H2OME

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Micro-hydro alone, or micro-hydro with hydrogen storage

A good stream with some fall can power a house day and night. Its weak points are floods that choke the intake and dry spells that shrink the flow.

Why micro-hydro is so good

Unlike wind, a stream runs around the clock. A micro-hydro turbine on a reliable creek produces a steady trickle of power that suits a house well, because the battery smooths out peaks while the turbine keeps topping it up. Where the water and the fall are there, micro-hydro is one of the best off-grid sources around. Many high-country homes have run on it for decades.

What it would keep running

  • Steady overnight charging from surplus flow
  • House essentials while the intake is cleared
  • Freezer and fridge through low flows
  • Water pump
  • Lighting and modem

Floods, debris and dry summers

The trouble comes at the extremes. A heavy rain event can bury the intake in gravel and leaves, or wash the penstock out, cutting power just when the house may also have lost the grid. In a dry summer flows drop and the turbine may have to throttle back or stop to leave water in the stream.

Both events tend to come when power is most needed. A flood-blocked intake usually arrives in the same storm that takes down the grid line, and low summer flows line up with heatwaves and fire season. A micro-hydro house with only a small battery has little to fall back on in either case.

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.

What storage adds

Micro-hydro often produces more overnight than a sleeping house uses. That surplus can run the electrolyser and fill the hydrogen buffer, which keeps for weeks without losing charge. When a flood blocks the intake or summer flows dwindle, the fuel cell draws on that store while you clear the screen or wait for rain. Round-trip efficiency is 30% or less, but the surplus water was going past unused anyway.

Questions

Can micro-hydro and the electrolyser share the stream?

The electrolyser does not use stream water directly unless it is filtered and de-ionised. Its pre-treatment draws a modest supply, about 9 litres per kilogram of hydrogen, and the fuel cell returns most of it.

What do I need to know about water rights?

Taking water for micro-hydro usually involves regional council rules about how much you take and what flow you leave in the stream. Check those before planning a scheme. They apply whether or not you add storage.

Is my stream big enough?

That depends on flow and fall, measured across the seasons. A professional assessment is the right start. The pilot can then size storage around what the stream actually delivers in its low months.

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