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It ran beside the analyzer from May to November 2007 to collect 720 operating hours of paired data. EPA ran the same tests itself on the startup and shutdown hours. It found that the PEMS output passed all three statistical tests for all unit operations. EPA approved the PEMS on 2 June 2009, with conditions that include daily checks and monthly audits. 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It installed a NOx analyzer in May 2007 as a temporary monitor and planned to replace it with a predictive emission monitoring system (PEMS). CMC Solutions supplied its SmartCEM-75 PEMS, which EPA describes as statistical hybrid software with a model developed from training data. The PEMS turns turbine sensor readings into NOx values. It ran beside the analyzer from May to November 2007 to collect 720 operating hours of paired data. EPA ran the same tests itself on the startup and shutdown hours. It found that the PEMS output passed all three statistical tests for all unit operations. EPA approved the PEMS on 2 June 2009, with conditions that include daily checks and monthly audits. The letter reports no cost figure and no change in emissions.","replication":{"produced_by":["CMC Solutions collected the training and test data for the 720-hour demonstration.","A certified NOx analyzer gave hourly reference data during training and testing.","The model read turbine inputs such as fuel flow, power output and exhaust temperatures."],"must_hold":["Inputs must stay within the range of the training data, or GRE must report the unit's maximum potential NOx rate.","The PEMS must keep passing daily checks and monthly audits against measured emissions."],"echoes":[]}}},"provenance":{"kind":"legacy_record","basis":"Editorial assignment.","record_fields":["account","replication"],"source_refs":[]},"review_state":"record_mapped","coverage":"partial"}},"summary":{"total":91,"addressed":91,"known":28,"reviewed":2,"reviewed_complete":2,"reviewed_partial":0,"record_mapped":26,"review_not_assessed":63,"not_assessed":0,"complete":false,"by_state":{"value_present":28,"not_reported":0,"unresolved":63,"not_assessed":0,"not_applicable":0,"withheld":0,"source_unavailable":0}}},"presentation_version":"3fa3a66b05aa0778840e7f65205509cf6b908638151a38992e6c3fc0a7197943"}