Mitsubishi Power M501J / M701J
330-574 MW J-class frames with 1,600 C class firing temperatures for utility and campus combined cycle
Mitsubishi Power M501J / M701J is one of 21 gas turbines tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.
Mitsubishi Power M501J and M701J J-class gas turbines: 330-574 MW specs, 1650 C JAC technology, market availability outlook, and inspection guidance.
The Mitsubishi Power M501J (60 Hz) and M701J (50 Hz) are J-class heavy-duty frame gas turbines, launched commercially in 2009 with first operation in 2011. The current air-cooled M501JAC delivers 453 MW simple cycle at 44.0% efficiency and 664 MW in 1x1 combined cycle above 64%, running a 1,650 C turbine inlet temperature. MHI reported 92 J-series units ordered by September 2022 and more than 3.2 million commercial operating hours on current product pages. J-class blocks anchor utility baseload and gigawatt campuses: the 5,300 MW Gulf Energy program in Thailand runs eight M701JAC units, and US deployments span Texas, Virginia, and Utah hydrogen-ready plants. The JAC's 25 ppm NOx combustor with 30% hydrogen co-firing demonstrated at T-Point 2 keeps it permittable worldwide. No M501 or M701 of any letter class appears on public resale channels as of August 2026; MHI's 35 GW large-frame backlog delivers 2028-2030. Effective secondary pricing is set by operating-plant M&A, which Enverus reports doubled to about 1.0 million USD per MW in 2025. The only mid-size MHI unit observed trading is the H-25, at about 198 USD per kW on USP&E.
Why it matters
J-class machines sit at the top of the efficiency ladder, and their absence from the secondary market is itself market intelligence: MHI's backlog rose from 23 GW to 35 GW in a year while the company doubles production capacity. Every JAC slot taken by a data center campus removes a utility block, feeding the M&A premium on operating combined-cycle plants.
Who buys it
Buyers are utilities, national power companies, and IPP or hyperscale campus developers procuring 600 MW-class combined-cycle blocks. All J-class purchases route through MHI order books delivering 2028-2030, so acquirers needing capacity sooner buy operating F/G/J-era plants at M&A premiums. The purchase trigger is firm load growth against a sold-out OEM queue.
Role in the data center
Gigawatt campus anchor: one M501JAC 1x1 block supplies about 664 MW of combined-cycle capacity behind the meter, with 2x1 blocks at 1.3 GW for the largest compute campuses.
Key specifications
| SC output, M501JAC | 453 MW |
|---|---|
| SC efficiency, M501JAC | 44.0 % LHV |
| SC heat rate, M501JAC | 8182 kJ/kWh |
| CC output, M501JAC 1x1 | 664 MW |
| CC output, M501JAC 2x1 | 1332 MW |
| SC output, M501J steam-cooled | 330 MW |
| SC output, M701JAC (50 Hz) | 448-574 MW |
| Turbine inlet temperature, JAC | 1650 C |
| Pressure ratio, JAC | 25:1 |
| Exhaust flow, M501JAC | 815 kg/s |
| Exhaust temperature, M501JAC | 649 C |
| NOx / CO at 15% O2 | 25 / 9 ppm |
| Start time / ramp rate | 30 min / 42 MW/min |
| Shaft speed / frequency, M501 | 3600 / 60 rpm / Hz |
| Package size / weight, M501JAC | 15.0 x 5.6 x 5.6 / 347000 m / kg |
| J-series cumulative operating hours | 3200000 hours (more than) |
Technical summary
SC output, M501JAC: 453 MW at 44.0 % SC heat rate, M501JAC: 8182 kJ/kWh CC output, M501JAC 1x1: 664 MW above 64.0 % CC output, M501JAC 2x1: 1332 MW SC output, M501J (steam-cooled): 330 MW at 42.1 % SC output, M701JAC: 448-574 MW Turbine inlet temperature, JAC: 1650 C Pressure ratio, JAC: 25:1 Exhaust flow / temperature, M501JAC: 815 kg/s / 649 C NOx / CO: 25 / 9 ppm at 15% O2 Start time: 30 minutes, ramp 42 MW/min Hydrogen: 30 % co-firing demonstrated
Configurations and options
Sold as combined-cycle power trains: gas turbine, generator, HRSG, steam turbine, and TOMONI plant controls. Order options include hydrogen co-firing readiness, air-cooled versus steam-cooled combustion (JAC standard on new orders), and enhanced load-flexibility cooling-air paths. No used configurations exist.
Compatibility and dependencies
Requires transmission-voltage interconnection, heavy foundations, high-pressure fuel gas, and full water treatment; steam-cooled J units additionally depend on combustor cooling steam from the bottoming cycle. Long-term service agreements with MHI govern parts and outage cadence across the fleet.
Pricing and availability
Trend: up No J-class unit has traded publicly. Directional evidence: MHI's large-frame backlog grew from 23 GW to 35 GW in the year to August 2026 with 2028-2030 deliveries, while US gas plant M&A multiples doubled from about 0.5 to about 1.0 million USD per MW in 2025 per Enverus, setting the effective price of operating advanced-class capacity. Lead time, new: 30-54 months.
Lifecycle and maintenance
MHI does not publish J-class inspection intervals; long-term service agreements govern outage cadence in practice. Fleet validation ran roughly 2,800 temporary measurements at T-Point 2 in 2020, and MHI reports 99.5% fleet reliability with more than 3.2 million cumulative J-series operating hours. First-year JAC inspections found no long-term reliability problems per MHI's technical review; hot-parts life at 1,650 C remains the cost driver inside LTSA pricing.
Common failure points
- Stage 1 hot parts — Oxidation and coating distress at 1,600-1,650 C firing temperatures
- Steam-cooled combustors (J) — Cooling-steam dependency complicates cycling and restarts
- Combustion dynamics — Excursions under load-following and co-firing operation
- Cooling-air path hardware (JAC) — Changeover valve and clearance-control faults
- Generator auxiliaries — Seal oil and purity excursions on hydrogen-cooled machines
Inspection checklist
Cooling system lineage — identify steam-cooled J versus air-cooled JAC hardware; steam-cooled units carry bottoming-cycle dependencies that reprice diligence Hours and starts — audit actual operating hours against the fleet baseline; the 50 Hz lead JAC logged 8,000 hours before fleet rollout Hot parts — borescope stage 1 nozzles and blades for oxidation and coating loss at every combustion inspection window Combustor cans — inspect all 16 (M501) or 22 (M701) cans for liner distress and record dynamics data across the load range TIT validation — verify 1,650 C class operation against MHI temporary-measurement validation records where available Rotor — confirm complete hours-and-starts accounting from COD under MHI life methodology; flag any gap exceeding 100 fired hours Compressor — borescope stages 1-3 for erosion and FOD; enforce OEM blend limits Cooling-air system (JAC) — verify dual supply-path operation and changeover records between flexibility and performance modes Generator — hydrogen purity above 98%, seal oil records, stator insulation resistance at or above 100 megohms SCR and catalyst — catalyst age against design life; ammonia slip under the 5 ppmvd class permit limit Controls (TOMONI) — software revision, cybersecurity patching, and OEM support status LTSA — review transferability, credits, and next major outage date; J-class fleets run under OEM agreements Reliability record — compare unit availability against MHI's published 99.5% fleet reliability benchmark Performance test — ISO-corrected output within 5% of rating and CC heat rate within 3% of spec Records — complete outage reports, borescope history, and service bulletin log from COD
Procurement channels
New units through MHI order books only, with capacity expansion underway. In-service capacity moves through plant M&A brokered by advisors; the H-25 is the only mid-size MHI machine observed on dealer inventories (USP&E), and legacy Westinghouse 501-lineage frames trade occasionally.
Regional notes
M501 (60 Hz) serves the Americas and parts of Asia; M701 (50 Hz) serves Japan, Southeast Asia, Europe, and the Middle East. The anchor JAC fleets run in Japan and Thailand; US JAC plants concentrate in Texas, Virginia, and Utah. No resale market in either frequency.