Applications & Pathways

In 2023 global carbon dioxide emissions reached 40 billion tonnes 60 % more than in 1990 intensifying climate concerns. This study explores hydrogen-natural gas blending as a transitional strategy for decarbonization across several regions and energy sectors – residential commercial industrial and agricultural. A multi-regional analysis framework evaluates integration of 20 % by volume low-carbon hydrogen blending into natural gas systems by identifying hydrogen producers importers and exporters based on production and import costs. Applied to Canada 528 scenarios (2026–2050) assess inter-regional hydrogen trade within Canadian provinces. The lowest-cost scenario involves Alberta exporting hydrogen produced through autothermal reforming with 91 % carbon capture and storage and British Columbia producing its own. The grid electrolysis scenario achieves the highest GHG reductions with a 4.5 % GHG mitigation in Canada with full energy system representation. These findings provide insights for policymakers and stakeholders in advancing hydrogen infrastructure and decarbonization strategies.

Fluidized bed systems play a crucial role in industrial processes such as combustion and gasification. In the Iron Power Cycle fluidized bed systems are essential for enabling the reduction of combusted iron back to iron making them a critical component in the regeneration step of the cycle. This study investigates the impact of operating gas velocity on conversion by performing reduction experiments at three distinct fluidization numbers (us/umf): 16 (bubbling regime) 55 (transition region) and 100 (fully turbulent regime). Experiments were conducted to determine the appropriate velocities for each regime ensuring optimal fluidization conditions across reduction temperatures ranging from 500 to 700 ⚬C. The results reveal that conversion rates increase significantly with gas velocities. At 500 ⚬C operating at approximately six times higher velocity leads to a sixfold improvement in conversion when using iron-oxide particles with a Sauter mean diameter of 61 µm. However while enhanced velocities improve reaction efficiency challenges remain at elevated temperatures (T ≥ 500 ⚬C) where iron undergoes defluidization when exposed to hydrogen. Once defluidization occurs refluidization proves impossible with either hydrogen or nitrogen raising concerns about process stability. These insights highlight the potential for optimizing fluidized bed reduction through velocity control while also underscoring the need for additional measures to mitigate unstable fluidization during high-temperature iron oxide reduction.

This feasibility study has investigated the potential of repurposing existing gas installations for hydrogen use in Multi-Occupancy Buildings (MOBs). MOBs is a broad term extending from a single floor of flats over a shop to large tower blocks. For this study a MOB is defined as a building having at least one meter point and which meets one of these two criteria:

• The building contains at least three domestic dwellings

• The building contains a mixture of domestic dwellings and commercial units with there being at least three dwellings and units in total.

Due to the diverse nature of MOBs and the assets meter positions and appliances used in them it is necessary to sub-divide the population into archetypes and separately assess the risk posed in each category. Customers should only be exposed to Broadly Acceptable risk as defined as an individual risk of fatality of no more than 1 in 1 million per year in the HSE guidance document Reducing Risk Protecting People [1]. Due to the potential for multiple fatalities in MOBs it is important to understand how each building might respond to an incident and reduce risk to As Low As Reasonably Practicable (ALARP).

It is also reasonable to suggest that a customer’s risk after conversion to hydrogen should be comparable to that which currently exists for natural gas. Therefore risk to individuals within a building once converted to hydrogen should be no worse than either the risk faced by them prior to conversion or the average risk for that building height prior to conversion.

Based on SGN’s data the analysis has shown that with universally applied risk mitigation measures and up to two additional mitigations where required around 99% of MOBs can converted to hydrogen using repurposed assets. Detail can be located in Table 7 on page 12 of this report.

There are around 1% of MOBs where it is likely that existing natural gas installations cannot be repurposed for hydrogen use at an economic cost. The following options are available for this small proportion of buildings:

1. Accept a small individual risk increase in a small minority of building types.

2. Implement additional risk mitigation measures that would reduce those individual risks but at a disproportionate cost.

3. Remove gas supplies to these buildings and install an alternative energy source.

Based on the results the following recommendations are given:

• All MOBs to be divided into archetypes and subdivided by installation type prior to a pre-conversion site survey to identify the most practicable and cost-effective energy solution

• The survey will assess all the existing equipment which includes gas pipelines meter locations installation pipes and appliance locations against Gas Industry Standards

• Non-compliant installations will require further analysis and risk assessment on a case-by-case basis to determine their suitability for conversion to hydrogen

• It is proposed that where significant work will be required to re-purpose the existing installation to the required level of safety an economic assessment will be undertaken to determine the optimum solution for customers

• Further work should continue to develop and refine the risk assessment of hydrogen in MOBs. This will support the development of strategic decisions related to conversion. The risks associated with decommissioning gas installations in MOBs could also be assessed in future iterations

• Further work is required to assess Great Britain’s populations of MOBs and gas installation configurations

• Further work is required to provide a detailed cost benefit analysis across the Great Britain distribution networks to ensure that any proposals appropriately address societal expectations of risk versus investment and legal obligations

• Further work is required to define duty holders’ roles responsibilities and interoperability to convert MOBs to hydrogen

• The project has demonstrated that in most cases it is feasible to convert MOBs to hydrogen. The next steps include scoping of resource and operational strategies for conversion

• The additional MOB safety evidence recommendations detailed in Work Pack 3 - Task 12 of Appendix D should also be addressed.

This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.

Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.

This supplement gives additional requirements and qualifications for the conversion of Natural Gas installations in multi-occupancy buildings to Hydrogen and is only to be used in conjunction with IGEM/G/5 Edition 3. This supplement outlines the principles required for the conversion of existing Natural Gas installations in multi-occupancy buildings to 100% Hydrogen. A conversion to Hydrogen should consider the following options:

a) Repurposing existing installations

b) Renovating existing installations; this may involve for example an internal lining being applied to the existing network pipelines.

c) Replacing existing network pipelines with either:

     a. New network pipelines or

     b. An energy centre.

If following a risk assessment and cost benefit assessment none of the above options are considered suitable the remaining option would be to:

d) Decommission the existing gas installation and install a suitable alternative decarbonisation option (electrification heat pump heat network etc.).

This supplement covers the principles required for the repurposing renovating and replacement of existing gas installations for Hydrogen service and the decommissioning of existing gas installations.

This supplement provides the principles required to identify buildings and gas installations that are not suitable for repurposing and outlines remedial work that may be required prior to repurposing.

This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.

Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.

As part of Germany’s LuFo 6 program ’WOTAN’ Rolls-Royce Deutschland (RRD) investigated direct H2 combustion in Rich-Quench-Lean (RQL) mode. Two H2-injectors previously tested under atmospheric conditions were evaluated at elevated pressures and preheat temperatures in the High-pressure Optical Triple Sector (HOTS) at DLR’s HBK1 facility. These tests served as a safety check for the following full-annular test at take-off operating condition. Both injectors were tested at 7% take-off load with variations in air-to-fuel ratio (AFR) to examine the effects of stoichiometry on flame characteristics and NOx emissions. Flame imaging was conducted using ultra-violet (UV)- near-infrared (NIR)- and visible spectrum diagnostics to visualize OH* water vapor and flame luminosity. Exhaust gas measurements were performed downstream of the combustion chamber’s convergent section. Both injectors demonstrated stable combustion across all test conditions maintaining consistent flame position and shape despite changes in pressure temperature and AFR. However significant differences in NOx emission index (EI) were observed between the injectors. The injector with higher NOx emissions exhibited flame anchoring at the injector exit while the other maintained a lifted flame reducing thermal NOx formation. Additionally AFR variation revealed different sensitivities of EI NOx attributed to distinct fuel placement and local stoichiometry. One injector developed a second heat release zone in the inner recirculation region at higher AFRs further contributing to elevated NOx.

Biomethane plays a key role in the green transition offering a renewable carbon-neutral substitute for natural gas while enabling the storage and use of intermittent renewable energy. This work presents a techno-economic assessment of biomethane production through the Power-to-Biomethane concept which combines electrolytic hydrogen from renewable electricity with the direct catalytic methanation of raw biogas from anaerobic digestion. The main objective of this study is to identify the optimal plant size and configuration taking into account the different operational management strategies of the system’s constituting units. The analysis integrates thermochemical modeling with a techno-economic optimization procedure. Three different configurations for renewable energy production photovoltaic-based wind-based and hybrid photovoltaic–wind were evaluated for a case study in Southern Italy. Results show that the hybrid configuration provides the best techno-economic balance achieving the highest annual biomethane output (≈2288 t) and the lowest levelized cost of biomethane (EUR 97.4/MWh). While current biomethane production costs exceed natural gas prices the proposed pathway represents a viable long-term solution for renewable integration and climate-neutral gas supply