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Renewable energy and desalination

At the time of writing South Australia had so much wind and solar power installed that total renewable generation at times exceeded power consumption within the state and the capacity of the transmission links available to export power to the eastern, predominantly coal powered, states.

Consequently it is quite common for wind- and solar-farms to have to cut back (curtail) their generation so that they don't overload the grid.

Plainly it is foolish, in a world that is in dire need of reducing greenhouse emissions, to waste the opportunity to displace fossil fuel energy with renewables.

There seems to be an opportunity to use renewable electricity when it is plentifully and cheaply available to power desalination and then cutting back on the desalination when wind and solar power are producing less with the consequent increase in electricity prices. Surely a win-win situation, cheaper desalination and a bigger market for renewable energy.

This page was written 2019/11/12
Contact: David K. Clarke – ©
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Generation

In the above OpenNEM graph of one day's energy generation in South Australia:
  • Export of power from SA to the eastern states gets up to 43.8% at 12:50pm;
  • For the whole 24-hour period of the graph exports were equal to 20.5% of total consumption in the state;
  • From 1:40 am to 6:10 am wind power generated an amount equal to, or more than, total consumption in the state;
  • Wind farms generated 1200-1300 MW for much of the day;
  • Solar power provides up to 45% of the SA load at times (760 MW of about 1600 MW load);
  • Consumption in SA averaged about 1400 MW over the whole day.
Open NEM also showed that average power demand in SA for the previous year was about 250 GWh/week (about 1500 MW).

According to my records total installed wind capacity in SA at the time was 2141 MW, about 110% of maximum state consumption during the 24-hour period of the graph. Solar power generation in SA can reach 50% of state consumption at times.

The Adelaide desalination plant; some statistics from the internet:

  • "Maximum capacity 100 gigalitres per year. The state-of-the-art plant has the capacity to deliver up to 300 million litres [300 ML] of water each day" Acciona, projects.
  • "The plant uses 3.47 to 3.70 kilowatt-hours of electricity per kilolitre of water produced." Wikipedia. (That is, about 3.6 MWh/ML.)
From these figures it can be calculated that if the plant is running at full capacity it can require about 1100 MWh per day or 45 MW.

Existing and proposed demand-side power management

Batteries and pumped hydropower are at present used in Australia in a very limited way to store energy; there is plenty of potential for more of both. Compressed air energy storage and hydrogen generation have potential to 'soak-up' renewable energy when it is plentiful and cheap.

Some industries such as aluminium smelters can reduce their electricity consumption when supply is limited.

But at the time of writing none of these technologies or stratigies were sufficiently developed to fill the need.

More sensible use of the Adelaide desalinator

 

Impact of running the desalinator on SA's renewable energy

An additional load of 45 MW on top of the average 1500 MW for the previous year in SA is a significant increase (3%), equal to the average generation of about 30 modern wind turbines. This should reduce the amount of curtailment of the state's renewable energy.
A few days before I wrote this page the Australian federal government came to an agreement with the South Australia government to run the Adelaide desalinator at full capacity for a year to 'free-up' 100 GL of water for the growing of fodder crops much needed in the current drought.

The previous SA Labor government has come under a lot of criticism over the desalinator because of its cost and the fact that it has not had a lot of use since being completed in 2011.

It would seem to me that a usage relating to the variable cost of electricity would be more sensible than the past all-or-nothing approach.

A note on costs

An article by Lin Crase on the Conversation, 2019/11/14, gave the cost of water from the Adelaide desalinator as $0.95/kL and the price paid by domestic consumers in Adelaide as from $2.39 to $3.70/kL. Lin Crase is Professor of Economics and Head of School, University of South Australia.





Related pages

External sites...

Use of the desalinator on Rottnest Island varies according to power availability...

Diesel to de-sal on Rottnest Island

Hybrid energy solutions/success stories - Rottnest Island;

On this site...

Australia's energy future

Base load electricity

Elec. gen. methods compared

Glossary of technical terms relating to wind power

Impressive renewable energy developments in Australia

Mid-North South Australia, leading the nation in renewable energy

Northern SA's renewables

Pumped hydro energy storage

South Australia's energy future

South Australia's great success in changing toward renewable energy

Which electricity generation methods should Australia choose for the near future?

Wind farms, the electricity grid and desalination in Australia; a page written in 2004.

Wind power in Australia



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