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Types of Hydrogen

Brown – hydrogen produced by using coal where the emissions are released to the air;

Grey – hydrogen produced from natural gas where the associated emissions are released to the air;

Blue – hydrogen produced from natural gas, where the emissions are captured using carbon capture and storage; and.

Green – hydrogen produced using clean electricity from renewable energy technologies to electrolyse water (H2O), where the emission is clean oxygen.

What is green hydrogen, how is it made and will it be the fuel of the future?

ABC Science /

By technology reporter James Purtill

Solar panels, wind turbines, a white storage tank and a shipping container

'Green hydrogen' is pure hydrogen produced using renewable energy sources such as wind or solar power.

Abundant, cheap and clean-burning, hydrogen has long been described as the fuel of the future.

That future has never quite materialised, however, due to hydrogen's disadvantages. It's difficult to transport, it can make metal brittle and it's 20 times more explosive than petrol.

But in recent years, "green hydrogen" — hydrogen made without fossil fuels — has been identified as the clean energy source that could help bring the world to net-zero emissions.

'The solution is hydrogen': Andrew Forrest lays out his plan to address climate change

Green hydrogen gives Australia an opportunity to slash our emissions — and if we get this right, the impact could be nothing short of nation-building, argues business leader Andrew Forrest.

Billions of dollars of investment capital and taxpayer support has flowed into the industry, and company share prices have soared.

This has accelerated in recent months, driven by the rising adoption of zero-emission vehicles, a deadline set by many countries to go carbon-free by 2050 and US President Joe Biden's support for clean energy.

The European Union plans to scale up renewable hydrogen projects and invest a cumulative amount of 470 billion euros ($740 billion) by 2050.

In November, Western Australian mining magnate Andrew Forrest announced plans to invest billions of dollars in green hydrogen to grow his new energy business.

In the first of the ABC Boyer lectures on Friday, he focused on the potential for Australia to produce "green steel", which uses green hydrogen in place of fossil fuels to power the iron ore blast furnaces.

"The immediate and multiplier impact on the Australian economy, if we get this right, could be nothing short of nation-building," he said in the lecture.

So what is green hydrogen? How can it be used? And is the hype a lot of hot air?

What makes green hydrogen 'green'?

Hydrogen is the universe's most abundant element, but here on Earth it doesn't appear pure in nature, and requires energy to separate.

The most common technique is to extract hydrogen from water, which is two parts hydrogen and one part oxygen (hence H2O).

Doing this is fairly simple. You can use heat and chemical reactions to release hydrogen from organic materials such as fossil fuels.

But this is enormously polluting. Worldwide hydrogen production is responsible for CO2 emissions equivalent to that of the United Kingdom and Indonesia combined. (The hydrogen is mostly used in the oil refining industry and to produce ammonia fertilisers.)

There is a cleaner way of getting hydrogen: a strong electrical current passed through a tank of water splits the molecule into its two constituent elements. This is called electrolysis.

Hydrogen atoms form hydrogen molecules (H2) and oxygen molecules pair up too. Each can then be bottled up (more on that later).

If the electricity is generated from renewable sources such as solar or wind, production of hydrogen in this way emits no greenhouse gasses.

This is how we come to all the different shades of hydrogen:

brown hydrogen is produced using coal where the emissions are released to the air

grey hydrogen is produced from natural gas where the associated emissions are released to the air

blue hydrogen is produced from natural gas, where the emissions are captured using carbon capture and storage

green hydrogen is produced from electrolysis powered by renewable electricity.

Expensive, but getting cheaper

Conventional hydrogen and blue hydrogen cost about $2 per kilogram (though the price varies depending on where it's produced), while green hydrogen is around twice as much.

That price, however, is falling steeply with renewable energy prices and cheaper costs to make equipment used for electrolysis, called electrolysers.

An Australian National University report last year estimated Australia could currently produce green hydrogen at about $3.18-3.80 per kg and at $2 per kg by the end of the decade.

At that price, it would be cost-competitive with fossil fuels, experts say.

Fiona Beck, an ANU physicist and convenor of the Zero-Carbon Energy for the Asia-Pacific research initiative, a hydrogen fuel project, said there were no "technological blocks" to producing cheap green hydrogen.

"It's all feasible," she said.

"There's things that need to be solved but they're incremental solutions we know how to do — there's nothing we have to discover."

Tim Buckley, an energy market analyst from the Institute for Energy Economics and Financial Analysis (IEFA), predicts the price of green hydrogen will drop 70 per cent in the next decade in countries with cheap renewables.

"Where green hydrogen is almost inevitably going to work is where green energy is going to be almost free," he said.

"Places like Rajasthan in India or the Pilbara in Australia."

How can green hydrogen be used?

Hydrogen can be used in broadly two ways. It can be burnt to produce heat or fed into a fuel cell to make electricity.

A 2018 CSIRO report outlines several potential applications for hydrogen:

fuel-cell hydrogen electric cars and trucks

container ships powered by liquid ammonia made from hydrogen

"green steel" refineries burning hydrogen as a heat source rather than coal

hydrogen-powered electricity turbines that can generate electricity at times of peak demand to help firm the electricity grid

as a substitute for natural gas for cooking and heating in homes.

The report foresaw an opportunity for Australia to export hydrogen to energy-hungry countries that don't have access to cheap renewable energy.

It estimated potential demand for imported hydrogen in China, Japan, South Korea and Singapore could reach $9.5 billion by 2030.

By 2050, according to investment management firm Goldman Sachs, green hydrogen could supply up to 25 per cent of the world's energy needs and become a US$10 trillion ($13 trillion) market.

But amid all this hype, hydrogen's future is not yet assured.

To become a major export commodity, problems of storing and transporting hydrogen need to be overcome.

A few big caveats

Like any gas, hydrogen can be compressed and stored in tanks, then used as needed. However, the volume of hydrogen is much larger than that of other hydrocarbons; nearly four times as much as natural gas, for instance.

Its storage requires compression to 700 times normal atmospheric pressure or refrigeration to minus 253 degrees Celsius, which is near absolute zero.

It's estimated that the cost of doing this could add anything from 60 cents to $7 per kg, making it less competitive with other fuels.

On top of the cost of storage, there's a problem with pipes.

Hydrogen atoms under pressure are small enough to slip through solid steel, meaning natural gas plumbing often cannot be easily converted for pumping hydrogen, Dr Beck said.

Appliances set up for natural gas, like stoves and heaters, would also need to be replaced or refitted to handle hydrogen.

Given that's the case, in many cases it might be easier to simply use electricity, she said.

"However, there are certain things you might not be able to directly electrify, or there might be some places where you're not able to generate renewable energy," she said.

"In these places, having a liquid fuel is a very useful thing.

"That's where green hydrogen could be a very useful part of the puzzle."

One solution to transportation problems is converting the hydrogen into ammonia (where three hydrogen atoms bond to a nitrogen to make NH3).

Unlike hydrogen, ammonia can be relatively cheaply stored under pressure or refrigerated as a liquid at -33C at normal atmospheric pressure.

For many applications, once it arrived at its destination, the ammonia would then have to be converted back into hydrogen.

With each conversion — from water to hydrogen to ammonia and back to hydrogen — energy is lost.

Electric vehicles have 'won' transport: experts

Because of these shortcomings, hydrogen will struggle to compete with electricity in most situations, said Peter Newman, a professor of sustainability at Curtin University.

"Creating a whole new hydrogen grid will take decades and why bother when we already have an option that will be cheaper than gasoline and diesel in the 2020s?" he said.

He predicted hydrogen will have a more niche role and be used for industry in regional and rural areas.

Electric vehicles powered by lithium-ion batteries have "won" the battle for transport, he said.

"They're clearly the better option. We just need to roll it out."

How renewable hydrogen is produced.(Supplied: Renewable Hydrogen)

Tim Buckley from the IEFA similarly predicted green hydrogen's role would be to decarbonise industries and applications that can't be electrified.

The list of what can't be electrified is steadily decreasing as the cost of renewables and batteries falls, he said.

"What I've been watching is the Tesla share price," he said.

"That's the financial market saying 'who cares about hydrogen fuel cell transport?' Electric vehicles have already won the race."

Tesla, which makes electric cars as well as large batteries for power grids, has seen its stock market value go up seven-fold in the past year.

Richie Merzian, director of the climate and energy program at the Australia Institute, said the cost of converting appliances and upgrading gas networks meant hydrogen probably wouldn't be seen in most homes.

If that's the case, the future for hydrogen may be in high-temperature industrial processes such as steel works or to make ammonia-intensive products such as fertiliser.

"There's a lot of potential there and that's exciting," he said.

"We're likely to see manufacturing facilities crop up right near hydrogen facilities."

What's Australia doing?

Several major green hydrogen projects are in development in Australia.

Among the largest of these is the $51 billion Asian Renewable Energy Hub, which plans to produce 26 gigawatts of cheap solar and wind power for the Pilbara. That's more power than Australia's entire fleet of coal-fired power stations.

Some of this electricity will be used to electrolyse water to create hydrogen, which will be converted into ammonia for export.

The Pilbara, of course, is a major supplier of iron ore. With a plentiful supply of hydrogen, "green steel" could be produced in towns like Port Hedland or Karratha and exported to the world.

In October last year, the Federal Government granted the hub "major project status" to expedite its approvals process and help it export its first shipments in 2028.

To be seen.

The government has partly funded a trial to produce "blue hydrogen" from coal in Victoria's Latrobe valley, then ship it to Japan.

To be blue, the greenhouse emissions must be captured and stored underground in a process called carbon capture and storage.

So far, this hasn't happened, Mr Buckley said.

"It's brown hydrogen, not blue," he said.

There are also questions around whether money earmarked for clean energy projects will be used to finance carbon capture and storage, including blue hydrogen.

In May last year, the Government announced the Clean Energy Finance Corporation will administer a $300 million Advancing Hydrogen Fund.

A couple months later, it introduced amendments to allow the Clean Energy Finance Corporation to invest in technology such as natural gas and carbon capture.

The proposed legislation was opposed by the Greens and Labor, referred to a Senate committee, and has not yet passed.