Better water planning could avoid desalination

Apparently desalination plants are the answer to keeping Australian cities supplied with water. All that is required is to remove enough salt from an unlimited source of water to provide for each city’s needs now and in to the future. Easy, right? Wrong.

In the past decade, Australian water authorities have embarked on the construction of desalination plants in all major capital cities to waterproof urban centres.

Unfortunately, we can’t see far enough into the future to know either what the needs of cities are or what supplies can be harvested from the existing infrastructure.

For a number of reasons desalination is not the first or best option to achieve urban water security. The decision to build these plants reveals a failure in the way we plan for future water requirements.

Don’t panic

In a recently released report the Productivity Commission outlined a number of economic and financial failures associated with desalination that have plagued these projects, ranging from poor planning strategies to construction delays and cost overruns.

The long drought that affected large parts of this country provided the main impetus for augmenting supply. Could it be that desalination was an option based more on panic than rational thinking to cope with water security?

Proper water planning would avoid panic decision-making.

Let’s use what we know

Uncertainty about future climate and population trends is the biggest challenge facing water planners. To achieve water security and waterproof cities we need a flexible approach to water planning. It should be based on a suite of technological innovations that are deployed over time in the most cost efficient way.

These innovations need to be combined with economic incentives that add or reduce supply as needed to cope with the variability typical of the Australian climate in the most economically efficient way possible.

A city’s existing water supply can be augmented through a number of less costly and more environmentally effective interventions than desalination.

Water recycling, reuse, stormwater harvesting coupled with aquifer recharge all form a suite of alternative measures can be used augment supply in order to satisfy diverse water demands through quality differentiation.

For instance, managed aquifer recharge (MAR) is a cost-effective way of providing additional storage and passive treatment of water supply that can be combined with stormwater reuse and non-potable recycling.

These options also have positive environmental externalities such as improvement of waterway health, flood alleviation by eliminating peak flows and ecosystem protection.

Pipes are not enough: we need policy too

However, if the planning process is to truly to come to terms with the problem there is a need to combine these physical options with other economic and policy instruments. To achieve water security we need measures such as water trading. Economic efficiency must accompany better water efficiency.

Examples of the problems that arise from not knowing both the technical and economic efficiency impacts of decision-making are not difficult to find.

The Melbourne desalination plant has been widely criticised by economists in the past for failing the economic efficiency test. However, the desalination option also fails the technical and environmental tests when compared to other options.

For instance, having built the North-South pipeline, surely the Victorian Government would have found it far more efficient to use market instruments such as water trading to acquire additional water and then transport it when needed, rather than building the desalination plant.

This combined mechanism by itself could have eliminated the supply risk to Melbourne at a significant difference in the investment cost involved. The cost of the desalination plant is $6 billion while the cost of the pipeline was approximately $750 Mil.

Really, we could do this a lot more cheaply

Research carried out by the Institute of Public Affairs on water supply options for Melbourne estimated the costs of manufacturing (desalination) and distributing water at about $3.00 for every kilolitre of water supplied.

Compared to desalination, other alternatives would significantly less expensive. Average figures of cost savings for other alternative sources of water are North-South pipeline import (45%), stormwater harvesting (66%) and recycling (20%).

Environmentally, desalination incurs about 5 kw-h of power, which generates 2.7 kg of CO2, for every kilolitre of water produced. Water imported through the pipeline would incur 35% less carbon emissions.

Desalination is the most expensive option to augment water supply when compared to all other options. It is also the least economically efficient.

Desalination projects require large investments by private operators. They have to minimise their investment risk by shifting risk to water utilities and governments who must commit to purchasing a threshold volume of potable water regardless of requirements and climate variations over the life of the project.

Effectively, we are adding highly expensive water to the supply pool often at times when there is enough rainfall supply. This cost must ultimately be borne by the consumer through increased water charges.

Flexible, rational, holistic

A more flexible planning approach allows different supply options to come on line at different stages depending on changes in demand and eventual climate change.

Surely if we are not to repeat the mistakes of the past, the factors which influenced the governments in this case, need to be investigated and changed.

A more rational approach to urban water planning must consider all physical, economic and environmental aspects of the water cycle in a holistic way.

It must ensure better integration with policy instruments to attain physically as well as economically efficient strategies.

Brian Davidson receives funding from ACIAR and has previously received funding from ARC, CRC Irrigation Futures and CRC eWater.

Hector Malano does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.