(This letter was sent just before the February 2005 Western Australian State Election, when Colin Barnett, the Opposition party leader, committed his party if elected to immediately start building a 3500-km-plus canal from the Kimberley in WA's north to supply water to the capital Perth, in the southwest. The Opposition lost.)

Water AND energy from deep bores

There is a source of water for Perth which should be looked at in the current debate, as it could provide energy at the same time.

Colin Barnett is to be commended for bringing the Fitzroy canal scheme under examination, but it is a dud.

Mr Barnett says that a dam would not be needed on the Fitzroy, because the water would be pumped out of the ground there. That’s not too different to pumping it out of the ground much closer to where needed, and so avoiding use of a canal.

Brian Fleay has pointed out some of the likely problems of bringing masses of warm water down from the tropics. While mass invasions of cane toads may not be a problem, amoebic and bacterial diseases travel well under such conditions.

With warm, ultra-humid, low-oxygen conditions in the water within a membrane-lined and covered canal, it can be expected to rapidly become packed solid with algal bloom.

Every sort of wild animal and pest, and also plant roots, can be expected to home in on and breach the membrane liner. Many of the attackers will be protected local species.

The engineering problems of bringing a canal across the wide flood plains of more than 10 major rivers, which become torrents in the rainy season, are immense.

An unexpected result when the Russians drilled the world’s deepest drillhole in the 1970s and 1980s was that all the deep rock was saturated with water. This water was also very hot -- at 10,000 metres down it reached 180 deg C.

Locally, the Claremont Baths uses water from the Yarragadee aquifer, at 843 metres down, to heat its pools. The water comes up at 43 deg C and is returned to the aquifer at a lesser depth after transfer of its heat to the pool water.

We can think of the water beneath Perth as contained in a fairly leaky irregular basin, with similarly leaky horizontal partititions across it.

This basin is always overflowing, not just with stream runoff, but also with submarine freshwater springs which occur all round our coast.

There are said to be places off our south coast where a bucket can be dropped into the sea and pulled up containing fresh water. This resource, which could be very large, is at present unused and of no apparent value to the environment.

The way to tap it is, as Jorg Imberger has pointed out, to drill into our deep aquifers such as the Yarragadee. The water can be drawn exactly where it is needed, the basin is always overflowing and slow movement within the aquifers will replace whatever is drawn off.

Much of this water is sub-artesian, and so little pumping energy is needed. And as a bonus, it contains much heat energy.

With a bore down to around 4000 metres, the water source should be at over 100 deg C. When tapped, it can be used to generate electricity through steam turbines and then used directly as a drinking water source -- natural distilled water.

David Noel / 2005 Feb 14

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Last update 2005 Mar 13