Looking to the past for an alternative to cement

“More than 20 billion tons of concrete is produced around the world every year”–to fuel the building boom in cities as more and more people globally move to urban areas.

But, all that concrete has a large environmental cost.  “Cement, the main ingredient in concrete, creates 5% of global carbon emissions.”

Concrete is “sand and gravel held together with cement.”  The Romans “used a mixture of volcanic ash and lime to make concrete.”  And, Roman concrete structures have stood for thousands of years.

Now, engineers working in the United States have created a new material that could replace cement in the production of concrete.  They have used fly ash (“fine particles formed when coal is burned in power plants”); fly ash is similar to volcanic ash.  Using statistical analysis, the engineers determined the best ratio for combining fly ash with other ingredients and the optimum  type of fly ash to use.

Tests are showing that concrete made from this fly ash binder is “just as strong as conventional cement-based concrete after seven days.”

More testing awaits, but the new material and its “reduced CO2 footprint” may provide a low-cost, more environmentally-friendly binder for future building.  Plus, the use of fly ash reduces waste from coal-fired power plants.

Read the article (Prachi Patel, Quartz, June 26, 2018).

Solar windows and the future of building

“Houses and office buildings account for 75% of electricity use in the United States, and 40% of its energy use overall.”  And, all the windows in these buildings can be a problem–letting in heat or cold while leaking cooling or heating energy.

But, several research teams are working on ways to solve this problem.

Newer solar window technologies “absorb almost exclusively invisible ultraviolet (UV) or infrared light.”  That leaves the glass clear–a major step forward–while blocking the UV and infrared radiation that normally leaks through it.

By cutting heat gain while generating some power, these solar windows can reduce energy use while also supplying some of the building’s energy needs–plus, they are a step up aesthetically from older solar windows that are more opaque and can have a reddish or brownish tint.

Along these lines, research teams are working on various related technologies; from “developing a UV-absorbing perovskite solar window that can produce enough energy to power on-demand darkening glass that halts intense light in the heat of the day”–reducing the need for air conditioning.  To using “luminescent solar concentrators” or “quantum dots” in windows to absorb UV and infrared light, convert it into light that regular solar cells can capture, and shunt that light sideways to solar cells in the window frame.  With this technology, solar windows could be relatively inexpensive.

Challenges remain–testing window durability and dealing with the small amount of toxic material used in many solar window technologies.  But, down the road, “it’s a safe bet to expect that future buildings won’t draw all their power from the grid.  They will generate it, too.”

Read the article (Robert F. Service, Science, June 28, 2018).

The impact of sea level rise on Florida–and the world

Read these two excerpts (here and here) from a new book by Elizabeth Rush which details the effects of sea level rise on the south coast of Florida, USA.  “Sunny day flooding”–where coasts flood even without rain and storms due to rising seas and high tides is increasingly frequent today.  This is not a theory or a prediction; it is happening today “from Portland, Maine to Key West.”  High tides top seawalls and bubble up through storm sewers.  Local governments try to protect pricey real estate investments but often leave “low to middle-income neighborhoods where the majority of residents are people of color” to fend for themselves.

Most of the excess heat being driven by climate change is stored in the oceans.  That heat is causing sea level rise–by expanding ocean waters and, more importantly, causing increasingly rapid melting of ice at the Poles.  Estimates of sea level rise range from 2 to 6.5 feet by 2100; others predict more–“when sea levels have risen in the past, they have usually not done so gradually, but rather in rapid surges.”

Over about 130 years, the population along the south coast of Florida has grown from a few thousand to more than 6 million; the sea will continue to rise; what will all those people do?  Research suggests that approximately 13 million Americans may have to move due to sea level rise by the end of the century and economic losses and impacts will be huge.

But, Florida is just an example; this is happening today all over the world.

Facial recognition and privacy

Biometric systems, especially facial recognition scans, are being introduced at major U.S. airports–a response to a U.S. Congressional mandate “for recording the entry and exit of non-U.S. citizens at all air, sea, and land ports of entry.”

Facial-recognition systems have “improved significantly in recent years.”  Governments and law enforcement agencies are now using them.  Does use of facial recognition “violate [U.S.] Constitutional protections against unreasonable searches”?  In addition, research with facial recognition has shown it to be “less accurate with older photos and with images of women, African Americans, and children.”  Mistakes and deliberate abuse can happen.

Also, while Congress mandated the use of biometrics for non-U.S. citizens traveling into and out of the country, the faces of U.S. citizens are also being scanned at airports.  Both Congress and, more recently, President Trump have never authorized “the collection of facial scans from U.S. citizens at the border routinely and without suspicion.”

What happens to this scan data after it is collected at the airports?  The U.S. Department of Homeland Security says it is deleted … but, we don’t know.

Facial recognition is being promoted by airlines like JetBlue and Delta as a way to “speed up the boarding process.”  However, if you are a U.S. citizen, this may not be an option you want to choose.

Read the article (Mike Orcutt, MIT Technology Review, July 13, 2017).

Methane leaks undermine the benefits of using natural gas

Oil producer burning off natural gas
Natural gas has long been “promoted as a clean alternative to other fossil fuels.”  It’s main ingredient is methane.  Compared to other greenhouse gases, like carbon dioxide, methane does not stay in the atmosphere as long but, while it’s there, “its warming effect is much stronger.”
A new independent study shows that methane “has been leaking from oil and gas facilities [in the United States] at far higher rates than governmental regulators claim.”
These leaks “have nearly doubled the climate impact of natural gas, causing warming on par with carbon dioxide-emitting coal plants for 2 decades.”
The benefits of burning natural gas instead of coal “are being undermined by the leaks.”  Natural gas emits less CO2 than coal when burned.  The U.S. EPA is “understating industry methane leaks by approximately 60%.”
According to the study, “in 2015 methane leaks represented 2.3% of total gas production nationwide”; in comparison, the U.S. EPA estimated 1.4%.  While the percentages and the difference between them seems small, what they represent–the actual amount of methane leaked–is very large.  Earlier studies also showed that leaks of methane at both production and distribution sites are underestimated.
The more leakage, the smaller the environmental benefit of using natural gas.
Read the article (Warren Cornwall, Science, June 21, 2018).
 

Now that China will no longer take it, the U.S. and other countries will have to deal with their own plastic waste

Recycling plastic is a challenge.  Over the past few decades, plastic “recycling” has in fact consisted–about half the time–of sending that plastic to China (often through Hong Kong).  China and Hong Kong “have imported 72% of all plastic waste.”

But, this route is now at an end.  As of January 2018, China has banned the import of “nonindustrial plastic waste.”  As a result, according to a recent study, “that will leave the world–mostly high-income countries–with an additional 111 million metric tons of plastic to deal with by 2030.”  And, these countries, especially the United States, United Kingdom, Mexico, Japan, and Germany “have no good way to handle it.”

As an example, in 2016 “the U.S. exported 56% of its plastic waste to China, an additional 32% went to Hong Kong” (and most of that then went to China).  The rest (12%) went to Mexico, Canada, and India.  And, much of that plastic waste ultimately also went to China.

With a permanent ban now in place, plastic recyclers in other countries like the U.S. are seeing “a globally cascading effect.”  Outside of China, “little infrastructure exists … to manage the rejected waste.”  Plastic is piling up.

Previous studies have indicated “that only 9% of all plastic ever produced has been recycled”, the majority goes into the landfill or is thrown away into the oceans and on land.  In 2015, people threw out about 74% of all the plastic that was produced.  Changes are needed–in recycling programs, in how plastics are made, in how humans behave …

Read the article (Zoe Schlanger, Quartz, June 20, 2018).