What happened
Braintree Electric Light Department (BELD) runs Unit 3, a combined-cycle unit with a 76-megawatt gas turbine, at its Norton P. Potter II Station in Massachusetts. Since May 2002 it has monitored the unit's NOx with a predictive emission monitoring system (PEMS) under a test protocol that EPA approved. EPA describes the PEMS as software that converts turbine operating readings into NOx through relationships developed for each fuel. A temporary reference method system gave hourly data from May 2002 to December 2004, covering 676 hours on natural gas and 419 hours on fuel oil. EPA found that the PEMS output passed all three statistical tests for both fuels and approved it on 31 May 2006. EPA estimated that the PEMS, with the extra audits it required, would cost less than half as much a year as an analyzer. The letter does not name the vendor. It mentions training and retraining the PEMS but does not say whether the relationships are learned models or fixed equations.
Sources
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Regulatory document, by authors with no tie to the system.
U.S. Environmental Protection Agency, Clean Air Markets Division. Approval of the Predictive Emission Monitoring System Installed on Unit 3 at Braintree Electric Light Department's Norton P. Potter II Station (ORISPL 01660). Letter to Braintree Electric Light Department, 31 May 2006.
The PEMS NOx lb/mmBtu output passed each of the three statistical tests for both fuels.
Details
AI system
- Workflow
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The PEMS read fuel flow and properties, combustion air, steam injection and exhaust conditions. Relationships developed for each fuel converted the readings into a NOx emission rate. Redundant sensors and hourly manual readings of gauges checked the inputs.
Money
- Kind of value
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Estimated yearly saving of the PEMS over an analyzer even if outside contractors run the extra audits
- Amount
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Estimate: $12,950
- Recipients and payers
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Braintree Electric Light Department
Follow-up
- Conditions for replication
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Inputs must stay within the range of the training data, or BELD must report the unit's maximum potential NOx rate. During startup, shutdown or loss of steam injection, BELD must report the maximum potential NOx rate.
Entry details
- Sector
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Environment and climate.
- Purpose
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An unnamed vendor built the PEMS to compute Unit 3's NOx emission rate from turbine operating readings so that it can serve as the unit's emissions monitor.
Not yet checked: model, release, provider, role, configuration, inputs and outputs, autonomy, human oversight, AI contribution, beneficiaries, reach, distribution and access, duration, every measurement question, currency and prices, period and unit, realization, gross or net, included costs, comparison, method, return and payback, ownership and control, dependencies, cross-border connections, geopolitical implications, replication attempts, availability, institutional decision, grounds, action and result, success criterion, every evidence question, observed or intended, alternative assessments, related entries, other identifiers, category mappings.
Cite this record
Peter H. Vartanian. (2026). Braintree's predictive emission monitor passes EPA's NOx tests (AIBD-0846). Artificial Intelligence Benefits Database, edition of 31 October 2026. https://petervartanian.xyz/aibd/records/AIBD-0846.html (archived at https://doi.org/10.7910/DVN/AADSII, version 4.0)