NOT often do final speakers at industry conferences cause 'light bulb moments' for audiences.
They usually speak on lighter topics and learn to ignore a steady stream of early leavers and audience members surreptitiously checking emails or watching the clock for the start of the sundowner to follow.
But mining and automation technologies expert Damien Williams, who was closing out the recent Farm Machinery and Industry Association (FM&IA) conference, caused a few agriculturally connected 'bulbs' to light up.
As reported in last week's Farm Weekly, he polished the crystal ball and related a rapid uptake of electric vehicles (EVs) in general and by mining in particular, to likely acceptance by agriculture within a decade.
But it was references to 'green hydrogen' in this context - and not in encouraging or enthusiastic terms - that caused a 'light bulb moment' for some, including me.
Science and maths are not my strong suit, but I do recall from science classes many decades ago, hydrogen gas makes up the largest proportion of our atmosphere and humans, animals and plants do not specifically need it to survive.
Those credentials would seem to make it eminently suitable as a clean fuel of the future - there's lots of it and we don't need to breathe it or eat it.
Plug-in, rechargeable battery EVs (BEVs) might be the future for urban transport, but bigger distances between power points presents some problems yet to be solved for the regions.
With today's technology, it is hard to imagine long-distance transport drivers putting up with range anxiety crossing the Nullarbor in a BEV equivalent of a Kenworth or Volvo B-Double carting groceries into WA or heading down the Buntine Highway's single-lane asphalt strip in a BEV equivalent of a Mack hauling three double-deck trailers full of cattle.
Proponents of hydrogen technology point to the regions and long-haul as where 'green hydrogen' - hydrogen produced using solar or wind renewable energy - will fill the void.
Essentially, a hydrogen-fuelled vehicle is a BEV with smaller battery and no plug, or a hybrid EV with a fuel cell replacing the diesel or petrol engine.
Pressurised hydrogen from the fuel tank is mixed with air and fed into the fuel cell where a chemical reaction extracts electrons from the hydrogen, generating electricity to charge a battery which powers an electric drivetrain.
Toyota, Honda and Hyundai produce hydrogen-fuelled vehicles and California and Germany have rudimentary networks of hydrogen refuelling stations.
In Australia, the CSIRO announced early this year it will receive $1 million from the Victorian Government to build Australia's first hydrogen refuelling station at Clayton in Melbourne's south-east.
In May the Federal government announced $103m conditional funding through the Australian Renewable Energy Agency's Renewable Hydrogen Deployment funding round for three 'green hydrogen' projects - two in WA, at Karratha and Warradarge proposing 10 megawatt electrolysers.
The WA Government has committed more than $35m towards developing "a job-creating renewable hydrogen industry in WA" and added a Hydrogen Industry portfolio to Agriculture and Food Minister Alannah MacTiernan's brief.
Ms MacTiernan and the government have endorsed a massive Western Green Energy Hub hydrogen and ammonia project proposed along the South Coast by a consortium including the traditional owners.
As Mr Williams told the FM&IA conference: "Every man and his dog, parrot and pigeon wants to talk about hydrogen".
"They talk of it as though it is this magic fuel that is going to fix all our environmental problems - it's this fantastic green energy source," he said.
"Sorry, it's not an energy source, it's just a different battery," he pointed out.
But the 'light bulb moment' came when Mr Williams pointed out the basic feedstock for commercial production of hydrogen is something very precious to agriculture and likely to become more precious in a predicted drying climate across the south west of WA into the future - fresh water.
I suddenly recalled another fact from distant science classes about hydrogen, one which Mr Williams picked up on, a molecule of agriculture's most vital component comprises two atoms of hydrogen and one atom of oxygen.
He pointed out it takes just over nine litres of water - not skanky bore water that will block a float valve nozzle with calcite within 12 months, but distilled fresh water - to produce one kilogram of hydrogen gas by electrolysis.
It also requires about 39 kilowatts of electricity at 100 per cent efficiency - current technology is about 75pc - to produce a kilogram of hydrogen, according to US data.
There are several methods of producing hydrogen, most involve steam - which is of course evaporated water - and high temperatures, but some produce enough carbon dioxide and monoxide gas by-product to not be considered 'green'.
Just to "start plumbing the base level of hydrogen needed" to run WA's mining fleet would require "somewhere between 15 and 30 gigalitres of water", Mr Williams pointed out.
"Of the world's water, only 3pc is fresh water and of that 3pc, 70pc is used in agriculture," he said.
"WA alone is forecast to need another 65-69pc water for agriculture, just to keep up with the rest of the world - that's an increase of up to 69pc in our water consumption to keep up.
"If the nation's civil vehicle fleet and mining convert to hydrogen, what's that mean for farmers - greater reliance on an increasing number of desalination plants and water problems," he said summing up.
CSIRO and other proponents of 'green hydrogen' as a clean transport fuel point out the only waste products to come out the tail pipe of hydrogen-fuelled vehicles is some heat and water vapour.
But relative information on how much fresh water is required to produce a given amount of hydrogen fuel in the first place and how far that amount of fuel will take people and goods is not so easily found on their websites.
If, in the future, hydrogen producers of fuel for transport and mining are considered 'upstream users' and get first dibs on our fresh water supplies and agriculture is considered a 'downstream user' consigned to taking some of what is left, then WA potentially could have its own Murray-Darling Basin-style water usage conflict.
My conference light bulb triggered an alarm bell, but I do not know enough about the science to make a judgement on whether it is a false alarm or not.
I cannot say how far nine litres of water converted to a kilogram of hydrogen is likely to drive a pocket road train loaded with grain, or a tractor pulling an air cart and seeder bar or a header in a 3.5 tonne-per-hectare crop.
But I suspect the answer is: not far.
