- The H21 programme has shown that a city’s natural gas supply can be decarbonized using 100% hydrogen
- Converting existing gas networks to hydrogen is technically and economically feasible
- Tests are proving the safety case for such a switch
- The programme could support the case for low- and zero-carbon hydrogen becoming the world’s main energy carrier
While burning natural gas emits about half the carbon of an equivalent amount of oil or coal, combusting hydrogen (H2) gas emits none at point of use.
Steam-methane reforming (SMR) is the main process used to separate natural gas, which is mostly methane, to produce H2 and carbon dioxide (CO2). Hydrogen can then be used as a lower-carbon fuel, while captured CO2 can be transported to, and stored in, depleted oil and gas fields through carbon capture and storage (CCS; Figure 1 ).
Some gas distribution system operators (DSO) believe that H2 can make the continued economic use of existing gas infrastructure more socially and politically acceptable in a decarbonizing world.
One such operator is the UK’s Northern Gas Networks (NGN), whose H21 programme director, Dan Sadler, manages the H21 programme. This government-funded initiative, led by NGN on behalf of Britain’s DSOs, is researching and testing the distribution of H2 in the UK’s existing natural gas networks. “The aim is to provide customers with all the benefits of gas without the carbon footprint,” he said.
If the existing distribution network cannot be repurposed in a decarbonizing energy mix, it could effectively become a stranded asset that customers have already paid for” Dan Sadler, H21 programme director, Northern Gas Networks
The H21 programme is based on the original H21 Leeds City Gate project. The project used a modelling approach to demonstrate the technical and economic feasibility of converting the natural gas (predominantly methane) network in this large UK city to 100% low-carbon hydrogen (Figure 2 ).
In H21’s vision, the low-carbon H2 would be supplied initially by SMR or by a process called autothermal reforming. Supply would transition to entirely sustainable H2 from global renewable sources in the latter part of the century.1,2
The world is watching H21, Sadler noted: “Countries all over the world have the same huge challenge to meet obligations set by the Paris Agreement and the Kyoto Protocol. Many get 40–60% of their total energy from natural gas, and the vision behind H21 has galvanized global interest in hydrogen because the solution is globally applicable and allows bulk availability of hydrogen at point of use.”
As in other nations with established gas distribution networks, most infrastructure for using H2 in the UK already exists. Sadler explained: “From an infrastructure perspective, we need new hydrogen-production facilities, CCS, and a new hydrogen transmission pipeline system. This is very small compared with the length of the existing UK gas distribution network assets which can be repurposed. But we first need evidence-based answers to important safety case and strategic questions.”
Making the safety case
A significant project within the H21 programme aims to produce quantitative safety-based evidence to confirm, by 2021, that a 100% H2 grid would carry comparable safety risk to current networks supplying natural gas and/or town gas. The latter of these gases is a flammable, gaseous fuel mix containing 50% hydrogen. It is made, for example, by the oxygen-free combustion of coal, or from naphtha or a natural gas/naphtha feedstock.
The safety research is the focus of the GBP10 million (m) H21 Network Innovation Competition (NIC) initiative involving all UK DSOs and supported by the country’s gas and electricity markets regulator, Ofgem. DNV GL is among five organizations involved as primary partners. The company’s Spadeadam Testing and Research Centre is involved in critical studies whose findings will be used in quantitative risk analysis.
If we are to achieve impending climate change targets, we need to reinforce the will and the way to make clean hydrogen power a reality; it is a huge challenge” Andy Cummings, principal consultant, DNV GL – Oil & Gas
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