Chris Mills: When the Wind Blows, Water Flows

Sep 17, 2019

This is the paradox: as towns run out of potable water, our livestock and crops die, and water to fight infernos dries up, how can a Nation ‘girt by sea’ use unlimited volumes of sea water to slake a parched land? Wind and solar generated electricity costs have continued to decline, facilitating economic desalination of sea water and operation of water-pumping as an essential component of Australia’s response to the deleterious effects of climate change and climbing temperatures.

Recently in Australia’s National Energy Market, an extraordinary event occurred: some Wind Farm Generators paid to export surplus electricity to the National grid. The requirement for ‘Base Load Power’ (which is not actually required) is often mentioned; perhaps it is time to coin a new energy market term – ‘Base Dump Power’. When surplus, or very low-cost electricity becomes available, it is dumped into the desalination and movement of water to counter the consequences of global heating.

Like many, I was critical of the investment in Australian high-cost, high-carbon-emissions desalination plants. Now, with the heating of the planet accelerating at an alarming rate, Climate Emergency is real, and as we don’t have an escape to cooler land in the south, we need to develop other responses. With cheaper renewable electricity now flooding the energy market, I resile from my earlier position and propose that wind and solar energy be used to expand seawater desalination and to pump fresh water to our at-risk regional towns and land where water is an essential input to food and fibre production.

This fact sheet on desalination assesses that with cheaper energy, future water costs could drop below $1,000 a megalitre. In the current severe and enduring drought, market-based water costs are about $5,000 per megalitre, expected to rise to $7,000 by Christmas, 2019. Profitable food production requires water costs below $1,000 per megalitre.

The fact sheet also shows that installed desalination capacity is 534 Gigalitres per year and annual use about 200 Gigalitres per year, providing a reserve of 300 Gigalitres per year for ‘proof of concept’ trials. To meet future demand, this freshwater production capacity would have to be increased substantially, and boosted with expanded water recycling and water savings from retirement of coal-fired power stations.

Could Australia meet the challenge and build a nation-scale seawater-based supply system? The iconic Southern Cross Windmill (actually a wind-powered water pump) was a very successful engineering innovation of the early 1900’s that provided water across vast areas of our wide brown land. These ‘wind-watermills’ converted wind energy into mechanical energy to pump water, usually from a bore below the windmill head. This seawater desalination proposal is a two-step conversion. Wind (or solar) energy is converted to electrical energy at sites where it is efficient to do so. The electrical energy is then transmitted, perhaps over hundreds of kilometres, to locations where electric motors pump water for reverse-osmosis desalination and move fresh water to places where it is needed.

If the engineers could do it in the 1900s, then surely our engineers can do the same in the 2020s, especially with necessity being the mother of invention.

Part of the generation infrastructure is already in place. Flights often pass over large-scale wind farms, Sydney to Perth being an example. The large structure of a wind generator can be clearly seen from above 10,000 metres, with the gracefully rotating aerofoils extracting energy from the sun-generated wind. Desalination plants are in daily use in most of our capital cities.

Effective system design would integrate energy generation, water provision and carbon-emissions abatement. As an example, off-river pumped-hydro could include enough storage for desalinated water used to store energy for electricity generation and also have the capacity to provide drinking water to towns and for food and fibre production.

There is another use of this concept – soil desalination. Large tracts of Western Australia are contaminated with dryland salinity. Wind generators on the coast could transmit electrical power to inland desalination plants, where fresh water is extracted for food production and the concentrated salty water stored in evaporation pans. The water table would be lowered, the effects of salt contamination reduced and food production consequently increased. With Western Australia already supplying a large fraction of the world’s lithium from hard rock mines, there may be commercial quantities of lithium (and other useful minerals) in this brine. An alternative is to pump the brine back to the sea, reversing the effect of aeons of ocean breezes depositing salt on the land.

Participation in ‘water milling’ is an interesting social, economic and political question. Would it be seen as ‘infrastructure’ and an opportunity for Federal and State governments to invest in Australia’s future food and fibre security to continue to protect and grow Australia’s regional economy? Would Regional Councils and Towns decide that water security is essential for the future viability of their communities and build, own and operate generators, desalinators and pumps as part of their corporate business? Would large agribusinesses make the same choice to protect their long-term investments? Would ethical-investment Superannuation Funds provide these choices to investors and superannuants as part of their portfolio of investment choices? The electricity industry already provides a working model, with generation, transmission, storage and delivery provided by a mix of investors and operators.

Climate sceptics claim that because Australia’s carbon emissions are only about 1.3% of that of the world, our numerical insignificance provides an excuse for no action. However, living in the driest and hottest continent, we will endure more than 100% of the average consequences of global heating. The existential threat from rapid climate change must be met with a decisive and responsive campaign of action. Australia slaking parched land with seawater desalinated and moved with low-cost, renewable, zero-emissions energy is a key tactic in the coming battle for humanity’s survival, and a prototype for the rest of the world.

Chris Mills is a MSc in Systems Management and is a systems designer and builder.

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