HAGIs
The majority of our pipeline will be underground. However, we will need some hydrogen above ground installations (HAGIs) at certain points along the route. HAGIs are important. They allow us to control the flow and pressure of hydrogen at key points along the pipeline and act as the connection points for hydrogen industrial users. They also allow access to the pipeline network to carry out our routine maintenance programme.
We currently anticipate that there will be approximately 25 Hydrogen Above Ground Installations (HAGIs) including Block Valve Installations (BVIs) to control and operate the network at key points along the proposed pipeline.
HAGIs are expected to be located:
- At each of the hydrogen production and industrial user sites to enable connection to the network.
- Where there is a junction in the network, such as where pipeline spurs connecting the industrial users branch away from the main pipeline.
- To facilitate potential future connection to other hydrogen pipeline networks.
The HAGI search areas presented at our first consultation identify broad locations where the HAGIs could be located. These areas will be reduced following further technical work and feedback from stakeholders.
The location of the search areas have been informed by the points along the pipeline corridor where spur line connections are required. They have also been identified to avoid built development, key environmental / planning designations and any other development constraints.
You can find out more about HAGIs and BVIs, including the proposed location of search areas, in our consultation brochure in the Knowledge hub.
What do HAGIs look like?
The above ground components within HAGIs will be kept at a low level due to the nature of the equipment and to reduce visual impacts.
Permanent infrastructure will typically be approximately up to 4m in height, with the exception of CCTV and lighting masts that could be up to 6m in height.
Other features include:
- Pressure reduction stations – pipework and valves that control the pressure and flow of gas.
- Metering facilities – Metering facilities are required for volume measurements of the hydrogen gas.
- Pigging facilities – support in-line inspection and cleaning of the pipeline network. This is undertaken by passing a device known as an in-line inspection tool through the pipeline.
- Instrumentation kiosks – house monitoring equipment for flow, pressure and temperature measurements.
- Block valves – comprise an isolation valve which can isolate a section of pipeline to limit any loss of gas released in the event of a repair, maintenance or a failure of the pipeline section.
- Fencing
- General telecommunications equipment
- Electronic equipment will be included to support operations
The equipment will vary on a site-by-site basis, depending on the HAGI’s function. Car parking areas will be provided with the HAGI sites to support maintenance and monitoring activities, but it’s not expected that they will be permanently staffed. The design of HAGIs will be reviewed and updated as the Project progresses.
Block Valve Installations (BVIs)
Block Valves will be required as part of the project.
BVIs act as a cut-off point to isolate a section of pipeline for maintenance, repair or safety reasons. These are smaller than HAGI sites, typically measuring around half a hectare (half a football pitch). A gate will be required for access for maintenance. This is likely to include an access track (or similar) and space for vehicles to turn.
Environmental considerations
The underground pipeline and HAGIs will be designed and constructed to minimise as far as possible impacts on natural habitats and the environment. This includes looking at a wide range of factors, including ecology and wildlife, the historic environment and existing ground conditions. The project team will be carrying out a number of surveys, site and route investigations, as well as other assessments, to better understand potential environmental issues and impacts.
Some surveys may be required in areas beyond the preferred route corridor and HAGI search areas to gain a better understanding of local habitats and how the project may impact them. There is no intention of conducting surveys of private homes. Surveys will predominantly take place on open land and we will work with landowners to seek voluntary access.
More information on our proposals is available in our consultation brochure, our Design Evolution Report, and the Project’s Scoping Report in the Knowledge Hub
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