1. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) Gas Build-up in a Domestic Property Following Releases of Methane/Hydrogen Mixtures Barbara Lowesmith, Geoff Hankinson, Catalina Spataru and Michael Stobbart

2. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 2 Naturalhy Project  Aim is to assess the possibility of using the existing natural gas pipeline network for conveying natural gas/hydrogen mixtures  Provides ‘greener’ fuel if burned directly  H 2 can be separated out for use in fuel cells  Provides a means of introducing and developing the Hydrogen economy at an earlier stage

3. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 3 Naturalhy Project  Naturalhy Project studying the impact of introducing Hydrogen into Natural Gas pipelines  Effect on durability and integrity of pipeline network  Effect on safety of the public  Separating the Hydrogen from the mixture  Using the mixture in existing appliances  Socio-economic aspects

4. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 4  To assess the change in risk to the public caused by adding hydrogen to the gas network Objective of Safety Work  In particular, for Domestic customers – does the risk in the home increase?

5. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 5 Domestic Customers  To answer this question we are:  Assessing gas accumulation behaviour by performing large scale experiments and developing mathematical models  Determining minimum ignition energies and ignition probabilities by laboratory experiments  Assessing explosion severity by models and experiments

6. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 6 Gas Build Up Experiments  ‘Room’ - 3m x 3m x 2.3m  Door in front wall  Release in centre of back wall  Vent openings in two opposing walls – upward crossflow ventilation by wind

7. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 7 Gas Build-up Experiments  Methane, or methane:hydrogen mixtures (80:20 and 50:50)  At 20-30mbar from 5 or 10mm diameter hole close to floor or 1.1m above floor  Measured gas concentration throughout enclosure with time using oxygen cells

8. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 8 Typical Results – Release at 1.1m above floor

9. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 9 Typical Results – Layer Formation

10. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 10 Mathematical Model - Objectives  To predict with time the position of the interface and the concentration in the upper layer  To validate against experimental data  To apply model to study effect of different release conditions

11. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 11 Mathematical Model hshs h lower vent opening interface H upper buoyant layer lower layer upper vent opening air entrained into jet jet wind horizontal cross-sectional area, S QjQj Q in Q out HlHl

12. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 12 Mathematical Model  Equations describing:  Volume of layer formed and concentration within it  Air flow as a combination of wind and buoyancy induced flow  Buoyancy induced flow as a function density (and hence concentration) of layer  Air entrained into jet of gas released

13. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 13 Validation of Model- Transient Prediction

14. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 14 Steady State Comparison

15. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 15 Application of Model-Effect of H2 Content

16. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 16 Conclusions  Adding H 2 to Natural Gas results in increased volume flow when a leak occurs  This leads to increased gas concentration in an accumulation formed  However, the buoyancy forces are greater for the lighter gas resulting in increased ventilation  This mitigates the gas concentrations to some extent

17. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 17 Conclusions  However, the concentrations are higher and the flammability limits are wider  This means that a flammable inventory persists for longer  Hence the risk to the domestic customer may increase

18. Preparing for the Hydrogen Economy by Using the Existing Natural Gas System as a Catalyst // Project Contract No.: SES6/CT/2004/502661 NATURALHY is an Integrated Project funded by the European Commission’s Sixth Framework Programme (2002-2006) for research, technological development and demonstration (RTD) 18 Further Work  Extend capabilities of model  Quantify the ignitability of accumulations following methane/hydrogen releases  Assess the change in risk to the public in the home environment as a result of introducing a given level of hydrogen to the natural gas