Advanced Materials
Advanced Materials

Roofs Covered With Plastic Grass Could Harness Wind Energy

Advanced Materials
Advanced Materials

One group of scientists is trying to harness wind energy by mimicking the motions of a field of grass rippling in the breeze—except their grass is made of plastic and their field is on a roof.

According to the findings publishing in the journal Advanced Materials, a joint team of Chinese and American researchers created an experimental turboelectric nanogenerator (TENG). Here's how it works: The team adhered plastic strips to a board in a way that makes them stand upright in rows. One side of each strip is coated with nanowires and the other side with indium tin oxide (ITO). When the “grass” is pushed by the wind, the nanowires brush against the ITO sides of the surrounding strips, allowing electrons to pass from one piece to the next. This generates a current via the triboelectric effect.

This method of generating wind power could be practical in many situations. In addition to harnessing power from steady gusts, the technology would be able to effectively work with choppy winds blowing in any direction and would be ideal for spots where windmills would be impractical.

The experimental TENG—which so far has only been tested in a lab by using an electric fan and 60 strips of plastic on a model rooftop—generated enough energy to light 60 LEDs. The system was also functional in wind speeds as low as 13 mph and was most effective in close to 62-mph winds—a speed too high to be practical, as one researcher noted to New Scientist.

While the project is still far from ready to be used out in the real world, a 985-square-foot rooftop carpeted with the strips would generate 7.11 kilowatts, enough energy to mostly power a home, according to the researchers. For now, the team is focused on figuring out a way to efficiently store the energy that’s generated. They will also need to find a substitute for indium tin oxide because it's both toxic and expensive. 

[h/t: New Scientist]

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Air Quality in American National Parks and Big Cities Is Roughly the Same
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iStock

National parks usually have more vegetation, wildlife, and open spaces than urban areas, but the two don't look much different when it comes to air quality. As City Lab reports, a new study published in Science Advances found that U.S. national parks and the nation's largest cities have comparable ozone levels.

For their research, scientists from Iowa State University and Cornell University looked at air pollution data collected over 24 years from 33 national parks and the 20 most populous metro areas in the U.S. Their results show that average ozone concentrations were "statistically indistinguishable" between the two groups from 1990 to 2014.

On their own, the statistics look grim for America's protected areas, but they're actually a sign that environmental protection measures are working. Prior to the 1990s, major cities had higher ozone concentrations than national parks. At the start of the decade, the federal government passed the Clean Air Act (CAA) Amendments in an effort to fight urban air pollution, and ozone levels have been declining ever since.

The average ozone in national parks did increase in the 1990s, but then in 1999 the EPA enacted the Regional Haze Rule, which specifically aims to improve air quality and visibility in national parks. Ozone levels in national parks are now back to the levels they were at in 1990.

Ground-level ozone doesn't just make America's national parks harder to see: It can also damage plants and make it difficult for human visitors to breathe. Vehicles, especially gas-guzzling trucks and SUVs, are some of the biggest producers of the pollutant.

[h/t City Lab]

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India's Supreme Court Demands That the Taj Mahal Be Restored or Demolished
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iStock

The Taj Mahal is one of the most recognizable monuments on Earth, but over the years it's started to look less like its old self. Smog and insect droppings are staining the once pure-white marble exterior an unseemly shade of yellow. Now, The Art Newspaper reports that India's Supreme Court has set an ultimatum: It's threatening to shut down or demolish the building if it's not restored to its former glory.

Agra, the town where the Taj Mahal is located, has a notorious pollution problem. Automobile traffic, factory smoke, and the open burning of municipal waste have all contributed to the landmark's increasing discoloration. Insects and acid rain also pose a threat to the facade, which is already crumbling away in some parts.

India's highest court now says the country's central government must seek foreign assistance to restore the UNESCO World Heritage Site if it's to remain open. Agra's state of Uttar Pradesh has taken some steps to reduce pollution in recent years, such us banning the burning of cow dung, which produces heavy brown carbon. In 2015, India's Supreme Court ordered all wood-burning crematoriums near the Taj Mahal to be swapped for electric ones.

But the measures haven't done enough to preserve the building. A committee led by the Indian Institute of Technology in Kanpu reportedly plans to investigate the exact sources of pollution in the area, a process that will take about four months. The Supreme Court plans check in on the status of site every day from July 31.

Air pollution isn't the only factor damaging the Taj Mahal. It was constructed near the Yamuna River in the 17th century, and as the water gradual dries up, the ground beneath the structure is shifting. If the trend continues it could lead to the building's total collapse.

[h/t The Art Newspaper]

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