Wind turbines off the coast could help Australia become an energy superpower, research finds

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Sven Teske, University of Technology Sydney; Chris Briggs, University of Technology Sydney; Mark Hemer, CSIRO; Philip Marsh, University of Tasmania, and Rusty Langdon, University of Technology SydneyOffshore wind farms are an increasingly common sight overseas. But Australia has neglected the technology, despite the ample wind gusts buffeting much of our coastline.

New research released today confirms Australia’s offshore wind resources offer vast potential both for electricity generation and new jobs. In fact, wind conditions off southern Australia rival those in the North Sea, between Britain and Europe, where the offshore wind industry is well established.

More than ten offshore wind farms are currently proposed for Australia. If built, their combined capacity would be greater than all coal-fired power plants in the nation.

Offshore wind projects can provide a win-win-win for Australia: creating jobs for displaced fossil fuel workers, replacing energy supplies lost when coal plants close, and helping Australia become a renewable energy superpower.

Australia’s potential for offshore wind rivals the North Sea’s.
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The time is now

Globally, offshore wind is booming. The United Kingdom plans to quadruple offshore wind capacity to 40 gigawatts (GW) by 2030 – enough to power every home in the nation. Other jurisdictions also have ambitious 2030 offshore wind targets including the European Union (60GW), the United States (30GW), South Korea (12GW) and Japan (10GW).

Australia’s coastal waters are relatively deep, which limits the scope to fix offshore wind turbines to the bottom of the ocean. This, combined with Australia’s ample onshore wind and solar energy resources, means offshore wind has been overlooked in Australia’s energy system planning.

But recent changes are producing new opportunities for Australia. The development of larger turbines has created economies of scale which reduce technology costs. And floating turbine foundations, which can operate in very deep waters, open access to more windy offshore locations.

More than ten offshore wind projects are proposed in Australia. Star of the South, to be built off Gippsland in Victoria, is the most advanced. Others include those off Western Australia, Tasmania and Victoria.

Floating wind turbines can operate in deep waters.
SAITEC

Our findings

Our study sought to examine the potential of offshore wind energy for Australia.

First, we examined locations considered feasible for offshore wind projects, namely those that were:

• less than 100km from shore
• within 100km of substations and transmission lines (excluding environmentally restricted areas)
• in water depths less than 1,000 metres.

Wind resources at those locations totalled 2,233GW of capacity and would generate far more than current and projected electricity demand across Australia.

Second, we looked at so-called “capacity factor” – the ratio between the energy an offshore wind turbine would generate with the winds available at a location, relative to the turbine’s potential maximum output.

The best sites were south of Tasmania, with a capacity factor of 80%. The next-best sites were in Bass Strait and off Western Australia and North Queensland (55%), followed by South Australia and New South Wales (45%). By comparison, the capacity factor of onshore wind turbines is generally 35–45%.

Average annual wind speeds in Bass Strait, around Tasmania and along the mainland’s southwest coast equal those in the North Sea, where offshore wind is an established industry. Wind conditions in southern Australia are also more favourable than in the East China and Yellow seas, which are growth regions for commercial wind farms.

Average wind speed (metres per second) from 2010-2019 in the study area at 100 metres.
Authors provided

Next, we compared offshore wind resources on an hourly basis against the output of onshore solar and wind farms at 12 locations around Australia.

At most sites, offshore wind continued to operate at high capacity during periods when onshore wind and solar generation output was low. For example, meteorological data shows offshore wind at the Star of the South location is particularly strong on hot days when energy demand is high.

Australia’s fleet of coal-fired power plants is ageing, and the exact date each facility will retire is uncertain. This creates risks of disruption to energy supplies, however offshore wind power could help mitigate this. A single offshore wind project can be up to five times the size of an onshore wind project.

Some of the best sites for offshore winds are located near the Latrobe Valley in Victoria and the Hunter Valley in NSW. Those regions boast strong electricity grid infrastructure built around coal plants, and offshore wind projects could plug into this via undersea cables.

And building wind energy offshore can also avoid the planning conflicts and community opposition which sometimes affect onshore renewables developments.

Global average wind speed (metres per second at 100m level.
Authors provided

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Winds of change

Our research found offshore wind could help Australia become a renewable energy “superpower”. As Australia seeks to reduce its greenhouse has emissions, sectors such as transport will need increased supplies of renewable energy. Clean energy will also be needed to produce hydrogen for export and to manufacture “green” steel and aluminium.

Offshore wind can also support a “just transition” – in other words, ensure fossil fuel workers and their communities are not left behind in the shift to a low-carbon economy.

Our research found offshore wind could produce around 8,000 jobs under the scenario used in our study – almost as many as those employed in Australia’s offshore oil and gas sector.

Many skills used in the oil and gas industry, such as those in construction, safety and mechanics, overlap with those needed in offshore wind energy. Coal workers could also be re-employed in offshore wind manufacturing, port assembly and engineering.

Realising these opportunities from offshore wind will take time and proactive policy and planning. Our report includes ten recommendations, including:

• establishing a regulatory regime in Commonwealth waters
• integrating offshore wind into energy planning and innovation funding
• further research on the cost-benefits of the sector to ensure Australia meets its commitments to a well managed sustainable ocean economy.

If we get this right, offshore wind can play a crucial role in Australia’s energy transition.

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Sven Teske, Research Director, Institute for Sustainable Futures, University of Technology Sydney; Chris Briggs, Research Principal, Institute for Sustainable Futures, University of Technology Sydney; Mark Hemer, Principal Research Scientist, Oceans and Atmosphere, CSIRO; Philip Marsh, Post doctoral researcher, University of Tasmania, and Rusty Langdon, Research Consultant, University of Technology Sydney

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

An act of God, or just bad management? Why trees fall and how to prevent it

AP

Gregory Moore, The University of MelbourneThe savage storms that swept Victoria last week sent trees crashing down, destroying homes and blocking roads. Under climate change, stronger winds and extreme storms will be more frequent. This will cause more trees to fall and, sadly, people may die.

These incidents are sometimes described as an act of God or Mother Nature’s fury. Such descriptions obscure the role of good management in minimising the chance a tree will fall. The fact is, much can be done to prevent these events.

Trees must be better managed for several reasons. The first, of course, is to prevent damage to life and property. The second is to avoid unnecessary tree removals. Following storms, councils typically see a spike in requests for tree removals – sometimes for perfectly healthy trees.

A better understanding of the science behind falling trees – followed by informed action – will help keep us safe and ensure trees continue to provide their many benefits.

We must try to stop trees falling over to prevent damage to life and property.
James Ross/AAP

Why trees fall over

First, it’s important to note that fallen trees are the exception at any time, including storms. Most trees won’t topple over or shed major limbs. I estimate fewer than three trees in 100,000 fall during a storm.

Often, fallen trees near homes, suburbs and towns were mistreated or poorly managed in preceding years. In the rare event a tree does fall over, it’s usually due to one or more of these factors:

1. Soggy soil

In strong winds, tree roots are more likely to break free from wet soil than drier soil. In arboriculture, such events are called windthrow.

A root system may become waterlogged when landscaping alters drainage around trees, or when house foundations disrupt underground water movement. This can be overcome by improving soil drainage with pipes or surface contouring that redirects water away from trees.

You can also encourage a tree’s root growth by mulching around the tree under the “dripline” – the outer edge of the canopy from which water drips to the ground. Applying a mixed-particle-size organic mulch to a depth of 75-100 millimetres will help keep the soil friable, aerated and moist. But bear in mind, mulch can be a fire risk in some conditions.

Root systems can also become waterlogged after heavy rain. So when both heavy rain and strong winds are predicted, be alert to the possibility of falling trees.

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A combination of heavy rain and strong winds can cause trees to fall.
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2. Direct root damage

Human-caused damage to root systems is a common cause of tree failure. Such damage can include roots being:

• cut when utility services are installed
• restricted by a new road, footpath or driveway
• compacted over time, such as when they extend under driveways.

Trees can take a long time to respond to disturbances. When a tree falls in a storm, it may be the result of damage inflicted 10-15 years ago.

This elm, growing very close to a footpath, fell in Melbourne during a 2005 storm.
Author provided

3. Wind direction

Trees anchor themselves against prevailing winds by growing roots in a particular pattern. Most of the supporting root structure of large trees grows on the windward side of the trunk.

If winds come from an uncommon direction, and with a greater-than-usual speed, trees may be vulnerable to falling. Even if the winds come from the usual direction, if the roots on the windward side are damaged, the tree may topple over.

The risk of this happening is likely to worsen under climate change, when winds are more likely to come from new directions.

4. Dead limbs

Dead or dying tree limbs with little foliage are most at risk of falling during storms. The risk can be reduced by removing dead wood in the canopy.

Trees can also fall during strong winds when they have so-called “co-dominant” stems. These V-shaped stems are about the same diameter and emerge from the same place on the trunk.

If you think you might have such trees on your property, it’s well worth having them inspected. Arborists are trained to recognise these trees and assess their danger.

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Storms can trigger falling trees which block roads.
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Trees are worth the trouble

Even with the best tree management regime, there is no guarantee every tree will stay upright during a storm. Even a healthy, well managed tree can fall over in extremely high winds.

While falling trees are rare, there are steps we can take to minimise the damage they cause. For example, in densely populated areas, we should consider moving power and communications infrastructure underground.

By now, you may be thinking large trees are just too unsafe to grow in urban areas, and should be removed. But we need trees to help us cope with storms and other extreme weather.

Removing all trees around a building can cause wind speeds to double, which puts roofs, buildings and lives at greater risk. Removing trees from steep slopes can cause the land to become unstable and more prone to landslides. And of course, trees keep us cooler during summer heatwaves.

Victoria’s spate of fallen trees is a concern, but removing them is not the answer. Instead, we must learn how to better manage and live with them.

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Gregory Moore, Doctor of Botany, The University of Melbourne

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

How rain, wind, heat and other heavy weather can affect your internet connection

Gordonekoff / Shutterstock

James Jin Kang, Edith Cowan University and Paul Haskell-Dowland, Edith Cowan UniversityWhen your Netflix stream drops out in the middle of a rainstorm, can you blame the wild weather?

Quite possibly. The weather can affect the performance of your internet connection in a variety of ways.

This can include issues such as physical damage to the network, water getting into electrical connections, and wireless signal interference. Some types of connection are more vulnerable to weather than others.

The behaviour of other humans in response to the weather can also have an effect on your connection.

How rain can affect your internet connection

Internet connections are much more complicated than the router and cables in our homes. There are many networking devices and cables and connections (of a variety of types and ages) between our homes and the websites we are browsing.

How do we connect to the Internet?

An internet connection may involve different kinds of physical link, including the copper wiring used in the old phone network and more modern fibre optic connections. There may also be wireless connections involved, such as WiFi, microwave and satellite radio.

Example of multi-layered internet access.
Ferran, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Rain can cause physical damage to cables, particularly where telecommunication networks are using old infrastructure.

ADSL-style connections, which use the old phone network, are particularly vulnerable to this type of interference. Although many Australians may be connected to the National Broadband Network (NBN), this can still run (in part) through pre-existing copper wires (in the case of “fibre to the node” or “fibre to the cabinet” connections) rather than modern optical fibres (“fibre to the home”).

Different types of NBN connection.
Riick, CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons

Much of the internet’s cabling is underground, so if there is flooding, moisture can get into the cables or their connectors. This can significantly interfere with signals or even block them entirely, by reducing the bandwidth or causing an electrical short-circuit.

But it isn’t just your home connection that can be impacted. Wireless signals outside the home or building can be affected by rainfall as water droplets can partially absorb the signal, which may result in a lower level of coverage.

Even once the rain stops, the effects can still be felt. High humidity can continue to affect the strength of wireless signals and may cause slower connection speeds.

Copper cables and changed behaviour

If you are using ADSL or NBN for your internet connection, it is likely copper phone cables are used for at least some of the journey. These cables were designed to carry voice signals rather than data, and on average they are now more than 35 years old.

Only around 18% of Australian homes have the faster and more reliable optical-fibre connections.

There is also a behaviour factor. When it rains, more people might decide to stay indoors or work from home. This inevitably leads to an increase in the network usage. When a large number of people increase their internet usage, the limited bandwidth available is rapidly consumed, resulting in apparent slowdowns.

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This is not only within your home, but is also aggregated further up the network as your traffic is joined by that from other homes and eventually entire cities and countries.

Heatwaves and high winds

In Australia, extreme cold is not usually a great concern. Heat is perhaps a more common problem. Our networking devices are likely to perform more slowly when exposed to extreme heat. Even cables can suffer physical damage that may affect the connection.

Imagine your computer fan is not running and the device overheats — it will eventually fail. While the device itself may be fine, it is likely the power supply will struggle in extremes. This same issue can affect the networking equipment that controls our internet connection.

Satellite internet services for rural users can be susceptible to extreme weather, as the satellite signals have to travel long distances in the air.

Radio signals are not usually affected by wind, but hardware such as satellite dishes can be swayed, vibrated, flexed or moved by the wind.

Most of the time, human behaviour is the main cause

For most users, the impact of rain will be slight – unless they are physically affected by a significant issue such as submerged cables, or they are trying to use WiFi outside during a storm.

So, can weather affect your internet connection? Absolutely.

Will most users be affected? Unlikely.

So if your favourite Netflix show is running slow during in rainy weather, it’s most likely that the behaviour of other humans is to blame — holed up indoors and hitting the internet, just like you.

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James Jin Kang, Lecturer, Computing and Security, Edith Cowan University and Paul Haskell-Dowland, Associate Dean (Computing and Security), Edith Cowan 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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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.

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.

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Shutterstock/The Conversation

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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.
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.

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.

Jupiter’s magnetic fields may stop its wind bands from going deep into the gas giant

The colorful cloud belts dominate Jupiter’s southern hemisphere in this image captured by NASA’s Juno spacecraft.
NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

Navid Constantinou, Australian National University

One of the most striking features of Jupiter – a gaseous giant with no solid surface – is the coloured bands that encircle the planet.

These bands are so large and distinct that they can be seen from here on Earth using a modest telescope, and thus have fascinated astronomers since the era of Galileo.

In research published today in The Astrophysical Journal, Jeffrey Parker, from Lawrence Livermore National Laboratory in the United States, and I have developed a theory that could help explain what is going on beneath these bands and why they only go so deep into the planet.

The bands of Jupiter captured by an Earth-based astronomer.
NASA/Freddy Willems

Winds on Jupiter

These bands are actually strong steady winds, or jets, that flow in Jupiter’s atmosphere, carrying with them clouds of ammonia and other colourful elements. These jets are similar to the jet streams that flow high up in Earth’s atmosphere.

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But there is more to these jets than meets the eye. What goes on below Jupiter’s clouds is, to a large extent, still a mystery.

Although there exist many theories for how the jets on Jupiter form and how deep they penetrate beneath the clouds, until recently we had no direct observations to support them.

In mid-2016, NASA’s spacecraft Juno headed to Jupiter with a mission to approach the planet closer that any probe has done before. It reached distances of less than 4,500km above Jupiter’s clouds at its closest approach (about the distance from New York to Los Angeles).

Upon arrival, Juno began to make precise measurements of Jupiter’s gravitational and magnetic fields.

When the data started pouring in, it was found that the jets go as deep as 3,000km beneath Jupiter’s clouds, and then terminate. (This is about 5% of the planet’s radius at the equator.)

Only so deep for Jupiter’s bands.

This created a new puzzle for scientists: why do the jets penetrate as deep as they do, but no deeper?

Here is where our research comes into the picture. We have developed a theory that explains how magnetic fields have a tendency to shut down the jets.

What does this have to do with Jupiter?

Inside the gas giant

Jupiter’s gaseous bulk consists mostly of hydrogen and helium. As you go deep beneath the clouds into the interior, the pressure of the gas increases (similar to how the pressure increases when you dive deep into the ocean here on Earth).

Scientists understand that at about 3,000km below Jupiter’s clouds, the pressure is so high that electrons can get loose from the molecules of hydrogen and helium and start to move around freely, creating electric and magnetic fields.

Is it just a coincidence that this happens at about the same depth that the jets break down? Scientists speculate that it is not. As Steve Levin, Juno project scientist at NASA’s Jet Propulsion Laboratory, explains:

It’s very interesting that (the jets disappear at) about 3,000km, because that’s about where it might be conducting electricity enough to make a magnetic field.

So, it could be that the magnetic field has something to do with why the belts and zones only go that deep (…) But we don’t know this yet; this is just speculation.

Here is how our theory ties in. Using principles from statistical physics of turbulent systems, we devised a mathematical model which predicts that when magnetic fields are strong enough, the jets shut down.

Specifically, within our model a jet organises magnetic fluctuations in such a manner so that the coherent effect of these fluctuations acts to dampen the jet itself.

This offers a partial explanation as to why the jets terminate at about 3,000km below the clouds.

It’s hoped that theory and observation together will continue to give deeper insight on the physics of the universe as Juno and other probes, such as NASA’s new Parker Solar Probe, explore and gather data from our Solar system and beyond.

Navid Constantinou, Research fellow and researcher in climate and fluid physics, Australian National University

This article was originally published on The Conversation. Read the original article.

Australia’s Largest Wind Farm Approved in Queensland

The link below is to an article reporting on the approval of Australia’s largest wind farm in Queensland.

For more visit:
https://www.theguardian.com/environment/2018/jun/05/australias-largest-windfarm-wins-planning-approval

Wind farms are hardly the bird slayers they’re made out to be. Here’s why

The potential to harm local birdlife is often used to oppose wind farm development. But research into how birds die shows wind farms should be the least of our concerns.
from www.shutterstock.com

Simon Chapman, University of Sydney

People who oppose wind farms often claim wind turbine blades kill large numbers of birds, often referring to them as “bird choppers”. And claims of dangers to iconic or rare birds, especially raptors, have attracted a lot of attention.

Wind turbine blades do indeed kill birds and bats, but their contribution to total bird deaths is extremely low, as these three studies show.

A 2009 study using US and European data on bird deaths estimated the number of birds killed per unit of power generated by wind, fossil fuel and nuclear power systems.

It concluded:

wind farms and nuclear power stations are responsible each for between 0.3 and 0.4 fatalities per gigawatt-hour (GWh) of electricity while fossil-fuelled power stations are responsible for about 5.2 fatalities per GWh.

That’s nearly 15 times more. From this, the author estimated:

wind farms killed approximately seven thousand birds in the United States in 2006 but nuclear plants killed about 327,000 and fossil-fuelled power plants 14.5 million.

In other words, for every one bird killed by a wind turbine, nuclear and fossil fuel powered plants killed 2,118 birds.

A Spanish study involved daily inspections of the ground around 20 wind farms with 252 turbines from 2005 to 2008. It found 596 dead birds.

The turbines in the sample had been working for different times during the study period (between 11 and 34 months), with the average annual number of fatalities per turbine being just 1.33. The authors noted this was one of the highest collision rates reported in the world research literature.

Raptor collisions accounted for 36% of total bird deaths (214 deaths), most of which were griffon vultures (138 birds, 23% of total mortality). The study area was in the southernmost area of Spain near Gibraltar, which is a migratory zone for birds from Morocco into Spain.

Perhaps the most comprehensive report was published in the journal Avian Conservation and Ecology in 2013 by scientists from Canada’s Environment Canada, Wildlife Research Division.

Their report looked at causes of human-related bird deaths for all of Canada, drawing together data from many diverse sources.

The table below shows selected causes of bird death out of an annual total of 186,429,553 estimated deaths caused by human activity.

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Mark Duchamp, the president of Save the Eagles International is probably the most prominent person to speak out about bird deaths at wind farms. He says:

The average per turbine comes down to 333 to 1,000 deaths annually which is a far cry from the 2-4 birds claimed by the American wind industry or the 400,000 birds a year estimated by the American Bird Conservancy for the whole of the United States, which has about twice as many turbines as Spain.

Such claims from wind farm critics generally allude to massive national conspiracies to cover up the true size of the deaths.

And in Australia?

In Australia in 2006 a proposal for a 52-turbine wind farm plan on Victoria’s south-east coast at Bald Hills (now completed) was overruled by the then federal environment minister Ian Campbell.

He cited concerns about the future of the endangered orange-bellied parrot (Neophema chrysogaster), a migratory bird said to be at risk of extinction within 50 years. The Tarwin Valley Coastal Guardians, an anti wind farm group that had been opposing the proposed development.

Interest groups have regularly cited this endangered bird when trying to halt a range of developments.

These include a chemical storage facility and a boating marina. The proposed Westernport marina in Victoria happened to also be near an important wetland. But a professor in biodiversity and sustainability wrote:

the parrot copped the blame, even though it had not been seen there for 25 years.

Victoria’s planning minister at the time, Rob Hulls, described the Bald Hills decision as blatantly political, arguing the federal conservative government had been lobbied by fossil fuel interests to curtail renewable energy developments. Hulls said there had been:

some historical sightings, and also some potential foraging sites between 10 and 35 kilometres from the Bald Hills wind farm site that may or may not have been used by the orange-bellied parrot.

Perhaps the final word on this topic should go to the British Royal Society for the Protection of Birds. It built a wind turbine at its Bedfordshire headquarters to reduce its carbon emissions (and in doing so, aims to minimise species loss due to climate change). It recognised that wind power is far more beneficial to birds than it is harmful.

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Simon Chapman and Fiona Crichton’s book, Wind Turbine Syndrome: a communicated disease, will be published by Sydney University Press later this year.

Simon Chapman, Emeritus Professor in Public Health, University of Sydney

This article was originally published on The Conversation. Read the original article.

Alan Jones goes after wind farms again, citing dubious evidence

Simon Chapman, University of Sydney

Last week, Sydney radio announcer Alan Jones lambasted those concerned about climate change and what he called “renewable energy rubbish”.

Jones has been loose with the facts in the past, having been Factchecked in 2015 after confusing kilowatts with megawatts and quoting a cost for wind power he later confessed “where the 1502 [dollars per megawatt hour that he stated] comes from, I have absolutely no idea”.

Jones, who chaired the much hyped but poorly attended 2013 national rally against wind farms in June 2014 (see photo) told his listeners last week wind farms are “buggering up people’s health”.

He also said “harrowing evidence” had been given by sufferers to the 2014-15 Senate Select Committee on Wind Farms chaired by (now ex-) Senator John Madigan. He along with Bob Day, David Leyonhjelm, Chris Back and Nick Xenophon have been vocal opponents of wind farms.

Their report predictably savaged wind farms, while Labor Senator Anne Urquhart’s minority report was the only one I found to be evidence-based.

Jones then went on to interview Dr Mariana Alves-Periera, from the private Lusophona University in Portugal (world university ranking 1,805, and impact ranking 2,848) whom he described as a distinguished international figure.

She was “recognized internationally” and had published “over 50” scientific papers over 30 years, something of a modest output. Jones, who may or may not have read any of these publications, told listeners her findings were “indisputable”, there was “no opposing scientific evidence” and again in emphasis, “none of [her papers] have been disputed” to which Alves-Periera agreed instantly “no they haven’t”.

This is an interesting interpretation of the scientific reception that has greeted the work of the Lisbon group on the unrecognized diagnosis of “vibroacoustic disease” (or VAD), a term they have made their own.

I first encountered Alves-Periera when she spoke via videoconference to a NHMRC meeting on wind farms and health in 2011. She spoke to a powerpoint presentation which highlighted the case of a schoolboy who lived near wind turbines. Her claim was the boy’s problems at school were due to his exposure to the turbines, as were cases of “boxy foot” in several horses kept on the same property.

Intrigued by this n=1 case report, I set out with a colleague to explore the scientific reception that “vibroacoustic disease” had met. We published our findings in the Australian and New Zealand Journal of Public Health 2013.

We found only 35 research papers on VAD. None reported any association between VAD and wind turbines. Of the 35 papers, 34 had a first author from the Lusophona University-based research group. Remarkably, 74% of citations to these papers were self-citations by members of the group.

In other words, just shy of three quarters of all references to VAD were from the group who were promoting the “disease”. In science, median self-citation rates are around 7%. We found two unpublished case reports from the group presented at conferences which asserted that VAD was “irrefutably demonstrated” to be caused by wind turbines. We listed eight reasons why the scientific quality of these claims were abject.

In 2014 Alves-Periera and a colleague defended their work in a letter to the journal and I replied. They described themselves as the “lead researchers in vibroacoustic disease”. But as we had shown, they are almost the only researchers who were ever active on this topic, with self-citation rates seldom seen in research.

Other experts have taken a different view of the group’s work. One of the world’s leading acousticians Geoff Leventhall who also spoke at the NHMRC’s 2011 meeting, wrote in a 2009 submission to the Public Service Commission of Wisconsin about the Lisbon group’s VAD work.

The evidence which has been offered [by them] is so weak that a prudent researcher would not have made it public.

Another expert said:

vibroacoustic disease remains an unproven theory belonging to a small group of authors and has not found acceptance in the medical literature

And most recently, the UK’s Health Protection Agency said the:

disease itself has not gained clinical recognition.

Leventhall concluded his review by saying:

One is left with a very uncomfortable feeling that the work of the VAD group, as related to the effects of low levels of infrasound and low frequency noise exposure, is on an extremely shaky basis and not yet ready for dissemination. The work has been severely criticised when it has been presented at conferences. It is not backed by peer reviewed publications and is available only as conference papers which have not been independently evaluated prior to presentation.

Jones told his listeners the reason wind turbines are not installed on Bondi Beach, down Sydney’s Macquarie Street or Melbourne’s Collins Street was because governments “know they are harmful to health”. His beguiling logic here might perhaps also be the same reason we don’t see these iconic locations given over to mining or daily rock concerts. Most people would understand there are other factors that explain the absence of both wind turbines, mines or daily rock concerts in such locations.

Jones has given air time to a Victorian woman who is a serial complainant about her local wind farm and who has written:

Around the Macarthur wind farm, residents suffer from infrasound emitted by the turbines, even when they’re not operating.

At a time when we are seeing unparalleled increases in renewable energy and reductions in fossil fuels all over the world, one wonders why this is still public discussion in Australia.

Simon Chapman, Emeritus Professor in Public Health, University of Sydney

This article was originally published on The Conversation. Read the original article.

Wind and solar PV have won the race – it’s too late for other clean energy technologies

Andrew Blakers, Australian National University

Across the world, solar photovoltaics (PV) and wind are the dominant clean energy technologies. This dominance is likely to become overwhelming over the next few years, preventing other clean energy technologies (including carbon capture and storage, nuclear and other renewables) from growing much.

As the graph below shows, PV and wind constitute half of new generation capacity installed worldwide, with fossil, nuclear, hydro and all other renewable energy sources making up the other half. In Australia this dominance is even clearer, with PV and wind constituting virtually all new generation capacity.

Moreover, this trend is set to continue. Wind and PV installation rates grew by 19% in 2015 worldwide, while rates for other technologies were static or declined.

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PV and wind dominate because they have already achieved commercial scale, are cheap (and set to get cheaper), and are not constrained by fuel availability, environmental considerations, construction materials, water supply, or security issues.

In fact, PV and wind now have such a large head start that no other low-emission generation technology has a reasonable prospect of catching them. Conventional hydro power cannot keep pace because each country will sooner or later run out of rivers to dam, and biomass availability is severely limited.

Heroic growth rates would be required for nuclear, carbon capture and storage, concentrating solar thermal, ocean energy and geothermal to span the 20- to 200-fold difference in annual installation scale to catch wind and PV – which are themselves growing rapidly.

Both wind and PV access massive economies of scale. Their ability to saturate national electricity markets around the world severely constrains other low-emission technologies. Some of the other technologies may become significant in some regions, but these will essentially be niche markets, such as geothermal in Iceland, or hydro power in Tasmania.

Around 80% of the energy sector could be electrified in the next two decades, including electrification of land transport (vehicles and public transport) and electric heat pumps for heat production. This will further increase opportunities for PV and wind, and allows for the elimination of two-thirds of greenhouse gas emissions (based upon sectoral breakdown of national emissions data).

Storage and integration

What about the oft-cited problems with the variable nature of photovoltaics and wind energy? Fortunately, there is range of solutions that can help them achieve high levels of grid penetration.

While individual PV and wind generators can have very variable outputs, the combined output of thousands of generators is in fact quite predictable when coupled with good weather forecasting and smoothed out over a wide area.

What’s more, PV and wind often produce power under different weather conditions – storms favour wind, whereas calm conditions are often sunny. Rapid improvements in high-voltage DC transmission allows large amounts of power to be transmitted cheaply and efficiently over thousands of kilometres, meaning that the impact of local weather is less important.

Another option is “load management”, in which power demands for things like domestic and commercial water heating, and household and electric car battery charging, are moved from night time to day to coincide with availability of sun and wind. Existing hydro and gas or biogas generators, operated for just a small fraction of the year, can also help.

Finally, mass power storage is already available in the form of pumped hydro energy storage (PHES), in which surplus energy is used to pump water uphill to a storage reservoir, which is then released through a turbine to recover around 80% of the stored energy later on. This technology constitutes 99% of electricity storage worldwide and is overwhelmingly dominant in terms of new storage capacity installed each year (3.4 Gigawatts in 2015).

Australia already has several PHES facilities, such as Wivenhoe near Brisbane and Tumut 3 in the Snowy Mountains. All of these are at least 30 years old, but more can be built to accommodate the storage needs of new wind and PV capacity. Modelling underway at the Australian National University shows that reservoirs containing enough water for only 3-8 hours of grid operation is sufficient to stabilise a grid with about 90% PV and wind – mostly to shift daytime solar power for use at night.

This would require only a few hundred hectares of reservoirs for the Australian grid, and could be accomplished by building a series of “off-river” pumped hydro storages. Unlike conventional “on-river” hydro power, off-river PHES requires pairs of hectare-scale reservoirs, rather like oversized farm dams, located in steep, hilly, farm country, separated by an altitude difference of 200-1000 metres, and joined by a pipe containing a pump and turbine.

One example is the proposed Kidston project in an old gold mine in north Queensland. In these systems water goes around a closed loop, they consume very little water (evaporation minus rainfall), and have a much smaller environmental impact than river-based systems.

How renewables can dominate Australian energy

In Australia, if wind and PV continue at the installation rate required to reach the 2020 renewable energy target (about 1 GW per year each), we would hit 50% renewable electricity by 2030. This rises to 80% if the installation rates double to 2 GW per year each under a more ambitious renewable energy target – the barriers to which are probably more political than technological.

PV and wind will be overwhelmingly dominant in the renewable energy transition because there isn’t time for another low-emission technology to catch them before they saturate the market.

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Wind, PV, PHES, HVDC and heat pumps are proven renewable energy solutions in large-scale deployment (100-1,000 GW installed worldwide for each). These technologies can drive rapid and deep cuts to the energy sector’s greenhouse emissions without any heroic assumptions.

Apart from a modest contribution from existing hydroelectricity, other low-emission technologies are unlikely to make significant contributions in the foreseeable future.

Andrew Blakers, Professor of Engineering, Australian National University

This article was originally published on The Conversation. Read the original article.