During the energy transition, it is likely that consumers will have differing gas composition requirements, and the National Transmission System (NTS) will have to transport varying percentages of natural gas and hydrogen within the gas blend. This creates a challenge for compression as centrifugal compressors will have to operate at variable speeds to compress varying gas blends. Automated systems at compressor stations will be required, which can sense the gas composition at the inlet of the compressor and feedback to control compressor operation. This desktop-based study will investigate the effects of varying hydrogen blend on the operational parameters of a compressor and research potential modifications to existing compressors, alternative compression technologies and sensing systems which could enable compression of variable gas blends on the NTS.
Benefits
The project results will inform our hydrogen compression strategy and therefore could provide savings in future applications. Each compressor on the network will cost at least £40m to replace and the opportunity to repurpose existing assets could result in significant savings.
Learnings
Outcomes
Whilst the challenges associated to re-purposing compression systems are in development, the methodology for enabling variability in these systems is a much harder challenge at different levels across its strategic, operational, and technical processes. This means that, although this study was scoped to seek retrofitting solutions to a technology challenge, the solutions have also had to consider the operational and strategic effects of change.
In particular, the need to accommodate gas mix variability and the potential for rapidly changing gas mix in the compression system places potentially unmeetable technical requirements on a future compression system. FrazerNash’s background technology research has not found similar use cases, where an organisation requires to compress equivalent mass or volume flow rates of a rapidly changing gas blend. Novel compression drive solutions are identified, which enable NGT the ability to dynamically control the speed of the gas compressor when there is variability in the gas mix, although the challenges that exist to implement these solutions as a retrofit programme are significant. We therefore propose a ‘Variability Incubate’ in Section 4.2 the primary purpose of which is to develop systems which can operate with variable gas mix. However, a key secondary purpose is to allow NGT to have a better understanding of the costs and benefits that operational choices place on technical requirements in the hydrogen transition. We would suggest that limiting variability through operational or strategic choices about how stakeholders are allowed to supply hydrogen to the future grid are likely to be more cost effective than trying to implement technology solutions for that variability.
There is limited value to be tracked from this desktop research study, the knowledge attained is to feed into HyNTS Compression and enable future development of our hydrogen network. The net benefits delivered so far are associated to knowledge transfer, the project has prevented us from progressing further with expensive development programmes regarding variability.
Value tracking
Data Point Data Point Definition
Maturity TRL 2-3
Opportunity 100% of single asset class The research focused on NTS compressors
Deployment costs -
Innovation cost £140,000
Financial Saving - The project did not focus on this aspect. The research looked at the
challenges not the savings.
Safety -
Environment - The project did not focus on this aspect, however, the overall strategy to
pivot towards net zero and green hydrogen will have significant CO2 savings for which the project is an enabler.
Compliance Supports compliance
Skills & Competencies -
Future proof Supports business strategy This research is an enabler to the wider hydrogen transition.
Lessons Learnt
The approach for this project was to undertake the work with a 3rd party to provide a unbiased view of the opportunity for the NTS compression assets. Whilst this achieved its goal, further work is now required with OEMs and other suppliers to develop technologies for the future. It may have been prudent to include these parties in this early study instead of relying on published literature and interviews.
