Is perovskite solar cell efficiency more hype than reality?

Perovskite solar cell material tested in the lab. But there are questions over their efficiency and stability. [Credit: Dennis Schroeder/NREL]

Perovskite solar cell material tested in the lab. But there are questions over their efficiency and stability. [Credit: Dennis Schroeder/NREL]

Matthew Gunther asks some searching questions about the potential of perovskite solar cells over at Chemistry World.

Reports now suggest they are capable of efficiencies greater than 20% – a milestone which took other solar cells decades to reach.
But how realistic are these efficiency values? This question is now being asked by national laboratories, with a cluster of research groups finding that the very nature of efficiency testing, as well as the questionable stability of perovskites themselves, is only serving to exaggerate device performance. And unless this stability problem can be solved perovskite devices may never become a viable alternative to silicon solar cells. 

He talks to Keith Emery, chief scientist at the National Renewable Energy Laboratory’s (NREL) photovoltaic cell and module performance characterisation group in the US, who says, 

All the exciting efficiencies and any energy claims that are associated with [perovskite solar cells] should be taken with a grain of salt...
To solve the stability problem the economics of that material system may go out the door. Until the stability problem is solved, you do not know how much it is going to cost you.’

Martin Green, director of the Centre for Advanced Photovoltaics in Australia, agrees:

Measurement is complicated by the fact that devices are not stable,’ says Green. ‘They display hysteresis in their output.

Cosmos magazine looked at the progress of research into alternatives to silicon in solar cell manufacture last week.


What Earth’s other ‘moon’ could tell us about the Solar System

You probably didn't know that the Earth has a second 'moon', which orbits our planet on a crazy path called a horseshoe orbit, as can be seen in the video above.

The other 'moon', known as 3753 Cruithne, was discovered in 1997, as Duncan Forgan
Research Fellow at University of St Andrews, explains on The Conversation.

Cruithne is tiny – about the size of the comet 67P/Churyumov-Gerasimenko, which is currently playing host to the Rosetta orbiter and the Philae lander

Forgan says Cruithne is of more value to us than just curiosity.

So what can we learn about the solar system from Cruithne? Quite a lot. Like the many other asteroids and comets, it contains forensic evidence about how the planets were assembled. Its kooky orbit is an ideal testing ground for our understanding of how the solar system evolves under gravity...
One day, Cruithne could be a practice site for landing humans on asteroids, and perhaps even mining them for the rare-earth metals our new technologies desperately crave. Most importantly of all, Cruithne teaches us that the solar system isn’t eternal – and by extension, neither are we.

Could this be the model of life that lives on Titan?

A artist's impression of a 9-nanometer azotosome, about the size of a virus, with a piece of the membrane cut away to show the hollow interior. [Credit: James Stevenson]

A artist's impression of a 9-nanometer azotosome, about the size of a virus, with a piece of the membrane cut away to show the hollow interior. [Credit: James Stevenson]

A team of scientists at Cornell University has modelled a new type of methane-based, oxygen-free life form that could live on Saturn's moon Titan.

We discussed the possibilities of life on Titan with the paper's co-author Jonathan Lunine last month for our cover story Could there be life in Titan's methane sea? Lunine has been working on the problem for years, having been inspired by Voyager 1's fly-by of Titan at the beginning of his graduate career.

“Hydrocarbon life on Titan, if it exists, is so fundamentally different from aqueous biochemistry that one would immediately know it had an independent origin. How can one not be passionate about exploring this enigmatic world?” he told Cosmos.

The latest research gives a possible structure for life that could metabolise and reproduce in a similar way to life on Earth.

It was led by chemical molecular dynamics expert Paulette Clancy and first author James Stevenson, a graduate student in chemical engineering. 

"We're not biologists, and we're not astronomers, but we had the right tools," Clancy said. "Perhaps it helped, because we didn't come in with any preconceptions about what should be in a membrane and what shouldn't. We just worked with the compounds that we knew were there and asked, 'If this was your palette, what can you make out of that?'"

The engineers named their theorized cell membrane an "azotosome," "azote" being the French word for nitrogen. "Liposome" comes from the Greek "lipos" and "soma" to mean "lipid body;" by analogy, "azotosome" means "nitrogen body."
The azotosome is made from nitrogen, carbon and hydrogen molecules known to exist in the cryogenic seas of Titan, but shows the same stability and flexibility that Earth's analogous liposome does. This came as a surprise to chemists like Clancy and Stevenson, who had never thought about the mechanics of cell stability before; they usually study semiconductors, not cells.
The engineers employed a molecular dynamics method that screened for candidate compounds from methane for self-assembly into membrane-like structures. The most promising compound they found is an acrylonitrile azotosome, which showed good stability, a strong barrier to decomposition, and a flexibility similar to that of phospholipid membranes on Earth. Acrylonitrile - a colourless, poisonous, liquid organic compound used in the manufacture of acrylic fibers, resins and thermoplastics - is present in Titan's atmosphere.

Below is a graphic that first appeared in the current issue of Cosmos magazine print edition of how the mechanics of methane-based life might work. Click to expand the graphic.

Wind-powered freighter design could revolutionise international shipping

The hull of the cargo ship Vindskip would act as a large wing sail. [Credit: Lade AS]

Norwegian engineer Terje Lade has designed a wind-propelled cargo ship that could revolutionise the way we transport goods around the world.

The ship, dubbed the Vindship, uses the hull as a wing-like sail that would drive the ship at sea. In low-wind passages it would be equipped with a liquefied natural gas (LNG)-powered engine.

Lade estimates that fuel consumption would be only 60% of a similarly sized freighter using conventional propulsion.

ship on average. Carbon dioxide emissions are reduced by 80 percent, according to calculations by the Norwegian company.

Lade has already tested the ship's hull design in wind tunnels and says the freighter could be ready to set sail as soon as 2019. First, the ship model has to pass numerous tests in a marine research model tank – also called a towing tank. 

Not only would the ship be good for the environment it would improve profitability of shipping lines, Lade says:

International shipping is transporting 90 percent of all goods on earth. Running on heavy fuel oil freighters contribute to pollution. The International Maritime Organization (IMO) wants to reduce the environmental impact of ocean liners. One of the measures: Starting from 2020, ships will only be allowed to use fuel containing maximum 0.1 percent sulfur in their fuel in certain areas. However, the higher-quality fuel with less sulfur is more expensive than the heavy fuel oil which is currently used. Shipping companies are thus facing a major challenge in reducing their fuel costs while complying with the emission guidelines.



Astronauts complete their third spacewalk

Terry Virts on his third spacewalk in eight days. [Credit: NASA]

NASA have released this exciting image of Expedition 42 Flight Engineer Terry Virts on the third spacewalk in eight days outside the International Space Station. It was originally tweeted by Virts (@AstroTerry).

Virts and Commander Barry "Butch" Wilmore on Sunday completed installing 120 metres of cable and several antennas associated with the Common Communications for Visiting Vehicles system known as C2V2.

Boeing’s Crew Transportation System (CST)-100 and the SpaceX Crew Dragon will use the system in the coming years to rendezvous with the orbital laboratory and deliver crews to the space station.

It's official – cats despise your music collection

Just so long as it isn't Bach – cats march to a different beat. [Credit: iStock]

Just so long as it isn't Bach – cats march to a different beat. [Credit: iStock]

To the long list of things your cat despises about you, you can now add your music collection. Scientists in the United States have discovered there is a feline preference for "species-appropriate" music – purring tempos and sliding wails are the things that soothe the average cat.

Two psychologists, Charles Snowdon and Megan Savage, and a composer, David Teie, teamed up for the project at the University of Wisconsin, Madison. They created three purpose-written melodies and tested them out on a group of 47 domestic cats, also compared in "human" music by composers such as Johann Sebastian Bach and Gabriel Fauré.

The cats showed trademark disdain for the great composers but when "their" tunes came on they reacted positively rubbing the speakers with their faces.

"We looked at the natural vocalisations of cats and matched our music to the same frequency range, which is about an octave or more higher than human voices," says Snowdon. "We incorporated tempos that we thought cats would find interesting – the tempo of purring in one piece and the tempo of suckling in another – and since cats use lots of sliding frequencies in their calls, the cat music had many more sliding notes than the human music."

The same team of researchers has done this sort of thing before. In 2009, they showed tamarin monkeys ignored human music but were calmed by music tailored for them.

They say that the finding could provide a way to soothe the nerves of animals in zoos and other forms of captivity.

Click on the links to hear the three melodies – Spook's Ditty, Cozmo's Air and Rusty's Ballad.


Russia makes plans for its own space station and missions to the Moon

The International Space Station (ISS) as seen from the space shuttle Discovery as the two spacecraft begin their relative separation in March 2009. [Credit: NASA]

The International Space Station (ISS) as seen from the space shuttle Discovery as the two spacecraft begin their relative separation in March 2009. [Credit: NASA]

The Russian Federal Space Agency, or Roscosmos, announced on last Tuesday that it will be building its own national space station in 2024 – and aims to send cosmonauts to the Moon by 2030.

Roscosmos intends to construct this new space station using modules from its segment that is currently connected to the International Space Station (ISS), which is only commissioned for operation until 2024. 

A close-up view of the ISS in an image photographed by a crew member on space shuttle Discovery after the station and shuttle began another post-undocking relative separation, this time in March 2011. [Credit: NASA]

A close-up view of the ISS in an image photographed by a crew member on space shuttle Discovery after the station and shuttle began another post-undocking relative separation, this time in March 2011. [Credit: NASA]

The ISS is made up of two segments, the United States Orbital Segment (USOS) and the Russian Orbital Segment (ROS). The station is shared by about 15 countries, and five space agencies fund it – NASA, the Japan Aerospace Exploration Agency (JAXA), the European Space Agency (ESA), the Canadian Space Agency (CSA) and Roscosmos.

Roscosmos has been the only space agency able to send crew and cargo up to the ISS on its Soyuz rockets since 2011, when NASA retired its space shuttles.

Take a tour of the Russian segment of the ISS with Expedition 33 Commander Suni Williams. [Credit: Video]

The space agency aims to use the station as its cosmonauts’ base – and later, to actually send both orbiting missions around the moon and manned missions to the surface of the moon by 2030.

Roscosmos’ plans were discussed at a Scientific and Technical Council meeting under the chairmanship of Russian Space Agency’s Yuri Koptev, and they are hoping to develop a more detailed document of their plans at an upcoming meeting in March.

 H/T The Guardian

Statins linked to a reduced risk of liver cancer in the UK

Statins, such as Lipitor, are prescribed to reduce cholesterol levels and help prevent heart attacks and strokes. [Credit: iStock]

Statins, such as Lipitor, are prescribed to reduce cholesterol levels and help prevent heart attacks and strokes. [Credit: iStock]

A new study of people living in the UK links taking statins – a drug widely prescribed to reduce cholesterol levels – to a decreased risk of liver cancer.

Although this isn’t the first time that the drug has been associated with a reduced risk of liver cancer, previous studies on the matter have used data from regions already associated with high liver cancer incidence rates, such as Asia. Researchers wanted to examine the statin-liver cancer relationships in regions where there were low rates of liver cancer.

The team of scientists, led by Katherine A. McGlynn from the Division of Cancer Epidemiology and Genetics at the National Cancer Institute in Maryland, USA, conducted a nested case-control study using data from the United Kingdom’s Clinical Practice Research Datalink (CPRD). The study examined 1,195 liver cancer cases that were diagnosed between 1988 and 2011 and compared them to 4,640 control patients.

Their results, published in JNCI: Journal of the National Cancer Institute, showed that statin use was associated with a reduced risk of liver cancer. This was especially true for people who had liver disease and those who had diabetes – two groups at higher risk of developing liver cancer.

Liver cancer is the sixth most common cancer in the world, excluding non-melanoma skin cancers, according to the World Cancer Research Fund International.

The authors concluded that “the results of the current study suggest that use of statins among persons at high risk of developing liver cancer, even in low-risk settings, may have a net cancer protective effect”.

But the drug itself comes with controversy. Statins have been at the centre of a heated debate since they were first available two decades ago, with arguments over whether or not its benefits outweigh the risks of its potential side effects – especially for men over the age of 50.

Capturing the captivating flight paths of seagulls with special video effects

[Credit: Paul Parker]

Videographer Paul Parker created a fascinating video that displays the flight paths of seagulls against the scenic landscapes of Cornwall, UK, where he is based. In this 2:30 video, the birds ribbon their way through the skies in mesmerising curves and bends.

Parker produced the video using the echo effect in Adobe’s editing software After Effects.

Filming the flight paths of birds gives us the chance to not only appreciate their graceful movements but also study the science behind them, such as why birds fly in V formations.


Astronaut pays tribute to Leonard Nimoy from space

[Credit: NASA]

[Credit: NASA]

Astronaut Terry Virts (@AstroTerry) tweeted this image of a Vulcan hand salute from orbit in the International Space Station as a tribute to actor Leonard Nimoy, who died on Friday.

Nimoy played science officer Mr. Spock in the Star Trek series. Cape Cod, on the east coast of the United States, and Nimoy's home town of Boston can be seen from the window of the ISS to the right of Virts' index finger.

Below, a picture from 1976 shows the cast of Star Trek gather as NASA's space shuttle Enterprise rolled out of the Palmdale manufacturing facilities.

Nimoy can be seen sixth from the left.

The cast from Star Trek greets the space shuttle Enterprise in 1976. From left to right: NASA Administrator Dr. James D. Fletcher; DeForest Kelley, who portrayed Dr. "Bones" McCoy on the series; George Takei (Mr. Sulu); James Doohan (Chief Engineer Montgomery "Scotty" Scott); Nichelle Nichols (Lt. Uhura); Leonard Nimoy (Mr Spock); series creator Gene Roddenberry;  U.S. congressman. Don Fuqua and, Walter Koenig (Ensign Pavel Chekov). [Credit: NASA]


The future of self-driving vehicles could involve more long-haul trucks than cars

The Mercedes-Benz Future Truck 2025 

Until now most of the focus on self-driving vehicles has been on personal transport – cars. But Scott Smith on Quartz suggests it might be long distance road transport where the revolution really takes place.

in terms of near-term impact, the self-driving semi could make a bigger splash given the trucking industry contributed $642 billion to the US economy last year.

As he points out, a lot of groundwork has already been done.

Major delivery companies such as Fedex, UPS, and DHL have been refining the algorithms that direct their human drivers’ routes for years though this is now reaching the point where the drivers and the algorithms are seeing eye to eye less frequently, and drivers’ learned experience from years on the road is clashing with the cold logic of software, where routes can seem less intuitive to a single driver even while being more economical for the whole company. DHL, for one, sees self-driving trucks as completing an already rapidly automating supply chain, where container ports on one end and distribution warehouses further down the line are already filling with robotics.

He also points to progress in the development of the technology itself, including at Mercedes Benz which already has a demo model. And then there's this

A company appropriately called Peloton has been working on the capability of platooning autonomous trucks to gain greater economic efficiencies. And of course, the omnipresent Elon Musk has proposed even skipping highways altogether and putting road freight on his Hyperloop tube transport system.