H2OME

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Drought: tank water, pumps and the water the system uses

When rain stops, rural households watch their tank levels daily. Anything that uses water, including a hydrogen system, deserves an honest look.

Pumps on backup

Household tank pumps and pressure pumps are small loads that matter enormously, because without them there is no shower, no toilet flushing and no washing up. In dry, hot spells outages also tend to be fire or heat related. Pressure pumps cycle on and off all day, and a supply that switches over instantly stops them stalling or losing prime when the grid drops. Bore pumps can be bigger, so check the rating before assuming they fit.

What it would keep running

  • Household pressure pump
  • Submersible tank transfer pump
  • Bore pump within the rated output
  • UV steriliser on the drinking supply
  • Fridge and freezer

How much water the system itself uses

Making hydrogen takes about 9 litres of water per kilogram. That sounds alarming in a drought, but the fuel cell gives most of it back as it makes electricity, and that water goes back into the loop. The net draw on your tank is the gap between the two, plus what the de-ionising filter rejects.

During a long drought you can choose to limit charging to what you actually need, keeping the hydrogen buffer topped up for outages rather than cycling it every night. A full buffer keeps for weeks without losing charge, so there is no penalty in letting it sit until the grid fails or the rain returns.

How it works →
The H2OME loop: an electrolyser splits water into hydrogen, the hydrogen is stored in a tank for weeks, a fuel cell turns it into electricity for your home, and the water returns to the loop.

Water quality when tanks run low

Low tanks stir up sediment, and water carted in from a tanker can differ from your rainwater. The electrolyser needs filtered, de-ionised water, so its pre-treatment cartridges may work harder at the bottom of a tank. Check the filter status more often in a drought, and never connect it to an untreated dam or trough supply without the pilot team confirming the treatment can cope.

Questions

Will it empty my water tank?

No. It uses about 9 litres per kilogram of hydrogen made, and the fuel cell returns most of that as it runs. The net use is small next to a household's daily water, though in a severe drought you can cut back how often it charges.

Can it run a large irrigation pump?

Large irrigation pumps can exceed 15 kW and run for long hours, which would need a larger or multi-unit setup sized in the pilot, or may not be a fit. This page is about household supply, where the pumps are small.

Can tanker water feed the electrolyser?

It can feed the pre-treatment, which filters and de-ionises it first. Water quality varies by source, so keep an eye on filter life. Never bypass the treatment stage, because impure water damages the electrolyser membrane.

More in outages, weather and how it works

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