Blog: Hydrogen blending scenarios: Preparing the gas grid for a multi-gas future

Considerations for a changing gas grid

Previously, we talked about four practical challenges and solutions for blending hydrogen in the gas grid. Following this, we’ve been analysing three different scenarios for hydrogen blending, and the impact they might have on the gas grid.

1. Blending of up to 5% hydrogen
2. Blending of up to 20% hydrogen
3. Blending of up to 20% hydrogen, with daily injections of varying calorific values

Let’s take a look at each of these scenarios in turn.

Scenario 1: Blending of up to 5% hydrogen

This is considered to be a low-impact move towards decarbonising the gas network. It requires minimal changes to systems and processes, and works within current calculations for flow-weighted average calorific values.

However, gas quality would need to be monitored and network adjustments made to ensure hydrogen blending doesn’t exceed the 5% limit. The Gas (Calculation of Thermal Energy) Regulations would also need to be updated.

On Xoserve’s part, the following changes would need to be made:

• Maintaining gas quality: The Gemini System, which manages the transportation of gas through the National Transmission System, would need to ensure the calorific value of the gas mixture in the grid remains within a specific acceptable range.
• Adapting gas billing: In addition to this, UK Link, which connects the complex information, technology and communications systems that are essential for Britain’s retail gas market, will need to exclude certain areas that have different gas blends from the flow-weighted average calorific value calculation. Instead, these areas will need to be tracked separately and bills calculated based on their specific gas mix. For most of the network, however, we can apply a default calorific value.

To discuss this scenario in more detail, the working group 0849R was established. Facilitated by KPMG, this intends to be a collaborative review of existing market structures to ensure they effectively support the introduction of hydrogen into Britain's gas networks.

Before we look at the next scenario, we need to understand charging zones.

Scenario 2: Blending of up to 20% hydrogen

This is considered to be a medium-impact move towards decarbonising the gas network.

Our analysis explores blending hydrogen into the gas grid by dividing existing LDZs into smaller, more precise charging zones. This allows for more accurate tracking of the gas composition. Each charging zone would have multiple points, where the gas is measured to determine its energy content. The industry's current method of flow-weighted average calorific value would be used to calculate the energy content of the gas blend within each charging zone, taking into account the flow rate and energy content from different entry points.

Similarly to scenario 1, gas quality would need to be monitored and network adjustments made to ensure hydrogen blending doesn’t exceed the 20% limit. The Gas (Calculation of Thermal Energy) Regulations would also need to be updated.

On Xoserve’s part, the following changes would need to be made:

• Precise allocation: Existing gas supply sites would need to be assigned to their corresponding charging zones.
• Accurate energy calculation: Specific calorific values would need to be determined for each charging zone, to enable precise energy calculations.
• Streamlined billing: Reconciliation and invoicing processes are tailored to each charging zone, ensuring accurate billing based on actual gas composition.
• Integrated energy balancing: Gemini would need to be updated to incorporate charging zone information, including volume, calorific value and energy data, for efficient energy balancing across the network.

Scenario 3: Blending of up to 20% hydrogen, with daily injections of varying calorific values

This approach towards gas decarbonisation has significant implications.

The analysis explores the dynamic blending of hydrogen within the gas grid, with hydrogen levels of different calorific values fluctuating throughout the day.

Because hydrogen blending will vary within each charging zone within any given day, multiple calorific value measurements will be required. This is because hydrogen production might not always be constant, and it won't be generated solely for blending purposes.

To accurately reflect these changing hydrogen levels, calorific values will need to be updated more frequently for each charging zone. This ensures precise billing and settlement that accommodates the dynamic nature of this scenario.

In addition to gas quality monitoring, network adjustments and changes to the Gas (Calculation of Thermal Energy) Regulations, serious considerations must be given to scaling hydrogen production to enable this level of blending.

As part of our research for this scenario, we’ve explored various approaches to billing and settlement. These depend on different kinds of gas meter portfolios and the consumers they represent.

• Daily Metered Portfolio: This refers to larger consumers of gas who have meters that are read daily. These are typically industrial or commercial customers with significant levels of gas consumption.
• Non-Daily Metered Portfolio: This refers to smaller consumers, usually residential customers, whose meters are not read daily. Their gas consumption is estimated based on various factors like historical usage, weather patterns and the time of year.

For larger customers, daily meter readings might be combined with estimates of gas usage at different times to calculate bills. Smaller customers might have less frequent meter readings, so their bills rely more on estimates. And in some cases, both might have devices that track their actual gas usage throughout the day, providing more accurate data for billing.

Depending on which approach is taken, the impact on Xoserve’s systems and services will be different, and require further investigation.

Revolutionising gas settlement

To support this transition, we're developing a new settlement methodology that can accurately and efficiently handle the complexities of a multi-gas grid.

Building on previous research, the Real-Time Settlement Methodology (RTSM) project aims to create a flexible and robust system for settling gas transactions in a dynamic energy environment. This involves developing new models, assessing their feasibility and pinpointing potential risks.

It’s hoped the RTSM will enable accurate billing for consumers, facilitate the smooth integration of low-carbon gases and support the UK's net zero goals. This innovative solution will revolutionise the gas industry, ensuring a fair and sustainable energy future for everyone.

Towards a decarbonised gas grid

Successfully integrating hydrogen into the UK's gas grid requires careful planning and collaboration. By understanding the complexities of each blending scenario and adapting our systems accordingly, we can ensure a smooth transition towards a decarbonised energy future that is both sustainable and equitable for all.

Get in touch

To learn more about hydrogen and the role it can play in decarbonising the gas grid, take a look at our dedicated hydrogen pillar page.

If you have any feedback, questions or suggestions for our Decarbonisation Team, please email us.

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