What’s next, a Senate inquiry into infrasound from trees, waves or air conditioners?

Simon Chapman, University of Sydney

At the centre of claims about wind farms allegedly causing health problems is the infrasound that wind turbines generate as they turn in the wind.

Infrasound is sound below 20Hz, which is generally inaudible. Wind turbines are just one source of artificial man-made infrasound. Others include power stations, industry generally, motor vehicle engines, compressors, aircraft, ventilation and air conditioning units, and loudspeaker systems. Everyone living in an urban environment is bathed in infrasound for most of their lives.

As I sit at my inner Sydney desk writing this I’m copping infrasound from the planes that pass some 200-300 metres over my house sometimes many times an hour, the sound of passing road traffic on a quite busy road 100 metres from our house, and the stereo system I listen to as I write. Don’t tell anyone, but I feel fine and I’ve lived here 25 years.

But infrasound is generated by natural phenomena too. These include rare occurrences such as volcanoes and earthquakes, but also sources like ocean waves and air turbulence (wind) that countless millions, if not billions, are exposed to on most days. Anyone living close to the sea is surrounded by constant infrasound from waves.

The inclusion of wind as a source of infrasound is of particular significance to claims made that wind turbine-generated infrasound is noxious. In a Polish research paper published in 2014, the authors set out to measure infrasound from wind turbines and to compare that with naturally occurring infrasound from wind in trees near houses and from the sound of the sea in and around a house near the seaside.

The researchers used the average G-weighted level (LGeq) over the measurement period. This is the standardised measurement of infrasound which approximately follows the hearing threshold below 20Hz and cuts off sharply above 20Hz.

The infrasound levels recorded near 25 100-metre high wind turbines ranged from 66.9 to 88.8 LGeq across different recordings. Those recording infrasound in noise from wind in a forest near houses ranged from 59.1- 87.8 LGeq. The recordings of sea noise near seaside houses ranged from 64.3 to 89.1 LGeq. These infrasound levels were thus very similar cross the three locations.

The peak 88.8 LGeq was recorded very close to the turbines – virtually directly under the blades. The lower 66.9LGeq was 500m away, which is more like a common scenario for the nearest residences to turbines. Similarly, for the other sources, highest levels were nearest the source.

Wind is, of course, a prerequisite for wind turbines to turn and generate their mechanical infrasound. Here, the Polish authors noted that:

natural noise sources … always accompany the work of wind turbines and in such cases they constitute an acoustic background, impossible to eliminate during noise measurement of wind turbines.

This is a fundamentally important insight: wherever there are wind turbines generating infrasound, there is also wind itself generating infrasound. And it is impossible to disentangle the two. Indeed, every time I’ve been near wind turbines, easily the most dominant sound has been that of the wind buffeting my ears.

In 2013, the South Australian Environmental Protection Authority measured infrasound in a variety of urban and rural settings. With the latter, this included locations near and well away from wind farms.

They reported that in urban settings, measured infrasound ranged between 60-70 decibels. In fact, at two locations – the EPA’s own offices and an office with a low frequency noise complaint – building air conditioning systems were identified as significant sources of infrasound. These locations exhibited some of the highest levels of infrasound measured during the study.

They concluded:

This study concludes that the level of infrasound at houses near the wind turbines assessed is no greater than that experienced in other urban and rural environments, and that the contribution of wind turbines to the measured infrasound levels is insignificant in comparison with the background level of infrasound in the environment.

Wind farm opponents claim infrasound is the cause of this Old Testament-like plague of plagues (now numbering 244 different problems). If that were true, how is it that hundreds of thousands of Australians who are daily exposed to infrasound in cities, in their houses surrounded by dastardly infrasound-generating fans, air conditioners and stereo systems, and those who live near trees or the sound of the ocean aren’t breaking down the door of those sworn enemies of infrasound Senators John Madigan, Nick Xenophon, Chris Back, David Leyonhjelm and Bob Day who brought us their scathing report on wind farms in June?

The explanation lies in factors we recognise frequently in risk-perception studies, popularised by Peter Sandman. Sandman has produced matrices of factors which have been often found to be associated with increased levels of community “outrage” about putative environmental threats to health.

Sandman distinguishes primary from additional factors, with primary factors being those which have been shown to be more strongly associated with increased levels of community concern.

I applied these to a case study of mobile phone tower complaints in the 1990s. I’ve now constructed the table below indicating the likely applicability of these factors to the case of predicting community worry about wind farms.

People don’t worry about infrasound in wind, trees and ocean waves because these sources are natural, while the same levels of infrasound from wind turbines are considered quite differently as they are sourced from what anti-wind farm activists like to call evil “industrial” wind farms.

The rare examples of people complaining who host wind turbines on their land for rental payment, compared with the far more common situation of non-hosting neighbours complaining, illustrates the voluntary vs coerced exposure factor, as well as the fair vs unfair factor. Those not benefiting from lucrative rental payments because of unsuitable local topography, while near neighbours can, understandably feel this as unfair.

Wind turbines are very memorable and exotic (a new experience to many), while wind in trees or the pounding of the ocean is very familiar and unremarkable, both factors likely to greatly diminish concerns.

Table: Primary and additional components predicting community outrage about putative environmental risks to health: the case of wind turbines. (two ticks = applies strongly to wind turbines; one tick = likely to apply less strongly)

The 2015 Senate (majority) report into wind farms roundly rejected the idea that psychosocial factors such as nocebo effects were largely responsible for the challenging historical and geographical variance in wind farm complaints. A nocebo effect is the opposite to a placebo effect: instead of exposure to an inactive agent making people feel better because of belief that it will, nocebo effects are when a benign agent makes people feel worse because they have been told it will.

The Committee, chaired by avowed wind farm opponent John Madigan, was emphatic that infrasound was the culprit but did not produce convincing evidence for this.

If the committee is sincere in its concerns about the health effects of infrasound, will we soon learn of a new inquiry about the pernicious and unappreciated dangers of living near the sea or trees, having air conditioners, stereos, ceiling fans, or travelling in motor vehicles?

The Conversation

Simon Chapman, Professor of Public Health, University of Sydney

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

The Greens’ plan for 90% renewables by 2030 sounds hard, but it stacks up

Andrew Blakers, Australian National University

The Australian Greens this weekend announced a target of 90% renewable electricity by 2030 – pledging to go further than Labor, which has already backed a target of 50%. How hard is it to reach these targets?

The Abbott government made plain its dislike of renewable energy by reducing the renewable electricity target (RET) for 2020 to 33 terawatt hours (TWh) of new renewable electricity.

Under this target, about 24% of electricity will come from renewable sources in 2020, comprising existing renewables (mostly hydro-electricity with some biomass) and new renewables (mostly wind energy and photovoltaic (PV) solar energy). It’s straightforward to calculate the annual additions (gigawatts, GW) of wind and PV required to hit a 50% or 90% RET in 2030.

First, let’s assume that Australia’s electricity demand remains static at about 200 TWh per year. Demand has been falling or static since 2008, caused by improving energy efficiency of buildings and appliances, reduced demand from heavy industry, and increased price of retail electricity, together with the rise and rise of behind-the-meter rooftop PV systems.

Second, let’s assume that wind and PV will each constitute half of new generation. These two technologies constitute virtually all new generation capacity in Australia, and together are being installed at a greater rate worldwide than the combined amount of new fossil and nuclear capacity. They are set to dominate the world’s energy future because they are effectively unconstrained by energy resource, raw materials, greenhouse gas emissions, local pollution, security concerns, or price.

Third, let’s assume that the “capacity factors” of these technologies remain at their current typical values of 25% for tracking PV and 40% for wind. (Capacity factor is the effective proportion of time that an electricity generator operates at nominal full load.)

Under these assumptions, we would need about 3 GW of new PV and 2 GW of new wind power capacity each year to reach a 90% renewables target by 2030. This is about 5% of the current worldwide installation rates, which themselves are increasing at 10-20% per year.

The corresponding figures for Labor’s target of 50% by 2030 are 1.2 GW of PV and 0.8 GW of wind per year.

An achievable prospect

Labor’s target is a straightforward prospect. In years gone by, Australia has installed this much PV and wind in a year, and can readily do so again. It is not much more than the installation rate needed to meet the 2020 RET.

The Greens’ target, meanwhile, is about 2.5 times more challenging than Labor’s, but still readily achievable. The Australian Capital Territory and South Australia have shown the way by adding new renewable electricity capacity equivalent to 90% and 40% respectively of their annual electricity consumption – mostly over a period of about 5 years. There are no practical constraints in terms of land because of Australia’s vast solar and wind resources.

Australia’s electricity system is becoming increasingly renewable. From the greenhouse point of view, natural gas should be pushed out of the market in favour of electrically driven heat pumps for the supply of water heating and space heating and cooling. This may happen anyway for economic reasons.

Similarly, conversion of land transport to electric vehicles will eliminate another substantial source of greenhouse gas emissions. As heat pumps and electric cars are about three times more efficient than gas heating and petrol cars, only a few years of extra building of PV and wind would be required to meet the extra electricity demand. A combination of existing hydroelectric power stations, new off-river pumped hydro energy storage, and battery storage, allows stabilisation of a 100% renewable electricity system.

The most straightforward mechanism to achieve a 50% or 90% renewables target by 2030 is simply to extend and uplift the existing 2020 RET. However, recent experience shows how easily governments can create investment risk by seeking to reduce the target, and how this can inhibit investment. Various other mechanisms can be introduced to confer investment certainty, including reverse auctions to lock in prices for 20 years (as pioneered in Australia by the ACT Government).

How much will it cost?

This question is difficult to answer. At present, wind power costs about 8 cents per kilowatt hour (kWh), and PV about 12 cents per kWh in Australia when constructed on a moderate scale (less than a gigawatt per year). PV in particular is falling rapidly in price, and both are likely to reach 6-8 cents per kWh by 2020 when constructed at a scale greater than a gigawatt per year.

The overall wholesale price of electricity is currently 3-4 cents per kWh, but this is mostly from old fossil fuel generators for which the capital cost has already been repaid, and for which there is no longer a carbon price. Energy from new-build gas or coal generators would cost 8-12 cents per kWh – so it could potentially end up being more expensive than new renewables.

Most of Australia’s existing coal power stations will be retired over the next two decades in the ordinary course of business, perhaps replaced by cheaper PV and wind. In this sense, the conversion to renewables would cost nothing extra.

One way of measuring whether a rapid phase-out of fossil fuel generation will affect the economy is to observe that the carbon price during 2012-14 was 2.5 cents per kWh, and that this constitutes most of the difference in cost between old (sunk-cost) fossil fuel generators and the 2020 cost of electricity from PV and wind. That carbon price did not noticeably affect the economy.

The Conversation

Andrew Blakers, Director of the Centre for Sustainable Energy Systems (CSES) , Australian National University

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

Shrinking Antarctic glaciers could make Adélie penguins unlikely winners of climate change

Jane Younger, University of Tasmania

Penguin numbers exploded in East Antarctica at the end of the last ice age, according to research published today in BMC Evolutionary Biology. Despite their image as cold-loving creatures, the increase in Adélie penguin numbers seems to be closely linked to shrinking glaciers, raising the possibility the these penguins could be winners from current climate change.

Adélie penguins are one of only two penguin species that live on the Antarctic continent. Their cousins, emperor penguins, may be the movie stars, but it is the Adélies that are the bigger players in the Southern Ocean. They outnumber emperors by more than ten to one, with a population of over 7.5 million breeding adults and counting.

Given the abundance of Adélie penguins and their crucial role in Southern Ocean ecosystems, there has been a great deal of interest in understanding how the species is likely to respond to future climate change.

There are more then 7 million of these guys in Antarctica.
Jane Younger, Author provided

Sensitivity to sea ice

Breeding colonies have been monitored for decades to determine the effects of a changing environment on the penguins. A common finding of many of these studies is that Adélies are highly sensitive to sea ice conditions.

Unlike emperor penguins, Adélies do not nest on the sea ice, but they must cross it to reach their nests on land. As everyone knows, penguins are not the most efficient walkers, and in years with a lot of sea ice their journeys to and from the ocean to feed their chicks can become lengthy. With a longer wait between meals chicks are less likely to survive.

In an extreme case, extensive sea ice at one breeding colony had a devastating impact in 2014, and not a single chick survived.

Based on these observations over years and decades, there has been concern that changing sea ice conditions, including increases in certain parts of Antarctica, could have a serious impact on Adélie penguin numbers in the future.

Short-term vs long-term climate change

However, the climate change that is taking place now is not a decadal trend. Rather, the shrinking glaciers and ice sheets, changing sea ice conditions, and shifting currents and weather patterns represent a global change to a new climate.

We therefore set out to understand how Adélie penguins in East Antarctica were affected by the last big shift to a different climate: the ending of the last ice age.

Following similar methods to our previous study on emperor penguins, we used genetic data to uncover the trend of the Adélie population in East Antarctica over the past 22,000 years.

Researchers have been investigating penguins to see how they might respond to climate change.
Laura Morrissey, Author provided

The end of the ice age

We found that, as for the emperor penguins, Adélies were far less common during the ice age. This is not at all surprising since most of their nesting sites would have been covered with glaciers and their feeding grounds encased in sea ice that never melted.

Following the end of the ice age 20,000 years ago, temperatures increased slowly, and after a few thousand years of warming the glaciers and ice sheets began to shrink. Fast forward to 10,000 years ago and the annual sea ice melting cycle that we see today was established.

Given the sensitivity of Adélie penguins to sea ice changes today, we predicted that Adélie numbers would remain very small until 10,000 years ago when sea ice conditions became similar to what they are now.

However, the penguins surprised us again. We found that the number of Adélies exploded by around 135-fold, but the expansion pre-dated the sea ice change by at least 3000 years.

Penguin numbers exploded at the end of the last ice age.
Jane Younger, Author provided

Shrinking glaciers

The proliferation of Adélie penguins in East Antarctica began during a period of ice sheet and glacier retreat, which would have increased the amount of ice-free ground available for nesting.

A study of Adélie penguins at the Scotia Arc, on the opposite side of the continent, found that numbers in this region rose 17,000 years ago. That expansion was several thousand years before the growth of the East Antarctic population, but coincided with the shrinking of glaciers in the Scotia Arc. This lends further support to our conclusion that it was glacier retreat, rather than changing sea ice conditions, that caused the hike in Adélie penguin numbers after the last ice age.

This is an important finding, as it suggests that the effects of climate change on a species over thousands of years can be quite different to the effects over years or decades. Given the long-term nature of contemporary climate change, we suggest that it is critical to consider millennial-scale trends alongside decadal ecological studies when predicting the effects of climate change on a species.

Could penguins benefit from future climate change?

Glaciers and ice sheets in Antarctica will continue to shrink. As this happens, ground that was previously covered in ice will become suitable for Adélie penguin nesting. In regions with adequate food supplies and where sea ice conditions remain favourable, Adélie penguin numbers may continue to grow.

A recent study using satellite images showed that one breeding colony in the Ross Sea grew by 84% between 1983 and 2010, as a direct result of a glacier shrinking by 543 m and uncovering new nesting sites.

While it seems that East Antarctic Adélie penguins might come out on top as climate change winners, it is important to keep in mind that for penguins to flourish their food supplies must be plentiful enough to meet the demands of a growing population. Whether this will be the case in the future remains to be seen, as Adélie penguin prey species, such as Antarctic krill, are threatened by both climate change and commercial fisheries.

The Conversation

Jane Younger, Postdoctoral research fellow, University of Tasmania

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