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NETWORK / 28 / JULY/AUGUST 2017 Low-carbon gas injection C limate change has been described as one of the greatest threats to humanity. Like many countries around the world, the UK has responded by committing itself to tough reductions in carbon dioxide emissions. But while efforts to decarbonise electric- ity generation have made significant pro- gress, the decarbonisation of Britain's heat and transport sectors have lagged behind. However, a groundbreaking initiative could be about to change that. This year, Cadent, Britain's biggest gas distribution network, along with Northern Gas Networks (NGN) and the HyDeploy con- sortium started a pioneering three-year pro- ject at Keele University. The project is designed to demonstrate that a blend of hydrogen – which emits no carbon dioxide when burnt – and natural gas can be distributed and used safely and efficiently in a live part of the distribution network without disruptive changes for cus- tomers – and at the same time cut carbon dioxide emissions. It will be the first time that a hydrogen blend has been used in a live distribution network since Britain's conversion from town gas to natural gas. The project was awarded £6.7 million from the Network Innovation Competition (NIC) last November and a further £760,000 was funded by Cadent Gas and NGN. The challenge Like most other countries around the world, the UK recognises the challenge of climate change. Not only has it resolved, by 2050, to reduce carbon emissions by 80% of their level in 1990, but it has also made it a legal obligation under the Climate Change Act (2008). Although significant progress is being made towards a low-carbon future in elec- tricity generation, the projected carbon emissions reductions for the heat and trans- port sectors are minimal. This is an ideal opportunity for "first of their kind" projects such as HyDeploy to show how repurposing of the gas grid can play a significant role in decarbonising heat. It makes considerable sense both from an economic and engineering perspective to use the gas grid as the vector to decarbonise heat. The gas network is designed to deliver gas safely and reliably to more than 23 mil- lion customers and over 83% of homes are connected to the gas network. The gas grid is a world class infrastruc- ture that has received decades of investment from consumers and stretches the length and breadth of the country. The gas network can meet a 1-in-20 peak day demand – a winter defined as the worst in 20 years. At these winter peaks, the gas networks can transport four times as much energy as the electricity network. Cadent's London network alone provides 24GW at peak hours, which would require the equivalent output of seven Hinckley Point C nuclear power stations if heat were electrified, not to mention the significant extra network infrastructure investment that would be needed. Peak heat demand across the UK is about 300GW (peak half-hour). To supply this amount of heat through the electricity network, even with effective heat pumps, would require an electrical system (either generation, or generation plus storage) with capable of delivering 100GW more than existing electrical demand – which is typi- cally between 25 and 50GW. The investment required to upgrade the electricity network to cater for the peak heat demand that is met by today's gas grid would run into the many billions and this cost would be borne by UK consumers. The mix Today, 99% of our domestic gas is tradi- tional natural gas, with about 1% biometh- ane from anaerobic digestion (AD). However, if we are serious about decar- bonising heat and meeting the UK's carbon emission reductions, we must think of other forms of low-carbon or zero-carbon gases to replace natural gas. This will mean the increasing use of gases such as bio substi- tute natural gas (BioSNG), hydrogen and increased amounts of biomethane in the gas network. To enable these new sources of gas to be injected onto the network, our current regu- lations must change. The HyDeploy project will seek an exemption from the Gas Safety (Manage- ment) Regulation (GS(M)R) to allow poten- tially up to 20% of the volume of gas in the Keele network to be hydrogen. GS(M)R) cur- rently only allows 0.1% of gas volume in the network to be hydrogen, despite the net- work formerly distributed town gas that was 40-60% hydrogen. The GS(M)R was developed during the discovery of significant quantities of North Sea gas which, at the time, would supply the UK for the foreseeable future. With dimin- ished supplies of North Sea gas and the advent of low-carbon forms of gas, includ- ing hydrogen, this will require an update to the GS(M)R. There are some other considerations related to the flow weighted average calorific value (FWACV); and the way that energy content has to be average across the local distribution zone (LDZ). Currently, this would mean hydrogen would have to be fur- ther processed by adding propane. Recom- mendations for updating the current regime are being investigated in a separate Cadent NIC project called Future Billing Methodol- ogy (for more information see www.future- billingmethodology.co.uk). The HyDeploy programme HyDeploy is being hosted by the University of Keele, on the outskirts of Newcastle-Under- Lyme in Staffordshire. It is the UK's largest campus university, and has 12,000 students and staff, of which 5,000 live on site. The campus building have a variety of uses, including academic, business, com- mercial, retail, leisure and residential. These demands are serviced by the university's own private utility network, which makes it possible to use the campus as a "living labo- ratory" on the scale of a small town.