Predictive Emission Monitoring System: Achieving Accurate Emission Analytics

Predictive Emission Monitoring System: Achieving Accurate Emission Analytics

Sustainability has already become a strategic cornerstone for many companies that want to minimize their environmental footprint. 

Why so?

That is because the acquisition of emission data is no longer an expectation. It is a legal requirement to monitor the pollutants process industries release into the atmosphere so that they do not exceed the maximum defined by numerous regulations. 

Just imagine, in 2021, the Environmental Protection Agency (EPA) got $1,06 billion in fines and penalties from companies that didn’t comply with environmental regulations and laws

So it’s no surprise that, as a plant owner, you probably are searching for reliable emission data acquisition tools to help you with environmental constraints as they may affect your production or even result in a plant shutdown. 

But which one to choose to monitor your emissions accurately: hardware- or software-based?

To tell the truth, the era of hardware-based tools and equipment and hard manual work is far behind with the appearance of smart predictive emissions monitoring systems (PEMS).

In this article, you will find all the needed answers about PEMS such as what it is, how it works, and how it can help you streamline your carbon emission tracking.

Let’s start with a definition.

What is a Predictive Emissions Monitoring System (PEMS)?

A predictive emission monitoring system aka PEMS is a smart and innovative technology to assess the emission level. It uses process data along with multiple statistical methods to accurately predict pollution caused by the manufacturing process. 

Mostly, PEMS software is used as a replacement for continuous emissions monitoring systems (CEMS) or their backup. It provides real-time data so that you can find the issues in the early stage and solve it before emissions exceed the legal limit. Besides, it helps plant owners to meet their strategic goals more efficiently by helping them accurately monitor and adjust their emission parameters. 

You can find all the specifications, regulations, and details about PEMS in Performance Specifications and Test Procedures for Predictive Emission System 16 by EPA.

Which are the basic elements of a PEMS?

The PEMS dataset consists of two vital elements PC and PEMS software itself.

  • The PC, server, or workstation that hosts PEMS software. It connects with the plant infrastructure and gathers the input values for emission assessment and writing of predicted values. 
  • PEMS software which conducts modeling and estimation of emissions. 

Sometimes, you are also required to have a Data Acquisition System or simply DAS (in a case when PEMS serves as a backup for CEMS). 

Why is emissions monitoring important? 

Every year both the economy and industries keep growing globally. The result is the appearance of new industrial plants and factories, which, in turn, leads to the tightening of environmental regulations and legislation. 

Besides, over time, the existing methods of reaching sustainability goals need to be updated with new and sophisticated ones. And one of the methods to help plants keep up with all the ongoing changes and circumstances is by monitoring the emissions level. 

The limits of the emission caused by plants are regulated by environmental permits. Plants aren’t allowed to operate without them. According to such regulations, factories are juridically liable to control and measure emissions regularly. 

If talking about the main benefits that ongoing emissions monitoring bring to both plant and society, we can summarize them in the following: 

  • It allows us to create common global standards and keep pollutants at a set level. It also helps research and finds new ways to cope with climate change. 
  • The monitoring process helps decrease the level of harmful pollutants and make the air cleaner. Plus, it can indicate the weak spots a process plant has, and, thus, you will be able to optimize and improve them.
  • Emission tracking can reveal new opportunities on how you can lower unnecessary energy costs
  • Monitoring and reporting emissions also help bring transparency to your company for investors, clients, and the public

How does PEMS work?

There are three main types of PEMS, each work based on a certain method:

1. First principle method: 

This method of work is based on the mathematical correlations that, in turn, are based on the foundation of the emission generation. Compared to the other two methods, this one requires more modeling work. Plus, each of the models must be set specifically in line with the combustion source configuration. 

For example, boilers, gas turbines, and reformers must be configured in accordance with input signal availability. However, today, this method has got lots of models and a variety of collections for input signals.

  • This method is great because it uses physical facts and their relations. Plus, you need fewer calibration measurements if compared to the other methods.
  • The main drawback of this method is that you need to have an expert with profound knowledge of the combustion process and the needed equipment.

2. Statistical method:

As suggested by its name, this model works using statistical modeling (such as regression modeling, for example). Thus, the empirical correlation of the statistical method is developed between various inputs and emission rates.   

  • This model can be developed for any process, without the need for some expertise in the process or combustion chemistry. 
  • Although you don’t need to have expertise in chemistry, you do need to be skilled in statistical modeling for using this method. 

3. Neural network or machine learning method:

This PEMS working method is data-driven and is based on the neural network. Basically, it develops a connection or relation between various inputs and outputs generated through the neuron layers. Each neuron layer consists of neurons that connect to other neuron layers. And each of these connections has a weight used for the calculation. 

What’s the main goal of the neural network then? 

It is to find the right weights for these connections. This becomes possible by changing the network input values and known outputs. To work accurately, the neural network has to work with the so-called complete operation envelope which is a combo of multiple input signals. 

  • The main advantage of the PEMS machine learning method is that you don’t need to have expertise in the system.
  • The downside of this method is that it requires model training. To have such PEMS that works under various conditions, you have to perform calibration measurements under various conditions. 

PEMS vs. traditional hardware-based analyzers: pros and cons

Now that you know about PEMS, let’s find out the main differences between traditional CEMS and its counterpart (or not?) PEMS.

Continuous emission monitoring system or CEMS is widely popular for plants and is hardware-based. It mainly consists of the analyzers (they sample and identify the structure of the flue gas) and IT software (for management, recording, and storage of the received information). 

Unlike CEMS, predictive emission monitoring systems or PEMS are software-based and are an innovative solution that is able to assess the concentration of emissions through advanced mathematical modeling methods. It uses empirical, also known as data-driven, modeling to accurately create models for emission estimation. By employing such predictive monitoring software, you can get the relevant data from historical datasets and even predict the behavior of the pollutant concentration with the help of the physical variables. 

Now let’s clarify the main question is PEMS an alternative to CEMS or just a backup?

Sure, being accurate and reliable software, PEMS can be a great backup to the CEMS in case of difficult refinery processes. It also helps to find early signs of measurement drifts or malfunction of the hardware.

What is more, the main advantage of PEMS over CEMS is that it allows for conducting simulations of the behavior of emissions during different conditions. Thanks to such predictive analysis, you can find out how exactly emissions react to changes in various inputs and how each operating parameter affects the final value. 

But PEMS' role goes far beyond just being a backup. Today, it has already been employed as the main emission monitoring system in numerous industries. And, what is more, it is approved by many local regulations as a primary emission monitoring system. It is also a more cost-efficient option, as its initial capital investment (CAPEX) is much lower. 

Key takeaways

Did you know that the European Commission set the target of emission reduction by up to 40% by 2030 because of climate change? Of course, it has become a challenge for many European companies to meet this target fast and efficiently.  

However, with the right performance monitoring systems onboard it is not impossible at all. 

Today, predictive emission monitoring software is a great and cost-efficient investment in pollution control. It has lots of benefits if compared to the traditional hardware-based CEMS. Despite being able to predict the level of emissions, it is very easy to use, does not require additional hardware, and is affordable. And what is more important, it helps you avoid any fines and penalties due to non-compliance with environmental regulations. 

Ready for the next step? Talk to our client manager to launch your own PEMS.

Frequently asked questions


PEMS vs CEMS: what is the difference?


There are numerous benefits that PEMS can bring to your business operations. They also differentiate it from CEMS. They are:

  • Accuracy: the use of advanced analytics technologies provide you with more accurate emissions data. This, in turn, can improve your pollutant control and compliance strategies. 
  • Automation: PEMS automates numerous tasks connected with emission tracking and monitoring. It can also free up your staff from manual work and improve your overall emission monitoring operations. 
  • Easy installation: you do not need to have a complex infrastructure to be able to use PEMS. It connects directly to your plant control system without any additional hardware.
  • Lower costs: PEMS drastically cut the costs for manual emissions monitoring. Plus, by staying compliant, you will avoid any heavy fines and penalties from regulators.
  • Reliable backup: despite its autonomous work, PEMS can be a very reliable backup for your CEMS if it malfunctions or is in maintenance.

What are the requirements for PEMS solutions?


PEMS suits every combustion process for many industries such as pharma & petrochemical, O&G, cement, power utilities, or metal. 

As stated in Performance specifications 16 (or simply ps16) among its process requirements are:

  • The right inventory (such as T, F, and P sensors) and automation (PLC or DCS)
  • Proper instruments (such as pressure, temperature, and flow sensors to monitor the involved units)
  • Fuel gas should have either stable or real-time measured composition

What are the typical target units/processes where PEMS can be applied?


PEMS best suits gas turbine applications (such as compressor drivers or power), boilers, furnaces, and industrial combustion engines across various industries. However, it was successfully applied to more complex process units such as FCC and SRU as well. 


What kind of pollutant emissions can be monitored?


PEMS is a great software to assess all the common emission types from the process industry such as SO2, NOx, CO2, CO, flue gas flow, and many more. However, there are some specific pollutants (such as particulates) for which you should first check the parameters of your analytical instrumentation.  


Is PEMS approved by environmental legislation?


PEMS is a globally recognized method of emissions monitoring. However, there are some nuances with local regulations as there is no single standard for pollutants monitoring and each country employs its own standards. However, the most popular regulations are EPA and European Standards. 

Some countries allow using PEMS only as a backup for CEMS while others as a primary monitoring tool.


Can PEMS be used in Europe?


In Europe, PEMS can be used as a backup for the already existing CEMS or its alternative. Besides, there is a set of specifications (TS-17198) released in 2018 you need to apply when opting for PEMS.