> Does Sydney need a desalination plant?

Background

Sydney in Australia, NSW, has just come out of a long period of drought in which the dams that supply Sydney dropped to 34% of total storage ability. The Kurnell Desalination Plant was picked as a long term solution to Sydney's on going fresh water crisis

The plant will use reverse osmosis filtration membranes to remove salt from seawater and will be powered using 100 percent renewable energy; supplied to the national power grid from the Capital Wind Farm at Bungendore, NSW.

It is intended to supply up to 15% of the drinking water supply to Sydney, the Illawarra and the Blue Mountains. It is expected that the plant will be able to generate 250 megalitres of water every day (91 gigalitres a year), with the possibility of scaling up to 500 megalitres in the future if needed (182 gigalitres a year), as the pipes and infrastructure will be scaled to allow this.

The total cost of all this, including fees is around 2 billion dollars.

The hidden costs..

Lets examine each of the cost items associated with this plant..

Building Costs

At least this is a clear figure to see, $2 billion up front investment in building the plant and all associated infrastructure. More on what one could do with that instead at the end.

Running Costs

A little known fact is that fresh water harvested through desalination is considerably more expensive than dam collected water. It has been estimated that each house in Sydney could pay as much $50 more per annum for this facility (~$75 million total per year). This is spent on maintenance and materials to keep the plant ready to deal with the next possible drought.

Electrical consumption

It is estimated that the plant will require 900 gigawatt hours of electricity each year. It is intended that this will be completely supplied from the Capital Wind Farm at Bungendore; which is currently being built at a cost of $220 million for 63 wind turbines each capable of producing upto 2 megawatts each. This equates to a peak output of 126 megawatts, or rather in a year the wind farm would need to run at full power for 7146 hours (or 246 days), or full power for over 67% of the time.. Its a known fact that wind farms will only produce around 30% of their maximum power over any given year - so where is the missing 37% coming from? You've guessed it, other none renewable sources. This will create carbon emissions equivalent to around 150,000 new cars or 70,000 new homes. Ouch!

The alternatives

If one was not to build the desalination plant, what could be done with the $2 billion dollars instead? Or rather lets cost this over 5 years - so thats about $2.4 billion dollars for a desalination plant to produce initially a maxium of 91 gigalitres per year (or 250 megalitres a day).

1) Rain water grants

Instead of having BASIX's force people into having to buy in water tanks to meet their planning requirements, why not just provide a $1000 grant against the installation of any water harvesting system that improves the BASIX rating of a building? i.e. rainwater capture, grey water use, etc - that would provide 2.4 million individual grants. Now say this encourages people to install systems that use rainwater to flush toilets; if 1,000,000 such systems are installed and each toilet so connected was flushed four times a day (10 litres each flush) - that would equate to 14.6 gigalitres a year saved! Or look at it another way, thats 40 megalitres a day every day.

Now if the washing machine was connected to the water harvesting system and was used once a day (100 litres), that would save another 36.5 gigalitres a year. This is 100 megalitres a day. Add this to the water saved from the toilets and thats 140 megalitres a day saved.

NOTE: this is only spending $1 billion of the total $2.4 billion and we are already up to 140 megalitres of the 250 megalitres supplied by the desalination plant.

Now, people in face of this, usually say 'what will happen in a drought?' Well, remember that every day these systems have been operating 140 megalitres are not been taken from the dams. Now compare this to the daily water consumption in Sydney of around 1500 megalitres, we have got back 9% of the daily consumption. Or put it another way every 11 days you get back 1 day of water supply. To also see the dam levels look here.

Now, what can we do with the remaining $1.4 billion.. hmm

2) Leaks, darn leaks..

Sydney Water on average has been loosing 8.2% of water as it transits the system. This is better than most but that alone equates to about 120 megalitres every single day regardless of drought or not. Sydney Water currently spends around $100 millon every year on fixing leaks. What if the government was to spend $700 million over the next 5 years on helping Sydney Water address their leaks? Thats a 140% increase on direct spending per annum in leak reductions, its fair to assume that would reduce the leak rate to around 3.5% (over twice the resources available). Thats a saving of 72 megalitres a day...

Now remember this saving does not require anything more complicated than just improving the rate of repair on the existing infrastructure.

So what to do with the remaining $700 million dollars...

3) Water recycling and reclaimation

Now we have fixed the leaks, what about all that water that goes down the drains..  Australia has a very poor record in this regard; the water supply industry averages a 4% rate of recycling... Therefore why not spend the $700 million towards water recycling and reclaimation projects? This could also be used to 'cost offset' the usage of reclaimed water to those who wish to consume it (so its not more expensive to the end user than potable water).

Its difficult to work out the impact of doing this, but say it increased the rate of recycling to 8% - thats another 60 megalitres saved per day.

The end Result