Tag Archives: solar energy

photovoltaic research

The sunshine factory

Featured image above: World record holder Xiaojing Hao with CZTS thin-film cells atop the Tyree Energy Technologies Building at UNSW’s Kensington campus.

Xiaojing Hao couldn’t sleep. Two weeks earlier, the UNSW engineer had sent a thin black tile, barely the size of a fingernail, to the US for testing, and she was waiting anxiously for the results. Her PhD students were equally on edge.

It was midnight when Hao checked her email one more time. It was official: her team had broken a solar cell world efficiency record. “I was full of joy at the achievement,” Hao recalls. “I shared the good news with my team immediately – we made it!”

Hao’s thin black tile had become the newest champion in the solar cell race: one of seven world records UNSW photovoltaics researchers broke in 2016. Efficiency records are not just notches in the scientists’ belts. The more sunlight solar cells can convert, the less manufacturing, transport, installation and wiring is needed to deliver each watt – moving solar energy closer and closer to knocking coal off its perch as the cheapest form of energy.

UNSW photovoltaics researchers, led by Martin Green – often dubbed the ‘father of photovoltaics’  – have held world records for efficiencies in solar cells in 30 of the past 33 years. And with its strong track record in research commercialisation, UNSW’s prototype technology is setting the trends for the commercial solar market.

Meanwhile, their focus is on developing the next generation of solar cells – pushing forward to a zero-emission future. 

Martin Green and Wei Zhang measure the adhesion between metal contacts and solar cells.

Making a commercially viable product

Hao moved to Sydney in 2004 from China, where the solar industry is booming. A materials engineer by training, Hao was intrigued by the frontline photovoltaic research on thin-film solar cells at UNSW.

These cells have benefits over the more traditional silicon cells. The manufacturing process doesn’t require high temperature steps. They can also be much thinner than bulky wafer silicon, and so could engender new solar applications: imagine solar-powered electric cars,  building-integrated solar cells or photovoltaic glazing on windows.

So far, the thin-film uptake in the markets has been sluggish: commercial thin-film cells make up only around 8% of the solar market. The problem is that the commercial products available, cadmium telluride and copper indium gallium selenide (CIGS), are made of toxic or rare materials: cadmium is highly toxic and tellurium is about as abundant as gold.

So Hao decided to go back a step. “We’re trying to make the whole world ‘green’, right?” she says. “So, we should choose materials that are non-toxic and cheap, and that would ensure their deployment in the future – without constraint on raw materials.”

Finding a material worth investigating

Her quest for a greener world began in 2011, after she returned from maternity leave. Hao and her PhD supervisor, Martin Green, knew what they were looking for: a mix of elements that would absorb and conduct energy from sunlight, and are commonly found in nature.

“We worked our way through the periodic table for materials that met those criteria – CZTS was the one that popped out at you as worthy of investigation,” Green explains.

In 2012 CZTS – copper, zinc, tin and sulphide – was recorded for the first time in the solar cell efficiency tables, an internationally curated list of solar cell performance. Inclusion in the tables means a new cell has been independently tested for efficiency by a recognised test centre, and indicates the new cell has features that will be interesting for the photovoltaic community.

Hao began making her own version of the CZTS cell, looking for defects, ironing out the kinks and pushing efficiencies, bit by bit.

At the basic level, all solar cells absorb photons from sunlight and funnel them into an electric current. Hao discovered that tiny holes in her CZTS cells, formed as the components were baked during production, acted like a roadblock for that charge. By adding a microscopic grid layer through the cells, her team stopped these holes from forming, and raised their efficiency to 7.6% in a 1cm2 cell.

That was Hao’s first world record. By changing the buffer that helps the CZTS cell collect charge, the team could further tweak the current flow and voltage output. This buffer netted Hao another world record in September 2016 – a 9.5% efficiency for a 0.24cm2 cell, beating a 9.1% record previously held by Toyota.

“We’re completely leading CZTS solar cell technology at the moment,” Hao says with a smile.

The energy output of Xiaojing Hao’s CZTS cells are tested.

According to Hao, these records have already sparked interest from Chinese, US partners China Guodian Corp – one of the five largest power producers in China – and Baosteel, the giant state-owned iron and steel company based in Shanghai.

Hao is also in talks with thin-film manufacturers MiaSolé of the US, Sweden’s  Midsummer and Solar Frontier in Japan. The companies are commercial producers of CIGS cells and their production lines use similar methods; Hao says they could easily adapt them
for CZTS production.

Hao believes efficiencies of above 15% will start moving CZTS to the commercial market. She is already well on her way, aiming to bring her CZTS cells to 13% efficiency by 2018.

Taking on the solar cell market

After four decades in photovoltaics research at UNSW, Martin Green has a healthy scepticism when it comes to marrying new breakthrough technologies with commercial markets. “The solar industry is just so huge that you need enormous resources to introduce a new product to the market – and there’s a huge risk associated with that,” he says.

With a firm grip on 90% of the commercial solar cell market, “the situation with silicon is a bit like that of the internal combustion engine,” Green explains. “That engine is not the best fossil fuel engine, but the huge industry supporting it means it has been very difficult to displace.”

But CZTS does not need to compete with silicon – the two can complement each other. Silicon absorbs red light better than blue, while CZTS absorbs blue wavelengths better. A CZTS layer on top of a silicon cell can catch the wavelengths silicon does not use efficiently. Green says the big silicon manufacturers could trial the new CZTS technology by selling these ‘stacked cells’ as a premium product line.

“Companies that are well established would be interested in exploring that space – it just seems like a natural evolutionary path for photovoltaic technology,” he says.

Collaborating with the competition

Just a few labs down the corridor of the Tyree Energy Technologies Building at UNSW’s Kensington campus, Anita Ho-Baillie is working with Green to put another ‘stackable’ thin-film solar cell through its paces.

In 2009, a material called perovskite arrived on the thin-film solar cell stage with an efficiency of 3.8%. Perovskites have since shot up in efficiency ratings faster than any other solar cell technology.

After Ho-Baillie’s team found a new way to apply perovskite to a surface in an even layer, their solar cells broke three more world records in 2016. Her next step is to make perovskites more durable to match the current lifetime of silicon solar cells – an essential prerequisite for large-scale commercial deployment.

Anita Ho-Baillie with her record-setting perovskite cells.

As the leader of the perovskites project in UNSW-based Australian Centre for Advanced Photovoltaics (ACAP), Ho-Baillie stands at the nexus of Australia’s greatest cluster of scientists pushing thin-film technologies forward. 

This alliance consists of six research organisations around Australia: the national research agency, CSIRO; Melbourne’s Monash University and the University of Melbourne; the University of Queensland in Brisbane; the Australian National University in Canberra; and UNSW in Sydney.

ACAP director Martin Green says, “We’ve been able to draw on the expertise of all these groups and come at problems from different angles, so it’s really put us in a good spot internationally”.

Ho-Baillie admits balancing collaboration with competition is tricky in a field where everyone is trying to claim the top spot. “It’s hard, but we find working together really helps,” she says. 

Much like CZTS and other thin films, perovskite cells are flexible, making them a perfect candidate for energy-harvesting glazes on building materials, cars or windows. But Ho-Baillie has even greater ambitions: with their low weight-to-power ratio, perovskites would be perfect for supplying precious energy to spacecraft, where every kilo counts. 

“Perovskites came from nowhere,” she says. “Now I think they will lead us to something that we never even thought would work.”

Improving the cost of solar energy by 150 fold

Thin films are making their mark, but Green is also working to squeeze more energy from sunlight using silicon, smashing two more world records in 2016. Using specialised mirrors and prisms, Mark Keevers from Green’s team pushed silicon cells to collect concentrated sunlight with 40.6% efficiency, and unconcentrated sunlight at 34.5%.

Mark Keevers made silicon cells more efficient using specialised mirrors and prisms.

Although these prototypes are perfect for soaking up photons on solar tower ‘concentrators’ with heavy-duty efficiency, their manufacturing costs are too high to make them viable in the consumer market.

But on the rooftop, silicon is still king. And it’s thanks to plunging costs made possible by a UNSW-led boom in silicon solar cell production in China, which now provides more than half the world’s solar cells.

In 1995, Green and his long-term collaborator Stuart Wenham – along with (then) PhD student Shi Zhengrong – started solar cell company Pacific Solar in Australia.

Solar pioneers Martin Green and Stuart Wenham

After six years racking up a wealth of management and manufacturing know-how, Zhengrong returned to his native China and founded the silicon solar manufacturing company Suntech Power in 2001, using technology developed at UNSW to dramatically reduce costs.

By 2005, Zhengrong became the world’s first ‘solar billionaire’, and a wave of Chinese companies hit the market, following Suntech’s recipe. The global solar industry was growing at an average 41% year-on-year. And within a decade, China’s market share of the global photovoltaic industry had grown from near zero to over 55%. Suntech itself delivered more than 13 million solar panels to 80 countries.

Where photovoltaic solar cells used to deliver one watt for US$76.67 in 1977,  that’s down to just US49¢ today. That’s a 150-fold improvement in the 40 years Green has been in the field.

“Shi was the right person at the right place and the right time to move in both Chinese and Western cultures,” Green says.

“It’s interesting to ponder what would have happened if UNSW hadn’t kick-started the Chinese industry.”

Breaking through the next barrier of photovoltaic research

With plunging module prices, rising efficiencies and more durable cells, why is the world still relying on coal for the lion’s share of its electricity needs? 

Perhaps it’s not the solar technology that we’re waiting for. A fundamental challenge remains: how to store the energy we can now capture from sunlight for later use.

“I think photovoltaics has already reached the tipping point – the efficiency and cost is already able to compete with fossil fuels,” says Wenham. “I think the next breakthrough needs to be in energy storage, to bring down that cost enough to make photovoltaics usable everywhere at any time.”

This doesn’t mean UNSW photovoltaics scientists are calling it a day. Instead, they continue to push silicon to its limits, while new technologies, such as Hao’s record-breaking CZTS tile, are racing to catch up to silicon’s powerhouse.

“Solar technology will continue to be higher-efficiency, lower-cost – and will keep getting better,” says Wenham. “The more we develop photovoltaic technology, the easier the transition will become.”

“We’ve reached a new era where coal is no longer the cheapest way of making electricity – it’s solar,” says Green. “And the exciting thing about that is – I regard solar as still in a very primitive stage of development, so there is plenty more cost reduction to come.”

– Viviane Richter

Photography: Quentin Jones

For more stories at the forefront of engineering research, check out Ingenuity magazine.

Recommended for you: The Quantum Gamble

New science magazine INGENUITY launched

Featured image above: At the launch of INGENUITY with UNSW Dean of Engineering Mark Hoffman, Refraction Media cofounders Karen Taylor-Brown and Heather Catchpole, and UNSW Engineering’s senior communications advisor Wilson da Silva

INGENUITY, a new science magazine focusing on the frontiers of engineering research at UNSW and with a global distribution, was launched on Tuesday by UNSW’s Dean of Engineering, Mark Hoffman.

“We are, without question, a powerhouse of engineering research in Australia,” said Hoffman. “With nine schools, 32 research centres and participating or leading 10 Cooperative Research Centres, we do truly amazing research – among the world’s best. And we work with more than 500 partners in industry and government to bring the fruits of that research to society.

“We have capacity to do more, as many potential research partners in Australia and overseas are not necessarily aware of the breadth and depth of what we do,” he added. “If we are to have the greatest impact in the world at large, as a university and as engineers, we need to get our research out to the world.  And the creation of INGENUITY is part of that effort.”

Hoffman said the magazine was one of a number of initiatives UNSW Engineering is pursuing to enhance the Faculty’s global impact and its academic and research excellence.

“In May, we hosted the first Ingenuity Fellow, a journalist-in-residence program for overseas science journalists. Our inaugural recipient was Rebecca Morelle, global science correspondent for BBC News in London, and she spent three weeks on-campus meeting some of our best minds and most impressive innovators. And last month, we held a sold-out public event with Peter Norvig, Research Director at Google, talking about Google’s approach to artificial intelligence and machine learning.

“We mean to not just be the leading engineering faculty in the country but, in a global industry, to be seen as one of the great engineering faculties of the world,” he concluded.

Through engaging storytelling by some of the country’s finest science writers, stylish design and beautiful photography, INGENUITY will bring to life the Faculty’s work in areas like quantum computing, bionic vision, solar energy, water and city environments, artificial intelligence, biomedical instrumentation, robotics, advanced polymers, space research, materials and membranes, cyber security and sustainable design.

The free magazine is being distributed to senior executives of Australia’s largest corporations, federal and state parliamentarians and senior government officials, scientific and industry collaborators of UNSW’s Faculty of Engineering globally, as well as science and technology journalists worldwide. The print edition is also being distributed to Australian embassies and trade offices overseas, and at the biennial World Conference of Science Journalists and the Annual Meeting of the American Association for the Advancement of Science.

The magazine is produced by specialist custom publishing house Refraction Media, whose clients include Google, the CRC Association, the Office to the Chief Scientist and ANSTO, and who was named Best Small Publisher in 2015 at the annual Publish Awards.

“Quality long-form journalism in science and technology is hard to come by in Australia,” said Wilson da Silva, the faculty’s senior communications advisor and former editor-in-chief of COSMOS magazine, which he co-founded with Alan Finkel, now Australia’s Chief Scientist. “There’s a wealth of great research stories to tell at UNSW, and we hope that everyone, including the general public, will enjoy the quality writing in INGENUITY and the great stories of Australian research excellence it has to tell.”

How to receive INGENUITY:

This information was first shared by UNSW Engineering on 5 July 2017. 

Testing zero-energy homes

Featured image credit: D-Max Photography

The CRC for Low Carbon Living (CRCLCL) has announced $500,000 in funding for a new national zero-energy homes project. The project will research consumer attitudes and aim to influence the building industry to construct new dwellings to zero-energy standards.

At present the energy efficiency of a home is measured according to the Nationwide House Energy Rating System (NatHERS). This star rating system measures the energy required to heat and cool a home, with new buildings being required to meet a minimum six-star rating.

Zero-energy homes, on the other hand, are homes that are carbon neutral across the year – they produce as much (or more) energy than they consume. All aspects of energy consumption are accounted for – not just heating and cooling, but also lighting, appliances and so on.

Project lead Dr Josh Byrne, senior research fellow with Curtin University’s Sustainability Policy Institute, believes that the current six-star requirement is merely “eliminating worst practice”. He has built two 10-star rated homes as part of his project, Josh’s House, which was part of the CRCLCL’s Living Labs project near Fremantle in Western Australia. Now he’s keen to bring zero-energy homes into the mainstream.

“It’s not just about bunging on more solar panels to offset the power usage, it’s about how the houses can be designed to perform better thermally,” Byrne says. “We know that simple things like orientation, cross-ventilation, and building air tightness can all dramatically reduce the build performance.”

The project team will be working with developers and builders from three different climate areas – WA, the ACT and Queensland – to design and build zero-energy display homes and present them alongside conventional homes to gauge the response from consumers. Instead of focusing on the sustainability benefits, they want to see how the public thinks zero-energy homes stack up on liveability. “We’re really interested in seeing how people respond to the look, feel and comfort of the zero-energy homes,” Byrne says.

The researchers will then present this data to the regulatory bodies, in the hope that an evidence-based approach will help shift the common perceptions that sustainable building practices are too costly and that there is no market demand for these homes.

With 100,000 new homes being built in Australia each year, moving to zero-energy homes would reduce carbon emissions by 700,000 tonnes. California has committed to achieving this by 2020, and members of the European Union are doing the same. Byrne thinks it’s more than possible here. “I would like to see us setting a realistic goal of achieving that within 10 years,” he says.

Find out more at LOWCARBONLIVINGCRC.COM.AU

Read more CRC discovery in KnowHow 2017

renewable energy

Renewable energy is getting cheaper

The stars are aligning for Australia to transition to 100% renewable energy. Our fossil fuel infrastructure is ageing, which means we will soon need to invest in new power generators. New technologies such as battery storage could revolutionise long-standing business models. With care, the transitions away from fossil fuels could offer greater job opportunities.

Our latest research, which corroborates previous work, shows the technology already exists to solve many of the remaining questions around technological capability. For instance, the fact that wind and solar don’t generate electricity when the wind isn’t blowing and the sun isn’t shining can be dealt with by installing a network of diverse generators across a wide area, or by increasing our use of energy storage.

One of the biggest remaining barriers to transition is cost. But this is also rapidly changing. Much work is going into reducing the cost of renewable energy, including the latest funding announcement from the Australian Renewable Energy Agency (ARENA) of A$92 million for 12 solar projects.

The cost of building renewable energy

The cost of renewable energy is highly variable across the world and even within Australia. The picture is not simple, but it does help to start by looking at the big picture.

Average capital costs of constructing new wind, solar PV and ocean/tidal generators are already lower than equivalent coal generation infrastructure.

Research suggests that, overall, the cost of moving to 100% renewable energy is not significantly higher than the cost of hitting a lower target.

The capital cost of investment in renewable energy generation technologies is also falling rapidly. In its 2014 report on global renewable power generation costs, the International Renewable Energy Agency (IRENA) showed that the total cost of installation and operation over a lifetime of small-scale residential PV systems in Australia has fallen from US$0.35 to US$0.17 per kilowatt-hour between 2010 and 2014.

In part this has been because of reduced installation costs, together with our exceptional abundance of sunshine.

As a result, Australian new residential solar installation has soared to the fifth highest in the world. Installed capacity accounts for 9% of national electricity generation capacity and 2.8% of electrical energy generation.

The historical reductions in installation costs for wind energy are similar globally and in Australia. Recent 2016 reverse auctions in the Australian Capital Territory have received Australia’s lowest known contract price for renewables with bids at A$77 per megawatt-hour.

Beyond building

But the capital cost of building generation infrastructure is not the whole story. Once the generator is built, operations and maintenance costs also become important. For most renewables (biomass excluded) the fuel costs are zero because nature itself provides the fuel for free.

Other costs that we must consider are variable and fixed costs. Fixed costs, such as annual preventative maintenance or insurance, don’t change with the amount of electricity produced. Variable costs, such as casual labour or generator repairs, may increase when more electricity is produced.

The variable costs for some renewables (biomass, hydropower and large-scale solar PV) are lower than coal. For other renewable technologies they are only slightly higher. Fixed costs for almost all renewable technologies are lower than for coal.

We also need to think about costs beyond individual generators. The vastness of our Australian continent is a bonus and a challenge for building 100% renewable energy.

It can be used strategically to give a 100% renewables supply reliability by using an interconnected network of generators. For instance, it may be very sunny or windy in one region. Excess electricity produced in this region can fill a gap in electricity demand in less sunny or windy places elsewhere.

But this also poses challenges. To take advantage of the reliability that a highly distributed renewable electricity system can provide, we must also consider the costs associated with expanding the transmission network.

For example, in our research we investigated one possible 100% renewables electricity scenario. This was conservatively based on current technology and demand (conservative because technology is likely to change, and electricity demand has been unexpectedly falling). The scenario required a transmission grid two-and-a-half times larger than our current grid, including new cross-continental linkages between Western Australia and the Northern Territory, which currently stand alone from the well-integrated eastern Australian networks.

The challenges of transitioning to a renewable electricity sector are no doubt great, but our ageing generator infrastructure means that an overhaul will soon be due. Even though the price of electricity from old coal power plants is currently cheaper than that from many new renewable plants (because the former are already paid off), cost reductions mean a strong business case now exists for renewable technologies investment.

In a recent article on The Conversation, John Hewson wrote that “renewable energy is one of our most ‘shovel ready’ business opportunities”.

Now is the time to pre-empt the looming deadline for infrastructure overhaul to ensure future economic resilience for Australia.

– Bonnie McBain

This article was first published by The Conversation on September 8 2016. Read the original article here.

microgrid

Disruptive microgrid clusters

Microgrids are independently managed, locally-generated energy grids that allow communities to supply and manage their own power supply.

A prime example of a microgrid is WA’s Alkimos Beach project, which will use lithium-ion batteries and rooftop solar to power a new housing development.

“Microgrids are becoming more of a reality than ever before, and not only for remote communities, but also on an urban and utility scale,” Curtin University’s Professor Arindam Ghosh says.

“They’re reliable, energy-diverse and environmentally friendly, and these advantages are driving microgrid research and development.”

Because urban microgrids can connect or disconnect from the main grid as required, they can also provide backup when the main grid goes down, Ghosh says.

For example, when Japan’s 2011 tsunami knocked out Sendai City’s power grid for weeks, the microgrid at its local university didn’t blink, using fuel cells, solar panels and natural gas turbines to power its way through the entire disaster.

But any grid can be knocked out when demand exceeds supply.

Cooperative resource sharing

“The main problem with microgrids is that you have limited resources,” Ghosh says.

“You might not have sufficient backup to cope with peak energy loads, which means there’s the possibility that your grid will go down.”

The answer is to create microgrid clusters, Ghosh says.

His research indicates that connecting independently managed microgrids enables mutual support during peak demand periods.

“Say you know you’re able to supply your microgrid with four generators, but for some reason—maintenance or failure—you lose one generator, you might have a shortfall of twenty or thirty kilowatts, and that’s enough for your microgrid to collapse,” he says.

“That’s when you need to ask your neighbour for help.”

If your microgrid is connected with a neighbour’s microgrid, you could fill your shortfall with their excess supply, but managing this sharing can become complicated, especially where grids are connected using a simple switch.

Ghosh’s simulations employed the more sophisticated option of connecting with a back-to-back converter.

“With a back-to-back converter, I have control over how much power I can take from my neighbour, and how much power I can send…it allows me to give you ‘X’ amount of power, but to keep the rest for myself,” he says.

Ghosh says reducing power demand during peak times is also essential.

– Cris Burne

This article was first published by ScienceNetwork WA on23 April 2016. Read the original article here.