How South Australia can function reliably while moving to 100% renewable power

February 23, 2017 by Mark Diesendorf, The Conversation
Peak energy demand sometimes occurs when there’s no wind. Credit: Shutterstock

Despite the criticism levelled at South Australia over its renewable energy ambitions, the state is nevertheless aiming to be carbon neutral by mid-century, which will mean moving to 100% renewable electricity over the next 15-20 years.

The biggest challenge will be meeting the 2-3 hours of peak demand during the evenings, when wind generation happens to be low. This will require a mix of different technologies and strategies, including solar, wind, storage, and possibly a new interconnector to New South Wales.

The issue is the variable nature of some – wind turbines only generate electricity when there's sufficient wind, solar panels when the sun shines. But peaks in demand occasionally coincide with periods of low renewable generation, as was the case during the heatwave a few weeks ago. Although sufficient gas-fired generated capacity existed to pick up the slack, it was not all available at the time and short, localised blackouts were implemented.

Without strategic preparation, these events are going to be more difficult to handle in future as wind and solar farms grow, especially if the interconnector between SA and Victoria fails at a critical time.

But here are some of the things we can do in the short term (the next 2-3 years) and medium term (the coming decade) to create a reliable system on the path to 100% renewable electricity.

The short-term

The key point is that the challenging periods will be infrequent and only last for a few hours. Coal or nuclear power stations, which operate best when run continuously at full power, are too inflexible in operation to pick up the slack at peak demand. They would also be too expensive, hazardous and slow to construct.

In the short term, then, we need to install options that are flexible and dispatchable (i.e. able to generate when required). The options include open-cycle gas turbines (OCGTs), preferably each with a dedicated gas storage; concentrated solar thermal power with thermal storage (CST); and batteries. With the right policies these technologies could make significant contributions to peak supply within 2-3 years.

Currently 320 megawatts of OCGT capacity have been proposed for SA. These generators have the advantage of low capital cost and, as they would be operated infrequently, low annual operating cost. They can be started from cold in about 10 minutes, compared with up to a day for coal power. OCGT owners would be compensated for keeping their units on standby, ready to go when we need it. OCGTs are also sustainable when they operate on renewable fuels – biofuels, hydrogen and ammonia.

There are already several proposals for CST power stations near Port Augusta. Initially about 100MW could be installed. Subsequently, as the global CST market expands and the cost declines, more modules could be added. To use CST for evening peak demand periods, we would need to pay a time-variable feed-in tariff or a contracted price that is highest for supply during those periods.

Battery prices are declining rapidly as mass production takes off, so they could also make a significant short-term contribution. Together with solar panels on both residential and commercial rooftops, batteries could help reduce the overall demand on the grid. Residential and commercial solar owners should be given incentives to install batteries by raising electricity prices during peaks in demand, thus increasing the economic savings from self-consumption and the benefit of feeding-in any excess power generated.

While extra solar and wind farms should be constructed, they should also be balanced by flexible, dispatchable . To drive the implementation of CST and large batteries in the absence of federal government support, SA could hold reverse auctions, as Canberra does.

To offset, at least partially, increased peak electricity prices and to help electricity users reduce unnecessary demand, state and federal governments should also expand their energy-efficiency programs.

The medium term

Globally, we are at the beginning of a transition to "smart" grids, in which demand for electricity can be modified almost instantaneously by both the customer and the utility. For the utility to do this, a contract is needed to reward customers for being occasionally and partially "offloaded" (that is, having your air conditioning, refrigerator, or hot water turned off for a short period of time). Currently, only some huge electricity consumers such as aluminium smelters are subject to offloading.

For this to be expanded to residential and smaller commercial customers, we need some kind of "smart" switch. These would be operated remotely, turning off supply to electricity-hungry appliances. While the technologies already exist for smart demand reduction, it could take 5-10 years to mass-produce and roll them out on a large scale.

The cheapest form of electricity storage for the grid is pumped hydro. This is where excess electricity generated during off-peak periods – for instance by wind and solar in the middle of the day – is used to pump water from a low to a high reservoir. During peak periods, the water is then released from the upper reservoir and flows through a turbine, generating electricity.

Pumped storage is well established and can even be found on the Tumut River as part of the Snowy Mountains hydroelectric scheme. Although SA has negligible potential for hydro based on rivers, it appears to have considerable potential for pumping seawater up into many small reservoirs in coastal hills. A research group, led by Andrew Blakers at ANU and funded by ARENA, is investigating this.

Another option is to build a new transmission line to join SA directly to eastern New South Wales via Broken Hill. Although such a line could take a decade to plan and build, and would be expensive, it would make the National Electricity Market grid more resilient and controllable, and would link up renewable energy generation in South Australia (wind and possibly future geothermal) and western NSW (solar and wind) with demand centres in the east. Since it would be valuable national infrastructure, the cost could be shared between the federal and state governments.

A 100% renewable future

Over the next 20 years it is entirely feasible for SA to aim for 100% continuous . The important requirements for reliability and stability are a diverse set of sources, especially a balanced mix between variable and flexible-dispatchable technologies, storage, geographic dispersion of wind and solar farms, smart demand management, energy efficiency and possibly a new interconnector joining SA and NSW.

Furthermore, CST, OCGTs, batteries with appropriate inverters, and synchronous condensers can all contribute to a stable and 100% renewable SA.

As a driver of long-term investment, a national carbon price that steadily increases to a high level would compensate for the environmental costs of burning fossil fuels. Furthermore, the Renewable Energy Target (RET) should be extended from 2020 to 2030 and increased in scale. We should also create separate targets for CST with thermal storage and large-scale storage. Finally, the NEM Objective and several of its rules will have to be changed.

However, even without national drivers, SA could transform its grid to one that is renewable, reliable and affordable – in the process showing other states how it can be done.

Explore further: Switching is not so simple: 100% renewable energy sources require overcapacity

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14 comments

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Display comments: newest first

WillieWard
2.6 / 5 (5) Feb 23, 2017
"100% RE started as a hope, then it became a religion. Matter now settled. It's an alternative fact."
gkam
2 / 5 (8) Feb 23, 2017
This must terrify nuclear power advocates, since they were not even considered. Who wants to wait over ten years for power? My PV system, went up in and was connected four hours.
WillieWard
2.6 / 5 (5) Feb 23, 2017
"This wind turbine was bored of killing innocent birds and bats, so decided to destroy vehicles on GTA style."
https://www.faceb...0560964/
WillieWard
3 / 5 (4) Feb 23, 2017
My PV system, went up in and was connected four hours.
"Study throws cold water on residential solar-plus-storage economics"
"storing solar power can increase energy consumption and emissions levels."
http://www.utilit.../436482/
gkam
2 / 5 (8) Feb 23, 2017
I do not have storage, Willie, I use the grid for mine, so those losses do not pertain to me.
WillieWard
3 / 5 (4) Feb 24, 2017
I use the grid for mine
Of course, PV (placebo voltaic) system is not self-sufficient/sustaining, so it is necessary to stay connected to the fossil-fueled grid to hide intermittencies.
TheGhostofOtto1923
4.3 / 5 (6) Feb 24, 2017
I do not have storage
You do not have a lot of things georgie. You do not have EV/PV, you do not have undergrad diplomas, you do not have a real MS degree nor a phd, you do not have self-control, you do not have sanity (ask your shrinks down at the VA), you do not have sobriety, you do not have emotions or a conscience, you do not have the respect of anyone here and you do not have any meaningful connection to reality.

But none of that bothers you does it?
gkam
1 / 5 (5) Feb 27, 2017
My gosh, folks, it says it all right here:

https://phys.org/...ity.html

With this and PV, Australia can be riding high.

unrealone1
5 / 5 (1) Mar 03, 2017
Adelaide wind power is only active 20 to 30% of the time?
The alarmist say more storms are the future then why use wind power if the future weather will be more unstable?
There is no wind at night, especially on a hot night in Adelaide.
Adelaide is the worlds renewable energy crash test dummy, and it's not working very well
Coca Cola leaving Adelaide
The company was leaving his home state because of high business costs and concerns about the reliability of the power supply.
https://www.thegu...200-jobs
humy
not rated yet Mar 03, 2017
When cheap long-lasting flow batteries for off-the-grid energy storage which have only cheap non-toxic non-corrosive recyclable chemicals in them thus making it a cost effective solution to intermittent power even without a supergrid, there would be absolutely no more excuses to go 100% renewable;

https://techxplor...eep.html

It isn't a question of if, it is just a question of when.
All the religious anti-renewable morons and the big greedy oil companies will just hate this.
WillieWard
not rated yet Mar 03, 2017
When cheap long-lasting flow batteries for off-the-grid energy storage...
If climate change solutions involving intermittent renewables depend on cheap long-lasting battery technologies that don't exist, in what way are they solutions?
First battery 1749
No major commercial battery breakthrough since Li-phosphate 1996(two decades), it's a very mature technology, its physics is well known and understood, it is not expected any major breakthrough.
https://pbs.twimg...5BVh.jpg
https://pbs.twimg...A4Q1.jpg
https://pbs.twimg...Kv3G.jpg
"The renewable energy cult is as dishonest and divorced from reality as any religion, and it is a religion, not science."

humy
not rated yet Mar 03, 2017
When cheap long-lasting flow batteries for off-the-grid energy storage...
If climate change solutions involving intermittent renewables depend on cheap long-lasting battery technologies that don't exist, in what way are they solutions?

WillieWard

WOW you really are a total moron. So you have a problem with the word "when"? Get this into your thick skull, They don't exist yet but they will because they are currently under development. WHEN they come to exist, which they obviously will not too far into the future, they will be A solution (out of several solutions). Which part of the word "when" do you not comprehend?

+ even without them, a supergrid is a perfectly reasonable alternative solution therefore a solution does NOT depend on cheap long-lasting battery technologies, moron.
WillieWard
not rated yet Mar 03, 2017
They don't exist yet but they will because they are currently under development. WHEN they come to exist, which they obviously will not too far into the future, they will be A solution...
Unicorns don't exist yet but they will because they are currently under development. WHEN they come to exist, which they obviously will not too far into the future, they will be A solution...
https://s-media-c...27b5.jpg
https://uploads.d...8da6.jpg
http://humerusonl...s001.jpg
PPihkala
not rated yet Mar 06, 2017
I seem not to be the only one having this idea for pumped air underwater storage:

https://www.green...-storage

Every off-shore wind turbine could even have it's own storage field under it at bottom or the sea.

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