Exploit the scourge of salinity to economic benefit and industry to Australia

The Salt Burden

Salinity in WA results from rising water tables bringing a huge salt burden closer to the surface. That salt burden has been there for thousands, if not millions of years, and is topped up every year with tonnes more. Land clearing disrupted the balance of supply and run-off (which took the annual arrival with it), as well as allowing the saline water to rise, so there is now a double whammy.

Treatments currently proposed are specious:

• tree planting will put things back in balance when we replace them to the extent of those cleared, but where will agriculture then take place? • drainage, the current proposal for on-farm correction, simply moves the salinity to be “someone else’s problem”, into an already “lost” lake or sump.

On the other hand, commercial exploitation of a resource is feasible – the proposed resource is saline water pumped from beneath agricultural land. This resource is of higher concentration salt that that pumped from the ocean and which is commercially viable in salt production. Only cheap energy is required.

Alternative Approaches

This proposal is put in the face of Western Australian government projects and concepts of:

• a salt-water pipeline from Esperance to Kalgoorlie to provide cooling water which will generate saline waste • improvements to the fresh-water pipeline from Perth to Kalgoorlie • distillation plants to provide potable water to remote townships and communities such as Esperance and Kalgoorlie • private co-generation power stations connected to the grid • “massive” tree planting to combat salinity.

Federal minister Tuckey is promoting a scheme to build drainage channels to return to the sea saline water leached from farms by on-farm drainage.

Salt Exploitation

To the east/south-east of WA’s agricultural districts rainfall and cloud cover are low. Solar energy is plentiful and is the same energy used in the north-west to farm salt from the sea. The technology used to refine and separate salt from sea-water could be appropriately applied in the changed locality.

In addition, low grade coal/lignite has been widely identified associated with paleo-drainage channels to the east of the main agricultural land in the South West of the State. The efficacy of Victoria’s exploitation of brown coal says the technology exists to use it as an alternative, effective energy source.

Lowering the Water Table

Those same paleo-drainage channels once returned salt to the sea before changing land forms caused loss of function as drains on the surface. They became a series of salt pans when the drainage function failed. Underground, however, they do still drain to the E/SE away from agricultural land. Drawing water from these underground channels in their lower reaches affects an extensive water-shed that extends deep into agricultural land. Using geological data to carefully select channels for mining saline water provides the mechanism to lower the water table in agricultural land. Such withdrawal has a much greater effect on lowering water tables under agricultural land than planting trees.

A comparison of the efficacy of two methods of lowering the water table is instructive. The WA Government expects to spend millions on tree planting that can only be described as marginally effective. The best information from CSIRO shows that each tree affects the land by lowering the water table to about 35 m around and down to 6 m. And this is only when the tree is transpiring most efficiently after 10 or more years of growth. Occupying the least amount of land, trees would occupy 20 to 30% of that land.

Removing saline water by pumping out has an immediate effect and occupies a negligible portion of that land, leaving the remainder for agricultural purposes. Typical agricultural land affected by salinity would require 1400 trees on 700 Ha to lower the water table 6 m. The same land equally affected by an elevated saline water table and pumped out would produce about 8 million tonnes of salt per annum and be almost immediately productive for agricultural purposes.

A saline aquifer fed by one or more of the paleo-drainage channels provides a near limitless resource for commercial salt farming, at the same time lowering the water table of land draining into the channels. Lowering the water table of the aquifer downstream by two or three metres lowers the water table of the land surrounding the channels by the fall to the aquifer. The effort needed to develop surface, off-farm drainage channels proposed by Wilson Tuckey will be huge; that effort is more productively spent mapping underground channels and aquifers to feed salt farms.

An Industrial Complex

The Government offices are investigating pumping saline ocean water from Esperance to Kalgoorlie as cooling water - this will generate a saline waste. The distance from Esperance to Kalgoorlie is similar to that from the agricultural areas to Kalgoorlie.

Instead we propose a salt processing works associated with lignite energy. It would seem to be a better investment than planting trees, building a saltwater pipeline and establishing unconnected distillation and electricity plants.

An industrial/commercial approach that linked and integrated these elements would provide:

• commercial salt at the very least, and another export from Esperance Port • a drainage sump to draw water away from salt-affected agricultural land, lowering water tables with greater efficiency than planting trees • salt as a feedstock to a caustic/chlorine industry, having lignite as the energy base • lignite as the feedstock to a catalytic process generating methane and ethane as hydrocarbon precursors to plastic monomer production • an electricity generation station to supply regional towns such as Kalgoorlie and Esperance. • power to drive reverse osmosis for fresh-water supply from the light brackish Officer Basin water confirmed by Anaconda. A pipeline might then be warranted to move the beneficiated water to Kalgoorlie and Esperance.

A salt/hydrocarbon complex at, say, Salmon Gums would attract secondary industries such as magnesium chloride separation to provide feedstock to a magnesium refining plant fed by electricity from the lignite power plant.

There are good indications that both saline aquifers fed by paleo-drainage channels and lignite deposits exist near Salmon Gums, Lake King and Lake Grace. These districts have insignificant surface drainage to assist with salt removal such as rivers like the Avon or Blackwood.

A complex comprising all the elements indicated would employ some 20 000 people and support a regional centre of some 100 000.

Investment and Funding

The funds required to conduct appropriate feasibility planning are moderate, but small compared with those directed at tree planting, at regional power and desalination plants, and at saltwater pipelines. The economic benefits of one or more industrial complexes as described are more positive and productive than the prop-up programs proposed. The benefit to the entire State is on a shorter timescale than tree planting.

The technology to undertake this proposal is understood and currently in commercial use in Australia. Investment funds would be found should the State Government make appropriate noises to encourage such development similarly to what was done for the Burrup petrochemical complex. Diversion of some of the funds proposed to be allocated to combating salinity would be a positive first step. An effective step would be to undertake evaluation of State-directed funds for combating salinity, for desalination plant, for the saltwater pipeline to Kalgoorlie, and for regional power stations. The value of these non-performing investments may be assessed against the investment in an industrial complex as discussed.

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