News Picks

Physics Today’s online staff summarize the most important and interesting news about science from the world's top media outlets.

There are 8 posts for the selected month (August 2015).
August 4, 2015 3:15 PM

Cutting carbon emissions is better than carbon removal, says study

Science: Although carbon dioxide removal (CDR) from the atmosphere has been proposed as one method to mitigate global warming, a new study shows that it would have only limited effect. Sabine Mathesius of the Potsdam Institute for Climate Impact Research in Germany and colleagues used computer simulations to model the effects of removing about half the atmospheric CO2 currently being emitted from manmade sources. Such an effort would require some 5000 new facilities, each the size of a sports stadium, and could cost a trillion dollars. Yet the researchers found that the environmental benefits were surprisingly small. That’s because CDR removes CO2 from the air but not from the deep ocean, which has been shown to be a significant carbon sink.The carbon sequestered in seawater, organic matter, and the shells of sea creatures takes thousands of years to return to the surface, so the only way to significantly reduce ocean acidification, they say, is to cut the amount of carbon being emitted into the atmosphere. "Our paper shows that emitting CO2 today and taking it out sometime later is not the same as never emitting it at all,” says study coauthor Ken Caldeira.
August 4, 2015 1:55 PM

Google uses Street View cars to map pollution

Wired: Last month, Google revealed that it had partnered with Aclima, an environmental monitoring startup, to map pollution levels for a month in Denver, Colorado. Now it is expanding to do the same in San Francisco. For several years, the two companies had been testing Aclima's air-quality sensors at Google's facilities around the world. Putting the sensors in Google Street View vehicles is the next step in developing the system. Devices for measuring pollutants have to account for a wide range of atmospheric variables, which makes them complex and potentially expensive. One of Aclima's goals is to reduce the sensors' cost significantly so that public networks of the sensors can be established. The companies are sharing the collected data with the host cities in order to help them make more informed choices about how to handle local air quality.

August 4, 2015 12:25 PM

Measurements of methane leaks may be lower than reality

New York Times: The Environmental Protection Agency requires monitoring of methane levels at natural gas facilities and has approved certain sensors for the purpose. An analysis of one of those devices—the Bacharach Hi Flow Sampler—suggests that unless the device is regularly calibrated it fails to accurately measure levels above a certain point. The device is supposed to switch between two sensors, depending on how high the emissions rate is. Touché Howard, who invented the high-flow-rate sensor in the device, found that when the device is not properly calibrated, it fails to transition from the low-flow sensor to the high-flow one. That means that the reported levels could be tens to hundreds of times lower than the actual levels. Nonetheless, the authors of a recent study that measured methane emissions at US natural gas facilities believe that the levels they measured are accurate because they used multiple systems for collecting their data.
August 4, 2015 11:45 AM

Researchers claim to have created stanene, a graphene-like structure of tin

Nature: Since the isolation in 2004 of graphene, which has many unusual and sought-after characteristics such as extraordinary strength and electrical conductivity, researchers have tried to isolate other similar two-dimensional materials. The latest is stanene, a 2D lattice of tin atoms. Among its predicted characteristics is that of being a topological insulator, a structure that conducts electrons along its surface but not through its interior. Shou-Cheng Zhang of Stanford University and his colleagues now claim to have grown stanene crystals through the use of molecular beam epitaxy by vaporizing tin and allowing the atoms to form a lattice on a surface of bismuth telluride. However, the researchers have yet to confirm that the material they created is a true topological insulator, because the bismuth telluride interacts with the stanene crystals. Further testing will be needed to confirm the discovery, and other surfaces are being investigated that might form a better substrate.
August 3, 2015 3:33 PM

First atom-thick electrical junction

Ars Technica: A p–n junction, essential to most electronic devices, is a boundary between two types of semiconducting materials and is usually created through chemical doping. Creating those junctions on the scale of a single atom has proven difficult. Now, an international team of researchers has succeeded in creating a single-atom-thick p–n junction by using vapor deposition to layer two different two-dimensional semiconductor materials. Because the two materials vaporize at significantly different temperatures, one layer can be set in place before the second material, which vaporizes at the lower temperature, is deposited on top. Testing revealed that the resulting material behaved like a p–n junction, but the team has not yet demonstrated its use in any actual circuits.

August 3, 2015 2:40 PM

Graphene explored for use in anticorrosive coatings

Financial Times Magazine: Among the many extraordinary properties of graphene, it may now serve to inhibit rust on oil rigs, bridges, and other large-scale industrial structures. Such corrosion, which is caused by long-term exposure to weather and chemicals, has been estimated to cost the global economy some $3 trillion a year. Now researchers at Manchester University and AkzoNobel, an Amsterdam-based paints and coatings company, have teamed up to develop an ultrastrong and noncorrosive coating made from graphene oxide. "It can be applied to virtually any kind of material and is transparent,” according to Simon Gibbon of AkzoNobel.
August 3, 2015 1:30 PM

Obama sets new limits on power-plant emissions

Nature: Today, President Obama is announcing a set of regulations to limit greenhouse gas emissions from power plants over the next 15 years. The primary goal will be a 32% reduction from 2005 emissions levels by 2030 for the entire electricity-generating industry. The regulations set targets for each state and require each state to submit, by 2016, plans to reach those targets. However, the states can request a 2-year extension and participate in emissions trading. The regulations will not go into effect until 2017. Even though they don't require congressional approval, the regulations are expected to be challenged by Republicans in Congress and the coal industry.

August 3, 2015 12:00 PM

Hydropower regaining favor as sustainable power source

Time: The generation of electricity via hydropower dams grew rapidly from the end of the 19th century through the first half of the 20th century. But by the 1960s, environmental concerns over the destructive effects on nearby ecosystems forced communities to find alternative power sources. Now, however, hydropower is seeing a resurgence in popularity because of the possibility of modifying existing dams so they can harness electricity. Of the some 80 000 dams in the US, just 2000 currently generate hydropower, according to Rocío Uria-Martinez, an energy researcher at Oak Ridge National Laboratory. Total hydropower capacity could be increased by 15–20% just by adapting existing structures.
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Scitation: News Picks - Blog