The sunlight that powers solar panels also damages them. ‘Gallium doping’ is providing a solution


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Matthew Wright, UNSW; Brett Hallam, UNSW, and Bruno Vicari Stefani, UNSWSolar power is already the cheapest form of electricity generation, and its cost will continue to fall as more improvements emerge in the technology and its global production. Now, new research is exploring what could be another major turning point in solar cell manufacturing.

In Australia, more than two million rooftops have solar panels (the most per capita in the world). The main material used in panels is silicon. Silicon makes up most of an individual solar cell’s components required to convert sunlight into power. But some other elements are also required.

Research from our group at the University of New South Wales’s School of Photovoltaics and Renewable Energy Engineering shows that adding gallium to the cell’s silicon can lead to very stable solar panels which are much less susceptible to degrading over their lifetime.

This is the long-term goal for the next generation of solar panels: for them to produce more power over their lifespan, which means the electricity produced by the system will be cheaper in the long run.

As gallium is used more and more to achieve this, our findings provide robust data that could allow manufacturers to make decisions that will ultimately have a global impact.

The process of ‘doping’ solar cells

A solar cell converts sunlight into electricity by using the energy from sunlight to “break away” negative charges, or electrons, in the silicon. The electrons are then collected as electricity.

However, shining light on a plain piece of silicon doesn’t generate electricity, as the electrons that are released from the light do not all flow in the same direction. To make the electricity flow in one direction, we need to create an electric field.




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In silicon solar cells — the kind currently producing power for millions of Australian homes — this is done by adding different impurity atoms to the silicon, to create a region that has more negative charges than normal silicon (n-type silicon) and a region that has fewer negative charges (p-type silicon).

When we put the two parts of silicon together, we form what is called a “p-n junction”. This allows the solar cell to operate. And the adding of impurity atoms into silicon is called “doping”.

An unfortunate side effect of sunlight

The most commonly used atom to form the p-type part of the silicon, with less negative charge than plain silicon, is boron.

Boron is a great atom to use as it has the exact number of electrons needed for the task. It can also be distributed very uniformly through the silicon during the production of the high-purity crystals required for solar cells.

But in a cruel twist, shining light on boron-filled silicon can make the quality of the silicon degrade. This is often referred to as “light-induced degradation” and has been a hot topic in solar research over the past decade.

The reason for this degradation is relatively well understood: when we make the pure silicon material, we have to purposefully add some impurities such as boron to generate the electric field that drives the electricity. However, other unwanted atoms are also incorporated into the silicon as a result.

One of these atoms is oxygen, which is incorporated into the silicon from the crucible — the big hot pot in which the silicon is refined.

When light shines on silicon that contains both boron and oxygen, they bond together, causing a defect that can trap electricity and reduce the amount of power generated by the solar panel.

Unfortunately, this means the sunlight that powers solar panels also damages them over their lifetime. An element called gallium looks like it could be the solution to this problem.

A smarter approach

Boron isn’t the only element we can use to make p-type silicon. A quick perusal of the periodic table shows a whole column of elements that have one less negative charge than silicon.

Adding one of these atoms to silicon upsets the balance between the negative and positive charge, which is needed to make our electric field. Of these atoms, the most suitable is gallium.

Gallium is a very suitable element to make p-type silicon. In fact, multiple studies have shown it doesn’t bond together with oxygen to cause degradation. So, you may be wondering, why we haven’t been using gallium all along?

Well, the reason we have been stuck using boron instead of gallium over the past 20 years is that the process of doping silicon with gallium was locked under a patent. This prevented manufacturers using this approach.

Gallium-doped silicon heterojunction solar cell.
Robert Underwood/UNSW

But these patents finally expired in May 2020. Since then, the industry has rapidly shifted from boron to gallium to make p-type silicon.

In fact, at the start of 2021, leading photovoltaic manufacturer Hanwha Q Cells estimated about 80% of all solar panels manufactured in 2021 used gallium doping rather than boron — a massive transition in such a short time!

Does gallium really boost solar panel stability?

We investigated whether solar cells made with gallium-doped silicon really are more stable than solar cells made with boron-doped silicon.

To find out, we made solar cells using a “silicon heterojunction” design, which is the approach that has led to the highest efficiency silicon solar cells to date. This work was done in collaboration with Hevel Solar in Russia.

We measured the voltage of both boron-doped and gallium-doped solar cells during a light-soaking test for 300,000 seconds. The boron-doped solar cell underwent significant degradation due to the boron bonding with oxygen.

Meanwhile, the gallium-doped solar cell had a much higher voltage. Our result also demonstrated that p-type silicon made using gallium is very stable and could help unlock savings for this type of solar cell.

To think it might be possible for manufacturers to work at scale with gallium, producing solar cells that are both more stable and potentially cheaper, is a hugely exciting prospect.

The best part is our findings could have a direct impact on industry. And cheaper solar electricity for our homes means a brighter future for our planet, too.




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The Conversation


Matthew Wright, Postdoctoral Researcher in Photovoltaic Engineering, UNSW; Brett Hallam, Scientia and DECRA Fellow, UNSW, and Bruno Vicari Stefani, PhD Candidate, UNSW

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

Africa’s great migrations are failing but there is a solution – and you can eat it too


File 20180327 188619 hgwow8.jpg?ixlib=rb 1.1
A Wildebeeste, or Gnu.
Wikimedia Commons

Penny van Oosterzee, James Cook University

Until I went to southern Africa last year, I couldn’t imagine an African savanna without its awe-inspiring migrations. But Africa’s plains are increasingly empty of wildlife. My subsequent investigation showed that fences are marching across the savannas instead.

An audit of 24 large mammal species, which used to migrate regularly, showed that many migrations are already extinct. Fences stopped animals in their tracks, often within sight of the food and water that would sustain them. These fences had severed historically massive migrations. Millions of wild animals – wildebeest, zebra, hartebeest, springbok and many others – have likely died of thirst or hunger since the 1950s.

It’s a huge problem, yet it has received little attention. In Kenya, fences form clusters and virtual battle lines, threatening the collapse of the entire Greater-Mara ecosystem. A recent global study of 57 species of moving mammals shows that the future of the planet’s most spectacular natural events is on the cusp.




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A land divided

Botswana is one of the last great places on earth for free-ranging wildlife. Here, fences erected to protect European beef producers from foot-and-mouth disease (FMD) slice the country into 17 “islands”.

Fencing is expensive – especially fencing strong enough to keep out migrating animals – and it favours only a small proportion of cattle owners, locking local livestock farmers out of the export industry. To make matters worse, this comes as wildlife-based tourism is overtaking livestock as a proportion of GDP in countries like Botswana.

An elephant, behind one of the high double layered veterinary fences used in Botswana.
M. Atkinson

With colonial-era subsidies of the fencing system gone, what’s left is a lose-lose system that hinders local farmers, tourism and sustainability. Many savanna landscapes are now conflict zones between local people and wildlife.

Against this bleak backdrop, a rare good news story has emerged, driven by myth-busting science and patient advocacy. It turns out that wildlife does not play a significant role in the transmission foot-and-mouth disease, apart from the African buffalo; ironically it is more likely to be spread by cattle. Many areas, like the Kalahari, have no cattle or buffalo – so the fences in those areas serve no disease control purpose.

Careful scientific sleuthing is showing that migrations restart when these fences are removed. The longest animal migration ever recorded, of zebras across Botswana, resumed a few years ago after just a portion of fence was removed.

Process over place

Perhaps the most important breakthrough has been a relatively new scientific approach called One Health. One Health is a problem-solving strategy that tackles issues at the interface of wildlife, domestic animal and human health. A monumental effort by veterinarians and other scientists, working with communities and animal health organisations, has teased out a solution. Instead of looking at livestock’s geographic origin, it looks at the meat production process itself – from farm to fork – through a food safety lens.

This approach was initially developed for astronauts in the 1960s to avoid illness from contaminated food. It is now used throughout the food industry, from growing vegetables, to canning fruit and processing meat. For beef, it means that even in foot-and-mouth zones, a combination of vaccination, veterinary surveillance, and standardised meat preparation ensures disease-free, wildlife-friendly beef.

But it is one thing to have the solution, and quite another to convince policy makers to implement it. The focus of the One Health team soon turned to policy and advocacy. After years of research and dialogue between sectors that rarely sat at the same table, in 2012 the Southern African Development Community (SADC) issued The Phakalane Declaration on Adoption of Non-Geographic Approaches for Management of Foot and Mouth Disease.

Put simply, these new “non-geographic approaches” are not reliant on fencing.

Policy into practice

This consensus statement from southern African animal health experts was a shot heard ‘round the world. A genuine policy breakthrough finally came in 2015, in Paris, where the World Animal Health Organisation (OIE) rewrote the Terrestrial Animal Health Code to allow for international trade of fresh meat from countries or zones with foot-and-mouth disease.

Since then, Ngamiland, home to world-renowned wildlife and the recently World Heritage-listed Okavango Delta, committed late last year to reassessing its fences with wildlife-friendly beef and wildlife concerns in mind.

Okavango Delta, Botswana.
Wikimedia Commons, CC BY

Botswana is also at the centre of the Kavango Zambezi Transfrontier Conservation Area which spans parts of Angola, Botswana, Namibia, Zambia and Zimbabwe, and is home to the world’s largest remaining population of elephants. The Animal and Human Health for the Environment And Development (AHEAD) program, based at Cornell University, have been working with local partners to resolve FMD-related conflicts in the largest peace park in Africa. Meanwhile, non-fence solutions were at the forefront of a recent multi-country summit in late 2016.




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The new meat processing-focused approach seems like common sense but, after generations of conflict, it is bold and brave. Botswana, leading the charge, is now on the cusp of redeeming itself in the eyes of conservationists after 70 years of fence-related wildlife deaths.

The ConversationNow, not only can this new way forward allow wildlife to rebound, but a regional economy benefiting from both wildlife and livestock can do the same – if policy-makers can indeed move – beyond fences.

Penny van Oosterzee, Adjunct Associate Professor James Cook University and University Fellow Charles Darwin University, James Cook University

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

China: Air Pollution Solution


The link below is to an article reporting on China’s intention to find a solution to its air pollution problem.

For more visit:
http://www.reuters.com/article/2013/07/25/us-china-pollution-idUSBRE96O01Z20130725

Great Barrier Reef: Crown of Thorns Starfish


The link below is to an article that reports on a possible solution to the Crown of Thorns Starfish problem in the Great Barrier Reef.

For more visit:
http://www.australiangeographic.com.au/journal/new-hope-to-stop-crown-of-thorns.htm

Copenhagen Summit Fails to Deliver


In news that has delighted the ears of climate change sceptics the world over, the Copenhagen summit on climate change has failed to deliver anything of real value that will actually make a difference. It is truly disappointing that even in the face of a massive environmental disaster that will affect the entire planet, global leaders have failed to lead and work together in finding solutions to the major issues we face over the coming decades and century.

Newspapers in Australia have reported the failure of the summit and are reporting on the leader of the opposition gloating over the failure of the summit. His solution is to ignore the real issue and hope that the Australian people prove to be as oblivious to climate change as the coalition he leads.

Typically, the usual anti-Kevin Rudd biased journalists and climate change sceptics of the newspaper (The Sunday Telegraph) I read this morning, were also quick to pour further scorn on the Prime Minister and the problem of climate change itself (which they deny). One particular vocal climate change sceptic in the Sunday Telegraph has very little credibility with me and I find his obsessive anti-Rudd tirades more than a little tiring. This self-opinionated buffoon is little more than an embarrassment for both the Sunday Telegraph and the Daily Telegraph for which he also writes. His columns are becoming more of a personal vendetta against Kevin Rudd than anything resembling real journalism.

I’ll be finding a better way to become acquainted with the daily news than continuing to read the biased diatribes that continue to be put forward by these papers in future. I’ll also be hoping that our leaders can overcome the various preoccupations each have with self-interest (whether it be personal or national) in order to reach a real workable agreement on dealing with the growing threat of climate change