What makes renewable hydrogen a clean energy source?

Green hydrogen

As the world sets its sights on net zero emissions, renewable hydrogen has been identified as an important renewable energy product – and the stage is set for Australia, with our abundant natural resources, to be a major player in the global hydrogen industry. 

Here’s what makes renewable hydrogen so green. 

What sets renewable hydrogen apart from the rest?

Hydrogen (from the Greek word for ‘water former’) is actually the most abundant element in the universe, and the simplest – it’s made up of just one proton and one electron. But here on Earth, hydrogen doesn’t occur in its elemental (pure) form.  

Instead, it must be separated from other elements. Traditionally, this has been achieved using fossil fuels, either via a steam methane reformation process using natural gas or via a coal gasification method. The resulting emissions are then released into the atmosphere, or reduced through the use of carbon capture and storage technology. 

Renewable hydrogen, on the other hand, is produced from water, using renewable energy. 

Currently, hydrogen is most commonly produced using fossil fuels, which is why worldwide hydrogen production is responsible for carbon emissions equivalent to those of the United Kingdom and Indonesia combined. But when hydrogen is produced using renewable energy sources like solar or wind, it can be a clean, zero-carbon fuel. 

To produce renewable hydrogen, a strong electrical current is passed through purified water, splitting the molecules into their constituent elements – oxygen and hydrogen. This process is known as electrolysis. The device used to do this is called an electrolyser, and it’s powered by solar or wind energy. 

At the moment, hydrogen produced using fossil fuels costs about $2 per kilogram, while renewable hydrogen presently costs about twice that much. But a 2020 Australian National University report found the cost of green hydrogen could fall to $2 per kilogram by the end of the decade, as a result of falling renewable energy prices and the availability of cheaper electrolysers. At that price, it would be cost-competitive with fossil fuels, even before you take the environmental advantages into account. 

What’s the potential for green hydrogen in Australia? 

The CSIRO’s National Hydrogen Roadmap outlined several potential uses for hydrogen in Australia, all of which get us closer to net zero if green hydrogen is used in place of hydrogen produced by fossil fuels. 

These applications include: 

  • Transport fuel. Hydrogen fuel cells offer an alternative to batteries for powering electric motors, and are especially suited to powering heavier transport like buses, trucks, trains and aircraft. 
  • Powering container ships that run on liquid ammonia. The renewable hydrogen can be converted into ammonia and used as fuel. 
  • Powering refineries and other industrial facilities in place of coal, helping to reduce emissions in energy-intensive industries.
  • Stabilising the electricity grid. Hydrogen can be stored for long periods of time and converted back into electricity when the energy market needs it. Electrolysers can also ramp production up and down rapidly to match or supplement the variable output of wind and solar generators, helping to ensure electricity supply at times of peak demand. 
  • Replacing or partially substituting natural gas for cooking and heating in homes. 

But the greatest potential for green hydrogen in Australia is likely to be in international trade, with Australia poised to export hydrogen to energy-hungry countries that don’t have access to cheap renewables of their own. 

With abundant solar and wind resources and a flourishing renewable energy industry, Australia is in a strong position to export green hydrogen to countries like Japan and Korea, who will use it to help decarbonise their own economies. 

Queensland, in particular, is well-placed because of its close proximity to Asia, renewable energy resources, established infrastructure and recognised manufacturing capabilities. 

To that end, Queensland Government-owned energy company Stanwell formed a consortium with four leading Japanese companies (Iwatani Corporation, Marubeni, Kansai Electric Power Company and Kawasaki Heavy Industries) and an Australian gas infrastructure business (APA Group) to develop a renewable hydrogen export supply chain in Central Queensland. If progressed, the proposed project would be the largest in the State, scaling up to over 3,000 megawatts (MW) of electrolysis capacity by the early 2030s.

The consortium has commenced a $10.4 million detailed feasibility study into the development of a large-scale renewable hydrogen production facility at Aldoga, 20 kilometres west of Gladstone in Central Queensland, and a liquefaction plant at the Port of Gladstone. The consortium aims to produce approximately 36,500 tonnes of renewable hydrogen per annum by 2026 (Phase 1), scaling up to 328,500 tonnes per annum in 2031 (Phase 2). 

The feasibility study is funded by the consortium partners as well as the Australian Renewable Energy Agency (ARENA) and the Japanese Ministry of Economy, Trade and Industry (METI). If progressed, the project will export hydrogen to Japan and supply large industrial customers in the Central Queensland region. 

The feasibility study will be finalised in March 2022.

Where will the water come from? 

We know the electrolysers required to produce green hydrogen in Australia will be powered by renewable solar and wind energy, and will also require significant amounts of water. 

Water is used for both the production of hydrogen and for cooling the plant. Water used must be demineralised and can be sourced from the local water supply, wastewater, or desalination plants. The basic chemistry is that each kilogram of hydrogen produced through an electrolyser requires
roughly nine kilograms of demineralised water. The amount of water required for plant cooling will differ depending on the technology used.

Australia is the driest inhabited continent on the planet, and prone to frequent droughts, which usually come with water restrictions. In 2019, the Council of Australian Governments (COAG) Energy Council – since replaced by the Energy National Cabinet Reform Committee (ENCRC) and the Energy Ministers’ Meeting (EMM) – released Australia’s National Hydrogen Strategy, which estimated that under strong hydrogen growth settings, water consumption for hydrogen in Australia in 2050 may be the equivalent of about one third of the water used today by the Australian mining industry. 

The National Hydrogen Strategy noted that demand for water from the hydrogen industry will need to be balanced with existing demand from agriculture, industry, mining and households, and warned that the social licence for this water usage will be based on whether or not it’s perceived as taking away from other uses with higher economic, social or cultural value. 

The Strategy flagged desalination – the process of removing salt and impurities from seawater to produce fresh water – as an option to increase water supply for hydrogen, because the cost of the electricity required to desalinate seawater is likely to be less than five cents per kilogram of hydrogen. 

But there are only six existing desalination plants in Australia that could supply water at the scale required for hydrogen production, which could mean that operators looking to establish hydrogen plants will need to consider building their own desalination plants, as well. 

The Strategy also flagged recycled wastewater as a solution because it’s cheaper than fresh or desalinated water. A recent report by multinational engineering group Jacobs found that wastewater treatment plants, which use oxygen-based treatments to purify water that’s been extracted from sewerage systems and industrial processes, could be co-located with renewable hydrogen production plants in a symbiotic set-up that makes both processes more cost-effective, because oxygen is a by-product of electrolysis. 

The oxygen required for the wastewater treatment would be sourced from the hydrogen facility, and the water required for the hydrogen production would be sourced from the wastewater facility. 

Stanwell is considering a mix of raw water and desalinated water for its project. Currently, all of the wastewater in Gladstone is recycled in industrial processes, so that supply is not practical for the Stanwell-led consortium renewable hydrogen project. The Queensland Government is currently evaluating enhancement options to the water supply in Gladstone which, among other benefits and opportunities, would support phase two of the project. 

No matter which solution they choose, potential hydrogen producers will need to ensure they secure a long-term supply of water and add the cost of that supply to the baseline costs of hydrogen production.

If that can be achieved, then Australia will be well on its way to taking its place as a major supplier of green hydrogen to the world. 

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