Wonder-Material Graphene Could be Dangerous to Humans and the Environment

Jacob D Lanphere, a Ph.D. student at UC Riverside, holds a sample of graphene oxide.

People have been waiting for some time to write a headline along the lines of "scientists discover thing that graphene is not amazing at" ... and here it is. Everybody's favorite nanomaterial may have a plethora of near-magical properties, but as it turns out, it could also be bad for the environment – and bad for you, too.

It's easy to get carried away when you start talking about graphene. Comprised of single atom thick layers of carbon, graphene is incredibly light, incredibly strong, extremely flexible and highly conductive both of heat and electricity. Its properties hold the promise of outright technological revolution in so many fields that it has been called a wonder material.

But it's only been 10 years since graphene was first isolated in the laboratory, and as researchers and industries scramble to bring graphene out of the lab and into a vast range of commercial applications, far less money is being spent examining its potential negative effects.

Two recent studies give us a less than rosy angle. In the first, a team of biologists, engineers and material scientists at Brown University examined graphene's potential toxicity in human cells. They found that the jagged edges of graphene nanoparticles, super sharp and super strong, easily pierced through cell membranes in human lung, skin and immune cells, suggesting the potential to do serious damage in humans and other animals.

"These materials can be inhaled unintentionally, or they may be intentionally injected or implanted as components of new biomedical technologies," said Robert Hurt, professor of engineering and one of the study's authors. "So we want to understand how they interact with cells once inside the body."

Another study by a team from University of California, Riverside's Bourns College of Engineering examined how graphene oxide nanoparticles might interact with the environment if they found their way into surface or ground water sources.

The team found that in groundwater sources, where there's little organic material and the water has a higher degree of hardness, graphene oxide nanoparticles tended to become less stable and would eventually settle out or be removed in sub-surface environments.

But in surface water such as lakes or rivers, where there's more organic material and less hardness, the particles stayed much more stable and showed a tendency to travel further, particularly under the surface.

So a spill of these kinds of nanoparticles would appear to have the potential to cause harm to organic matter, plants, fish, animals, and humans. The affected area could be quick to spread, and could take some time to become safe again.

"The situation today is similar to where we were with chemicals and pharmaceuticals 30 years ago," said the paper's co-author Jacob D. Lanphere. "We just don't know much about what happens when these engineered nanomaterials get into the ground or water. So we have to be proactive so we have the data available to promote sustainable applications of this technology in the future."

At this stage, the Material Safety Data Sheet governing the industrial use of graphene is incomplete. It's listed as a potential irritant of skin and eyes, and potentially hazardous to breathe in or ingest. No information is available on whether it has carcinogenic effects or potential developmental toxicity.

But researchers from the first study point out that this is a material in its infancy, and as a man-made material, there are opportunities at this early stage to examine and understand the potential harmful properties of graphene and try to engineer them out. We've got a few years yet before graphene really starts being a big presence in our lives, so the challenge is set to work out how to make it as safe as possible for ourselves and our planet.

Source: http://ucrtoday.ucr.edu/22044

Israeli Solar Plant is Now 100 Percent Self-Cleaning

The dusty desert environments where many solar plants are located can make their photovoltaic arrays dirty and reduce their effectiveness. Cleaning the panels can be a time-consuming and expensive process. An Israeli solar plant is now said to be the first to have fully-automated cleaning in place.

Ketura Sun was the first commercial solar field in Israel. It spans 8 hectares (20 acres) and produces 9 million kilowatt-hours of electricity each year. Located in the Negev desert, the plant is jointly owned by Siemens AG and Arava Power, which is Israel's leading solar developer.

Due to the expense of cleaning the Ketura Sun panels manually, the process was only carried out nine times a year, meaning the plant was mostly operating in a state of dusty inefficiency. Each cleaning process took five days and meant that efficiency was further reduced as crews carried out the work. Damage to the sensitive equipment was also a risk.

Now, the panels at Ketura Sun are being cleaned nightly by a fleet of almost 100 water-free, energy-independent robots. The Ecoppia E4 robots are mounted on a frame that moves laterally along the panels and the robots themselves move up and down the panels. They use a rotating brush made up of soft microfiber in conjunction with air blowers to remove what Ecoppia says is 99 percent of dust build-up.

This approach means that no water is required, unlike the Heliotex solar cleaning system, avoiding the need to pipe a potentially limited resource to the devices. The robots also use their own solar panels and energy-recovery systems to generate the power they need to operate. As such, they are completely self-contained and independent.

Ecoppia says that dust accumulation on solar panels (or "soiling") can reduce the energy output of panels by up to 35 percent. By removing up to 99 percent of dust on a nightly basis, its E4 robots can help to keep the panels at near-optimum performance constantly.

The video below shows the Ecoppia E4 robots in action..
https://www.youtube.com/watch?feature=player_embedded&v=kBjS95-ALTc

Source: Ecoppia

"Superparamagnetic" Particles Used to Harvest Phosphorus from Polluted Water

A demonstration of how the phosphorus-laden particles can be removed from water using a magnet.

Phosphorus is a mineral that's widely used in fertilizer, which itself has an unfortunate tendency to leach out of farmers' fields and into our waterways. Now, researchers from Germany's Fraunhofer Institute for Silicate Research have devised a method of retrieving some of that phosphorus from the water – thus both reducing pollution, and providing a source of reclaimed phosphorus.

The Fraunhofer team has been using superparamagnetic particles, which are ordinarily non-magnetic, but that turn magnetic when exposed to a magnetic field. These particles also contain bonding sites for phosphorus, and are added to phosphorus-polluted water. When this happens, the phosphorus anions in the water bond with the particles.

The particles, along with the attached anions, are then removed from the water simply using a magnet. Once the removed particles are in turn removed from the magnetic field, they de-magnetize and release the phosphorus for subsequent re-use. The water, meanwhile, is left phosophorus-free.

Apparently the technology could be tweaked to remove other types of pollutants, such as heavy metals, by applying different types of bonding sites to the particles.

Fraunhofer developed the system in collaboration with the University of Stuttgart.

Source: Fraunhofer

Study Links Stronger Pacific Trade Winds to Pause in Global Warming

Despite an overwhelming consensus among climate scientists that warming trends over the past century are most likely the result of human activities, some claim that a plateau in global surface air temperatures since 2001 is evidence to the contrary. However, a new study suggests the recent stabilization of air temperatures is a result of abnormally strong east to west trade winds, causing warmth to be stored temporarily beneath the western Pacific ocean.

The joint research, published in the journal Nature Climate Change and conducted by Australian and US researchers, outlines an unprecedented intensification of trade winds, easterly surface winds swirling about near the Earth's equator, which has accelerated the circulation of the Pacific ocean.

This causes heat to be drawn from the atmosphere into the waters below the ocean's surface and the colder water to rise to the top, ultimately leading to cooler average global temperatures.

"Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures, but the mechanism behind the hiatus remained unclear," said the study's lead author, Professor Matthew England of the University of New South Wales in Sydney, Australia.

According to the researchers, the strengthening of the Pacific trade winds actually dates back to the 1990s. Climate models used previously had not been able to account for the stalling of global surface temperature, as they didn't incorporate the strengthening of these winds.

When England and his fellow researchers added data from the heightened winds to their modeling, they found it accounted for a cooling of 0.1 to 0.2° C (0.18 to 0.36° F) in the 2012 global average surface air temperature, very closely mirroring the offset currently being observed.

"The winds lead to extra ocean heat uptake, which stalled warming of the atmosphere," said Professor England. "Accounting for this wind intensification in model projections produces a hiatus in global warming that is in striking agreement with observations."

While the stronger winds offer respite from an overall warming trend, Professor England warns that in the grand scheme of things, the pause will be short lived and to little effect.

"This pumping of heat into the ocean is not very deep, however, and once the winds abate, heat is returned rapidly to the atmosphere," he said. "When the trade wind strength returns to normal – as it inevitably will – our research suggests heat will quickly accumulate in the atmosphere. So global temperatures look set to rise rapidly out of the hiatus, returning to the levels projected within as little as a decade."

Source: University of New South Wales