installed Energy Server 5 fleets managing service and replacement, and sites that standardised on the platform between roughly 2015 and 2023. New buyers are routed to the ES6 platform, where ES6-2500 covers the same 250 kW rating and ES6-2495 sits at 249.5 kW.

Role in the data center

Primary on-site generation in arrays for data halls and campuses of the 2015 to 2023 build era, operating grid parallel under California Rule 21 and IEEE 1547.

Key specifications

Technical summary

Rated output: 250 kW net AC nameplate and base load Model number: ES5-EAXAAC, document DOC-1013935 Rev A Electrical efficiency: 65-53% LHV net AC cumulative Heat rate: 5,811-7,127 Btu/kWh Fuel: natural gas and directed biogas Emissions: NOx 0.0017, CO 0.034, VOC 0.0159 lb/MWh; CO2 679-833 lb/MWh Dimensions: 14 ft 4 in x 8 ft 8 in x 6 ft 9 in, or 28 ft 8 in x 4 ft 4 in x 7 ft 2 in linear Weight: 13.6 tons; noise below 70 dBA at 6 ft Certification: UL Listed, ANSI/CSA FC1-2014, California Rule 21, IEEE 1547, CARB 2007 Family: ES5 spans 200, 250 and 300 kW; the 300 kW ES5-YA8AAN weighs 15.8 tons

Pricing and availability

Trend: up Lead time, new: Superseded; new orders route to the ES6 platform.

Lifecycle and maintenance

Solid oxide stacks are the consumable and the manufacturer controls them. Bloom reports a fleet of more than 20,000 fuel cell modules deployed since 2009, with modules from 2014 and 2015 showing a median recorded life of 4.9 years, more than 900 running past 5 years and a maximum to date of 7.7. Replacement is a manufacturer operation performed on site in under an hour, after which title to the removed module passes back to the manufacturer and the hardware goes to its own repair and overhaul centre. Contracted service runs 5 to 20 years and covers filter and adsorbent replacement alongside periodic fuel cell replacement, and the dollar rate per kilowatt is redacted in every public filing reviewed.

Common failure points

• Stack degradation — Cumulative electrical efficiency falls from 65% toward 53% LHV across module life
• Title reversion on replaced modules — Every swapped fuel cell module reverts to the maker by contract, so a used unit may be missing its stacks
• Thermal cycling — High-temperature ceramic stacks tolerate a limited number of shutdowns and no maker publishes an allowance
• Sulfur and siloxane contamination — Sulfur deactivates catalysts and siloxanes deposit silica across anode surfaces
• Certification lapse — A California siting certification issued to the maker expires on a schedule the buyer does not control
• Service dependency — Third-party service is contractually barred on financed fleets and only the maker supplies stacks

Inspection checklist

Chain of title — establish whether the seller holds title or a project company does; Bloom contracts carry a right of first refusal at section 3.6 Repurchase right — get a written waiver; the contractual repurchase value is the greater of fair market value or 100% of purchase price reduced annually Module inventory — confirm which fuel cell modules are physically present; replaced modules revert to the maker under section 4.04 Measured heat rate — test against the 7,550 Btu/kWh minimum efficiency level in Bloom's own contracts and the 5,811-7,127 datasheet band Efficiency band — published cumulative efficiency runs 65% down to 53% LHV, so a mid-life unit is not a 65% machine Module age — Bloom reports a median recorded module life of 4.9 years and a maximum of 7.7 across more than 20,000 modules Thermal cycle count — the DOE lists limited shutdowns as an explicit challenge for stacks running at 500-1,000 degrees C, and no maker publishes an allowance Fuel quality history — total sulfurs above 5,000 ppbV average or H2S above 1,000 ppbV average exceed the published natural gas limit Siloxane exposure — 10 ppm of D5 caused total solid oxide failure in 30 hours at 1,000 degrees C in the Argonne fuel quality work Ammonia and halogens — the natural gas specification limits are 40 ppmV ammonia and 0.28 micrograms per cubic metre halogens Regulatory status — confirm a live CARB executive order covers the exact model; DG-044 for the ES-5 lapsed on 2026-03-27 Service entitlement — get a written service quotation first; third-party service is barred at section 10.01 of the standard agreement Operating data — request the remote monitoring history, which the maker holds under a 5 to 20 year service term Site scope — gas polishing media, wastewater and permitting sit outside maker scope, and cleanup ran about 1.8 cents per kWh in the Argonne 300 kW case Removal and rigging — a 325 kW unit runs 28,745 lb across 29 ft 5 in, so verify crane access and transport width

Regional notes

California siting depended on CARB Executive Order DG-044, which expired 2026-03-27 for natural gas; the digester gas and landfill gas orders DG-050 and DG-051 expire 2026-09-07. Certification is issued to the manufacturer, so a buyer cannot renew it independently.