Australia is the runaway global leader in building new renewable energy


Matthew Stocks, Australian National University; Andrew Blakers, Australian National University, and Ken Baldwin, Australian National University

In Australia, renewable energy is growing at a per capita rate ten times faster than the world average. Between 2018 and 2020, Australia will install more than 16 gigawatts of wind and solar, an average rate of 220 watts per person per year.

This is nearly three times faster than the next fastest country, Germany. Australia is demonstrating to the world how rapidly an industrialised country with a fossil-fuel-dominated electricity system can transition towards low-carbon, renewable power generation.

Renewable energy capacity installations per capita.
International capacity data for 2018 from the International Renewable Energy Agency. Australian data from the Clean Energy Regulator., Author provided

When the Clean Energy Regulator accredited Tasmania’s 148.5 megawatt (MW) Cattle Hill Wind Farm in August, Australia met its Renewable Energy Target well ahead of schedule.




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Australia has met its renewable energy target. But don’t pop the champagne


We have analysed data from the regulator which tracks large- and small-scale renewable energy generation (including credible future projects), and found the record-high installation rates of 2018 will continue through 2019 and 2020.

Record renewable energy installation rates

While other analyses have pointed out that investment dollars in renewable energy fell in 2019, actual generation capacity has risen. Reductions in building costs may be contributing, as less investment will buy you more capacity.

Last year was a record year for renewable energy installations, with 5.1 gigawatts (GW) accredited in 2018, far exceeding the previous record of 2.2GW in 2017.

The increase was driven by the dramatic rise of large-scale solar farms, which comprised half of the new-build capacity accredited in 2018. There was a tenfold increase in solar farm construction from 2017.

We have projected the remaining builds for 2019 and those for 2020, based on data from the Clean Energy Regulator for public firm announcements for projects.

A project is considered firm if it has a power purchase agreement (PPA, a contract to sell the energy generated), has reached financial close, or is under construction. We assume six months for financial close and start of construction after a long-term supply contract is signed, and 12 or 18 months for solar farm or wind farm construction, respectively.

This year is on track to be another record year, with 6.5GW projected to be complete by the end of 2019.

The increase is largely attributable to a significant increase in the number of wind farms approaching completion. Rooftop solar has also increased, with current installation rates putting Australia on track for 1.9GW in 2019, also a new record.

This is attributed to the continued cost reductions in rooftop solar, with less than A$1,000 per kilowatt now considered routine and payback periods of the order of two to seven years.

Current (solid) and forecast (hashed) installations of renewable electricity capacity in Australia.
Author provided

Looking ahead to 2020, almost 6GW of large-scale projects are expected to be completed, comprising 2.5GW of solar farms and 3.5GW of wind. Around the end of 2020, this additional generation would deliver the old Renewable Energy Target of 41,000 gigawatt hours (GWh) per annum. That target was legislated in 2009 by the Rudd Labor government but reduced to 33,000GWh by the Abbott Coalition government in 2015.

Maintaining the pipeline

There are strong prospects for continued high installation rates of renewables. Currently available renewable energy contracts are routinely offering less than A$50 per MWh. Long-term contracts for future energy supply have an average price of more than A$58 per MWh. This is a very reasonable profit margin, suggesting a strong economic case for continued installations. Wind and solar prices are likely to decline further throughout the 2020s.

State governments programs are also supporting renewable electricity growth. The ACT has completed contracts for 100% renewable electricity. Victoria and Queensland both have renewable energy targets of 50% renewable electricity by 2030. South Australia is expecting to reach 100% by 2025.

The main impediment to continued renewables growth is transmission. Transmission constraints have resulted in bottlenecks in moving electricity from some wind and solar farms to cities.

Tasmania’s strong wind resource requires a new connection to the mainland to unlock more projects. The limitations of current planning frameworks for this transition were recognised in Chief Scientist Alan Finkel’s review of the National Electricity Market, with strong recommendations to overcome these problems and, in particular, to strengthen the role of the Australian Energy Market Operator.




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Now we need state and federal governments to unlock or directly support transmission expansion. For example, the Queensland government has committed to supporting new transmission to unlock solar and wind projects in the far north, including the Genex/Kidston 250MW pumped hydro storage system. The New South Wales government will expedite planning approval for an interconnector between that state and South Australia, defining it as “critical infrastructure”.

These investments are key to Australia maintaining its renewable energy leadership into the next decade.The Conversation

Matthew Stocks, Research Fellow, ANU College of Engineering and Computer Science, Australian National University; Andrew Blakers, Professor of Engineering, Australian National University, and Ken Baldwin, Director, Energy Change Institute, Australian National University

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

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We can make roof tiles with built-in solar cells – now the challenge is to make them cheaper



This, except printed directly onto your roof tiles.
Cole Eaton Photography/Shutterstock

Md Abdul Alim, Western Sydney University; Ataur Rahman, Western Sydney University, and Zhong Tao, Western Sydney University

Despite being such a sunkissed country, Australia is still lagging behind in the race to embrace solar power. While solar panels adorn hundreds of thousands of rooftops throughout the nation, we have not yet seen the logical next step: buildings with solar photovoltaic cells as an integral part of their structure.

Our lab is hoping to change that. We have developed solar roof tiles with solar cells integrated on their surface using a specially customised adhesive. We are now testing how they perform in Australia’s harsh temperatures.

Our preliminary test results suggest that our solar roof tiles can generate 19% more electricity than conventional solar panels. This is because the tiles can absorb heat energy more effectively than solar panels, meaning that the tiles’ surface heats up more slowly in sustained sunshine, allowing the solar cells more time to work at lower temperatures.

The solar roof tile.

Australia’s greenhouse emissions continue to rise, making it harder to meet its commitments under the Paris agreement.

Globally, commercial and residential buildings account for about 40% of energy consumption. Other countries are therefore looking hard at reducing their greenhouse emissions by making buildings more energy-efficient. The European Union, for example, has pledged to make all large buildings carbon-neutral by 2050. Both Europe and the United States are working on constructing buildings from materials that can harness solar energy.

Here in Australia, buildings account for only about 20% of energy consumption, meaning that the overall emissions reductions on offer from improved efficiency are smaller.

That’s not to say that we shouldn’t go for it anyway, especially considering the amount of sunshine available. Yet compared with other nations, Australia is very much in its adolescence when it comes to solar-smart construction materials.




Read more:
New solar cells offer you the chance to print out solar panels and stick them on your roof


Taking Australia’s temperature

In a recent review in the journal Solar Energy, we identified and discussed the issues that are obstructing the adoption of solar power-generating constructions – known as “building-integrated photovoltaics”, or BIPV – here in Australia.

According to the research we reviewed, much of the fear about adopting these technologies comes down to a simple lack of understanding. Among the factors we identified were: misconceptions about the upfront cost and payback time; lack of knowledge about the technology; anxiety about future changes to buildings’ microclimates; and even propaganda against climate change and renewable energy.




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Worldwide, BIPV systems account for just 2.5% of the solar photovoltaic market (and virtually zero in Australia). But this is forecast to rise to 13% globally by 2022.

Developing new BIPV technologies such as solar roof tiles and solar façades would not only cut greenhouse emissions but also open up huge potential for business and the economy.

According to a national survey (see the entry for Australia here), Australian homeowners are still much more comfortable with rooftop solar panels than other systems such as ground-mounted ones.

In our opinion it therefore stands to reason that if we want to boost BIPV systems in Australia, our solar roof tiles are the perfect place to start. Our tiles have a range of advantages, such as low maintenance, attractive look, easy replaceability, and no extra load on the roof compared with conventional roof-mounted solar arrays.

Challenges ahead

Nevertheless, the major challenges for this technology are the current high cost, poor consumer awareness, and lack of industrial-scale manufacturing process. We made our tiles with the help of a 3D printing facility at Western Sydney University, which can be attached to an existing tile manufacturing machine with minor modifications.

The current installation cost of commercial solar tiles could be as high as A$600 per square metre, including the inverter.

What’s more, we have little information on how the roof tiles will perform in long-term use, and no data on whether solar tiles will have an effect on conditions inside the building. It is possible that the tiles could increase the temperature inside, thus increasing the need for air conditioning.




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To answer these questions, we are carrying out a full life-cycle cost analysis of our solar tiles, as well as working on ways to bring down the cost. Our target is to reduce the cost to A$250 per square metre or even less, including the inverter. Prices like that would hopefully give Australian homeowners the power to put solar power into the fabric of their home.


The lead author thanks Professor Bijan Samali for valued supervision of his research.The Conversation

Md Abdul Alim, Postdoctoral researcher on sustainable development (Energy and Water), Western Sydney University; Ataur Rahman, Associate Professor, Western Sydney University, and Zhong Tao, Professor, Western Sydney University

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

Australia has met its renewable energy target. But don’t pop the champagne



Wind energy has played a major role in Australia’s fulfilment of the renewable energy target.
Olivier Hoslet/AAP

Dylan McConnell, University of Melbourne

A wind farm project in Tasmania this week helped Australia reach something of a milestone, nudging it over the line to reach its renewable energy target.

The Clean Energy Regulator announced it had approved capacity from the 148.5 megawatt Cattle Hill wind farm project, meaning the nation’s Large-scale Renewable Energy Target will be fulfilled.

Federal energy and emissions reduction minister Angus Taylor seized on the development, suggesting it showed the government’s record investment in renewable energy was world-leading.

Energy and Emissions Reduction Minister Angus Taylor said renewables investment would continue to grow.
AAP

Taylor has previously declared his government will not extend the target – the primary national mechanism supporting renewable energy. But this week he insisted “investment is not slowing down”.

This bold claim flies in the face of the evidence. Investment in new renewable energy capacity is slowing down.

Losing momentum: Australian renewables investment has cooled in 2019.
Bloomberg New Energy Finance

The latest data from Bloomberg New Energy Finance clearly shows a 21% drop in investment from the 2018 to 2019 financial years.

As Australia’s emissions reduction task becomes ever more urgent, the investment downturn begs the question: what happens next?

In fact, Australia cruised over the line

It is ironic that the Morrison government rushed to claim a win on the renewable energy target when many in the Coalition had claimed it would be difficult to meet, or wanted it scrapped altogether.

The policy involved tradeable certificates which created a financial incentive for new or expanded renewable energy power stations, such as wind and solar farms.

Under the target just met, 33 terrawatt-hours (TWh) of Australia’s electricity would be produced by new renewables by 2020, bringing the total share of renewable energy to about 23.5%.

Mount Majura Solar farm near Canberra.
AAP/Lucas Cochleae



Read more:
At its current rate, Australia is on track for 50% renewable electricity in 2025


The target was established by the Rudd Labor governmentand overhauled by the Abbott Coalition government after it came to power. It commissioned a contentious review of the target, then in 2015 reduced it to 33TWh after protracted negotiations with Labor.

As it transpired, that target was easily met. But the then industry minister Ian Macfarlane described the task as an “enormous challege”, and industry figures suggested the required wind energy was “almost impossible”. Even Taylor initially said the target was “too high”.

The cut itself was bad enough for the renewable energy industry. But the uncertainty created during the review devastated investment.

Renewable energy investment in Australia. There was a drop in investment during the review of the target, and a significant uptick once the bipartisan ship and a new target was restored. [Available from: https://www.abc.net.au/news/2018-01-18/renewable-energy-investment-in-australia/9339350%5D
BNEF

Investment did boom following bipartisan support for the new, lower target. But we can only speculate what may have been possible without the uncertainty created by the review.

It’s not looking rosy for renewables

The drop-off in investment is a worrying trend for the renewable energy industry, and for climate action more broadly. We can expect a drop-off in new additions in capacity in line with the drop in investment.

Australian Energy Market Commission data showing committed renewable energy projects for the next 12-18 months.

The table above shows the current committed projects for next 12-18 months. While more projects are likely to be committed over the next 18 months, it’s hard to see the peak of 2018 repeated soon, particularly with investment dropping away.

The achievement of the renewable energy target leaves a federal policy void. Renewable energy may now be the lowest-cost source of new electricity supply. But it is competing against assets such as coal-fired power stations with sunk costs – meaning that new renewables projects are essentially competing only with a coal plant’s fuel costs. Absent a price on carbon or similar policy, coal assets are allowed to pollute the atmosphere for free.

The renewable energy target has helped displace fossil fuel-derived power from the electricity mix.
AAP



Read more:
Making Australia a renewable energy exporting superpower


What next?

There are lessons to be learned from Germany to ensure a less bumpy transition to a decarbonised electricity sector. “Deployment corridors” help make the development of renewable energy sources more predictable, improve integration into the power system, and keep additional costs to consumers manageable.

But unless emissions-intensive generation closes or renewable energy support is reintroduced, renewable energy expansion in Australia is unlikely to proceed at the pace required to meet the Paris targets. Keeping the global average temperature rise well below 2℃ requires “rapid and profound near-term decarbonisation of energy supply” and strong upscaling of renewables.

The states are attempting to fill the federal policy gap. Several have their own renewable energy support schemes and all states in the east coast’s National Electricity Market have committed to net zero emissions by 2050.

A coal station in Victoria’s Latrobe Valley.
Julian Smith/AAP

Continued renewables growth also requires transmission infrastructure and storage technologies to ensure the distributed energy can be delivered where it is needed, and that reliability is maintained. Several states have also recently committed resources to transmission investment.




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The state-led action calls into question the effectiveness of the Council of Australian Governments’ (COAG) energy council. The group comprises the nation’s energy ministers and claims to maintain national “policy leadership” on energy. However it hasn’t met in almost nine months and its overarching agreement is more then 15 years old, and doesn’t refer to environmental outcomes or emissions cuts.

A new direction for the council is probably wishful thinking in the current political environment. But as emissions continue to rise in Australia, the need for significant reform only intensifies.The Conversation

Dylan McConnell, Researcher at the Australian German Climate and Energy College, University of Melbourne

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

We need a national renewables approach, or some states – like NSW – will miss out



In the absence of federal policy, states are pursing their own renewable targets.
Karsten Würth/Unsplash

Scott Hamilton, University of Melbourne; Changlong Wang, University of Melbourne, and Roger Dargaville, Monash University

Australia’s primary federal renewable energy target – to have 33 terawatts of renewable energy by 2020 – has essentially been achieved. There is much uncertainty as to what is next.

In the absence of a new national target, the states have been leading the way and driving renewable energy in Australia. Victoria, New South Wales and Queensland between them have invested some A$20 billion into building 11,400 megawatts of generation capacity.

While the states have worked admirably to advance renewable energy – and federal energy policy has long been politically toxic – there is a clear cost to pursuing many fragmented policies instead of a unified vision.

Our research, modelling the effect of state versus national renewable energy targets in the National Energy Market system found there was little difference in the overall cost, but that states without strong renewable targets tended to miss out on investment.

We need national thinking

Most jurisdictions have net zero emissions targets by 2050. States also have ambitious but achievable shorter-term renewable energy targets and programs.

There are plenty of arguments for states pursuing their own renewable energy targets, not least because they can fill the policy vacuum left at the national level.

States are responding to the immediate need to replace retiring power stations and can explore innovation with greater ambition. It makes perfect sense for states to compete to attract jobs and investment.

But Australia’s federal government has a domestic and international obligation to reduce greenhouse gas emissions from fossil fuels. National policies are more efficient, can harness better resources across our diverse geography and maximise returns for the whole system.

What’s more – as many column inches have pointed out – strong federal policy improves investment certainty and reliability, lowering the cost of inevitable infrastructure upgrades. And those upgrades can be better integrated into our existing national electricity system if the building (and money) doesn’t stop at internal borders.

To provide some insight and help move the debate forward, the University of Melbourne, Monash University and the Australian-German Energy Transition Hub have collaborated on research that was presented at an international conference in Denmark earlier this year.

Quantifying the difference

We simulated two scenarios: first, that all states implement polices to achieve their respective renewable energy and net zero emissions targets by 2050.

The second scenario assumed a national target would be used to result in the “same outcome” of 100% renewable energy by 2050.

The model calculates required energy investments with 5-year increments from today to 2050, including considering the existing generation currently operating. The model simultaneously optimises the mix of generation, transmission and storage to minimise the total system cost from 2020 to 2050.

A key difference in results is where and when new generation is built. Under the state-driven approach, unsurprisingly, investment shifts towards states with more ambitious targets.

The two figures below show how state-based targets drive more investment into Queensland than would be the case under a national target scheme.

Spatial distribution of renewable generation

Broadly speaking, under a national target, we see more efficient use of renewable energy and associated resources. NSW – with net zero 2050 target but no interim renewable energy target – would get a greater share of the renewable energy investment.

Change in energy generation %

NSW would consistently see substantially more investment under a national target scheme. This would be around 20% more generation in the 2030s in NSW, and up to 20 terawatt-hours more energy generated in the years 2030 to 2045.

The rollout of “where and when” to build new renewable and other generation to replace ageing fossil fuel power plants also impacts heavily on the sequencing and timing for major transmission upgrades across the NEM – especially interconnectors between states.

Transmission networks modelled.

The graph shows that under a state target based approach we build more transmission infrastructure earlier than under a national approach. Under a national target approach, we would end up building more transmission infrastructure – albeit later.

Again, broadly speaking, we would build more generation at renewable energy resource-rich areas such as NSW which happen to be near major demand centres like cities. This would delay the need for some infrastructure spend.

What about system reliability and energy costs?

The good news is it appears under either a state-based or a national target approach the outcome in 2050 is similar. The difference in total system costs is only about 1% higher in the state-based targets scenario – so, virtually nothing.

Evolution of electricity generation – total system.

State-based renewable energy targets lead to redistribution of renewable investments in favour of the states with a mid-term renewable energy target.

In the Australian context, the current state-based renewable energy targets have no impact on undermining power system reliability and virtually negligible impact on pushing up power prices.

Perhaps NSW should take particular note – as it would appear that it would benefit greatly from either a national target approach or an interim state target for itself.

The debate about state versus national approaches to energy policy has been going for the past 30 years and no doubt will be around for another 30. In the meantime, we need a stronger hand on the transition tiller or we will waste precious resources and time, and likely have major unintended consequences.




Read more:
Making Australia a renewable energy exporting superpower


The Conversation


Scott Hamilton, Strategic Advisory Panel Member, Australian-German Energy Transition Hub, University of Melbourne; Changlong Wang, Researcher, The Energy Transition Hub, University of Melbourne, and Roger Dargaville, Senior lecturer, Monash University

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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What caused South Australia’s state-wide blackout?


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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South Australian blackout: renewables aren’t a threat to energy security, they’re the future


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.
Shutterstock

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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Are public objections to wind farms overblown?


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.
Shutterstock

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.
Shutterstock

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.

Five gifs that explain how pumped hydro actually works


Roger Dargaville, Monash University

People have used moving water to create energy for thousands of years. Today, pumped hydro is the most common form of grid-connected energy storage in the world.

This technology is in the spotlight because it pairs so well with solar and wind renewable energy. During the day, when solar panels and wind farms may be generating their highest level of energy, people don’t need really need much electricity. Unless it is stored somewhere the energy is lost.




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Pumped hydro can cheaply and easily store the excess energy, releasing it again at night when demand rises.

Here’s how it all works:

How it works

Put as simply as possible, it involves pumping water to a reservoir at the top of a hill when energy is in plentiful supply, then letting it flow back down through a turbine to generate electricity when demand increases.

Like all storage systems, you get less energy out than you put in – in this case, generally around 80% of the original input – because you lose energy to friction in the pipes and turbine as well as in the generator. For comparison, lithium ion batteries are around 90-95% efficient, while hydrogen energy storage is less than 50% efficient

The benefit is we can store a lot of energy at the top of the hill and keep it there in a reservoir until we need the energy back again. Then it can be released through the pipes (this is called “penstock”) to generate electricity. This means pumped hydro can create a lot of additional electricity when demand is high (for example, during a heatwave).

The disadvantage of pumped hydro is you need to have two reservoirs separated by a significant elevation difference (more than 200m is typically required, more than 300m is ideal). So it doesn’t work where you don’t have hills. However, research has identified 22,000 potential sites in Australia.




Read more:
Want energy storage? Here are 22,000 sites for pumped hydro across Australia


Pumped hydro is traditionally paired with relatively inflexible coal or nuclear power stations, using under-utilised electricity when demand is low (weekends and nighttime), then providing additional generation when demand increases during the day and into the evening.

With the rapid increase in deployment of wind and solar, pumped hydro is again gaining interest. This is because the output of wind and solar plant is subject to the variability in the weather. For example, solar power plants generate the most electricity in the middle of the day, while demand for electricity is often highest in the evening. The wind might die down for hours or even days, then suddenly blow a gale. Pumped hydro can play a key role in smoothing out this variability.

If the electricity being produced by wind and solar plant is greater than demand, then the energy has to be curtailed (and is lost), unless we have a way to store it. Using this excess power to pump water up hill means the solar or wind energy is not wasted and the water can be held in reservoirs until demand rises in the evening.

There are lots of different kinds of energy storage technologies, each with their own advantages and disadvantages. For large-scale grid-connected systems where many hours of storage are required, pumped hydro is the most economically viable option.




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Snowy Hydro gets a boost, but ‘seawater hydro’ could help South Australia


The Conversation


Roger Dargaville, Senior lecturer, Monash University

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