Different low carbon technologies from wind or solar energy to fossil carbon capture and sequestration (CCS) differ greatly when it comes to indirect greenhouse gas emissions in their life cycle. Unlike what some critics argue, the researchers not only found that wind and solar energy belong to the more favorable when it comes to life-cycle emissions. They also show that a full decarbonization of the global power sector by scaling up these technologies would induce only modest indirect greenhouse gas emissions — and hence not impede the transformation towards a climate-friendly power system.
“Both fossil and non-fossil power technologies still come with a certain amount of greenhouse gas emissions within their life cycle — on the one hand because it needs energy to construct and operate them, on the other hand because of methane emissions, e.g. from coal and gas production,” explains lead author Michaja Pehl. “However, we found there are substantial differences across technologies regarding their greenhouse gas balance. Electricity production from biomass, coal, gas and hydropower for instance induces much higher indirect greenhouse gas emissions than nuclear electricity, or wind and solar-based power supply.”
With their study the researchers provide an innovative and comprehensive global analysis of embodied energy use and indirect greenhouse gas emissions — from all relevant power sector technologies. For the first time, their study combines the strengths of simulations based on integrated energy-economy-climate models that estimate cost-optimal long-term strategies to meet climate targets with life cycle assessment approaches. So far, these research branches have operated separately. Exploring the life cycle emissions of future low-carbon supply systems and the implications for technology choices, they found that fossil power plants equipped with CCS will still account for life-cycle emissions of around 100 grams of CO2-equivalents per kWh of electricity produced, ten times more than the around 10 grams of CO2-equivalents for wind and solar power they project for 2050 in a climate protection scenario in which power production is almost completely decarbonized.
Wind and solar provide a much better greenhouse gas emissions balance than fossil-based technologies
“There is no such thing as truly clean coal. Conventional coal power currently comes with around 1000 grams of CO2-equivalents per kWh. Capturing CO2 from coal plants can reduce emissions per kWh by around 90 percent, but substantial life-cycle greenhouse gas emissions remain,” says Gunnar Luderer, energy system analyst from PIK and project leader. “To keep global warming below 2°C, however, virtually carbon free electricity is necessary. This makes it increasingly implausible that coal power will play a major role in the future, even if equipped with CO2 scrubbers.”
“When it comes to life cycle greenhouse gas emissions, wind and solar energy provide a much better greenhouse gas balance than fossil-based low carbon technologies, because they do not require additional energy for the production and transport of fuels, and the technologies themselves can be produced to a large extend with decarbonized electricity,” states Edgar Hertwich, an industrial ecologist from Yale University who co-authored the study. Due to technological innovation, less and less energy will be needed to produce wind turbines and solar photovoltaic systems.
“Some critics have argued renewable energies could come with high hidden greenhouse gas emissions that would negate their benefits to the climate. Our study now shows that the opposite is true,” concludes Luderer. “During the transition to clean power supply, the additional life-cycle emissions for building up wind and solar capacities are much smaller than the remaining emissions from existing fossil power plants before they can finally be decommissioned. The faster the low-carbon transformation of power supply is accomplished, the lower is the overall remaining carbon burden for the climate.”
Much of the enthusiasm around gene-editing techniques, particularly the CRISPR-Cas9 technology, centers on the ability to insert or remove genes or to repair disease-causing mutations. A major concern of the CRISPR-Cas9 approach, in which the double-stranded DNA molecule is cut, is how the cell responds to that cut and how it is repaired. With some frequency, this technique leaves new mutations in its wake with uncertain side effects.
In a paper appearing in the journal Cell on December 7, scientists at the Salk Institute report a modified CRISPR-Cas9 technique that alters the activity, rather than the underlying sequence, of disease-associated genes. The researchers demonstrate that this technique can be used in mice to treat several different diseases.
“Cutting DNA opens the door to introducing new mutations,” says senior author Juan Carlos Izpisua Belmonte of the Salk Institute for Biological Studies whose laboratory developed the new technique. “That is something that is going to stay with us with CRISPR or any other tool we develop that cuts DNA. It is a major bottleneck in the field of genetics — the possibility that the cell, after the DNA is cut, may introduce harmful mistakes.”
That fact guided every experiment in the Belmonte lab as they developed the technique using a modified CRISPR-Cas9 system that does not cut the DNA. Their findings are the first to provide evidence that one can alter the phenotype of an animal with a epigenetic editing technology, preserving DNA integrity.
The principal idea behind the Salk technique is the use of two adeno-associated viruses (AAVs) as the machinery to introduce their genetic manipulation machinery to cells in post-natal mice. The researchers inserted the gene for the Cas9 enzyme into one AAV virus. They used another AAV virus to introduce a short single guide RNA (sgRNA), which specifies the precise location in the mouse genome where Cas9 will bind, and a transcriptional activator. The shorter sgRNA is only 14 or 15 nucleotides compared with the standard 20 nucleotides used in most CRISPR-Cas9 techniques, and this prevents Cas9 from cutting the DNA.
“Basically, we used the modified guide RNA to bring a transcriptional activator to work together with the Cas9 and delivered that complex to the region of the genome we were interested in,” says co-first author Hsin-Kai Liao of the Belmonte laboratory.
The complex sits in the region of DNA of interest and promotes expression of a gene of interest. Similar techniques could be used to activate virtually any gene or genetic pathway without the risk of introducing potentially harmful mutations.
“We wanted to change the cell fate with therapeutic efficiency without a DNA cut,” co-first author Fumiyuki Hatanaka explains.
Strikingly, the team demonstrated disease reversal in several disease models in mice. In a mouse model of acute kidney disease, they showed that the technique activated previously damaged or silenced genes to restore normal kidney function. They were also able to induce some liver cells to differentiate into pancreatic ?-like cells, which produce insulin, to partially rescue a mouse model of type 1 diabetes.
The team also showed that they could recover muscle growth and function in mouse models of muscular dystrophy, a disease with a known gene mutation. Instead of trying to correct the mutated gene, the researchers increased the expression of genes in the same pathway as the mutated gene, over-riding the effect of the damaged gene. “We are not fixing the gene; the mutation is still there,” says Belmonte, “Instead, we are working on the epigenome and the mice recover the expression of other genes in the same pathway. That is enough to recover the muscle function of these mutant mice.”
Preliminary data suggest that the technique is safe and does not produce unwanted genetic mutations. However, the researchers are pursuing further studies to ensure safety, practicality, and efficiency before considering bringing it to a clinical environment.
Belmonte sees this technology as a way of potentially treating neurological disorders such as Alzheimer’s and Parkinson’s diseases. Just as the technique restored kidney, muscle, and insulin-producing function in the mouse models, he sees a future for rejuvenating neuronal populations.
Black holes are famous for their muscle: an intense gravitational pull known to gobble up entire stars and launch streams of matter into space at almost the speed of light.
It turns out the reality may not live up to the hype.
In a paper published today in the journal Science, University of Florida scientists have discovered these tears in the fabric of the universe have significantly weaker magnetic fields than previously thought.
A 40-mile-wide black hole 8,000 light years from Earth named V404 Cygni yielded the first precise measurements of the magnetic field that surrounds the deepest wells of gravity in the universe.
The measurements bring scientists closer to understanding how black holes’ magnetism works, deepening our knowledge of how matter behaves under the most extreme conditions — knowledge that could broaden the limits of nuclear fusion power and GPS systems.
The measurements also will help scientists solve the half-century-old mystery of how “jets” of particles traveling at nearly the speed of light shoot out of black holes’ magnetic fields, while everything else is sucked into their abysses, said study co-author Stephen Eikenberry, a professor of astronomy in UF’s College of Liberal Arts and Sciences.
“The question is, how do you do that?” Eikenberry said. “Our surprisingly low measurements will force new constraints on theoretical models that previously focused on strong magnetic fields accelerating and directing the jet flows. We weren’t expecting this, so it changes much of what we thought we knew.”
Study authors developed the measurements from data collected in 2015 during a black hole’s rare outburst of jets. The event was observed through the lens mirror of the 34-foot Gran Telescopio Canarias, the world’s largest telescope, co-owned by UF and located in Spain’s Canary Islands, with the help of its UF-built infrared camera named CIRCE (Canarias InfraRed Camera Experiment).
Smaller jet-producing black holes, like the one observed for the study, are the rock stars of galaxies. Their outbursts occur suddenly and are short-lived, said study lead author Yigit Dalilar and co-author Alan Garner, doctoral students in UF’s astronomy department. The 2015 outbursts of V404 Cygni lasted only a couple of weeks. The previous time the same black hole had a similar episode was in 1989.
“To observe it was something that happens once or twice in one’s career,” Dalilar said. “This discovery puts us one step closer to understanding how the universe works.”
Researchers from the University of Bristol have revealed how a small feathered dinosaur used its colour patterning, including a bandit mask-like stripe across its eyes, to avoid being detected by its predators and prey.
By reconstructing the likely colour patterning of the Chinese dinosaur Sinosauropteryx, researchers have shown that it had multiple types of camouflage which likely helped it to avoid being eaten in a world full of larger meat-eating dinosaurs, including relatives of the infamous Tyrannosaurus Rex, as well as potentially allowing it to sneak up more easily on its own prey.
Fiann Smithwick from the University’s School of Earth Sciences led the work, He said: “Far from all being the lumbering prehistoric grey beasts of past children’s books, at least some dinosaurs showed sophisticated colour patterns to hide from and confuse predators, just like animals.
“Vision was likely very important in dinosaurs, just like today’s birds, and so it is not surprising that they evolved elaborate colour patterns.” The colour patterns also allowed the team to identify the likely habitat in which the dinosaur lived 130 million years ago.
The work involved mapping out how dark pigmented feathers were distributed across the body and revealed some distinctive colour patterns.
These colour patterns can also be seen in modern animals where they serve as different types of camouflage.
The patterns include a dark stripe around the eye, or ‘bandit mask’, which in modern birds helps to hide the eye from would-be predators, and a striped tail that may have been used to confuse both predators and prey.
Senior author, Dr Jakob Vinther, added: “Dinosaurs might be weird in our eyes, but their colour patterns very much resemble modern counterparts.
“They had excellent vision, were fierce predators and would have evolved camouflage patterns like we see in living mammals and birds.”
The small dinosaur also showed a ‘counter-shaded’ pattern with a dark back and light belly; a pattern used by many modern animals to make the body look flatter and less 3D.
This stops animals standing out from their background, making them harder to spot, avoiding detection from would-be predators and potential prey.
Previous work on modern animals, carried out by one of the authors, Bristol’s Professor Innes Cuthill, has shown that the precise pattern of countershading relates to the specific environments in which animals live.
Animals living in open habitats, such as savannahs, often have a counter-shaded pattern that goes from dark to light sharply and high on the side of the body, while those living in more closed habitats, like forests, usually change from dark to light much lower and more gradually.
This principal was applied to Sinosauropteryx, and allowed for the reconstruction of its habitat 130 million years ago. The countershading on Sinosauropteryx went from dark to light high on the body, suggesting that it would be more likely to live in open habitats with minimal vegetation.
Behavioural ecologist Professor Cuthill, who was also a co-author of this study, said: “We’ve shown before that countershading can act as effective camouflage against living predators. It’s exciting that we can now use the colours of extinct animals to predict the sort of environment they lived in.”
Fiann Smithwick added: “By reconstructing the colour of these long-extinct dinosaurs, we have gained a better understanding of not only how they behaved and possible predator-prey dynamics, but also the environments in which they lived.
“This highlights how palaeocolour reconstructions can tell us things not possible from looking at just the bones of these animals.”
Scientists from MIT and other institutions, working closely with amateur astronomers, have spotted the dusty tails of six exocomets comets outside our solar system orbiting a faint star 800 light years from Earth.
These cosmic balls of ice and dust, which were about the size of Halley’s Comet and traveled about 100,000 miles per hour before they ultimately vaporized, are some of the smallest objects yet found outside our own solar system.
The discovery marks the first time that an object as small as a comet has been detected using transit photometry, a technique by which astronomers observe a star’s light for telltale dips in intensity. Such dips signal potential transits, or crossings of planets or other objects in front of a star, which momentarily block a small fraction of its light.
In the case of this new detection, the researchers were able to pick out the comet’s tail, or trail of gas and dust, which blocked about one-tenth of 1 percent of the star’s light as the comet streaked by.
“It’s amazing that something several orders of magnitude smaller than the Earth can be detected just by the fact that it’s emitting a lot of debris,” says Saul Rappaport, professor emeritus of physics in MIT’s Kavli Institute for Astrophysics and Space Research. “It’s pretty impressive to be able to see something so small, so far away.”
“Where few have traveled”
The detection was made using data from NASA’s Kepler Space Telescope, a stellar observatory that was launched into space in 2009. For four years, the spacecraft monitored about 200,000 stars for dips in starlight caused by transiting exoplanets.
To date, the mission has identified and confirmed more than 2,400 exoplanets, mostly orbiting stars in the constellation Cygnus, with the help of automated algorithms that quickly sift through Kepler’s data, looking for characteristic dips in starlight.
The smallest exoplanets detected thus far measure about one-third the size of the Earth. Comets, in comparison, span just several football fields, or a small city at their largest, making them incredibly difficult to spot.
However, on March 18, Jacobs, an amateur astronomer who has made it his hobby to comb through Kepler’s data, was able to pick out several curious light patterns amid the noise.
Jacobs, who works as an employment consultant for people with intellectual disabilities by day, is a member of the Planet Hunters — a citizen scientist project first established by Yale University to enlist amateur astronomers in the search for exoplanets. Members were given access to Kepler’s data in hopes that they might spot something of interest that a computer might miss.
In January, Jacobs set out to scan the entire four years of Kepler’s data taken during the main mission, comprising over 200,000 stars, each with individual light curves, or graphs of light intensity tracked over time. Jacobs spent five months sifting by eye through the data, often before and after his day job, and through the weekends.
“Looking for objects of interest in the Kepler data requires patience, persistence, and perseverance,” Jacobs says. “For me it is a form of treasure hunting, knowing that there is an interesting event waiting to be discovered. It is all about exploration and being on the hunt where few have traveled before.”
“Something we’ve seen before”
Jacobs’ goal was to look for anything out of the ordinary that computer algorithms may have passed over. In particular, he was searching for single transits — dips in starlight that happen only once, meaning they are not periodic like planets orbiting a star multiple times.
In his search, he spotted three such single transits around KIC 3542116, a faint star located 800 light years from Earth (the other three transits were found later by the team). He flagged the events and alerted Rappaport and Vanderburg, with whom he had collaborated in the past to interpret his findings.
“We sat on this for a month, because we didn’t know what it was — planet transits don’t look like this,” Rappaport recalls. “Then it occurred to me that, ‘Hey, these look like something we’ve seen before.'”
In a typical planetary transit, the resulting light curve resembles a “U,” with a sharp dip, then an equally sharp rise, as a result of a planet first blocking a little, then a lot, then a little of the light as it moves across the star. However, the light curves that Jacobs identified appeared asymmetric, with a sharp dip, followed by a more gradual rise.
Rappaport realized that the asymmetry in the light curves resembled disintegrating planets, with long trails of debris that would continue to block a bit of light as the planet moves away from the star. However, such disintegrating planets orbit their star, transiting repeatedly. In contrast, Jacobs had observed no such periodic pattern in the transits he identified.
“We thought, the only kind of body that could do the same thing and not repeat is one that probably gets destroyed in the end,” Rappaport says.
In other words, instead of orbiting around and around the star, the objects must have transited, then ultimately flown too close to the star, and vaporized.
“The only thing that fits the bill, and has a small enough mass to get destroyed, is a comet,” Rappaport says.
The researchers calculated that each comet blocked about one-tenth of 1 percent of the star’s light. To do this for several months before disappearing, the comet likely disintegrated entirely, creating a dust trail thick enough to block out that amount of starlight.
Vanderburg says the fact that these six exocomets appear to have transited very close to their star in the past four years raises some intriguing questions, the answers to which could reveal some truths about our own solar system.
“Why are there so many comets in the inner parts of these solar systems?” Vanderburg says. “Is this an extreme bombardment era in these systems? That was a really important part of our own solar system formation and may have brought water to Earth. Maybe studying exocomets and figuring out why they are found around this type of star … could give us some insight into how bombardment happens in other solar systems.”
The researchers say that in the future, the MIT-led Transiting Exoplanet Survey Satellite (TESS) mission will continue the type of research done by Kepler.
Apart from contributing to the fields of astrophysics and astronomy, Rappaport says, the new detection speaks to the perseverence and discernment of citizen scientists.
“I could name 10 types of things these people have found in the Kepler data that algorithms could not find, because of the pattern-recognition capability in the human eye,” Rappaport says. “You could now write a computer algorithm to find this kind of comet shape. But they were missed in earlier searches. They were deep enough but didn’t have the right shape that was programmed into algorithms. I think it’s fair to say this would never have been found by any algorithm.”
Scientists from The Open University (OU) have discovered a process that could explain the long-debated mystery of how land features on Mars are formed in the absence of significant amounts of water.
Experiments carried out in the OU Mars Simulation Chamber — specialised equipment, which is able to simulate the atmospheric conditions on Mars — reveal that Mars’ thin atmosphere (about 7 mbar — compared to 1,000 mbar on Earth) combined with periods of relatively warm surface temperatures causes water flowing on the surface to violently boil. This process can then move large amounts of sand and other sediment, which effectively ‘levitates’ on the boiling water.
This means that, in comparison to Planet Earth, relatively small amounts of liquid water moving across Mars’ surface could form the large dune flows, gullies and other features, which characterise the Red Planet.
“Whilst planetary scientists already know that the surface of Mars has ‘mass-wasting’ features — such as dune flows, gullies, and recurring slope lineae — which occur as a result of sediment transportation down a slope, the debate about what is forming them continues.
“Our research has discovered that this levitation effect caused by boiling water under low pressure enables the rapid transport of sand and sediment across the surface. This is a new geological phenomenon, which doesn’t happen on Earth, and could be vital to understanding similar processes on other planetary surfaces.”
Dr Raack conducted these experiments in the Hypervelocity Impact (HVI) Laboratory based at the OU. He added:
“The sources of this liquid water will require more observational studies; however, the research shows that the effects of relatively small amounts of water on Mars in forming features on the surface may have been widely underestimated.
“We need to carry out more research into how water levitates on Mars, and missions such as the ESA ExoMars 2020 Rover will provide vital insight to help us better understand our closest neighbour.”
A small, recently discovered asteroid or perhaps a comet appears to have originated from outside the solar system, coming from somewhere else in our galaxy. If so, it would be the first “interstellar object” to be observed and confirmed by astronomers.
This unusual object — for now designated A/2017 U1 — is less than a quarter-mile (400 meters) in diameter and is moving remarkably fast. Astronomers are urgently working to point telescopes around the world and in space at this notable object. Once these data are obtained and analyzed, astronomers may know more about the origin and possibly composition of the object.
A/2017 U1 was discovered Oct. 19 by the University of Hawaii’s Pan-STARRS 1 telescope on Haleakala, Hawaii, during the course of its nightly search for near-Earth objects for NASA. Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy (IfA), was first to identify the moving object and submit it to the Minor Planet Center. Weryk subsequently searched the Pan-STARRS image archive and found it also was in images taken the previous night, but was not initially identified by the moving object processing.
Weryk immediately realized this was an unusual object. “Its motion could not be explained using either a normal solar system asteroid or comet orbit,” he said. Weryk contacted IfA graduate Marco Micheli, who had the same realization using his own follow-up images taken at the European Space Agency’s telescope on Tenerife in the Canary Islands. But with the combined data, everything made sense. Said Weryk, “This object came from outside our solar system.”
“This is the most extreme orbit I have ever seen,” said Davide Farnocchia, a scientist at NASA’s Center for Near-Earth Object Studies (CNEOS) at the agency’s Jet Propulsion Laboratory in Pasadena, California. “It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back.”
The CNEOS team plotted the object’s current trajectory and even looked into its future. A/2017 U1 came from the direction of the constellation Lyra, cruising through interstellar space at a brisk clip of 15.8 miles (25.5 kilometers) per second.
The object approached our solar system from almost directly “above” the ecliptic, the approximate plane in space where the planets and most asteroids orbit the Sun, so it did not have any close encounters with the eight major planets during its plunge toward the Sun. On Sept. 2, the small body crossed under the ecliptic plane just inside of Mercury’s orbit and then made its closest approach to the Sun on Sept. 9. Pulled by the Sun’s gravity, the object made a hairpin turn under our solar system, passing under Earth’s orbit on Oct. 14 at a distance of about 15 million miles (24 million kilometers) — about 60 times the distance to the Moon. It has now shot back up above the plane of the planets and, travelling at 27 miles per second (44 kilometers per second) with respect to the Sun, the object is speeding toward the constellation Pegasus.
“We have long suspected that these objects should exist, because during the process of planet formation a lot of material should be ejected from planetary systems. What’s most surprising is that we’ve never seen interstellar objects pass through before,” said Karen Meech, an astronomer at the IfA specializing in small bodies and their connection to solar system formation.
The small body has been assigned the temporary designation A/2017 U1 by the Minor Planet Center (MPC) in Cambridge, Massachusetts, where all observations on small bodies in our solar system — and now those just passing through — are collected. Said MPC Director Matt Holman, “This kind of discovery demonstrates the great scientific value of continual wide-field surveys of the sky, coupled with intensive follow-up observations, to find things we wouldn’t otherwise know are there.”
Since this is the first object of its type ever discovered, rules for naming this type of object will need to be established by the International Astronomical Union.
“We have been waiting for this day for decades,” said CNEOS Manager Paul Chodas. “It’s long been theorized that such objects exist — asteroids or comets moving around between the stars and occasionally passing through our solar system — but this is the first such detection. So far, everything indicates this is likely an interstellar object, but more data would help to confirm it.”