Eyre Peninsula water supply: a suggested cure

An old windmill water pump and modern wind turbines at Wattle Point, Yorke Peninsula, South Australia Groundwater level record in the Uley Basins, 1961 to 2000 (in metres below ground level) Note that groundwater levels in all basins/lenses have been falling, particularly steeply over the past 15 or so years.

A practicable water supply for Eyre Peninsula

Background

To be accurate, Eyre Peninsula does not lack water, it lacks fresh water. It is shaped like an equilateral triangle with the sea on two of its sides. Apart from the good quality groundwater that is being mined, there is also quite a bit of saline groundwater, although the rate of its recharge is very slow.

So far as I know, waste water is not cleaned-up and recycled anywhere on Eyre Peninsula. There is certainly scope of this in at least the cities.

The Proposal

For more on wind-generated electricity in South Australia see Wind Power. On my page Wind Power Potential I have estimated that the west coast of Eyre Penensula has good sites for more than 5000 utility-scale turbines, which could generate 10 000MW of electricity. (South Australia's total conventional electricity generation capacity as of 2008 is about 3500MW.) These turbines have not been built because:

1. the local electricity market is not sufficient to use that amount of electricity (although it would find a market in the eastern states);
2. there are not the transmission lines to carry that amount of power;
3. and Australian governments are not serious about moving away from fossil-fuel generated power.

An ideal use of wind energy

Wind turbines at Wattle Point, Yorke Peninsula, South Australia

If the rate of production of fresh water exceeds demand then it can relatively easily and cheaply be stored; electricity cannot economically be stored.

If the wind generator is connected to the grid then the power will be available for desalination when there is low electricity demand on the grid, and when electricity demand is high (and wholesale electricity prices are high) desalination can be stopped and the electricity from the wind turbine(s) can be sold into the grid.

Sustainability

Feasibility, economics, alternatives

In regard to using wind power to desalinate sea water, the economics of running the desalinator only when wind power was available would have to be compared to running it full time. It could be that the capital cost of building the desalinator might only be justified if it ran full time.

Alternative to desalination

Laying new pipeline – between Whyalla and Kimba

A pipeline has recently (mid 2006) been built from Whyalla to Kimba. There are two problems or limitations with this.

1. The pipeline is not big enough to solve Eyre Peninsula's water problems, only to alleviate them somewhat;
2. The water that is pumped through this pipeline comes from the Murray River, which is already heavily overcommitted (future flows in the Murray are likely to be lower than past flows due to climate change);

True cost of water

The true cost of water on Eyre Peninsula would be much higher than $1/kL, probably more like $3/kL. Since on Eyre Peninsula the cost of water to SA Water is higher than the price at which they sell it, it is to their advantage to sell as little water as possible. Therefore it is also to their advantage to discourage anyone from setting up a desalination plant that produces water at, say, $3/kL; every kilolitre sold would represent a loss to them.

I do not say this as a criticism of SA Water, I am just pointing out that under the current government pricing policy, however well meaning that may be, there is a built-in disincentive to SA Water to desalinate Eyre Peninsula's water supply. (The same might well apply to recycling Port Lincoln's waste water.)

Desalination can compete with $3/kL, it is much more doubtful that it can compete with water sold at a heavily subsidised $1/kL. So whether a desalination scheme, this one or any other, is viable on Eyre Peninsula will depend on how the Government decides to charge for the water.

Renewable electricity currently costs around $30/MWh more than fossil fuel generated electricity. The latter is cheap because the operators of the power stations do not have to pay for the damage that they are doing to the world's atmosphere; the burning of fossil fuels is the major cause of climate change, it is unsustainable and must eventually be phased out. The Federal Government's Mandatory Renewable Energy policy currently helps to fund some wind farms (see Mandatory Renewable Energy Target). Would any similar subsidy be available for wind-powered desalination? This could be a critical point.

Wattle Point wind farm from Troubridge Hill, Yorke Peninsula

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Cost of wind-powered desalination

Wind Resource of Eyre Peninsula

The wind resources of Eyre Peninsula; click on the image for a larger map. Image courtesy of Renewables-SA

In August 2010 Tim O'Loughlin, SA Commissioner for Renewable Energy, talked about a Renewable Energy Strategy for SA. It involves a 'Green Grid' (set of high capacity electricity transmission lines) for Eyre Peninsula. The wonderful wind resource there has not been developed to now due to the lack of such a grid.

The existing power transmission lines (as shown on the map) are only 66kV and have no reserve capacity.

Tim has proposed the construction of transmission lines to enable the development of four areas in particular:

1. Western (around Eliston);
2. Central (north of Cleve);
3. Northern (north-west of Port Augusta);
4. Southern (north of Port Lincoln);

Average wind speeds in these areas are anticipated to be greater than eight metres per second, a capacity factor of greater than 38% is expected to be achievable and 10GW (10 000MW) of wind power capacity could be installed (3000 to 5000 turbines of the size being built in 2010).

Tim said that "four internationally experienced wind developers were ready to build more than 2000MW" at the time of his talk.

Similar power lines have been built at government expense for coal-fired power stations and mines in the past, but never for renewable energy in Australia.

Wind energy on Eyre Peninsula

Location

The current water supply and consumption on Eyre Peninsula

Seawater desalination in WA

Which desalination method?

A comparison is given in: CommonwealthKnowledge.net.

The best method appears to depend on plant capacity. If less than 10ML/day (3.6GL/yr) is required reverse osmosis is generally used, if more than 25ML/day (9.1GL/yr) then multistage flash is almost always used. (These figures may be skewed by the fact that the largest desalination plants are in the oil-rich Middle East where fuel is cheap.)
From Seawater Desalination: A Source for Supply of Drinking Water; Western Australian Water Symposium, Perth, WA, 7-9 October 2002

Flash distillation

The boiling point of water is lower at lower pressures. In the flash distillation process heated water flows into a chamber where the pressure is sufficiently low for some of the water to change to steam. This steam is taken away, condensed, and much of the heat recovered via a heat exchanger. The remaining water, now cooler, passes into the next chamber where the pressure is still lower; more water changes to steam and the process is continued. With each stage more steam is taken off, and both pressure and temperature are reduced.

Of course the salt stays in the liquid water, the water condensed from steam is quite fresh.

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Desalination data from the Internet