Australia is known to be a dry continent overall (except when the floods come, as is the case at the moment in Queensland). So, a study decrying the huge amount of clean water that is needed to produce green hydrogen is going to get a few readers. I see it as another part of the fight to keep fossil fuel fracked gas in the energy mix.
Senior Process Engineer Retha Coertzen states: “The perception is that we need 9 L per kilogram of hydrogen through electrolysis. That is true, from a stoichiometric perspective. However, once you start adding all the other elements this balance can change quite dramatically.
“Electrolysis needs a very pure stream of demineralised water. Depending on the quality of the incoming water, there can be a rejection rate of 30–40%. If the water stream is effectively a brine, it’s not a viable source for electrolysis.
“Further, once the water needs for evaporative cooling are added, the demand increases again.
“Suddenly, the need is about 50 L per kilogram of hydrogen. And if renewable demands are considered, it can be up to about 80 L per kilogram.”
I think that desalination plants might prove to be part of the answer. “Australia is the driest habitable continent on Earth and its installed desalination capacity has been increasing. … As a result of the water supply crisis during the severe 1997–2009 drought, state governments began building desalination plants that purify seawater using reverse osmosis technology … over 30 plants are currently operating across the country. Many plants are utilizing nearby wind or wave farms to use renewable energy and reduce operating costs, and solar powered desalination units are used for remote communities.”
Two of these plants have been mothballed in Queensland since the drought broke 12 years ago. It would make sense to me for these to be put into service to supply the electrolysers which will create the green hydrogen. These plants can be powered by solar — of which Queensland has abundance.
But, the authors counter – there aren’t enough electrolysers. That is why Twiggy Forest is building a factory in Gladstone to churn these out. There will need to be consideration of co-location of renewable energy assets, electrolysers, and clean water resources.
The authors of the above report say that carbon capture will be used in conjunction with the creation of blue hydrogen. Sadly, this is just another furphy about a failed technology.
There are difficulties facing the energy industry in its transition from gas and coal to green hydrogen and renewables. But none of them are insurmountable given the will and the finance. We need to see beyond the FUD.
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