Up to 90% of electricity from solar and wind the cheapest option by 2030: CSIRO analysis



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Paul Graham, CSIRO

With the cost of energy generated from wind and solar now less than coal, the share of Australia’s electricity coming from renewables has reached 23%. The federal government projects the share will reach 50% by 2030.

It is at this point that integrating renewables into the energy system becomes more costly.

We can add wind and solar farms at little extra cost when their share is low and other sources – such as coal and gas generators now – can compensate for their variability. At a certain point, however, there comes a need to invest in supporting infrastructure to ensure supply from mostly renewable generation can meet demand.

But by 2030, even with these extra costs, adding new variable renewable generation (solar and wind) to as high as a 90% share of the grid will still be cheaper than non-renewable options, according to new estimates from the CSIRO and Australian Energy Market Operator.

Calculating energy costs

International research, including from the International Renewable Energy Agency, suggests solar and wind power are now the cheapest new sources of electricity in most parts of the world.

Our estimates, made for the third annual “GenCost” report (short for generation cost), confirm this is also now the case in Australia.

We compare the cost of new-build coal, gas, solar photovoltaics (both small and large scale), solar-thermal, wind and a number of speculative options (such as nuclear).

What we’ve been able to more accurately estimate in the new report is the cost of integrating more and more renewable energy into the energy system, as coal and gas generators are retired.

The two key extra integration costs are energy storage and more transmission lines.




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Storage costs

For any system dominated by renewables, storing energy is essential.

Storage means renewable energy can be saved when it is overproducing relative to demand – for example, in the middle of the day for solar, or during extended windy conditions. Stored energy can then be used when renewables cannot meet demand – such as overcast days or at night for solar.

Among options being considered for large-scale investment in Australia are batteries and pumped hydro energy storage (using excess renewable power to pump water back up to dams to again drive hydroelectric turbines).


Capital costs of storage technologies in $/kWh (total cost basis). Aurecon and Entura are engingeering businesses who publish project cost estimates. AEMO ISP is the Australian Energy Market Operator’s Integrated System Plan, which also includes technology cost estimates.
CSIRO

Pumped hydro sites can provide storage for hours or days. There are three schemes in Australia: Talbingo and Shoalhaven in New South Wales, and Wivenhoe near Brisbane.

Battery costs have been falling steadily and tend to be most competitive for storage electricity for less than eight hours. South Australia’s big battery (officially known as the Hornsdale Power Reserve) is the most obvious example.

Transmission costs

The other key cost to integrate more renewable energy generation into the electricity grid is building more transmission lines. Right now those lines mostly run from coal and gas power stations near coal mines.

But this not where new large-scale renewable generation will be. Solar farms are best placed inland, where there is less cloud cover, and in the mid to northern regions of Australia. Wind farms are generally better located in elevated areas and in the southern regions. We’ll need to build new transmission links to these “renewable energy zones”.

Transmission links between the states in the National Electricity Market (Queensland, New South Wales, Australian Capital Territory, Victoria, Tasmania and South Australia) will need to be improved so they can better support each other if one or more are experiencing low renewable energy output.




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Total integration costs

So how much extra will it cost for Australia to have a higher share (up to 90%) of electricity from wind and solar (variable renewable energy)? The following graph summarises our findings based on 2030 cost projections.


Projected renewable generation and integration costs by variable renewable energy share in 2030.
Projected renewable energy generation and integration costs by variable renewable energy share in 2030.
CSIRO

The cost of generating energy from wind and solar (shown in light blue) is about A$40 per megawatt-hour (MWh). This is is slightly below current average market prices.

A higher share of renewable energy adds storage costs (in black) and transmission costs (grey and dark blue). These integration costs increase from A$4/MWh to A$20/MWh as the variable renewable energy share increases from 50% to 90%.

At 90% renewable energy, the total cost is A$63/MWh. But that’s still cheaper than the cost of new coal and gas-fired electricity generation, which is in the range of A$70 to A$90/MWh (under ideal assumptions of low fuel pricing and no climate policy risk).


The 2020-21 GenCost report is now in the formal consultation period with stakeholders including industry, government, regulators and academia. The final report is due to be published in March 2021.The Conversation

Paul Graham, Chief economist, CSIRO energy, CSIRO

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

Why is the Australian energy regulator suing wind farms – and why now?



Michael Coghlan/Flickr, CC BY-SA

Samantha Hepburn, Deakin University

The Australian Energy Regulator (AER) is suing four of the wind farms involved in the 2016 South Australian blackout – run by AGL Energy, Neoen Australia, Pacific Hydro, and Tilt Renewables – alleging they breached generator performance standards and the national electricity rules.

These proceedings appear to contradict the conclusions of a 2018 report which said while the AER had found some “administrative non-compliance”, it did not intend to take formal action given the “unprecedented circumstances”.




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However the AER has since said this report focused on the lead-up and aftermath of the blackout, not the event itself. The case hinges on whether the wind farms failed to provide crucial information during the blackout which hindered recovery.

In particular, the AER is arguing the software protecting the wind farms should have been able to cope with voltage disturbances and provide continuous energy supply. On the face of it, however, this will be extremely difficult to prove.

Rehashing the 2016 blackout

The 2016 South Australian blackout was triggered by a severe storm that hit the state on September 28. Tornadoes with wind speeds up to 260 km/h raced through SA, and a single-circuit 275-kilovolt transmission line was struck down.




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After this, 170km away, a double-circuit 275kV transmission line was lost. This transmission damage caused the lines to trip and a series of subsequent faults resulted in six voltage dips on the South Australian grid at 4.16pm.

As the faults escalated, eight wind farms in SA had their protection settings activated. This allowed them to withstand the voltage dip by automatically reducing power. Over a period of 7 seconds, 456 megawatts of power was removed. This reduction caused an increase in power to flow through the Heywood interconnector. This in turn triggered a protection mechanism for the interconnecter that tripped it offline.

Once this happened, SA became separated from the rest of the National Energy Market (NEM), leaving far too little power to meet demand and blacking out 850,000 homes and businesses. A 2017 report found once SA was separated from the NEM, the blackout was “inevitable”.




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What went wrong at the wind farms?

The question then becomes, is there any action the wind farms could reasonably have taken to stay online, thus preventing the overloading of the Heywood interconnector?

The regulator is arguing the operators should have let the market operator know they could not handle the disruption caused by the storms, so the operator could make the best decisions to keep the grid functioning.

Wind farms, like all energy generators in Australia, have a legal requirement to meet specific performance standards. If they fall short in a way that can materially harm energy security, they have a further duty to inform the operator immediately, with a plan to remedy the problem.

To determine whether a generator has complied with these risk management standards, a range of factors are considered. These include:

  • the technology of the plant,
  • whether its performance is likely to drift or degrade over a particular time frame,
  • experience with the particular generation technology,
  • the connection point arrangement that is in place. A generator will have an arrangement with a transmission network service provider (TNSP) that operates the networks that carry electricity between generators and distribution networks. TNSP’s advise the NEM of the capacity of their transmission assets so that they can be operated without being overloaded.
  • the risk and costs of different testing methods given the relative size of the plant.

Plenty of blame to go around

The series of events leading up to the 2016 blackout was extremely difficult to anticipate. There were many factors, and arguably all participants were involved in different ways.

  • The Heywood interconnector was running at full capacity at the time, so any overload may have triggered its protective mechanism.

  • The transmission lines were damaged by an unprecedented 263 lightning strikes in five minutes.

  • The market operator itself did not adopt precautionary measures such as reducing the load on the interconnector, or providing a clearer warning to electricity generators.

Bearing this in mind, the federal court will be asked to determine whether the wind farms complied with their generator performance standards and if not, whether this breach had a “material adverse effect” on power security.

This will be difficult to prove, because even if the generator standards require the wind farms to evaluate the point at which their protective triggers activated, it is unlikely the number of faults, the severity of the voltage dip, and the impact of the increased power flow on the Heywood interconnector could have been anticipated.




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The idea AEMO could have prevented the blackout if the wind farms had alerted it to the disruptive potential of their protective triggers is probably a little remote.

None of the participants could have foreseen the series of interconnected events leading to the blackout. Whilst lessons can be learned, laying blame is more complex. And while compliance with standards and rules is important, in this instance, it is unlikely that it would have changed the outcome.The Conversation

Samantha Hepburn, Director of the Centre for Energy and Natural Resources Law, Deakin Law School, Deakin University

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

Taller, faster, better, stronger: wind towers are only getting bigger



Wind towers are getting taller.
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Con Doolan, UNSW

Former Australian Greens leader Bob Brown made headlines this week after he objected to a proposed wind farm on Tasmania’s Robbins Island. The development would see 200 towers built, each standing 270 metres from base to the tip of their blades.

Leaving aside the question of the Robbins Island development, these will be extraordinarily tall towers. However, they fit right in with the current trend for wind turbines.




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Wind turbines come in many designs, but the most common is the so-called “horizontal axis” kind, which look like giant fans on poles. This type of turbine is highly efficient at turning the energy in the wind into electrical energy.

Keen observers will have noticed that these turbines have been gaining in size over the years. In the 1990s, wind turbines typically had hub heights and rotor diameters of the order of 30m. Today, hub heights and rotor diameters are pushing well past 100m.



Shutterstock/The Conversation

Bigger is better

When it comes to wind turbines, bigger is definitely better. The bigger the radius of the rotor blades (or diameter of the “rotor disc”), the more wind the blades can use to turn into torque that drives the electrical generators in the hub. More torque means more power. Increasing the diameter means that not only more power can be extracted, but it can be done so more efficiently.

Larger and longer turbine blades mean greater aerodynamic efficiency. Creating more power in one turbine means less energy is lost as it is moved into the transmission system, and from there into the electrical generator. The economies of scale provide an overwhelming push for wind energy companies to develop larger rotor blades.




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Wind turbines are also growing taller because of the way wind travels around the world. Because air is viscous (like very thin honey) and “sticks” to the ground, the wind velocity at higher altitudes can be many times higher than at ground level.

Hence it is advantageous to put the turbine high in the sky where there is more energy to extract. Hilly terrain (like a mountain ridge) may also distort the wind, requiring engineers to design the wind turbines to be even taller to catch the wind. Wind turbines used offshore are generally larger and taller because of the higher levels of wind energy available at sea.

Typically, onshore turbines (most common in Australia) have blades between 40m and 90m long. Tower heights are usually in the range of 150m. Offshore turbines (those situated at sea and common in Europe) are much larger.

Offshore turbines are typically much larger than onshore towers.
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One of the largest wind turbine designs in the world, General Electric’s offshore 12-megawatt Haliade-X, has 107m blades and a total height of 260m. As a comparison, Sydney’s Centrepoint tower is 309m tall.

If the Robbins Island turbines are indeed built to 270m, as reported in the media, they would eclipse General Electric’s behemoths. I cannot speak to the likelihood of this, but I would assume engineers will have to select the best turbine for the prevailing wind conditions and existing infrastructure.

Challenging heights

The quest for bigger and taller turbines comes with its fair share of engineering challenges.

Longer blades are more flexible than shorter ones, which can create vibration. If not controlled, this vibration affects performance and reduces the life of the blades and anything they are attached to, such as the gearbox or generator.

Materials and manufacturing techniques are constantly being refined to create longer, and longer-lasting, turbine blades.

The longer the turbine’s blades, the more pressure is put on internal mechanisms.
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Taller turbines generate more power, which puts greater loads on the gearbox and transmission system, requiring mechanical engineers to develop new ways of converting the ever-increasing torque into electrical power. Taller wind turbines also need stronger support towers and foundations. The list of challenges is long.

As turbines grow, so too does the noise they make. The dominant source of noise occurs at the outer edge of the blades. Here, turbulence caused by the blade itself creates a “hissing” sound as it passes over the trailing edge. More noise is created when the blade chops through atmospheric turbulence in the wind as it blows into the tower.

Noise isn’t just a matter of size. If one turbine is placed in the wake of another, the sound of its blades passing through the highly turbulent air created by the upstream turbine will be very loud.

Keeping noise under control requires inventive solutions, such as borrowing ideas from nature: the silent-flying owl uses serrated feathers to control noise and these are now being used to make noisy turbines quieter.




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Of course, engineering challenges are not the only considerations for creating wind farms. Environmental effects, noise, visual impacts and other community concerns all need to be considered, as with any large infrastructure project. But wind turbines are one of the most cost-effective and technologically sophisticated forms of renewable energy, and as the developed world comes to grips with climate change we will only see more of them.The Conversation

Con Doolan, Professor, School of Mechanical and Manufacturing Engineering, UNSW

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

Wind Energy: Cost Benefits


The link below is to an article that claims wind energy is half the cost of coal.

For more visit:
http://reneweconomy.com.au/2012/the-true-cost-of-electricity-why-wind-is-half-price-of-coal-73416