Could you provide references for PEMS installations? What types of turbines and boilers have been certified with the SmartCEMS® PEMS product to date?

CMC has certified over eighty sources at various sites in the U.S. and abroad including power generation, automotive, university, municipal, governmental, and research facilities. SmartCEMS® PEMS has been applied to gas turbines (both simple cycle and combined cycle) or various sizes from microturbine, small turbines, and mid size turbines all the way up to the largest turbines manufactured. These turbines are of varying configuration with all types of NOx controls including dry low NOx, steam and water injection, solid catalytical reduction, and custom firing controls. Boiler applications include small to large size units of various configuration and those equipped with post combustion controls. In addition, CMC has provided PEMS at a number of ethanol facilities and automotive or university steam plants. Please contact CMC for a detailed list of references and contacts from the regulatory agencies who are familiar with the CMC product line and the performance of the statistical hybrid PEMS.

Does SmartCEMS® replace a CEMS? If so, what do we do with the existing CEMS we have installed onsite?

In most cases, SmartCEMS® is installed to replace an older CEMS or in lieu of CEMS on a new installation. SmartCEMS® was designed to work as a stand-alone solution to provide data acquisition, display of real-time and averaged emission data, and report generation to meet regulatory compliance requirements. In one mode of operation, the CEMS provides a critical role in the optimization of the process, but not a mandatory role in compliance monitoring of the exhaust emissions. In most instances, however, SmartCEMS® is deployed using historical CEMS or temporary mobile CEMS data. SmartCEMS® provides real-time analysis of process efficiency and predictive capability for any failed input in additional to emissions monitoring for compliance purposes. SmartCEMS® can operate without a CEMS when certified as a primary continuous monitoring system for the source through a petition for approval of an alternate monitoring system (40 CFR Part 75, Subpart E) or utilizing a performance testing specification promulgated by U.S. EPA (such as 40 CFR Part 60, Performance Specification 16 or PS-16).

If you have an existing CEMS, we would recommend that the CEMS not be removed, but that it is turned off during most of the year to save in operational, maintenance, and support costs.

The CEMS would be used to retrain the model if new operating or ambient conditions are encountered or following a major maintenance event and for tuning or optimization of the combustion controls. The plant can certify the CEMS along with SmartCEMS®-75 as a backup system if a testing team is mobilized for a relative accuracy test audit. If the CEMS is operated according to 40 CFR Part 60 Reference Methods, the existing CEMS can be used by the source owner to recertify the SmartCEMS®-60 system each year in lieu of an annual certification test (typically performed by an independent third party testing team) or for performing periodic audits. CMC Support, L.L.C. could provide support to both an existing CEMS and the SmartCEMS®-75 or SmartCEMS®-60 PEMS.

Is the first correlation valid for a long time or should we tune SmartCEMS® PEMS each year?

The validity of the SmartCEMS® PEMS model is entirely dependent on the training dataset and the quality assurance program in place at the site. If a comprehensive model is developed initially, there would be no reason to limit the range of time that it would be valid. An initial model that includes all normal operations, startups, shutdowns, and transitional operating states is deemed ‘robust’ and will provide valid predictions for compliance purpose for many years. The model can easily be retrained if required for any extreme ambient or other operating conditions not encountered during the initial training data collection. The system keeps track of when the model is valid for a given set of process data in real-time and provides alarms for tracking excursions from the established model envelope and records the status of the model prediction automatically.

Requirements for a periodic or annual recertification test would be dependent on the local regulatory requirements and the facility quality assurance program. We would recommend retraining the PEMS model (and recertification if required) following any major process change or the addition of pollution controls or for changes in fuel and fuel quality. Validation of the PEMS model can be conducted following tuning or annual maintenance activities (such as a extensive overhaul), but this would not be mandatory. The PEMS can be retuned at any time (periodically or continuously) using existing CEMS equipment or by mobilizing temporary or mobile emission monitoring equipment and collecting the process data concurrently with the target pollutant emission rates.

Is the prediction just valid for NOx? Does the model work for CO? What other process and emission parameters can be predicted with SmartCEMS® PEMS?

The prediction is valid for any emission or process data that can be continuously measured and included in the initial training dataset that can be correlated with the available process data. The model is initially developed with NOx, CO, CO2, O2, SO2, and total hydrocarbon data. Particulate, H2S, NH3, PM10, PM2.5, opacity and other emission parameters can also be predicted with the statistical hybrid engine.

The accuracy of the prediction for NOx mass emission rates from gas turbines and gas-fired boilers have been the most extensively studied and demonstrated to date. Other pollutant emission rates that have been established to be accurately modeled by SmartCEMS®-60 including CO, SO2, and hydrocarbon emission rates, as well as, exhaust gas diluent O2 and CO2. Other turbine or boiler parameters such as exhaust temperature and flow rate have also been evaluated and show good accuracy. Hydrocarbon, CO, SO2, NOx, and O2 have also been demonstrated to be accurately modeled from sewage sludge incinerators and industrial boilers.

Is the SmartCEMS® PEMS also valid during start-up and shutdown of the unit?

The model is valid during normal operation of the turbine or boiler, during start-ups and during shutdowns, as well as, trips, interruptions, etc. Each of the deployed SmartCEMS® PEMS to date has been certified to continuously monitor emissions during all normal operations including startups and shutdowns. The accuracy of the model during startups and shutdowns is demonstrated, however, the accuracy is improved as more transition data is included in the historical training dataset. It is important to include startup and shutdown data along with other data from transient operations in the initial historical training dataset to ensure accuracy of predictions for these operating conditions.

What are the accuracy and reliability levels achieved by SmartCEMS®?

The accuracy of the system is entirely dependent on the quality of the training dataset including the emission testing data and the site configuration of the SmartCEMS®. The accuracies achieved under the demonstration on gas turbines and boilers to date have been comparable to a CEMS achieving less than 10% relative accuracy even at very low levels of NOx (less than 10 ppmv). SmartCEMS® has consistently met the EPA requirement of less than 7.5% relative accuracy for NOx compliance under 40 CFR Part 75. In many cases, SmartCEMS® can achieve accuracy levels less than 5% and maintain this level of accuracy for many years running the same model. SmartCEMS® reliability approaches 100% in our installations, typically better than the majority of CEMS installed to date.

What are the features of SmartCEMS® and the statistical hybrid engine?

The statistical hybrid approach is a unique empirical predictive system that requires only a fixed sample of paired process and emissions data. A statistical hybrid PEMS has the following features:

  • Robust model that is accurate across the full load range of the unit
  • Valid for normal operations and during transitional states such as startup and shutdown
  • Equivalent accuracy as a CEMS with superior reliability – tied to the plant control system
  • Flexibility to be implemented using existing process instrumentation and data interfaces
  • Certified as an alternative system under U.S. EPA for continuous compliance monitoring
  • 
Can be assessed using quality control procedures required under programs of the U.S. EPA
  • Can be developed and retrained by non-technical onsite staff or consultants
  • Can be tested against EPA reference methods
  •  Has been demonstrated under 40 CFR Part 60, Performance Specification 16
  • Has been demonstrated under 40 CFR Part 75, Subpart E.

The statistical hybrid model exploits the existing statistical relationships of the historical training dataset depending on the input parameters available and how they are represented in the empirical data. The historical dataset is fixed prior to certification when used in compliance monitoring. This allows the PEMS to calculate a model envelope that defines the operating conditions represented in the historical training dataset. Alarms can be configured to detect when the process is operated outside the model envelope. All normal operating conditions including startups, shutdowns, and transitional states can be tested such that envelope excursions are minimized. This type of historical training dataset (containing all normal operating conditions) is deemed to be ‘robust’. Robust statistical hybrid models produce minimal monitor downtime over long periods.

What are the requirements for certification of SmartCEMS®-60 PEMS under 40 CFR Part 60, PS-16?

The minimum data required for a SmartCEMS® PEMS model is from 3 to 5 days of data to build a successful model. The entire range of operations at various loads and including a startup and/or shutdown is typically required. The initial certification under PS-16 requires a 27-run relative accuracy test audit, with three quarterly audits, and statistical analysis of the data. The minimum quality assurance requirements for the first year are three quarterly audits, and every other year a single quarterly audit along with annual 9-minute RATA is required.

What are the steps required to move forward with a PEMS installation? Who do we contact for a proposal for SmartCEMS® PEMS?

Contact Mr. Brian Swanson at CMC Solutions (U.S. 248-960-1632) or via email at Sales@CMCSolutions.org or to fill out a request online click here. The first step in the process will be to develop a site-specific datasheet for each of the sources to be monitored to identify the specific needs of the customer and the regulatory program. CMC will provide a proposal that may include computer hardware, temporary CEMS, mobile emission testing services, training, onsite support, certification testing, commissioning, warrantee, and quality assurance programming onsite. Together with our business alliance partners, CMC can provide a turnkey quotation for products and services as part of a facility wide emissions tracking program that can meet the requirements of your air permit and applicable federal regulations.

The software will be delivered (typically within 30 to 60 days of receipt of purchase order) and certification can be scheduled anytime following startup and collection of the training data. Training data is typically collected for a period of three days and up to 30 days during normal operation to develop the model. Sites with existing CEMS may have available data to build a model without additional testing or training. Certification can typically be achieved within 60 to 90 days of receipt of your purchase order for a SmartCEMS® PEMS.

What is SmartCEMS® – who is CMC Solutions?

SmartCEMS® is a predictive emissions monitoring system (PEMS) that is used for compliance with U.S. EPA regulations. CMC Solutions, L.L.C. is the software manufacturer and provides PEMS software based on a patented statistical hybrid engine. CMC Solutions, L.L.C. provides complete turnkey software and hardware solutions including predictive emissions monitoring systems (PEMS) and continuous parametric monitoring system (CPMS) with data acquisition systems (DAS) and components as required to industrial, municipal, governmental, and original equipment manufacturers. CMC works with a number of global business alliance partners who provide additional services such as environmental permits, reference method testing, continuous emission monitors and gas analyzers, and other supporting services for the environmental compliance monitoring system. These predictive emission monitoring systems are typically required by air emissions regulations and plant operating permits. SmartCEMS®-60 is a complete predictive emissions monitoring package for compliance with 40 CFR Part 60 regulations. SmartCEMS®-75 is a custom solution for compliance with 40 CFR Part 75 regulations and is provided with a data acquisition system that generates electronic data reports (EDR) in the XML format specified by U.S. EPA.

What is the basis for the PEMS predictive engine? Is it a neural network or a first principle (physical correlation and gas theory)?

The engine is a unique statistical hybrid model. It is neither a neural network nor a first principle type, but it is an empirical method. All CMC PEMS run the same core module – the statistical hybrid engine. The model does not use a theoretical methodology such as a first principle formula nor does it require an iterative model development and testing regimen with experts onsite. There is no specialized staff required to build or maintain the emission model. Continuous Emissions Monitoring (CEM) or Reference Method (RM) test data is used to build the initial model. The empirical SmartCEMS®model utilizes historical data, paired emissions data and process data, to generate predictions in real-time. The predictions are derived directly from the historical training dataset using input parameters from the process that are available from the existing control system and are configured in the PEMS model.

Unlike more complicated empirical systems such as neural network and first principle formulations, the statistical hybrid model can be developed for any given process without any knowledge of the underlying combustion chemistry or of the pollutional controls. The system uses the historical data collected during normal operations and during startups, shutdowns, or transitional states to accurately predict emissions for compliance purposes over the full load range of the unit. This feature allows the system to predict the value of any failed input (or pollutant emission data in lieu of CEMS) with the accuracy of the system entirely dependent on the range and quality of the original data in the training dataset. The system is deterministic in that a given set of inputs (process variables or lack of them) along with a given fixed training dataset will yield a single result for each value to be predicted. The model is unique in its ability to be developed by non-specialized staff that have no familiarity with the process, pollution control devices, or the methodology used by the model. Customers and third party consultants can update the model without support of the manufacturer’s engineering staff.

What kind of instrumentation and process inputs are needed to train the model and what interface is required to the SmartCEMS® PEMS?

SmartCEMS® utilizes any quality assured process input parameter that correlates with emission data for model generation. Typically around a dozen parameters are utilized in a simple cycle gas turbine or gas-fired boiler PEMS model with more parameters required associated with any add-on pollution control technologies. Ambient data is utilized when it is available. There are no mandatory inputs required for a given model (with the exception of the unit load in megawatts and the fuel flow rate). The system analyzes the training dataset to determine which of the available inputs or control system data is relevant to the model. Instrumentation and field devices that are determined to be used in the emission model may be subjected to additional quality controls per the local regulatory requirements and the site quality assurance program.

Interfacing with existing control and emission monitoring systems can be accomplished using serial communications, Ethernet connectivity, or through hardwiring to remote I/O devices. CMC can provide the hardware and equipment required or the system can be configured to utilize any standard ‘Windows’ based technology such as OPC, ODBC, OLE, DDE, Modbus, etc. to extract the data from the turbine control system. This interface between existing control and monitoring systems with the PEMS server deployed onsite can eliminate the need for hardwiring I/O to the SmartCEMS® system. Hardwire interfaces range from economical Ethernet-ready devices to a custom programmable controller with data-loggers and data buffering with uninterruptible power supply guaranteeing near 100% data availability.

What other statistical analyses are required to certify SmartCEMS®-75 PEMS under 40CFR Part 75, Subpart E?

The minimum data required to validate a SmartCEMS® PEMS model for compliance with 40 CFR Part 75 is 720 operating hours. There is an additional requirement to provide at least 24 hours under each type of fuel combusted as part of the 720 hour demonstration required of Part 75, Subpart E. The statistical analysis includes the F-test, t-test, correlation, and variance analysis along with a bias test of the 720 hour Subpart E demonstration dataset. CMC provides a Subpart E package that guarantees Part 75 Subpart E certification results that are successful and includes all statistical analyses, data quality assurance, and onsite support along with the required submittals and reports. The final decision for approval of all Part 75, Subpart E petitions resides with the Administrator of U.S. EPA.

What other uses could SmartCEMS® PEMS be applied to? Can the system be used to model turbine combustion efficiency? Can the system be used to provide input for scheduling of maintenance activity?


The model was developed for the purpose of providing operators with real-time feedback as to actual pollutant emission rates, unit efficiency, combustion efficiency, and compliance status. The rate in change of unit efficiency normalized for ambient and other operating conditions can be used to determine when maintenance should be scheduled and following completion of maintenance activities, if the unit was restored to optimal combustion efficiency. Yes, SmartCEMS® PEMS provides more than just efficient and cost-effective compliance emissions monitoring. The statistical hybrid engine can be used for plant and combustion process optimization and for tracking noncompliance emissions for waste minimization purposes of for process monitoring in applications where continuous monitoring with gas analyzers is extremely difficult or expensive to maintain.