We can’t know the future cost of climate change. Let’s focus on the cost of avoiding it instead



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Economists have searched for the mythical balance between the cost of climate action, and the future cost of doing nothing.
Joop Hoek/Shutterstock.com

Jack Pezzey, Australian National University

As delegates at the UN climate summit in Katowice, Poland, discuss the possibility of restraining global warming to 1.5℃, it might sound like a reasonable question to ask how much money it will cost if they fail.

Economists have spent the past 25 years trying – and largely failing – to agree on the “right” answer to this question. It’s an important consideration, because governments are understandably keen to balance the benefits of limiting long-term climate damage with the more immediate costs of reducing greenhouse emissions.

In simple economics terms, we can ask what price would be worth paying today to avoid emitting a tonne of carbon dioxide, given the future damage costs that would avoid.

This mythical figure has been called the “social cost of carbon”, and it could serve as a valuable guide rail for policies such as carbon taxes or fuel efficiency standards. But my recent research suggests this figure is simply too complicated to calculate with confidence, and we should stop waiting for an answer and just get on with it.




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Paul Romer and William Nordhaus – why they won the 2018 ‘economics Nobel’


While some climate economists have put the social cost of carbon at hundreds or even thousands of dollars per tonne of CO₂, one of the most influential analyses, by Yale University economist William Nordhaus, offers a much more modest figure of just over US$30.

Nordhaus won this year’s Nobel Prize in Economics, but his analysis has some uncomfortable conclusions for those familiar with the science.

At this level, it will be economically “optimal” for the world to reduce its CO₂ emissions quite slowly, so that global warming peaks at about 4℃ some time next century. But this certainly doesn’t sound optimal from a scientific perspective.

Reconstructed global mean temperature anomalies for 0–2000 CE, and DICE-2016R projections for 2015–2400.
CREDIT, Author provided

The impossibility of knowing the social cost of carbon

Calculating this magical economic balancing point is the holy grail of climate economics, and sadly it also seems to be an impossible task, because the question is so complex as to be unanswerable.

Why so? Normally, we gain knowledge via three main methods. The first option is to design an experiment. If that’s impossible, we can look for a similar case to observe and compare. And if that too is impossible, we can design a model that might hopefully answer our questions.

Generally, the laws of physics fall into the first category. It’s pretty straightforward to design an experiment to demonstrate the heat-trapping properties of CO₂ in a lab, for instance.

But we can’t do a simple experiment to assess the global effects of CO₂ emissions, so instead climatologists have to fall back on the second or third options. They can compare today’s conditions with previous fluctuations in atmospheric CO₂ to gauge the likely effects. They also design models to forecast future conditions on the basis of known physical principles.

By contrast, economists trying to put a dollar value on future climate damage face an impossible task. Like scientists, they cannot usefully test or make comparisons, but the economic effects of future climate change on an unprecedented 10 billion people are too fiendishly complex to model with confidence.

Unlike the immutable laws of physics, the laws of economics depend on markets, which in turn rely on trust. This trust could break down in some catastrophic future drought or deluge. So economists’ various rival calculations for the social costs of carbon are all based on unavoidable guesswork about the value of damage from unprecedented future warming.

This view is understandably unpopular with most climate economists. Many new studies claim that recent statistical techniques are steadily improving our estimates of the value of climate damage, based mainly on the local economic effects of short-run temperature and other weather changes in recent decades.

But so far, the world has experienced only about 1℃ of global warming, with at most 0.3℃ from one year to the next. That gives us almost no way of knowing the damage from warming of 3℃ or so; it may turn out to be many times worse than projected from past damage, as various tipping points are breached.

Focus on emission reduction, not damage cost

One reason why economists keep trying to value climate damage is a 1993 US Presidential Executive Order that requires cost-of-carbon estimates for use in US regulations. But my findings support what many other climate economists have been doing anyway. That is to build models that ignore the future dollar cost of climate damage, and instead look at feasible, low-cost ways to cut emissions enough to hit physical targets, such as limiting global warming to 1.5℃ or 2℃, or reaching zero net emissions by 2100.

Once we know these pathways, we don’t need to worry about the future cost of climate damage – all we need to ask is the cost of reducing emissions by a given amount, by a given deadline.

Of course, these costs are still deeply uncertain, because they depend on future developments in renewable energy technologies, and all sorts of other economic factors. But they are not as fiendishly uncertain as trying to pin a dollar value on future climate damage.




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Fresh thinking: the carbon tax that would leave households better off


Focusing on the cost of emissions-reduction pathways allows researchers to put their effort into practical issues, such as how far and fast countries can shift to zero-emission electricity generation. Countries such as Sweden and the UK have already begun implementing this kind of action-oriented climate policies. While far from ideal, they are among the best-ranked major economies in the Climate Change Performance Index. Australia, by contrast, is ranked third worst.

But aren’t trillion-dollar estimates of future warming damage, as featured in the recent US Fourth National Climate Assessment, necessary ammunition for advocates of climate action? Maybe, but it is still important to appreciate that these estimates are founded on a large chunk of guesswork.

Setting climate targets will always be a political question as well as a scientific one. But it’s an undeniably sensible aim to keep climate within the narrow window that has sustained human civilisation for the past 11,000 years. With that window rapidly closing, it makes sense for policymakers just to focus on getting the best bang for their buck in cutting emissions.The Conversation

Jack Pezzey, Senior Fellow, Fenner School of Environment and Society, Australian National University

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

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The science is clear: we have to start creating our low-carbon future today


Alan Finkel, Office of the Chief Scientist

This week’s release of the special report from the Intergovernmental Panel on Climate Change (IPCC) has put scientific evidence on the front page of the world’s newspapers.

As Australia’s Chief Scientist, I hope it will be recognised as a tremendous validation of the work that scientists do.

The people of the world, speaking through their governments, requested this report to quantify the impacts of warming by 1.5℃ and what steps might be taken to limit it. They asked for the clearest possible picture of the consequences and feasible solutions.




Read more:
The UN’s 1.5°C special climate report at a glance


It is not my intention in this article to offer a detailed commentary on the IPCC’s findings. I commend the many scientists with expertise in climate systems who have helped Australians to understand the messages of this report.

My purpose is to urge all decision-makers – in government, industry and the community – to listen to the science.

Focus on the goal

It would be possible for the public to take from this week’s headlines an overwhelming sense of despair.

The message I take is that we do not have time for fatalism.

We have to look squarely at the goal of a zero-emissions planet, then work out how to get there while maximising our economic growth. It requires an orderly transition, and that transition will have to be managed over several decades.

That is why my review of the National Electricity Market called for a whole-of-economy emissions reduction strategy for 2050, to be in place by the end of 2020.




Read more:
The Finkel Review at a glance


We have to be upfront with the community about the magnitude of the task. In a word, it is huge.

Many of the technologies in the IPCC’s most optimistic scenarios are at an early stage, or conceptual. Two that stand out in that category are:

  • carbon dioxide removal (CDR): large-scale technologies to remove carbon dioxide from the atmosphere.

  • carbon capture and sequestration (CCS): technology to capture and store carbon dioxide from electricity generation.

It will take a decade or more for these technologies to be developed to the point at which they have proven impact, then more decades to be widely deployed.

The IPCC’s pathways for rapid emissions reduction also include a substantial role for behavioural change. Behavioural change is with us always, but it is incremental.

Driving change of this magnitude, across all societies, in fundamental matters like the homes we build and the foods we eat, will only succeed if we give it time – and avoid the inevitable backlash from pushing too fast.

The IPCC has made it clear that the level of emissions reduction we can achieve in the next decade will be crucial. So we cannot afford to wait.

Many options

No option should be ruled off the table without rigorous consideration.

In that context, the Finkel Review pointed to a crucial role for natural gas, particularly in the next vital decade, as we scale up renewable energy.

The IPCC has made the same point, not just for Australia but for the world.

The question should not be “renewables or coal”. The focus should be on atmospheric greenhouse emissions. This is the outcome that matters.

Denying ourselves options makes it harder, not easier, to get to the goal.

There also has to be serious consideration of other options modelled by the IPCC, including biofuels, catchment hydroelectricity, and nuclear power.

My own focus in recent months has been on the potential for clean hydrogen, the newest entrant to the world’s energy markets.




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How hydrogen power can help us cut emissions, boost exports, and even drive further between refills


In future, I expect hydrogen to be used as an alternative to fossil fuels to power long-distance travel for cars, trucks, trains and ships; for heating buildings; for electricity storage; and, in some countries, for electricity generation.

We have in Australia the abundant resources required to produce clean hydrogen for the global market at a competitive price, on either of the two viable pathways: splitting water using solar and wind electricity, or deriving hydrogen from natural gas and coal in combination with carbon capture and sequestration.

Building an export hydrogen industry will be a major undertaking. But it will also bring jobs and infrastructure development, largely in regional communities, for decades.

So the scale of the task is all the more reason to press on today – at the same time as we press on with mining lithium for batteries, clearing the path for electric vehicles, planning more carbon-efficient cities, and so much more.

There are no easy answers. I hope, through this and other reports, there are newly determined people ready to contribute to the global good.The Conversation

Alan Finkel, Australia’s Chief Scientist, Office of the Chief Scientist

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

Australia must embrace transformation for a sustainable future



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Judy van der Velden/Flickr, CC BY-NC

Shirin Malekpour, Monash University

Last Friday, the Australian government released its first report on our progress towards meeting the United Nations’ Sustainable Development Goals by 2030.

These 17 goals are a call to action to ensure economic prosperity and social inclusion, while protecting the planet. They cover issues ranging from health to reducing inequalities and clean energy.

According to the report, Australia has made some steady progress towards most of our goals.




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In the quest to meet the SDGs, there’s a danger that some may be left behind


However, to achieve the goals in just 12 years from now, we need transformative actions. These are missing in the report. Without a strong vision and new models of partnership between government, industry and communities, we will not meet the 2030 deadline.

What the report says

In 2015, most of the world’s nations signed up to the United Nation’s 2030 Agenda. In July this year, Australia will present its first voluntary review of progress towards the goals at the UN. These reviews are a crucial component of accountability.

Australia’s Voluntary National Review (for which I facilitated a consultation workshop to give input from the university sector) is a showcase of policies, actions and initiatives from across different sectors that are, in the report’s language, “relevant” to achieving the goals.

The report highlights that Australia is a prosperous and generally healthy country. But it also acknowledges significant challenges, such as improving the health and prosperity of Australia’s Aboriginal and Torres Strait Islander peoples, and helping workers in the resources or manufacturing sectors who are facing technological and industrial transitions.




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Climate action is the key to Australia achieving the Sustainable Development Goals


The report highlights that local councils, statutory authorities, businesses and universities are taking actions that are explicitly aligned with the global goals. For example, a number of Australian universities have signed a commitment to the goals and are including the 2030 Agenda in their curricula.

However, no sector has fundamentally changed its practices in response to the Sustainable Development Goals, nor embedded the goals into its core business.

At the national level, there has been limited specific engagement with the goals. Most of the national policies outlined in the report were developed for other reasons, and some have been around for years or decades. Examples are the National Disability Strategy, which dates back to pre-2010, or the National Drought Policy, which began in 1992. In other words, at the national level, the report emphasises what we have already been doing – not new initiatives explicitly related to the goals.

Notwithstanding success stories from across different sectors, the reality is that we will not be able to meet the goals in just 12 years on a business-as-usual trajectory. Instead, we need transformative plans across all sectors.

What is transformative change?

Sustainable development, as opposed to conventional development, involves big systemic transformations. Let’s use the example of clean energy.

Taking carbon out of our energy system is not simply about using wind and solar instead of coal. It involves big changes in how we consume energy, in manufacturing technologies and in the ways governments help (or hinder) the adoption of new technologies and practices. It requires systemic transformation, rather than incremental improvements.

Research into systemic transformation has identified a range of factors for making change happen. Two critical factors are creative decision-making and strong partnerships across disciplines and sectors. If we are serious about achieving the Sustainable Development Goals by 2030, we need to act now.

Transformative decision-making

Conventional decision-making favours the status quo and is largely risk-averse. It can cope with small incremental changes, but not big ones. In transport, for instance, we often tend to augment or replicate existing infrastructure – building another highway, for example – rather than innovating by trying to get people out of their cars.

Conventional decision-making also prefers to react: we often wait for a crisis situation and then quickly respond. This almost always favours short-term over long-term benefits.

Transformative decision-making, on the other hand, is proactive and takes deliberate actions to shape a desired future. It works toward a long-term vision and doesn’t shy away from uncertainty and complexity along the way.

As Australia’s review correctly acknowledges, the Sustainable Development Goals are all about “longstanding, complex policy challenges with no simple solutions”. Solving complex problems requires a great deal of innovation and experimentation. We need governments, businesses and communities to be willing to try new things, even if they occasionally fail.

Developing partnerships

Improving the lives of people and the planet requires myriad skills, tapping into various networks and reaching out to all segments of society.

Universities, for instance, often play a key role in analysing problems, developing new solutions and providing the evidence base that a solution actually works. But it is only through partnering with communities, businesses and policy organisations that they can put these solutions into practice.




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Universities must act now on sustainability goals


The Voluntary National Review has highlighted the role of cross-sectoral partnerships. What is missing is a plan for fostering the partnerships that can enable substantial change in just 12 years.

The ConversationAs Australia prepares to present our progress report at the 2018 UN High Level Political Forum in July, we need more critical assessment of our performance. How can we start doing things differently to be able to celebrate achieving these ambitious global goals in 2030?

Shirin Malekpour, Research Leader in Strategic Planning and Futures Studies, Monash Sustainable Development Institute, Monash University

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

The future is fenced for Australian animals



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Mala, also known as rufous hare-wallabies, will be protected behind an enormous cat-proof fence.
Donald Hobern/Flickr, CC BY-SA

Michael Bode, The University of Queensland

Many of Australia’s mammals spend their entire lives imprisoned, glimpsing the outside world through tall chain-link fences and high-voltage wires. There are dozens of these enclosures across Australia. Many are remote, standing alone in the endless expanse of inland Australia, but others are on the outskirts of our largest cities – Melbourne, Perth, Canberra.

Every year there are more of them, the imprisoned population growing, while the wild populations outside dwindle. These are Australia’s conservation fences.




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The captives within our conservation fences are adorable – floppy-eared bilbies, tiny hare-wallabies, long-tongued numbats – and they all share an extreme susceptibility to introduced predators. At least 68 native mammal species cannot exist in the wild if either foxes or cats are present. Many of these species once numbered in the millions, ranging from the woodlands of Queensland to the deserts of Western Australia, but predation has driven them to the brink of extinction.

Fences offer these species a future in the wild, and conservation groups have risen to the challenge. Last week, the Australian Wildlife Conservancy completed a new cat-proof fence in their Newhaven Sanctuary, the largest conservation fence ever constructed.

Fences are extraordinarily successful

Make no mistake, these conservation fences work. Species that wilt at the sight of a fox, that have been exterminated from every corner of the Australian mainland, will explode in numbers behind fences. Along with offshore islands, inside these fences are the only places in Australia where these species can prosper – a few hundred square kilometres of safety, surrounded by 7.6 million lethal square kilometres.

Environmentalists have never particularly liked fences. Rather than hide behind walls, they repeatedly took the fight to the cats and foxes on the outside.

Their tactics have been diverse, innovative and brutal. Managers have rained bullets from helicopters and poison baits from planes. They have set cunning snares and traps, mimicked the smell and sound of their enemies, and have turned landscapes to ash with wildfire.

Nothing has worked for the most threatened marsupials. Some of the largest and most expensive management campaigns in Australian conservation history have ended in exhaustion and stalemate, and with a retreat back behind the fences.

Fences were once a source of vehement debate in conservation circles. Should they be permanent? Are fenced populations wild or captive? Should they contribute to species’ conservation status?

These arguments have effectively been abandoned. Scientific studies and painful experience has proven fences and offshore islands to be the only reliable method of protecting predator-threatened species http://www.wildliferesearchmanagement.com.au/Final%20Report_0609.pdf. In place of these debates, conservation organisations and governments have turned to more practical questions of fence height, electric wire voltage and skirt depth.

So now, on average, Australians are building a new fence every year, some of them truly enormous. The just-completed fence at Newhaven encloses a staggering 10,000 hectares of red sand and spinifex. By the time the project is complete, this fence will be home to 11 different threatened mammal species.

And Australia is not alone: around the world, from New Zealand to Hawaii to South Africa, an archipelago of fences is emerging from an ocean of predators. It is one of the great achievements of modern conservation and has already averted the extinction of critically endangered species. Although it’s much smaller than our network of protected areas, it offers refuge to species that are long-gone from our national parks and wilderness areas.

Red foxes have been extraordinarily successful in Australia.
Harley Kingston/Flickr, CC BY

A troubling pattern

However, in recent years a concerning pattern has begun to emerge. While the number and size of fences continue to increase, the number of new species being protected has stalled. In fact, the last five fences haven’t included any new species – they have only offered additional protection to species that were already protected behind existing fences https://www.nature.com/articles/s41559-017-0456-4.

As an example, the first two marsupials planned for introduction behind the Newhaven fence will be the mala (Lagorchestes hirsutus) and the burrowing bettong (Bettongia lesueur). These two species undeniably deserve more protection. Both are highly susceptible to foxes and cats and will derive tremendous benefit from the protection of this enormous fence. However, both species are already found elsewhere behind fences (four different fences for burrowing bettongs). Meanwhile, yet-to-be-published research from the National Environmental Science Program has found 41 other species that are desperately vulnerable to introduced predators are not protected by any fence.

This problem is not new to conservation. In the 1990s, Australian researchers suddenly realised that our national park system was failing to protect the full range of Australian ecosystems. Despite our best efforts, we had created a system of reserves that was biased towards mountainous landscapes and deserts, and away from the fertile valley floors. The solution was to create new national parks using systematic and mathematical methods.

This discovery – the theory of systematic conservation planning – revolutionised global conservation. In 2018, conservation fences need their own systematic revolution.

Unfortunately, the national park system had natural advantages that fences lack. The vast majority of Australia’s protected areas belong to the state and federal governments. The centralised nature of the protected area network is perfect for systematic thinking and top-down optimisation – picture the Soviet Union’s Politburo. In contrast, the conservation fencing sector is diverse and decentralised – picture the third day of Woodstock.




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All cost, little benefit: WA’s barrier fence is bad news for biodiversity



Fences are built by governments at the state, federal and municipal levels, by multimillion-dollar NGOs like the Australia Wildlife Conservancy, by tiny local environmentalist groups and by profit-making corporations. This diversity is a fundamental strength of the fence network, giving it access to a spectrum of funding and ideas. But it makes it almost impossible to plan in a systematic manner. You can’t tell a small bilby conservation group in western Queensland that they should protect the central Australian rock-rat instead (Zyzomys pedunculatus). It doesn’t necessarily matter to them that bilbies are already protected behind four different fences and the rock-rat has none.

While conservation science tries to work this problem out, new and larger fences will continue to be built at an accelerating rate into the foreseeable future. True, the absence of coordination will make mathematicians break their slide rules, but each fence will do its job. The furry denizens will hop, and scurry, and bounce around, heedless of their precarious safety.

The ConversationAnd for us, from the outside looking in, these fences will help us forget the parlous state of Australian marsupial conservation. It will be possible to forget our record-breaking rate of extinctions, to forget the empty forests and deserts, and to imagine what a bushwalk might have been like before Europeans unleashed foxes and cats onto Australia.

Michael Bode, Associate Professor of Mathematics, The University of Queensland

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

How protons can power our future energy needs



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The proton battery, connected to a voltmeter.
RMIT, Author provided

John Andrews, RMIT University

As the world embraces inherently variable renewable energy sources to tackle climate change, we will need a truly gargantuan amount of electrical energy storage.

With large electricity grids, microgrids, industrial installations and electric vehicles all running on renewables, we are likely to need a storage capacity of over 10% of annual electricity consumption – that is, more than 2,000 terawatt-hours of storage capacity worldwide as of 2014.

To put that in context, Australia’s planned Snowy 2.0 pumped hydro storage scheme would have a capacity of just 350 gigawatt-hours, or roughly 0.2% of Australia’s current electricity consumption.




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Tomorrow’s battery technologies that could power your home


Where will the batteries come from to meet this huge storage demand? Most likely from a range of different technologies, some of which are only at the research and development stage at present.

Our new research suggests that “proton batteries” – rechargeable batteries that store protons from water in a porous carbon material – could make a valuable contribution.

Not only is our new battery environmentally friendly, but it is also technically capable with further development of storing more energy for a given mass and size than currently available lithium-ion batteries – the technology used in South Australia’s giant new battery.

Potential applications for the proton battery include household storage of electricity from solar panels, as is currently done by the Tesla Powerwall.

With some modifications and scaling up, proton battery technology may also be used for medium-scale storage on electricity grids, and to power electric vehicles.

The team behind the new battery. L-R: Shahin Heidari, John Andrews, proton battery, Saeed Seif Mohammadi.
RMIT, Author provided

How it works

Our latest proton battery, details of which are published in the International Journal of Hydrogen Energy, is basically a hybrid between a conventional battery and a hydrogen fuel cell.

During charging, the water molecules in the battery are split, releasing protons (positively charged nuclei of hydrogen atoms). These protons then bond with the carbon in the electrode, with the help of electrons from the power supply.

In electricity supply mode, this process is reversed: the protons are released from the storage and travel back through the reversible fuel cell to generate power by reacting with oxygen from air and electrons from the external circuit, forming water once again.

Essentially, a proton battery is thus a reversible hydrogen fuel cell that stores hydrogen bonded to the carbon in its solid electrode, rather than as compressed hydrogen gas in a separate cylinder, as in a conventional hydrogen fuel cell system.

Unlike fossil fuels, the carbon used for storing hydrogen does not burn or cause emissions in the process. The carbon electrode, in effect, serves as a “rechargeable hydrocarbon” for storing energy.

What’s more, the battery can be charged and discharged at normal temperature and pressure, without any need for compressing and storing hydrogen gas. This makes it safer than other forms of hydrogen fuel.

Powering batteries with protons from water splitting also has the potential to be more economical than using lithium ions, which are made from globally scarce and geographically restricted resources. The carbon-based material in the storage electrode can be made from abundant and cheap primary resources – even forms of coal or biomass.




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Our latest advance is a crucial step towards cheap, sustainable proton batteries that can help meet our future energy needs without further damaging our already fragile environment.

The time scale to take this small-scale experimental device to commercialisation is likely to be in the order of five to ten years, depending on the level of research, development and demonstration effort expended.

Our research will now focus on further improving performance and energy density through use of atomically thin layered carbon-based materials such as graphene.

The ConversationThe target of a proton battery that is truly competitive with lithium-ion batteries is firmly in our sights.

John Andrews, Professor, School of Engineering, RMIT University

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

Semitransparent solar cells: a window to the future?


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Looking through semitransparent cells – one day these could be big enough to make windows.
UNSW, Author provided

Matthew Wright, UNSW and Mushfika Baishakhi Upama, UNSW

Can you see a window as you are reading this article?

Windows have been ubiquitous in society for centuries, filling our homes and workplaces with natural light. But what if they could also generate electricity? What if your humble window could help charge your phone, or boil your kettle?

With between 5 billion and 7 billion square metres of glass surface in the United States alone, solar windows would offer a great way to harness the Sun’s energy. Our research represents a step toward this goal, by showing how to make solar panels that still let through enough light to function as a window.




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Solar is now the most popular form of new electricity generation worldwide


The economics of renewable energy are becoming increasingly favourable. In Australia, and many other parts of the world, silicon solar cells already dominate the rooftop market.
Rooftop solar power offers an increasingly cheap and efficient way to generate electricity.

But while great for roofs, these silicon modules are opaque and bulky. To design a solar cell suitable for windows, we have to think outside the box.

When we put a solar panel on a roof, we want it to absorb as much sunlight as possible, so that it can generate the maximum amount of power. For a window, there is inevitably a trade-off between absorbing light to turn into electricity, and transmitting light so we can still see through the window.

When thinking about a cell that could be fitted to a window, one of the key parameters is known as the average visible transmittance (AVT). This is the percentage of visible light (as opposed to other wavelengths, like infrared or ultraviolet) hitting the window that travels through it and emerges on the other side.

Semitransparent solar cells convert some sunlight into electricity, while also allowing some light to pass through.
Author provided

Of course we don’t want the solar window to absorb so much light that we can longer see out of it. Nor do we want it to let so much light through that it hardly generates any solar power. So scientists have been trying to find a happy medium between high electrical efficiency and a high AVT.

A matter of voltage

An AVT of 25% is generally considered a benchmark for solar windows. But letting a quarter of the light travel through the solar cell makes it hard to generate a lot of current, which is why the efficiency of semitransparent cells has so far been low.

But note that electrical power depends on two factors: current and voltage. In our recent research, we decided to focus on upping the voltage. We carefully selected new organic absorber materials that have been shown to produce high voltage in non-transparent cells.

When placed in a semitransparent solar cell, the voltage was also high, as it was not significantly lowered by the large amount of transmitted light. And so, although the current was lowered, compared to opaque cells, the higher voltage allowed us to achieve a higher efficiency than previous semitransparent cells.

Having got this far, the key question is: what would windows look like if they were made of our new semitransparent cells?

Do you see what I see?

If your friend is wearing a red shirt, when you view them through a window, their shirt should appear red. That seems obvious, as it will definitely be the case for a glass window.

But because semitransparent solar cells absorb some of the light we see in the visible spectrum, we need to think more carefully about this colour-rendering property. We can measure how well the cell can accurately present an image by calculating what’s called the colour rendering index, or CRI. Our investigation showed that changing the thickness of the absorbing layer can not only affect the electrical power the cell can produce, but also changes its ability to depict colours accurately.

A different prospective approach, which can lead to excellent CRIs, is to replace the organic absorber material with one that absorbs energy from the sun outside the visible range. This means the cell will appear as normal glass to the human eye, as the solar conversion is happening in the infrared range.

However, this places limitations on the efficiency the cells can achieve as it severely limits the amount of power from the sun that can be converted to electricity.

What next?

So far we have created our cells only at a small, prototype scale. There are still several hurdles in the way before we can make large, efficient solar windows. In particular, the transparent electrodes used to collect charge from these cells can be brittle and contain rare elements, such as indium.




Read more:
Solar power alone won’t solve energy or climate needs


If science can solve these issues, the large-scale deployment of solar-powered windows could help to bolster the amount of electricity being produced by renewable technologies.

The ConversationSo while solar windows are not yet in full view, we are getting close enough to glimpse them.

Matthew Wright, Postdoctoral Researcher in Photovoltaic Engineering, UNSW and Mushfika Baishakhi Upama, PhD student [Photovoltaics & Renewable Energy Engineering], UNSW

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