Hydrogen – the Magic Rainbow Gas By Viv Forbes
If you believe in the tooth fairy, or vote Green, you probably believe that hydrogen is the magic rainbow gas that will banish global warming, replace wicked hydro-carbons in electricity generation, fuel tomorrow’s trucks, planes and heavy equipment, and earn unlimited export income.
There is one big problem – unlike coal, oil and gas, there are no hidden pools of hydrogen we can tap. Every bit of hydrogen has to be manufactured from water or hydrocarbons using huge amounts of energy.
The energy content of liquid hydrogen is about 70% of the energy required to produce it. Burn it in a combined cycle gas turbine (energy efficiency 50%) and see that energy return drop to around 35%. Use it as vehicle fuel and see energy efficiency fall even further.
The density of liquefied hydrogen is much lower than that of natural gas - thus the transportation costs will be higher. And because the tiny hydrogen atom finds any small leak, the safety risks are very high - imagine a road accident involving flammable lithium batteries plus explosive hydrogen gas.Most hydrogen is made directly from coal, oil or natural gas and the main process produces hydrogen and . . . more of the dreaded CO2.
But hydrogen is loved by Big Greens and little children because it has been named in a rainbow of pretty colours: grey, brown, black, green and blue.
Grey hydrogen comes from natural gas, brown from lignite (brown coal), and black hydrogen is made from black coal (no surprises there).
Green hydrogen is produced by electrolysis of water using intermittent green energy like solar or wind power. It requires heaps of fresh water and electricity neither of which can ever be fully recovered. Every tonne of hydrogen uses nine tonnes of water.
See here for pictorial comment on Green Hydrogen:https://saltbushclub.com/wp-content/uploads/2022/05/hydrogen-hype.jpgFeel free to use this cartoon with no alterations.)
Blue hydrogen is any of the above but the CO2 by-product is stored in carbon cemeteries, making blue hydrogen stupidly expensive.
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