Wind powered seawater desalination 1

Mr Joachim Kaeufler, SYNWATER. Wind powered seawater desalination (RO) – technical and economical specifics.

Mr Kaeufler notes that the world is in transition from fossil fuel economies to renewable economies and notes that Germany will achieve 30% renewables by 2020.

Renewables may be unreliable and Kaeufler notes must integrate and have backup, extending electricity grid systems to balance regional wind variations.

Load management is the process of responding to a fluctuating energy source: when you have more wind than you need you can store either electrical energy or water.

For Ro desalination, tyoically 30-60% of the cost is energy cost.

Kaeufler states that wind power can compete with fossils in terms of cost per KWh. PV and solar thermal is presently expensive by comparison, although a question from the floor notes that the figures presented for solar are quite high.

Seawater desalination at the coast is coincidently a good location for wind energy production.

Wind power is said to be ‘non-volatile’ and Kaeufler states that, “once the investment is done you can say how much the energy will cost for the next 20 years.” This is believed to be attractive for investors.

Different operating options are considered to account for the variation in load with high and low winds:

1. Wind energy into the ‘national’ grid at times of high wind / draw energy from the grid at times of low low. However, Kaeufler notes that operators may subject to the tariffs and interventions of an independent operator. I think this is the system used in the case of the Perth RO facility?… I must check this.

2. Sub-grid: remove the ‘national’ grid and use this only as a backup solution.

At a mean-level (overall balance between generation and consumption is equal) you will still require a buffer to account for the times when there is no wind/excess wind.

Kaeufler illustrated three options for buffering:

1. Buffer the electrical energy: batteries. But this is said not be cost effective. I think this could be a consequence of the high cost of batteries and the energy losses associated with battery storage?

2. Buffer on the product side. There must be enough RO capacity to account for the high wind periods, but these may not be required at low wind times. Store the excess water.

3. Buffer by the over-run. Have an RO system that can account for higher energy periods.

My observation is that electrical energy is also needed to pump water to the distribution system. Why not store water at a low level reservoir and at time of excess electrical production use this energy to pump water to the higher level aquifer?