Tag Archives: desalination

Fixing cities’ water crises could send our climate targets down the gurgler

The Conversation

File 20180207 74501 hkvy6c.jpg?ixlib=rb 1.1
Water treatment plants can’t afford not to think about electricity too. CSIRO/Wikimedia Commons, CC BY-SA

Peter Fisher, RMIT University

Two cities on opposing continents, Santiago and Cape Town, have been brought to their knees by events at opposing ends of the climate spectrum: flood and drought.

The taps ran dry for Santiago’s 5 million inhabitants in early 2017, due to contamination of supplies by a massive rainfall event. And now Cape Town is heading towards “day zero” on May 11, after which residents will have to collect their drinking water from distribution points.

Read more:
Cape Town is almost out of water. Could Australian cities suffer the same fate?

It’s probably little comfort that Santiago and Cape Town aren’t alone. Many other cities around the world are grappling with impending water crises, including in Australia, where Perth and Melbourne both risk running short.

In many of these places governments have tried to hedge their bets by turning to increasingly expensive and energy-ravenous ways to ensure supply, such as desalination plants and bulk water transfers. These two elements have come together in Victoria with the pumping of desalinated water 150km from a treatment plant at Wonthaggi, on the coast, to the Cardinia Reservoir, which is 167m above sea level.

But while providing clean water is a non-negotiable necessity, these strategies also risk delivering a blowout in greenhouse emissions.

Water pressure

Climate change puts many new pressures on water quality. Besides the effects of floods and droughts, temperature increases can boost evaporation and promote the growth of toxic algae, while catchments can be contaminated by bushfires.

Canberra experienced a situation similar to Santiago in 2003, when a bushfire burned through 98% of the Cotter catchment, and then heavy rain a few months later washed huge amounts of contamination into the Bendora Dam. The ACT government had to commission a A$40 million membrane bioreactor treatment plant to restore water quality.

At the height of the Millennium Drought, household water savings and restrictions lowered volumes in sewers (by up to 40% in Brisbane, for example). The resulting increase in salt concentrations put extra pressure on wastewater treatment and reclamation..

The energy needed to pump, treat, distribute and heat water – and then to convey, pump, reclaim or discharge it as effluent, and to move biosolids – is often overlooked. Many blueprints for zero-carbon cities underplay or neglect entirely the carbon footprint of water supply and sewage treatment.

Some analyses only consider the energy footprint of domestic water heating, rather than the water sector as a whole – which is rather like trying to calculate the carbon footprint of the livestock industry by only looking at cooking.

Yet the growing challenge of delivering a reliable and safe water supply means that energy use is growing. The United States, for example, experienced a 39% increase in electricity usage for drinking water supply and treatment, and a 74% increase for wastewater treatment over the period 1996-2013, in spite of improvements in energy efficiency.

As climate change puts yet more pressure on water infrastructure, responses such as desalination plants and long-distance piping threaten to add even more to this energy burden. The water industry will increasingly be both a contributor to and a casualty of climate change.

How much energy individual utilities are actually using, either in Australia or worldwide, will vary widely according to the source of supply – such as rivers, groundwater or mountain dams – and whether gravity feeds are possible for freshwater and sewage (Melbourne shapes up well here, for example, whereas the Gold Coast doesn’t), as well as factors such as the level of treatment, and whether or not measures such as desalination or bulk transfers are in place.

All of this increases the water sector’s reliance on the electricity sector, which as we know has a pressing need to reduce its greenhouse emissions.

Desalination plants: great for providing water, not so great for saving electricity. Moondyne/Wikimedia Commons, CC BY-SA

One option would be for water facilities to take themselves at least partly “off-grid”, by installing large amounts of solar panels, onsite wind turbines, or Tesla-style batteries (a few plants also harness biogas). Treatment plants are not exactly bereft of flat surfaces – such as roofs, grounds or even ponds – an opportunity seized upon by South Australian Water.

But this is a large undertaking, and the alternative – waiting for the grid itself to become largely based on renewables – will take a long time.

A 2012 study found large variations in pump efficiency between water facilities in different local authorities across Australia. Clearly there is untapped scope for collaboration and knowledge-sharing in our water sector, as is done in Spain and Germany, where water utilities have integrated with municipal waste services, and in the United States, where the water and power sectors have gone into partnership in many places.

The developing world

Climate change and population growth are seriously affecting cities in middle-band and developing countries, and the overall outlook is grim. Many places, such as Mexico City, already have serious water contamination problems. Indeed, in developing nations these problems are worsened by existing water quality issues. Only one-third of wastewater is treated to secondary standard in Asia, less than half of that in Latin America and the Caribbean, and a minute amount in Africa.

The transfer of know-how to these places is critical to reaching clean energy transitions. Nations making the energy transition – especially China, the world’s largest greenhouse emitter – need to take just as much care to ensure they avoid a carbon blowout as they transition to clean water too.

Just as in the electricity sector, carbon pricing can potentially provide a valuable incentive for utilities to improve their environmental performance. If utilities were monitored on the amount of electricity used per kilolitre of water processed, and then rewarded (or penalised) accordingly, it would encourage the entire sector to up its game, from water supply all the way through to sewage treatment.

Read more:
This is what Australia’s growing cities need to do to avoid running dry

Water is a must for city-dwellers – a fact that Cape Town’s officials are now nervously contemplating. It would be helpful for the industry to participate in the strategic planning and land-use debates that affect its energy budgets, and for its emissions (and emissions reductions) to be measured accurately.

In this way the water industry can become an influential participant in decarbonising our cities, rather than just a passive player.

The ConversationThis article is based on a journal article (in press) co-authored by David Smith, former water quality manager for South East Water, Melbourne.

Peter Fisher, Adjunct Professor, Global, Urban and Social Studies, RMIT University

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

Leave a comment

Filed under Reblogs

Cape Town is almost out of water. Could Australian cities suffer the same fate?

The Conversation

Ian Wright, Western Sydney University

The world is watching the unfolding Cape Town water crisis with horror. On “Day Zero”, now predicted to be just ten weeks away, engineers will turn off the water supply. The South African city’s four million residents will have to queue at one of 200 water collection points.

Cape Town is the first major city to face such an extreme water crisis. There are so many unanswered questions. How will the sick or elderly people cope? How will people without a car collect their 25-litre daily ration? Pity those collecting water for a big family.

Read more:
Cape Town’s water crisis: driven by politics more than drought

The crisis is caused by a combination of factors. First of all, Cape Town has a very dry climate with annual rainfall of 515mm. Since 2015, it has been in a drought estimated to be a one-in-300-year event.

In recent years, the city’s population has grown rapidly – by 79% since 1995. Many have questioned what Cape Town has done to expand the city’s water supply to cater for the population growth and the lower rainfall.

Could this happen in Australia?

Australia’s largest cities have often struggled with drought. Water supplies may decline further due to climate change and uncertain future rainfall. With all capital cities expecting further population growth, this could cause water supply crises.

Read more:
This is what Australia’s growing cities need to do to avoid running dry

The situation in Cape Town has strong parallels with Perth in Australia. Perth is half the size of Cape Town, with two million residents, but has endured increasing water stress for nearly 50 years. From 1911 to 1974, the annual inflow to Perth’s water reservoirs averaged 338 gigalitres (GL) a year. Inflows have since shrunk by nearly 90% to just 42GL a year from 2010-2016.

To make matters worse, the Perth water storages also had to supply more people. Australia’s fourth-largest city had the fastest capital city population growth, 28.2%, from 2006-2016.

As a result, Perth became Australia’s first capital city unable to supply its residents from storage dams fed by rainfall and river flows. In 2015 the city faced a potentially disastrous situation. River inflows to Perth’s dams dwindled to 11.4GL for the year.

For its two million people, the inflows equated to only 15.6 litres per person per day! Yet in 2015/6 Perth residents consumed an average of nearly 350 litres each per day. This was the highest daily water consumption for Australia’s capitals. How was this achieved?

Tapping into desalination and groundwater

Perth has progressively sourced more and more of its supply from desalination and from groundwater extraction. This has been expensive and has been the topic of much debate. Perth is the only Australian capital to rely so heavily on desalination and groundwater for its water supply.

Volumes of water sourced for urban use in Australia’s major cities. BOM, Water in Australia, p.52, National Water Account 2015, CC BY

Australia’s next most water-stressed capital is Adelaide. That city is supplementing its surface water storages with desalination and groundwater, as well as water “transferred” from the Murray River.

Australia’s other capital cities on the east coast have faced their own water supply crises. Their water storages dwindled to between 20% and 35% capacity in 2007. This triggered multiple actions to prevent a water crisis. Progressively tighter water restrictions were declared.

The major population centres (Brisbane/Gold Coast, Sydney, Melbourne and Adelaide) also built large desalination plants. The community reaction to the desalination plants was mixed. While some welcomed these, others question their costs and environmental impacts.

The desalination plants were expensive to build, consume vast quantities of electricity and are very expensive to run. They remain costly to maintain, even if they do not supply desalinated water. All residents pay higher water rates as a result of their existence.

Since then, rainfall in southeastern Australia has increased and water storages have refilled. The largest southeastern Australia desalination plants have been placed on “stand-by” mode. They will be switched on if and when the supply level drops.

Read more:
The role of water in Australia’s uncertain future

Investing in huge storage capacity

Many Australian cities also store very large volumes of water in very large water reservoirs. This allows them to continue to supply water through future extended periods of dry weather.

The three largest cities (Sydney, Melbourne and Brisbane) have built very large dams indeed. For example, Brisbane has 2,220,150 ML storage capacity for its 2.2 million residents. That amounts to just over one million litres per resident when storages are full.

The ConversationIn comparison, Cape Town’s four million residents have a full storage capacity of 900,000 ML. That’s 225,000 litres per resident. Cape Town is constructing a number of small desalination plants while anxiously waiting for the onset of the region’s formerly regular winter rains.

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University

This article was originally published on The Conversation. (Reblogged by permission).Read the original article.

Leave a comment

Filed under Reblogs

Melbourne’s desalination plant is just one part of drought-proofing water supply

The Conversation

Stephen Gray, Victoria University

Water has now been ordered from the Victorian desalination plant. The plant was built at the end of the millennium drought to provide security against drought. But once built, it then rained and rained.

Since then many have seen the desalination plant as a white elephant – an unnecessary expense that has burdened Victoria with debt. Indeed, it seems to have been demonised as something evil.

However, with dry weather over the past two years, water storages have begun to decline, both in Melbourne and particularly in regional Victoria. The desalination plant was built to be used in times of water shortages, and the Victorian government has now deemed it time to order water.

The order is being made to reduce the possibility of water restrictions in Melbourne and to negate the need for Melbourne to take water from the Goulburn system and so allow more water to be made available to localities such as Bendigo and Ballarat.

The cost of drought

Desalination membranes at Melbourne’s desalination plant.
Stephen Gray

It has now been six years since the millennium drought ended and it can be hard for city residents to remember the impact of drought on their lives.

To give one example, we conducted a study on the social impact of water restrictions on sportsgrounds during the drought. This study found that 70% of people used sports grounds, either for organised sport or informal relaxation, and that all users were adversely affected by the drought.

The most severely affected were those at women’s, disabled and junior sporting clubs, which were of low priority for irrigation. These groups were forced either to cancel their activities because of the hard playing surfaces or to reschedule their events and find other locations to play their sport. This became a major disruption to the lives of many people during the 13-year drought.

This was just one way that water restrictions and drought affected our lives. When water storage levels were etched in our minds through public billboards and television weather reports, neighbours were asked to report people who used water contrary to the restrictions, car washes became a growth industry, and communities were parched and brown. I am now enjoying my garden, which has sprung to life in recent years, and will be happy if we can avoid such water restrictions again.

For regional Victorians the impact of drought was greater. For them, the reminders of drought are already to the fore following several dry seasons. Parts of Victoria have received less than 50% of average annual rainfall for the past two years. Farmers are reducing the number of cattle on the land.

Water from the desalination plant will be delivered to regional Victoria via the state’s rivers and pipe networks that make up the water grid.


Some may argue that other sources of water such as dams, storm water harvesting and water recycling would have been better alternatives. However, all require significant investment and none are likely to be fully utilised during wetter periods. This has been one criticism of desalination, but is simply an outcome of reducing risk in a variable climate.

Storm water harvesting is often promoted as being a cheaper alternative to desalination, but a recent water industry article on the cost of such harvesting has estimated costs of A$10-25 per kilolitre (1,000 litres) when used as a substitute for drinking water. This compares to costs of A$2-3 per kL for desalinated water. Turning the desalination plant on adds up to an extra A$12 a year on Victorian water bills.

Perhaps one alternative that is worth considering is recycling waste water for drinking water supplies. This is currently against Victorian government policy, which the two major parties support.

Victoria uses recycled water for irrigation, in toilets and clothes washing, but such schemes require homes to receive water through a second pipe. These second-pipe systems are more costly to build and manage.

Recycling water for drinking avoids these costs, as you simply use the same pipe that supplies water from dams. The technology to recycle water for drinking is also well established and can be delivered to existing homes.

Given Melbourne has access to desalinated water that we are only just starting to use, it is unlikely Melbourne will need to consider recycling water for drinking in the near future. However, regional communities may like to have this option, and I believe this option should be allowed.

Australia’s rainfall patterns are among the most variable in the world, and prolonged periods of dry weather are normal. However, climate change predictions indicate longer, more severe periods of dry weather.

Indeed, one of my climate change colleague has suggested that climate change does not occur in a constant, slow progression, but rather through step changes. If this is the case, then the next drought will be more severe and the need for climate-independent water supplies more pressing.

Faced with this scenario, the desalination plant is a good investment and we should use it when it is needed.

The ConversationStephen Gray, Director of the Institute for Sustainability and Innovation , Victoria University

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.


1 Comment

Filed under Reblogs

Faulty risk assessment

by Tim Harding B.Sc., B.A.

Risk’ may be defined as the probability of something bad happening multiplied by the resulting cost/benefit if it does happen.  Risk analysis is the process of discovering what risks are associated with a particular hazard, including the mechanisms that cause the hazard, then estimating the probability that the hazard will occur and its consequences.

Risk assessment is the determination of the acceptability of risk in two dimensions – the likelihood of an adverse event occurring; and the severity of the consequences if it does occur,[1] as illustrated in the diagram below.

risk assessment diagram

By way of illustration, the likelihood of something bad happening could be very low, but the consequences could be unacceptably high – enough to justify preventative action.  Conversely, the likelihood of an event could be higher, but the consequences could low enough to justify ‘taking the risk’.

In assessing the consequences, consideration needs to be given to the size of the population likely to be affected, and the severity of the impact on those affected.  This will provide an indication of the aggregate effect of an adverse event. For example, ‘major’ consequences might include significant harm to a small group of affected individuals, or moderate harm to a large number of individuals.[2]

A fallacy is committed when a person focuses on risks in isolation from benefits, or takes into account one dimension of risk assessment without the other dimension.  To give a practical example, the new desalination plant to augment Melbourne’s water supply has been called a ‘white elephant’ by some people, because it has not been needed since the last drought broke. But this criticism ignores the catastrophic consequences that could have occurred had the drought not broken. In June 2009, Melbourne’s water storages fell to 25.5% of capacity, the lowest level since the huge Thomson Dam began filling in 1984. This downward trend could have continued at that time, and could well be repeated during the next drought.


Melbourne’s desalination plant at Wonthaggi

No responsible government could afford to ‘take the risk’ of a major city of 4 million people running out of water.  People in temperate climates can survive without electricity or gas, but are likely to die of thirst in less than a week without water, not to mention the hygiene crisis that would occur without washing or toilet flushing.  The failure to safeguard the water supply of a major city is one of the most serious derelictions of government responsibility imaginable.

A similar example of fallacious reasoning is in the area of climate change, where the public debate wrongly focusses on whether the science is true or false, rather than on the risks and consequences of it being true or false. This video explains the fallacy quite well.

Other examples of this fallacy are committed by the anti-vaccination and anti-fluoridation movements, often accompanied by conspiracy theories.  They both focus on the very tiny likelihood of adverse side effects without considering the major benefits to public health from the vaccination of children and the fluoridation public water supplies.  Hardly anybody has ever died or become seriously ill in Australia from the side effects of vaccination or fluoridation [3]; yet large numbers of people have died from the lack of vaccination.[4] The allegation of a link between vaccination and autism has been discredited, retracted and found to be fraudulent.  The benefits of fluoridation are well documented. The risks of general anaesthesia for multiple tooth extractions are not to be idly contemplated for children, and far outweigh the virtually nonexistent risk from fluoridation.[5]

[1] This is based on the Australian/New Zealand Standard for Risk Management.

[2] State Government of Victoria (2007) Victorian Guide to Regulation 2nd edition. Department of Treasury and Finance, Melbourne.

[3] In 2010, increased rates of high fever and febrile convulsions were reported in children under 5 years of age after they were vaccinated with the bioCSL Fluvax® vaccine. bioCSL Fluvax® has not been registered for use in this age group since late 2010 and therefore should not be given to children under 5 years of age. The available data indicate that there is a very low risk of fever, which is usually mild and transient, following vaccination with the other vaccine brands: Agrippal®; Fluarix®; Influvac®; and Vaxigrip®.  Any of these vaccines can be used in children aged 6 months and older. This and further information on flu vaccination is available here.

[4] The former Commonwealth Chief Medical Officer, Prof. Jim Bishop has argued that the flu vaccination program “changed dramatically the flu outlook for this country”, with admissions to intensive care from swine flu falling from 681 in 2009 to just 60 in 2010, and hospitalisations dropping from nearly 5000 to 600. Swine flu killed 191 Australians in 2009 and 36 in 2010. In contrast, seasonal flu killed 1796 Australians that year – but, unlike swine flu, the victims were mainly the frail and elderly. Prof. Bishop cautioned that one in every three hospital patients were “perfectly fit and well” before they caught swine flu, which was severe in pregnant women, teenagers who had lost their innate childhood immunity and indigenous people who tend to suffer underlying health problems. Three pregnant women died of swine flu, and 280 ended up in intensive care.  

[5] https://theconversation.com/fluoride-conspiracies-activism-harm-to-children-17723

If you find the information on this blog useful, you might like to consider supporting us.

Make a Donation Button


Filed under Logical fallacies