“Some fungi can use a molecule called melanin, a pigment also found in human skin, to harvest the energy from radiation and use it for growth”


“Discovery of radiotrophic fungi came from the observation of ‘black molds’ growing in and around the Chernobyl Nuclear Power Plant in Ukraine [5]. Specifically, fungal species that were later distinguished as melanin-containing were observed to have colonized the walls of the damaged reactor number 4 at Chernobyl [1]. Similarly, fungal species were found in the damaged reactor’s cooling pool water, which had circulated through the nuclear reactor core for cooling purposes and was largely radioactive [1].

Radiotrophic fungi have been observed to inhabit some remarkable environments on the planet where high levels of radiation naturally occur, including the Arctic and Antarctic regions, as well as high altitude terrains [2]. Interestingly, orbiting spacecrafts in outer space are another environment where radiotrophic fungi are found [1]. They are able to grow extensively despite the high levels of ionizing radiation present beyond the protective shield of the Earth’s atmosphere, as seen in the fact that the Russian orbital station, Mir, must be continually cleaned due to accumulation of fungal growth [1].”

A microscopic fungus thrives amidst acid, heavy metals and radiation
by Kate Baggaley  /  January 29, 2018

“During the Cold War, the United States produced a truly mind-boggling amount of radioactive waste. We failed to properly dispose of much of that sludge, and it’s been leaking from underground storage tanks since the 1950s. Over the years it has contaminated more than 2 billion cubic feet worth of soil and nearly 800 billion gallons of groundwater at low levels.

Cleaning this mess up will be a daunting task, but scientists have just enlisted a new ally. It turns out our best bet for containing radioactive waste might be to stick yeast on it. Many of these tiny fungi can survive extremely radioactive and acidic conditions, scientists reported January 8 in the journal Frontiers in Microbiology. What’s more, they form gunk called biofilms that could potentially trap the waste. “The potential for yeast is enormous,” says coauthor Michael Daly, a pathology professor at the Uniformed Services University of the Health Sciences (USU) in Bethesda, Maryland. “You have a huge group of organisms that are already there, naturally in the environment, that could be harvested for this sort of work.”

“Summer 1943, Hanford became the Manhattan Project’s newest atomic boomtown”

The scale of the problem these yeasts would tackle is almost indescribably vast, Daly says. Radioactive waste from the 46,000 nuclear weapons built between 1945 and 1986 is stored in 120 sites around the country. The largest is the sprawling Hanford Site in southeastern Washington, where the first atomic bombs were assembled during the Manhattan Project.

It houses more than 50 million gallons of waste. Leakage at Hanford has contaminated enough soil and sediments to bury 10,000 football fields a yard deep, and polluted enough groundwater to keep Niagara Falls flowing for a month. It’s mostly contained within the soils and aquifers at Hanford, Daly says, although small amounts are slowly seeping into the nearby Columbia River.

The Cold War waste is an assortment of radioactive versions of elements such as strontium, uranium, and plutonium: acids once used to extract metal out of uranium ores, heavy metals like mercury and lead, and toxic chemicals. Scientists have long hoped to find microbes tough enough capture it, a technique known as bioremediation. Bacteria and other microorganisms are relatively cheap to grow. Certain microbes can catch radioactive waste so rain doesn’t wash it away, feed on toxic chemicals, or transform heavy metals into less dangerous states.

For decades, Daly and his colleagues have tried to harness a microbe so tough its nickname is Conan the Bacterium. This microbe, more properly called Deinococcus radiodurans, is one of the most radiation-resistant life forms we know of (it can also withstand drought, lack of food, extreme temperatures, and the vacuum of space). Over time, scientists managed to genetically engineer this bacterium to have the ability to transform toxic chemicals and heavy metals into less deadly forms. But they couldn’t get it to thrive in acidic conditions. “At the end of the day the thing wouldn’t grow at lemon juice pH ranges,” Daly says.

“Genome analysis of R. taiwanensis MD1149”

He and his colleagues decided to search for better candidates in nature, and sampled microbes from deserts, mines, rivers, and hot springs around the world. The most promising was a red-hued fungus from an abandoned acid mine drainage facility in Maryland. The yeast, a species called Rhodotorula taiwanensis, surprised researchers with its endurance in the face of acid and chronic radiation.

“Pairwise genome alignments of R. taiwanensis MD1149 and related species”

On top of this, it tolerates heavy metals and even forms biofilms under these trying circumstances, a trick Conan never mastered. The researchers tested a total of 27 yeasts to see if they could handle exposure to noxious substances like mercury chloride. “These are really toxic heavy metals,” Daly says. “If we got a little bit in us they would kill us, and these microbes are flourishing in these mixtures of heavy metals, radiation, and [acid].”

“Ranking of representative fungi by the survival index

Most bacteria can’t tolerate acidity or radiation, but both skills turn out to be very common among yeasts. “They are masters of the low-pH world,” Daly says. On the other hand, fungi tend to be more sensitive to heat than bacteria. R. taiwanensis prefers to grow around room temperature, but the decaying nuclear wastes can heat the soil around the steel storage tanks to around 120 degrees Fahrenheit. This wouldn’t necessarily thwart the microbes, though. Placed a small distance away from the storage tanks, the yeasts could capture leaking waste without succumbing to the warmth.

Ideally, different strains of yeasts and bacteria could team up, says Rok Tkavc, an adjunct pathology professor and staff scientist at the Henry Jackson Foundation for the Advancement of Military Medicine at USU. He recently reported that when Deinococcus radiodurans mixes with other bacteria it seems to endow its neighbors with radiation resistance. These cocktails could potentially be used to combat radioactive waste released by nuclear meltdowns as well as that left over from the Cold War.

For the Hanford Site, a successful cleanup would mean keeping radioactive elements out of the Columbia River for the thousands of years it takes them to decay to less dangerous forms. “We cannot get rid of the radiation; no one can do that,” Daly says. “The only thing we can conceivably do to protect ourselves is to contain it, to keep it from coming out.”





“U of I Professor Peter Abbamonte (center) works with graduate students Anshul Kogar (right) and Mindy Rak (left) at the Frederick Seitz Materials Research Laboratory”

Physicists excited by discovery of new form of matter, excitonium
by Siv Schwink  /  12/7/2017

“Excitonium has a team of researchers at the University of Illinois at Urbana-Champaign… well… excited! Professor of Physics Peter Abbamonte and graduate students Anshul Kogar and Mindy Rak, with input from colleagues at Illinois, University of California, Berkeley, and University of Amsterdam, have proven the existence of this enigmatic new form of matter, which has perplexed scientists since it was first theorized almost 50 years ago. The team studied non-doped crystals of the oft-analyzed transition metal dichalcogenide titanium diselenide (1T-TiSe2) and reproduced their surprising results five times on different cleaved crystals. University of Amsterdam Professor of Physics Jasper van Wezel provided crucial theoretical interpretation of the experimental results.

Excitonium is a condensate—it exhibits macroscopic quantum phenomena, like a superconductor, or superfluid, or insulating electronic crystal. It’s made up of excitons, particles that are formed in a very strange quantum mechanical pairing, namely that of an escaped electron and the hole it left behind. It defies reason, but it turns out that when an electron, seated at the edge of a crowded-with-electrons valence band in a semiconductor, gets excited and jumps over the energy gap to the otherwise empty conduction band, it leaves behind a “hole” in the valence band. That hole behaves as though it were a particle with positive charge, and it attracts the escaped electron. When the escaped electron with its negative charge, pairs up with the hole, the two remarkably form a composite particle, a boson—an exciton.

“Artist’s depiction of the collective excitons of an excitonic solid. These excitations can be thought of as propagating domain walls (yellow) in an otherwise ordered solid exciton background (blue).”

In point of fact, the hole’s particle-like attributes are attributable to the collective behavior of the surrounding crowd of electrons. But that understanding makes the pairing no less strange and wonderful. Why has excitonium taken 50 years to be discovered in real materials? Until now, scientists have not had the experimental tools to positively distinguish whether what looked like excitonium wasn’t in fact a Peierls phase. Though it’s completely unrelated to exciton formation, Peierls phases and exciton condensation share the same symmetry and similar observables—a superlattice and the opening of a single-particle energy gap.

Abbamonte and his team were able to overcome that challenge by using a novel technique they developed called momentum-resolved electron energy-loss spectroscopy (M-EELS). M-EELS is more sensitive to valence band excitations than inelastic x-ray or neutron scattering techniques. Kogar retrofit an EEL spectrometer, which on its own could measure only the trajectory of an electron, giving how much energy and momentum it lost, with a goniometer, which allows the team to measure very precisely an electron’s momentum in real space. With their new technique, the group was able for the first time to measure collective excitations of the low-energy bosonic particles, the paired electrons and holes, regardless of their momentum.

“Relationship between energy and momentum for the excitonic collective mode observed with M-EELS.”

More specifically, the team achieved the first-ever observation in any material of the precursor to exciton condensation, a soft plasmon phase that emerged as the material approached its critical temperature of 190 Kelvin. This soft plasmon phase is “smoking gun” proof of exciton condensation in a three-dimensional solid and the first-ever definitive evidence for the discovery of excitonium.“This result is of cosmic significance,” affirms Abbamonte. “Ever since the term ‘excitonium’ was coined in the 1960s by Harvard theoretical physicist Bert Halperin, physicists have sought to demonstrate its existence. Theorists have debated whether it would be an insulator, a perfect conductor, or a superfluid—with some convincing arguments on all sides. Since the 1970s, many experimentalists have published evidence of the existence of excitonium, but their findings weren’t definitive proof and could equally have been explained by a conventional structural phase transition.”

Rak recalls the moment, working in the Abbamonte laboratory, when she first understood the magnitude of these findings: “I remember Anshul being very excited about the results of our first measurements on TiSe2. We were standing at a whiteboard in the lab as he explained to me that we had just measured something that no one had seen before: a soft plasmon. The excitement generated by this discovery remained with us throughout the entire project,” she continues. “The work we did on TiSe2 allowed me to see the unique promise our M-EELS technique holds for advancing our knowledge of the physical properties of materials and has motivated my continued research on TiSe2.”

“(top) M-EELS instrument at the Seitz Materials Research Laboratory. (bottom, left) Elastic momentum maps of the exciton condensate material, 1T-TiSe2, showing appearance of superlattice reflections at low temperature. (bottom, right) Softening of the plasmon in 1T-TiSe2, demonstrating the condensation of electron-hole pairs.”

Kogar admits, discovering excitonium was not the original motivation for the research—the team had set out to test their new M-EELS method on a crystal that was readily available—grown at Illinois by former graduate student Young Il Joe, now of NIST. But he emphasizes, not coincidentally, excitonium was a major interest: “This discovery was serendipitous. But Peter and I had had a conversation about 5 or 6 years ago addressing exactly this topic of the soft electronic mode, though in a different context, the Wigner crystal instability. So although we didn’t immediately get at why it was occurring in TiSe2, we did know that it was an important result—and one that had been brewing in our minds for a few years.”

The team’s findings are published in the December 8, 2017 issue of the journal Science in the article, “Signatures of exciton condensation in a transition metal dichalcogenide.” This fundamental research holds great promise for unlocking further quantum mechanical mysteries: after all, the study of macroscopic quantum phenomena is what has shaped our understanding of quantum mechanics. It could also shed light on the metal-insulator transition in band solids, in which exciton condensation is believed to play a part. Beyond that, possible technological applications of excitonium are purely speculative.”

[This research was made possible by generous support from the Gordon and Betty Moore Foundation’s EPiQS Initiative. Development of the new M-EELS instrument was supported by the U.S. Department of Energy Center for Emergent Superconductivity, an Energy Frontier Research Center. Please see journal article for entire funding acknowledgement.]


“Blacked-out San Juan with lights only showing in buildings that have generators”

Severe power failures in Puerto Rico and across the Caribbean spur new push for renewable energy
by Chris Mooney / September 28

“The ongoing electricity disaster in Puerto Rico in the wake of Hurricane Maria — and on several other Caribbean islands slammed at full force by strong storms — is driving new interest in ways of shifting island power grids toward greater reliance on wind, solar and even, someday, large batteries.

“For the most part, these island grids were completely devastated, and it will be four to six months before most of them can power their islands completely again,” said Chris Burgess, director of projects for the Islands Energy Program at the Rocky Mountain Institute. Adding more renewables, and moving away from centralized power grids to more so-called “microgrids,” could lower costs and increase resilience in the face of storms, several energy experts said.

“Combination NOAA Satellite images taken at night show Puerto Rico before and after Hurricane Maria: Top, Puerto Rico on July 24, 2014, and bottom, Sept. 24, 2017, after Hurricane Maria knocked out the island’s power grid.”

And island nations, already at the forefront of pushing for action on climate change, have been moving this way for a while. Members states of CARICOM, a consortium of Caribbean nations, already have a goal of reaching 47 percent renewable energy by 2027. The storms now only give greater impetus. “You look at islands like Dominica, Anguilla and the other islands affected by the recent hurricanes, I’ve spoken to a couple of the utilities, and they say they would prefer to rebuild using distributed generation with storage, and just trying to reduce the amount of transmission lines,” said Tom Rogers, a renewable energy expert at Coventry University in Britain who previously was a lecturer in energy at the University of the West Indies in Barbados. “Because that’s where their energy systems fail. It’s having these overhead cables.”

Even in good weather, islands like those in the Caribbean have an energy problem: They’ve tended to burn fossil fuels, such as diesel or heavy fuel oil, to drive centralized power plants. But being an island without its own fossil energy resources makes shipping in the fuel quite expensive — in turn translating into sky-high electricity bills — to say nothing of the environmental costs incurred by burning it.

“A solar and battery-powered microgrid got San Juan’s Children’s Hospital quickly back online after Hurricane Maria”

“They have energy prices which are some of the highest in the world,” Rogers said. “And that has a massive economic impact, especially as a lot of these islands’ economic dependence is on tourism, which introduces a high energy demand for their hotels, in particular from air conditioning loads.” And then when a storm comes through, the power lines stretching across the island lead to grid vulnerability.

“Solar generators like this one are being shipped to community centers in Puerto Rico by a group of islanders in the mainland United States.”

A different model would be to rely on wind, solar and batteries to store the electricity — with fossil-fuel backup ready to go when needed — and to set up small grids powered by renewables that link to a main grid but that also can be “islanded” from it and do not necessarily go down at the same time. Wind is very predictable in the Caribbean because of the trade winds, and being located in the tropics makes for a very efficient use of solar panels, Rogers pointed out.

“Sunrun brought over smaller solar panels with batteries to power water desalination tanks, left. Firefighters and Sunrun employees install panels on the roof of the Barrio Obrero fire station in San Juan to set up a microgrid to keep the lights and communications equipment running.”

“A PV [photovoltaic] system installed in the tropics will generate over one and a half times more than exactly the same PV system installed in the higher latitudes, say in Washington or Europe,” he said. However, at least until battery storage becomes more widely affordable, islanded grids could not solely be powered by the sun, which is only out during the day. They would instead need to alternate solar with some continuing use fossil fuels to ensure a continual electricity supply. Still, adding renewables would lessen dependence on burning a fuel that has to be continually replaced — which in turn means that it must be continually shipped to the island.

Some lessons here can actually be learned from Alaska. While not an island, it contains many remote communities, and so has been a testing ground for the deployment of hundreds of microgrids — smaller grids that can connect to a larger grid but also can operate independently of one — and for beginning to switch these villages from a strict reliance on burning shipped-in diesel fuel to more renewable resources.

“A coffee shop during a power outage in San Juan, Puerto Rico”

“When we are facing the sort of infrastructure destruction we have seen this hurricane season, it only makes sense to give some pause before reinvesting in the exact same system that proved to vulnerable,” Gwen Holdmann, who directs the Alaska Center for Energy and Power at the University of Alaska at Fairbanks, said by email. Referring to Puerto Rico, she continued, “If the system were redesigned around microgrids incorporating local power production, there would still be losses, but the number and duration of outages due to severe weather events would decrease.”

However, the Trump administration may have other plans, at least as far as Puerto Rico and the U.S. Virgin Islands go. For instance, Energy Secretary Rick Perry recently tossed out the idea of the potential for small modular nuclear reactors to be used in situations like the current disaster. “Wouldn’t it make abundant good sense if we had small modular reactors that literally you could put in the back of C-17 [military cargo] aircraft, transport it to an area like Puerto Rico, and push it out the back end, crank it up and plug it in?” Perry said recently, according to Bloomberg BNA.

And not all analyses of island energy changes focus solely on renewables. A recent report by the energy analytics firm GTM Research found that for islands, the most economical solution right now would actually be swapping in liquefied natural gas for diesel or heavy fuel oil at power plants. But before long, the report said, a combination of liquefied natural gas and solar would be the economic winner.

“Ta’u, an island in American Samoa, runs nearly 100% on renewable energy using Tesla technology”

Finally, once battery costs fall far enough, solar combined with energy storage would make the most sense — but the firm doesn’t expect that to happen until the late 2020s. “The potential market for displacing oil with new sources of power supply is very large,” said the report by Tom Heggarty, a senior analyst at GTM Research. “We estimate that there are around 3,600 islands around the world where oil products currently provide a large proportion of power supply.”

Some islands are already shifting — Jamaica has plans to convert diesel plants to natural gas, and the Hawaiian island of Kauai hosts combined solar and battery storage. “In Kauai, they actually produce about 90 percent of the island’s power during the midday peak just from solar and battery,” said Burgess.

“An Outback Power inverter, left, and battery storage, right, installed at fire station unit 60 in Barrio Obrero in San Juan to store solar power.”

Operating a centralized power plant with natural gas, rather than diesel or heavy fuel oil, would save costs but would not necessarily increase resilience when hurricanes strike. You would still have a central plant, distribution stations and a large number of transmission lines to get electricity out across the island.

This is where the idea of combining renewables with microgrids comes in. Microgrids naturally pair with renewables because you can generate electricity at, say, a number of rooftop and community solar installations and then build a local grid based around these resources, often backed by some fossil-fuel-powered generation as well.

Individual components of the grid may or may not fare well in a storm, but its fate would not affect other microgrids or the central grid. “A microgrid’s multiple generation sources and ability to isolate itself from the larger network during an outage on the central grid ensures highly reliable power,” a recent report from the National Electrical Manufacturers Association found.

“A damaged solar panel plant is seen in Humacao, eastern Puerto Rico”

It isn’t, to be sure, that solar panels are somehow especially resistant to the damage from hurricanes — images from Puerto Rico, for instance, show damaged panels at one major array, the Humacao solar project. However, if some panels go down, that doesn’t mean the others won’t work any longer, Burgess noted. “It’s like New Age Christmas lights: You lose a bulb here and there, but you don’t lose all of them.” In the future, “we’re going to see microgrids within the islands, but also the large generation being augmented, if not solely replaced, by renewables,” said Burgess.”