National Grid’s gas transmission business has been testing a world first in emissions monitoring technology that could save customers up to half a million pounds. Project Lead, Matt Williams has the full story.
Our business is committed to cutting emissions across our fleet of compressors as we continue to reduce our environmental impact.
Controlling emissions is also important from a regulatory perspective as we forge ahead with bringing all our equipment in line with the Industrial Emissions Directive (IED).
This EU regulation aims to reduce air pollutants by providing clear limits on how much nitrous oxide (NOx) and carbon monoxide (CO) industrial installations such as ours are permitted to generate.
The only way we can really know – and prove – we’re reducing emissions is by monitoring them closely. We do this by connecting various technologies to our compressors and their turbines to measure the levels of gas they’re emitting continuously.
The power of innovation
One of the challenges that we, like all industrial businesses, face is that emissions monitoring is both complex and expensive. So it’s an area where we’re keen to innovate and develop new technologies that can deliver the accurate readings we need in a simpler to manage and more cost-effective way.
As part of a project funded by Ofgem’s Network Innovation Allowance (NIA), we’ve been working with project partner Siemens to test the very latest generation of a predictive emissions monitoring system (PEMS).
‘Predictive’ is the key word here. Because compared to systems that constantly monitor emissions (known as CEMS), our PEMS prototype provides an opportunity to meet the latest IED standards at a significant cost saving.
Next generation technology
The project began early last year, when project partners Siemens built a prototype of a next generation PEMS that could be run in parallel with a continuously monitoring CEMS. The idea being that we could test its performance alongside a proven system to see whether it could provide the level of accuracy needed to meet the requirements of the IED.
What makes this PEMS unique is that it integrates closely with a turbine’s control system. This makes it potentially better able to predict emissions than existing PEMS, which focus more on what’s happening either upstream or downstream of the engine.
Since August 2016, we’ve been running the PEMS alongside a CEMS on a SGT-400 turbine. Testing ran for 12 months to allow us to build a detailed picture of how it performed across a range of operating conditions and seasons. This was important, as we know weather conditions can affect the ability of PEMS to predict emissions. Predicted values were compared to actual measured values throughout the process, to tell us whether the system would, in fact, meet our needs.
Progressing the prototype
Results to-date show that the prototype would meet the performance criteria of the IED. This requires an accuracy of +/-5ppm (parts per million) relative to measured values for NOx and CO. With further tuning of the model, which we’ll continue to do in collaboration with Siemens, we’re confident we can improve the performance of the prototype even further.
If the project’s successful, we’ll look to implement the new PEMS technology across our full fleet of SGT-400 turbines. Based on a price comparison with equivalent CEMS, we estimate a cost saving in the region of £490k.
What’s more, we expect the PEMS to require less maintenance and testing than existing models. This will bring both additional cost savings and reduced environmental impact as we won’t need to run our turbines specifically for testing.
The project offers further potential for the system to be developed for use on our ex-Rolls-Royce fleet. If this materialises, some 75% of gas turbines (51 units) currently on the National Transmission System (NTS) would be covered by the new Siemens PEMS.
It’s been rewarding to be part of a project that puts our business at the forefront of emissions measurement technology. We’ll now look forward to seeing how we can maximise its benefits and ensure we provide consumers with the most cost-effective solutions for meeting our important environmental responsibilities.
Read more about the innovations that are changing the way Gas Transmission does business in National Grid Gas Transmission’s Innovation Annual Summary.