Heavy rains are great news for Sydney’s dams, but they come with a big caveat


Ian Wright, Western Sydney University and Jason Reynolds, Western Sydney University

Throughout summer, Sydney’s water storage level fell alarmingly. Level 2 water restrictions were imposed and the New South Wales government prepared to double the capacity of its desalination plant.

But then it began to rain, and rain. Sydney water storages jumped from 41% in early February to 75% now – the highest of any capital city in Australia.

This is great news for the city, but it comes with a big caveat. Floodwaters will undoubtedly wash bushfire debris into reservoirs – possibly overwhelming water treatment systems. We must prepare now for that worst-case pollution scenario.

Reservoirs filled with rain

The water level of Sydney’s massive Lake Burragorang – the reservoir behind Warragamba Dam – rose by more than 11 meters this week. Warragamba supplies more than 80% of Sydney’s water.

Other Sydney water storages, including Nepean and Tallowa dams, are now at 100%.
WaterNSW report that 865,078 megalitres of extra water has been captured this week across all Greater Sydney’s dams.

This dwarfs the volume of water produced by Sydney’s desalination plant, which produces 250 megalitres a day when operating at full capacity. Even at this rate, it would take more than 3,400 days (or nine years) to match the volume of water to added to Sydney’s supply this week.

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The Warragamba Dam before the drought and after the recent heavy rains.

But then comes the pollution

Thankfully, the rain appears to have extinguished bushfires burning in the Warragamba catchment for months.

But the water will also pick up bushfire debris and wash it into dams.

Over the summer, bushfires burnt about 30% of Warragamba Dam’s massive 905,000 hectare water catchment, reducing protective ground cover vegetation. This increases the risk of soil erosion. Rain will wash ash and sediment loads into waterways – adding more nitrogen, phosphorous and organic carbon into water storages.




Read more:
Bushfires threaten drinking water safety. The consequences could last for decades


Waterways and ecosystems require nutrients like phosphorous and nitrogen, but excess nutrients aren’t a good thing. They bring contamination risks, such as the rapid growth of toxic blue-green algae.

Drinking water catchments will always have some degree of contamination and water treatment consistently provides high quality drinking water. But poor water quality after catchment floods is not without precedent.

We’ve seen this before

In August 1998, extreme wet weather and flooding rivers filled the drought-affected Warragamba Dam in just a few days.

This triggered the Cryptosporidium crisis, when the protozoan parasite and the pathogen Giardia were detected in Sydney’s water supplies. It triggered health warnings, and Sydneysiders were instructed to boil water before drinking it. This event did not involve a bushfire.




Read more:
Better boil ya billy: when Australian water goes bad


The Canberra bushfires in January 2003 triggered multiple water quality problems. Most of the region’s Cotter River catchments, which hold three dams, were burned. Intense thunderstorms in the months after the bushfire washed enormous loads of ash, soil and debris into catchment rivers and water reservoirs.

This led to turbidity (murkiness), as well as iron, manganese, nitrogen, phosphorus and carbon in reservoir waters. The inflow of organic material also depleted dissolved oxygen which triggered the release of metals from reservoir sediment. At times, water quality was so poor it couldn’t be treated and supplied to consumers.

The ACT Government was forced to impose water restrictions, and built a A$38 million water treatment plant.

Have we come far enough?

Technology in water treatment plants has developed over the past 20 years, and water supply systems operates according to Australian drinking water guidelines.

Unlike the 1998 Sydney water crisis, WaterNSW, Sydney Water and NSW Health now have advanced tests and procedures to detect and manage water quality problems.

In December last year, WaterNSW said it was aware of the risk bushfires posed to water supplies, and it had a number of measures at its disposal, including using booms and curtains to isolate affected flows.

However at the time, bushfire ash had already reportedly entered the Warragamba system.

The authors crossing the Coxs River during very low flow last September.
Author provided

Look to recycled water

Sydney’s water storages may have filled, but residents should not stop saving water. We recommend Level 2 water restrictions, which ban the use of garden hoses, be relaxed to Level 1 restrictions which ban most sprinklers and watering systems, and the hosing of hard surfaces.

While this measure is in place, longer term solutions can be explored. Expanding desalination is a popular but expensive option, however greater use of recycled wastewater is also needed.




Read more:
80% of household water goes to waste – we need to get it back


Highly treated recycled water including urban stormwater and even treated sewage should be purified and incorporated into the water supply. Singapore is a world leader and has proven the measure can gain community acceptance.

It’s too early to tell what impact the combination of bushfires and floods will have on water storages. But as extreme weather events increase in frequency and severity, all options should be on the table to shore up drinking water supplies.The Conversation

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University and Jason Reynolds, Senior Lecturer in Geochemistry, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Chief Scientist: we need to transform our world into a sustainable ‘electric planet’


Alan Finkel, Office of the Chief Scientist

I want you to imagine a highway exclusively devoted to delivering the world’s energy.

Each lane is restricted to trucks that carry one of the world’s seven large-scale sources of primary energy: coal, oil, natural gas, nuclear, hydro, solar and wind.

Our current energy security comes at a price, the carbon dioxide emissions from the trucks in the three busiest lanes: the ones for coal, oil and natural gas.

We can’t just put up roadblocks overnight to stop these trucks; they are carrying the overwhelming majority of the world’s energy supply.

But what if we expand clean electricity production carried by the trucks in the solar and wind lanes — three or four times over — into an economically efficient clean energy future?

Think electric cars instead of petrol cars. Think electric factories instead of oil-burning factories. Cleaner and cheaper to run. A technology-driven orderly transition. Problems wrought by technology, solved by technology.




Read more:
How to transition from coal: 4 lessons for Australia from around the world


Make no mistake, this will be the biggest engineering challenge ever undertaken. The energy system is huge, and even with an internationally committed and focused effort the transition will take many decades.

It will also require respectful planning and retraining to ensure affected individuals and communities, who have fuelled our energy progress for generations, are supported throughout the transition.

As Tony, a worker from a Gippsland coal-fired power station, noted from the audience on this week’s Q+A program:

The workforce is highly innovative, we are up for the challenge, we will adapt to whatever is put in front of us and we have proven that in the past.

This is a reminder that if governments, industry, communities and individuals share a vision, a positive transition can be achieved.

The stunning technology advances I have witnessed in the past ten years make me optimistic.

Renewable energy is booming worldwide, and is now being delivered at a markedly lower cost than ever before.

In Australia, the cost of producing electricity from wind and solar is now around A$50 per megawatt-hour.

Even when the variability is firmed with storage, the price of solar and wind electricity is lower than existing gas-fired electricity generation and similar to new-build coal-fired electricity generation.

This has resulted in substantial solar and wind electricity uptake in Australia and, most importantly, projections of a 33% cut in emissions in the electricity sector by 2030, when compared to 2005 levels.

And this pricing trend will only continue, with a recent United Nations report noting that, in the last decade alone, the cost of solar electricity fell by 80%, and is set to drop even further.

So we’re on our way. We can do this. Time and again we have demonstrated that no challenge to humanity is beyond humanity.

Ultimately, we will need to complement solar and wind with a range of technologies such as high levels of storage, long-distance transmission, and much better efficiency in the way we use energy.

But while these technologies are being scaled up, we need an energy companion today that can react rapidly to changes in solar and wind output. An energy companion that is itself relatively low in emissions, and that only operates when needed.

In the short term, as Prime Minister Scott Morrison and energy minister Angus Taylor have previously stated, natural gas will play that critical role.

In fact, natural gas is already making it possible for nations to transition to a reliable, and relatively low-emissions, electricity supply.

Look at Britain, where coal-fired electricity generation has plummeted from 75% in 1990 to just 2% in 2019.

Driving this has been an increase in solar, wind, and hydro electricity, up from 2% to 27%. At the same time, and this is key to the delivery of a reliable electricity supply, electricity from natural gas increased from virtually zero in 1990 to more than 38% in 2019.

I am aware that building new natural gas generators may be seen as problematic, but for now let’s assume that with solar, wind and natural gas, we will achieve a reliable, low-emissions electricity supply.

Is this enough? Not really.

We still need a high-density source of transportable fuel for long-distance, heavy-duty trucks.

We still need an alternative chemical feedstock to make the ammonia used to produce fertilisers.

We still need a means to carry clean energy from one continent to another.

Enter the hero: hydrogen.

Hydrogen is abundant. In fact, it’s the most abundant element in the Universe. The only problem is that there is nowhere on Earth that you can drill a well and find hydrogen gas.

Don’t panic. Fortunately, hydrogen is bound up in other substances. One we all know: water, the H in H₂O.

We have two viable ways to extract hydrogen, with near-zero emissions.

First, we can split water in a process called electrolysis, using renewable electricity.

Second, we can use coal and natural gas to split the water, and capture and permanently bury the carbon dioxide emitted along the way.

I know some may be sceptical, because carbon capture and permanent storage has not been commercially viable in the electricity generation industry.

But the process for hydrogen production is significantly more cost-effective, for two crucial reasons.

First, since carbon dioxide is left behind as a residual part of the hydrogen production process, there is no additional step, and little added cost, for its extraction.

And second, because the process operates at much higher pressure, the extraction of the carbon dioxide is more energy-efficient and it is easier to store.

Returning to the electrolysis production route, we must also recognise that if hydrogen is produced exclusively from solar and wind electricity, we will exacerbate the load on the renewable lanes of our energy highway.

Think for a moment of the vast amounts of steel, aluminium and concrete needed to support, build and service solar and wind structures. And the copper and rare earth metals needed for the wires and motors. And the lithium, nickel, cobalt, manganese and other battery materials needed to stabilise the system.

It would be prudent, therefore, to safeguard against any potential resource limitations with another energy source.

Well, by producing hydrogen from natural gas or coal, using carbon capture and permanent storage, we can add back two more lanes to our energy highway, ensuring we have four primary energy sources to meet the needs of the future: solar, wind, hydrogen from natural gas, and hydrogen from coal.




Read more:
145 years after Jules Verne dreamed up a hydrogen future, it has arrived


Furthermore, once extracted, hydrogen provides unique solutions to the remaining challenges we face in our future electric planet.

First, in the transport sector, Australia’s largest end-user of energy.

Because hydrogen fuel carries much more energy than the equivalent weight of batteries, it provides a viable, longer-range alternative for powering long-haul buses, B-double trucks, trains that travel from mines in central Australia to coastal ports, and ships that carry passengers and goods around the world.

Second, in industry, where hydrogen can help solve some of the largest emissions challenges.

Take steel manufacturing. In today’s world, the use of coal in steel manufacturing is responsible for a staggering 7% of carbon dioxide emissions.

Persisting with this form of steel production will result in this percentage growing frustratingly higher as we make progress decarbonising other sectors of the economy.

Fortunately, clean hydrogen can not only provide the energy that is needed to heat the blast furnaces, it can also replace the carbon in coal used to reduce iron oxide to the pure iron from which steel is made. And with hydrogen as the reducing agent the only byproduct is water vapour.

This would have a revolutionary impact on cutting global emissions.

Third, hydrogen can store energy, not only for a rainy day, but also to ship sunshine from our shores, where it is abundant, to countries where it is needed.

Let me illustrate this point. In December last year, I was privileged to witness the launch of the world’s first liquefied hydrogen carrier ship in Japan.

As the vessel slipped into the water I saw it not only as the launch of the first ship of its type to ever be built, but as the launch of a new era in which clean energy will be routinely transported between the continents. Shipping sunshine.

And, finally, because hydrogen operates in a similar way to natural gas, our natural gas generators can be reconfigured in the future to run on hydrogen — neatly turning a potential legacy into an added bonus.

Hydrogen-powered economy

We truly are at the dawn of a new, thriving industry.

There’s a nearly A$2 trillion global market for hydrogen come 2050, assuming that we can drive the price of producing hydrogen to substantially lower than A$2 per kilogram.

In Australia, we’ve got the available land, the natural resources, the technology smarts, the global networks, and the industry expertise.

And we now have the commitment, with the National Hydrogen Strategy unanimously adopted at a meeting by the Commonwealth, state and territory governments late last year.

Indeed, as I reflect upon my term as Chief Scientist, in this my last year, chairing the development of this strategy has been one of my proudest achievements.

The full results will not be seen overnight, but it has sown the seeds, and if we continue to tend to them, they will grow into a whole new realm of practical applications and unimagined possibilities.


This is an edited extract of a speech to the National Press Club of Australia on February 12, 2020. The full speech is available here.The Conversation

Alan Finkel, Australia’s Chief Scientist, Office of the Chief Scientist

This article is republished from The Conversation under a Creative Commons license. Read the original article.