Hydrogen makes itself at home

Among a cluster of new homes on the northern outskirts of Melbourne, there is one house that stands apart. Not that you’d know it by looking from the outside.

HyHome, unveiled this year by the Australian Gas Infrastructure Group, is Australia’s first hydrogen-powered home.

The demonstration house in Wollert is equipped with hydrogen-powered hot water systems, heating, cooktop and barbecue; some of the first 100 percent hydrogen compatible appliances to be developed for the domestic market.

The partners which built HyHome recognise what others, including billionaire mining magnate Andrew ‘Twiggy’ Forrest, have: hydrogen has the potential to revolutionise the way we power our economy.

While the hydrogen for HyHome is supplied by on-site gas tanks, the pipe fittings match those that would connect to the gas network. The project therefore serves as an accurate proof of concept for how future homes could run on a 100 percent hydrogen gas network.

Hydrogen is a cleaner fuel than natural gas because the combustion of hydrogen in air produces heat and water vapour, a carbon-neutral process, as opposed to the combustion of natural gas, which produces carbon dioxide.

Blending hydrogen into the existing natural gas mix, or the use of pure hydrogen in the gas network, reduces the amount of natural gas needed which can help cut carbon dioxide emissions in tricky to decarbonise sectors such as heating or industrial manufacturing processes.

The Australian Government’s National Hydrogen Strategy has identified the use of hydrogen in gas networks as a priority area for research, trials and demonstration projects.

The testing of hydrogen blending projects taking place across Australia includes energy company ATCO supplying a 2-10 percent (by volume) hydrogen gas blend to 2,700 gas network connections in Western Australia and the Australian Gas Infrastructure Group supplying 4,000 properties in Adelaide with a 5 percent hydrogen gas blend.

Currently, 41 countries have hydrogen strategies to help reach net zero targets by 2050.

Globally, governments and industry are pursuing hydrogen blending with serious intent. In the UK, the HyDeploy partnership at Keele University successfully supplied 668 houses, a school, several small businesses, and a church in a town in northern England with just a 20 percent hydrogen blend for a year.

The project has further successfully trialled using a 20 percent hydrogen blend at an industrial scale, supplying an energy-intensive glass factory and Unilever’s manufacturing plant in the northwest of England.

There are, however, several challenges in blending hydrogen into the gas network.

Hydrogen is in hot demand. For hydrogen blending to have a positive effect on reducing emissions, green hydrogen, produced via the electrolysis of water, should be used as opposed to grey or brown hydrogen, produced from fossil fuels.

Green hydrogen is currently expensive to produce. It requires renewable electricity and lots of clean water, both resources in high demand.

Low-emissions hydrogen currently accounts for less than 1 percent of all hydrogen production and use, according to the International Energy Agency.

There is an argument that blending hydrogen with natural gas is an inefficient use of an expensive resource, potentially “greenwashing” the continued use of natural gas when the focus could be on transitioning to electric technology such as heat pumps.

Getting it into the home

Hydrogen has a lower volumetric energy density than natural gas. This means a larger volume of hydrogen is required compared to natural gas for the same energy output.

The Australian Hydrogen Centre reports that a 100 percent hydrogen network would reduce network capacity by 13 percent, though it adds this wouldn’t impact supply.

Hydrogen is also incompatible with certain metals, with potential embrittlement leading to fractures in pipes and storage tanks which can lead to gas leaks.

The government-owned Evoenergy and the Canberra Institute of Technology have shown at their testing facility in Canberra that 100 percent green hydrogen is compatible with current Australian Capital Territory gas network pipes and fittings.

The facility also measured the performance of everyday household gas appliances when run on hydrogen gas, showing that modern cooktops can safely use a 20 percent hydrogen blend.

Hydrogen blends much higher than this would require the replacement of existing gas appliances. One approach is to phase in ‘hydrogen ready appliances’, allowing consumers the continued use of natural gas until the gas network switches to hydrogen.

Safety

Like natural gas, hydrogen is a clear, colourless and odourless. Odorants are added to natural gas so leaks can be easily detected by its distinctive smell. Odorising hydrogen with this same smell or a new smell will be important for hydrogens use in the home.

Hydrogen is easier to ignite than natural gas owing to its much larger range of flammable concentrations in the air and a lower ignition energy.

This sounds concerning but with appropriate engineering controls to prevent leaks and mandatory safety measures, such as ventilation and gas detectors, hydrogen in these applications is no more dangerous than natural gas.

In fact, some of hydrogen’s properties make it a safer alternative. It is non-toxic and 14 times lighter than air, so in the event of an open air leak it would rise and dissipate very quickly.

A less known fact about hydrogen is that it is considered an indirect greenhouse gas. Hydrogen reacts with molecules in the atmosphere which leads to the prolonged lifetime of certain greenhouse gases, such as methane.

Public opinion

Hydrogen’s misleading reputation as a dangerous, highly explosive gas, famously demonstrated by the Hindenburg disaster, is gradually being revised.

The success of long-term trials such as Hydrogen Park, in South Australia, which has been safely providing residents in Adelaide with a 5 percent hydrogen blend for over two years, should instil public confidence that hydrogen can be used at scale in the gas network and in our homes.

Interestingly, a study has shown that people believe hydrogen’s property of burning with a near-invisible flame would severely disrupt their cooking practices but largely not affect home heating.

Australia is moving forward with hydrogen blending as new projects — such as Hydrogen Park Gladstone and HyP Murray Valley, which will deliver a 10 percent hydrogen blend to 700 households in Queensland and to the gas network of Albury and Wodonga in 2024 — continue to receive funding.

Replacing gas with electricity appears to be the preferred end game in the extinction of fossil fuels in the home.

However, the reality remains that this transition will take time and the gas network that we rely on heavily will likely be part of the energy system for many years to come, perhaps forever.

During this time of transition blending green hydrogen into the natural gas mix could provide a quick fix solution that would play a small but important role in decarbonising the gas network and reducing our household emissions.

Hugh Davies is a PhD researcher in chemical engineering at the University of Bath and Monash University, his research focuses on energy materials for sustainable energy applications.