Is a hydrogen-powered future hiding in our wastewater?

Its first steps may have been hesitant – thanks to a funding slump following the 2008 financial crisis – but hydrogen is now back and looking like a winner for renewable, clean energy. And its success may lie in a dirty source.

It could provide 24% of global energy requirements by 2050 – but creating hydrogen is a thirsty process, triggering anxiety about the cost to the world’s water. Hydrogen is produced by splitting the molecules in water, and when this is done using electricity from clean, renewable sources, it qualifies as ‘green’ hydrogen, providing a viable alternative to fossil fuels.

Support for a hydrogen economy is now growing fast, with Japan, South Korea, China and Australia keen to invest in a clean future.

Only… it requires a lot of water. How do we square this with the urgent need to preserve and protect the planet’s ever more precious supply? A World Economic Forum report points out that the nations most in need of a hydrogen power revolution are also the driest. In some countries it would take a freshwater withdrawal of 10% to fully transition to a hydrogen-based economy – although the average water drain across 135 countries levels out at 3.3%. But science is the bringer of hope and frustration – and hydrogen power offers up both.

An H2O opportunity?

Hydrogen fuel consumption creates only air and water. What trickles from a hydrogen power cell as exhaust meets nearly all the WHO’s drinking water requirements. This means smaller countries which import hydrogen power could one day be simultaneously importing a boost to their water supply.

This requires technological advances, however, and doesn’t solve the issue of the impact on our water resources at scale, region by region, when a small state like Singapore would need to extract 46.4% of its supply to feed its hydrogen transition.

Even at the lowest level – less than 0.05% for Tajikistan – can we ever sanction the exploitation of yet more of our dwindling water supply for renewable energy? Can we even call hydrogen power green if it comes at this cost?

One solution to this conundrum could be water of a different colour.

A wastewater wonder

Australia’s solar and wind energy potential is vast. It’s also one of the driest places on earth. Yet it could become a hydrogen powerhouse – through its waste water. Analysis of Sydney Water’s wastewater treatment plants indicates an output of 37.6ML per day of tertiary effluent, currently unused.

If electrolysed, this level of supply alone could generate 100% of Australia’s estimated hydrogen power by 2030. The by-product oxygen also offers significant benefits – improving the wastewater industry’s environmental footprint when used in further treatment processes, and equilaterally bringing down costs – a genuinely circular economy. Most significantly, it does not compete with existing potable water demand, avoiding knock-on impacts on freshwater supply.

In partnership with utility companies around the world, this potential for simultaneously protecting water and generating green hydrogen power looks credible. It certainly outperforms desalination plants as an alternative, when these are built purely for hydrogen production. Not least because desalination’s large-scale diversion of seawater has a negative impact on marine life – more so if the brine by-product is dumped there.

There are many threats to the world’s water through decarbonisation. Copper mining will increase to meet the needs of solar and wind power and it’s a water-intensive process. Nuclear power plants require billions of gallons of water per year.

Few offer up as many compensations as hydrogen power.

It may yet entirely mitigate what water it uses.

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