The future of gas: chewing over the green-hydrogen cooked sausage

I am standing beside an outbuilding at Callaghan Innovation’s campus in Lower Hutt on a sunny winter’s day, watching engineer Robert Holt chuck a packet of sausages and a red pepper on the barbecue.

Not just any barbecue though. This is New Zealand’s only zero-carbon, hydrogen-powered barbecue. To my right are two wind turbines and above me on the roof of the building are some solar panels. Round the back is a fridge-sized electrolyser designed by Callaghan that is using the power from the wind turbines and the solar panels to split water into hydrogen and oxygen.

The hydrogen, pumped out at the rate of 100 grams an hour, is being fed into an underground storage pipe connected to the barbecue, a hot water heater and a smoker. And the “waste” oxygen is being spat out into the air in little hisses at the back of the electrolyser. I am here because the gas industry wants to convince me to help persuade you that gas has a future beyond natural gas – a carbon-free future based on green hydrogen.

The proof that’s possible is in the sausage, which has now cooked. But whether it is likely hinges on some complicated practicalities. Is hydrogen safe? Is it economic? How could the switch-over from natural gas be managed, and from an environmental point of view would it be better to just jump to electric appliances now?

Is the switch even possible?

First Gas hopes to start mixing a blend of up to 20 per cent green hydrogen with natural gas until some time from 2035, after which it would begin switching its network to 100 per cent hydrogen.
But there is a bit of a ‘chicken and egg’ problem. Rinnai New Zealand managing director Ray Ferner says a lot of gas hot water heaters and fires have been tested on blends of up to 20 per cent hydrogen “and we don't perceive any real challenge”.

But move much beyond that to a richer hydrogen mix, and they will no longer work safely. Callaghan Innovation converted its appliances, including a hot water heater, to run on hydrogen and Holt suggests there could be a market for conversion kits costing a few hundred dollars. But Ferner doubts converting appliances is going to be an option for most people.

That is because it would be logistically impossible to convert everyone on a gas pipeline from appliances that require natural gas to ones that could cope with a high hydrogen blend overnight.
And who would want to live without a stove or hot water heater for however long it took to do a switchover? Ferner says there is a solution, but it also comes with a cost.

There are prototype gas appliances being demonstrated in Europe that are capable of burning either natural gas or hydrogen or any blend, he explains.
“All the major manufacturers are working on them. “The appliances are smart enough to understand what they are burning, and they calibrate themselves to what is coming down the pipe.”
Ferner expects such devices to become commonplace between 2025 and 2030, and, surprising perhaps, he believes they could cost only “1 or 2 per cent” more than existing appliances.

“In a gas water heater for example, there's a heat exchanger, a burner, a gas control valve, a water control valve, and a computer that runs the whole thing.
“The only things that will really change is the design of the burner and the gas control valve, and the computer will control it all. There might be a couple more sensors, but I think we're talking about a nominal change.” As and when such appliances do go on sale, people should be able to future-proof their homes for a switch to green hydrogen.

But until then it is easy to see people becoming more hesitant about buying new or replacement natural gas appliances that they might only get 10 to 15 years’ use out of.
Ferner’s response is that the switch to high hydrogen blends probably won’t really begin before 2040 or 2045. Though that, of course, is not what climate change campaigners would want to hear. 

What about the Hindenburg?

Hydrogen may never live down the 1937 Hindenburg airship disaster in which 36 people lost their lives in what was one of the earliest deadly accidents to be caught on film. Holt notes hydrogen packs a punch, being “2½ times more energetic by weight than its nearest cousin”. And because hydrogen is a far smaller molecule that methane, which is the main component in natural gas, it can also leak out of tiny holes.

But Holt argues hydrogen is the safest flammable gas because it is very buoyant and disperses rapidly. Intentionally trying to create an explosion from hydrogen in the home environment is not as easy as it might sound, he says. “I talked to some consultants from the UK last year and they spent three years trying to get a house in Scotland to blow up with hydrogen and they haven’t managed to sustain an explosion inside because it leaks away so quickly.”

Holt admits there are safety issues, but says they are relatively easy to solve. “Hydrogen doesn’t need complicated technology to render it safe. For $30 you can have a sensor which tells you when you have got a leak and you just shut it down.”

Preventing leaks is a question of using the right materials “and fortunately high-density polyethylene, which is what gas pipelines are made of, is one of them”, he says. But there are still older gas pipes in New Zealand made out of types of steel that Holt describes as the “bogeyman of hydrogen”. These can become brittle and fracture when hydrogen is piped through them.

Powerco gas manager Mark Hermann says that it is laying pipes that can take hydrogen whenever it connects new subdivisions and replaces existing infrastructure. “When we are replacing older parts of the network, we're replacing it with newer materials, and most of that is polyethylene.” But the future of gas may be looking a bit brighter for people living in new subdivisions, rather than in old villas in established suburbs.

And the cost?

The price of hydrogen is going to be tied to the price of electricity, as that is what is used to produce green hydrogen. If the cost of electricity comes down, then the price of green hydrogen should come down in about the same proportion. That appears quite likely given expected investments in low-cost solar and wind power, and pumped hydro, and the growing possibility of reforms to the currently highly-profitable electricity market.

But in almost all situations, using electricity as “electricity”, rather than converting it first to a gas and then burning it, should be the cheaper option. That may be a bit ‘less true’ when comparing electric and gas home hot water heating, as there are some inefficiencies in having hot water sitting in a hot water cylinder waiting to be used.

Holt says the electrolyser that Callaghan has developed, HyLink, is about “70 to 75 per cent efficient”, meaning about three-quarters of the power generated from its solar panels and wind turbines is converted and stored as hydrogen energy. The rest is given off from the electrolyser as heat, which it is not entirely wasted and is instead used to heat one of Callaghan’s offices.

Inconveniently, though, the more hydrogen that has to be produced quickly, the harder it is to make the process efficient. “With almost all conversion processes, you can reach perfect efficiency when you're doing it infinitely slowly,” Holt says. The main uses of green hydrogen are expected to be in applications that require a high power-to-weight ratio, such as heavy transport and aviation, and where fine control is needed of industrial processes.

One reason green hydrogen might appeal over electricity financially in the home environment, despite its higher energy cost, is if a homeowner has nowhere convenient in their home to put an electric hot water cylinder, or if installing one would involve a lot of re-plumbing. But electric cylinders that are designed to be installed outside are now a more common option in New Zealand, which can alleviate those issues.

“Australians usually install electric cylinders outside and traditionally we have them inside,” Rinnai’s Ferner says. “But there is a now a range of cylinders, we sell them and there are several others, that can be installed externally. They have a superior finish on them and are waterproof and are built for the job. They suit some people, but not others.” 

Is waiting for green hydrogen the ‘right’ thing?

This is a tougher question than it sounds. The Climate Change Commission initially recommended banning new natural gas connections from 2025 before walking back on that after Energy Minister Megan Woods signalled she would not be on board with that change. Woods’ rationale seemed to be that it might not make sense to kill off the natural gas network if it could be repurposed to distributing green hydrogen.

So by that logic, by sticking with gas appliances now, perhaps consumers could claim they were helping pave the way for a greener future. There is also an argument that the natural gas that will be produced by the country’s existing gas fields is going be used for one purpose or another, and out of those uses, using it for home and hot water heating is one of the more energy-efficient.

It makes far less sense environmentally, for example, to burn gas to produce electricity, than to use it directly in homes. Doubling down on that argument, natural gas users could argue that they if they had switched to electricity this year, the net result would have been even more coal-burning and carbon emissions from Genesis’ Huntly power station. It is possible to take that argument too far though.

While the above might be the impacts in the short term, the more demand there is for electricity, the higher investment you would expect in renewable electricity generation– which has none of the emissions associated with natural gas. 

The mood on the ground

There is a little sign that many consumers’ faith in gas has been shaken just yet. Ferner says demand for Rinnai’s gas appliances is at record high thanks to the volume of new homes being built, and the company hasn’t seen any move away from the fuel as yet. Even with the ban on new offshore exploration permits, there is probably enough natural gas in New Zealand to power home gas appliances through to at least 2050 and perhaps decades longer.

The assumption may be that if green hydrogen doesn’t ride to the rescue, the consumption of natural gas will simply be allowed continue, so why worry? But given expected increases in the cost of carbon credits, the potential for electricity prices to fall, and the tough economics of green hydrogen, it may be worth accepting that gas, either natural or green, is going to become a bit of a luxury. A luxury some buyers would pay for, of course.

Wellington gas fitter Dermot O'Shaughnessy of Hospitality Gas Services, says professional chefs he works with couldn’t get their heads around the idea of cooking without gas and don’t see induction cooking as an option. That is especially as a lot of commercial cooking revolves around Asian cuisine cooked in woks.

Business owners were at a loss to think what they would do if they wanted to open a new restaurant and couldn’t put gas in and were “astonished” when the Climate Change Commission floated the idea of a ban on new connections, O'Shaughnessy says. “They are of the belief that will never happen because it can't happen. There will always be a demand for gas, whatever it looks like.”

But he says he knows other gas-fitters who lost work installing ducted gas heating systems in new homes after the commission’s draft recommendation. “Quite a bit of that got cancelled.” O'Shaughnessy hasn’t had many clients discuss the environmental conundrums, he says. “Not in my world. They are only interested in performance and if it’s not working. You know, ‘I’ve got 100 customers tonight and I want it working hot’.
“We have got to hope hydrogen can deliver on that, especially in hospo.” Younger gas-fitters shouldn’t be afraid of it, he says.

“There'll be plenty of work. There will be something where we'll be involved in that switch.” Does green hydrogen have a future in the home? At the moment you could find reason to support whatever answer you wanted to believe, so pass the ketchup, I’m mainly here for the sausage.

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