Today
A commissioning figure held with margin
- Minimum load is fixed at commissioning and held with margin.
- Emissions behaviour at low load is known mainly from experience.
- Shutdown is chosen by default when prices fall.
Know the real compliant floorbefore you turn down.
INSUS predicts CO, NOx and steam-side behaviour at low load for today's ambient conditions, configuration and machine state, so riding through a low-price period can be priced against shutting down. Operations and compliance keep every load decision.
01
The floor is often set by the CO limit, not the machine.
02
Loads never run are flagged as extrapolation.
03
Advisory. Operations and compliance decide every move.
The problem
A compliance boundarytreated as a fixed number.
Turning down is often cheaper than shutting down, if the unit stays inside its permit. CO typically rises at part load as combustion temperature falls. Low load also stresses steam-side limits: SCR temperature, economiser steaming and circulation stability. Most plants hold a commissioning minimum with margin and shut down when prices fall, paying for a start that may not have been necessary.
01Low-price window
02Shut down and restart
03Or hold at compliant floor
- 01Low-price window
- 02Shut down and restart
- 03Or hold at compliant floor
The shift
From an inherited minimumto a measured one.
The permit does not move. What can move is how confidently the plant knows where it sits relative to it.
With INSUS
A compliant floor predicted for today's conditions
- Floor is predicted for current ambient, configuration and machine condition.
- CO and NOx can be modelled with uncertainty before the load move.
- Holding online and shutting down can be compared with both costs quantified.
How it works
From current conditionsto a compliant floor.
This fits OptiStudio as optimisation under hard compliance constraints beside existing CEMS and plant systems. Access is read-only. Operations and compliance decide every load move.
Connect
Link emissions, combustion and HRSG data
Connect read-only to CEMS CO and NOx, load and fuel flow, combustion mode, exhaust and HRSG temperatures, SCR conditions, drum levels, ambient conditions and permit limits with averaging periods.
Understand
Learn this unit's real emissions behaviour
Learn how CO and NOx have behaved across the load range on this machine, under different ambient conditions and states of degradation, and mark where that experience ends.
Predict
Predict emissions and steam-side risk
Predict CO and NOx at candidate loads with uncertainty, plus steam-side indicators for SCR temperature, economiser steaming and circulation. Flag loads outside the observed range as extrapolation.
Advise
Advise the lowest load that holds every constraint
Recommend the lowest load that holds emissions and steam-side constraints with defined margin, and compare holding that load against shutting down and restarting using your start cost.
Verify
Treat unexplained excursions as model failure
Compare every low-load period with what was predicted. An unexplained permit excursion stops the recommendation until it is resolved.
Getting started
Start with one unitand the loads you already ran.
For combined-cycle operations and environmental compliance teams. Delivered through OptiStudio as low-load decision support. Expert Services can help with data assessment and validation. Advisory and read-only. No new hardware.
- What we need. Around two years of load, CEMS, HRSG and ambient data, permit limits with averaging periods, start records and any low-load trials already performed. CEMS and HRSG instrumentation already exist for permit and plant operation.
- What you see first. An emissions and constraint map across the load range one unit has actually used, with uncertainty, and a clear statement of how far below the current minimum the data can and cannot support going.
- Where the limits are. Data only covers loads already run. Loads below the demonstrated minimum are deliberate, approved trials, never routine recommendations. Closed-loop control against a permit limit is out of scope.
Related for power
Other powerstarting points
Minimum emissions-compliant load sits beside cycling damage and compressor wash economics on the same generating unit.
- 01Cycling Damage & Start-Up OptimizationTrack what a start costs in component life so hold-or-shut-down decisions have a fuller cost of restart.
- 02Compressor Fouling & Wash EconomicsTrack fouling on an ambient-corrected baseline. Machine condition can move where the compliant floor sits.
- 03Power industryThe wider picture for generating plants: unit performance, asset life and compliance limits around the operating band.
Questions operations and compliance teams ask us
Minimum load is often an inherited commissioning figure held with margin. This use case predicts emissions and steam-side behaviour at low load so the real compliant floor can be reviewed for today's conditions.
At least two years of load, CEMS, HRSG and ambient data, permit limits and averaging periods, and start records. No new sensors when CEMS and HRSG instrumentation already exist.
No. The permit holder remains responsible for compliance. The system does not interpret or negotiate permit terms.
The model flags extrapolation. A confident recommendation about loads the unit has never run is not offered as routine advice.
No. Operations and environmental compliance decide every load move. Access is read-only. Closed-loop control against a permit limit is out of scope.
Through OptiStudio as low-load decision support. Expert Services can support data assessment, integration and validation with your operations and compliance teams.
Confidence is bounded by the load range already operated. OEM combustor upgrades may lower the achievable floor more than software alone. The system does not schedule load or certify compliance.
Power · Flexible operation
Shut down, or stay on? Price both.
Start with the emissions and constraint map for the load range you have already operated, including an honest account of how far below it your data can support going.