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Leap in Lithium-Air Battery Tech Could Supercharge Electric Cars

Lithium-air batteries can in principle hold five to 10 times as much energy as a lithium-ion battery of the same weight and double the amount for the same volume. They could theoretically give electric cars the same range as gasoline ones. Now scientists in England claim to have overcome many of the current barriers preventing their use.

In a lithium-air battery, the anode is generally made of lithium metal, the cathode is typically a porous carbon material that brings in oxygen from the surrounding air, and the electrolyte is a liquid connecting the anode and the cathode, helping ions shuffle between them. As the lithium oxidizes, it discharges electricity. Recharging the device reverses the process.

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Chile's Hybrid PV-Solar Thermal Power Stations

SolarReserve, the technology developer behind the world’s biggest solar thermal power tower project optimized for energy storage, says its Crescent Dunes plant in Nevada recently delivered power to the grid for the first time and should reach its full 110-megawatt rating by the end of 2015. While SolarReserve has a similar plant starting construction in South Africa, much of its development activity—like that of a key rival, Spanish engineering firm Abengoa—is focused on a novel solar technology twist destined for Chile’s power hungry energy market. 

SolarReserve’s and Abengoa's Chilean projects both seek to unite solar power’s hitherto competing technology wings: solid-state photovoltaics and steam-raising thermal solar. The aim is to deliver cheap round-the-clock power for Chile's big mines. Their PV component will keep the power on during the day. Solar thermal installations akin to Crescent Dunes—with mirrors or 'heliostats' that concentrate sunlight to directly heat molten salt— will take care of the rest, efficiently storing heat to provide competitive generation overnight.

Chile, which is the world’s top producer of fine copper and second leading gold producer, is also the source of half of the world’s lithium, according to a 2014 report on Chile’s mining sector by consulting firm KPMG. As a result, Chile's mining sector is the country’s largest power user, consuming about 85 percent of capacity on the northern grid (the Sistema Interconectado del Norte Grande). Demand is growing: power use by copper mines is projected to double by 2025.

Imported natural gas is pricey, so Chile has met new demand with a mix of coal-fired generation, wind power, and PV farms. Utility-scale PV, much of which exploits the intense sun that bathes northern Chile's Atacama Desert, is surging this year. Chile will have installed 1 gigawatt of solar PV this year alone, according to PV-TECH, up from 493 megawatts in 2014. 

While PV is a good deal—it costs as little as $70 per megawatt-hour (before subsidies), which is well below the heavily-discounted bulk rate of $100 per MWh that Chilean mining firms pay for grid power—it is a glass-half-empty electricity source. As the flat line across the power chart on the Sistema Interconectado del Norte Grande homepage shows, Chile's mines don't stop gobbling power when the sun sets and PV shuts down. 

In fact, as a result of the surging PV development, Chilean power prices are now higher at night than during the day, according to Kevin Smith, SolarReserve’s CEO.

Hybrid PV-thermal solar plants promise a nearly complete 24-hour-a-day power solution. The first, which Abengoa began building last year in the Atamaca Desert city of Calama, combines a 100-MW PV farm with a 110-MW molten salt power tower designed to run 18 hours without sunlight. The PV plant is to be completed this year, while the salt tower (Abengoa’s first) is to begin operation in 2017. 

Abengoa entered the Calama plant’s solar thermal component into a government-mandated auction for renewable power supplies in 2014 and was approved to earn $115/MWh. SolarReserve, in contrast, is offering power from its Chilean hybrid PV-thermal solar projects as a bundle, which CEO Kevin Smith promises will sell for “well under” $100/MWh. 

Smith says SolarReserve’s first proposed Chilean hybrid plant, near Copiapó at the southern end of the Atacama, would combine a pair of 130-MW salt towers—each 18 percent more powerful than the tower at Crescent Dunes—with 150 MW of PV output. 

In August, environmental regulators approved the project (a critical hurdle, particularly since documentation of high avian mortality at the triple-tower Ivanpah installation in California’s Mohave Desert appeared). Smith says SolarReserve is seeking industrial buyers for its hybrid power, but may also bid it into a grid power auction in April 2016. 

Both solar thermal developers have big plans for additional hybrid plants in Chile. SolarReserve’s Smith says they have over 1,000 MW of solar projects in “advanced development” in Chile. Abengoa has filed for environmental permits for two follow-on projects, including a twin of its hybrid 110-MW plant approved by environmental regulators for the northern Atacama and a triple-tower, 315-MW project near Copiapó

Abengoa’s challenge will be raising the capital required. The company is struggling with a heavy debt load, and its financial valuation slid last week after an audit by KPMG, driven by Abengoa creditors, detected a larger than expected cashflow deficit

Analysis this weekend by OilPrice.com notes similar stock slides at other renewable energy firms. Among them is the one suffered by PV giant SunEdison, whose stock is down by about 70 percent from its valuation in July 2015.  The report suggests this is due both to the financial structure some renewable firms have adopted, and to fallout from sliding oil prices that has hurt the competitiveness of their renewable energy. 

Solar panels

This Is How Good Solar-to-Fuel Conversion Can Be

In the artificial photosynthesis world, the recent buzz has been about new records set on water splitting by solar energy to make hydrogen.

However, a slightly newer, but similar, field of research is looking at another form of artificial photosynthesis—using solar energy to turn carbon dioxide into fuel. Such a technology would have the added benefit of removing a potent greenhouse gas from the atmosphere or preventing it from getting there in the first place.

Researchers with the Joint Center for Artificial Photosynthesis at Lawrence Berkeley National Laboratory report today in the Proceedings of the National Academy of Sciences that they have evaluated the potential efficiencies of this process for several different photoelectric cell configurations, catalysts, and fuel end products.

The group concluded that solar energy could break down CO2 into synthesis gas—a blend of hydrogen and carbon monoxide that used to make other hydrocarbons—at an efficiency of 18.3 percent or could make liquid hythane—a mix of hydrogen and methane—at 20.3 percent efficiency.

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First New U.S. Nuclear Reactor in Two Decades to Begin Fueling in Tennessee

Yesterday, U.S. federal regulators approved an operating license for Unit 2 of Tennessee Valley Authority's Watts Bar nuclear power plant; it's only taken 19 years and almost 4.5 billion dollars. The Gen II plant should be producing power by the end of the year, and it shouldn’t bother you in the least that we mostly stopped building Gen II reactors sometime in the mid ‘90s. 

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Startup Time for Fukushima's Frozen Wall. Here’s Why it Should Work

Japan's TEPCO is about to flip the switch on the infamous ‘ice wall’ intended to divert flowing groundwater around its crippled reactors at Fukushima and thus help stem the contamination of fresh groundwater at the site. The widely mischaracterized and maligned installation—which is a barrier of frozen soil rather than a wall of ice—has every chance of delivering the hoped for results, say radiation cleanup experts at U.S. national laboratories and feedback from initial system tests.

"The frozen barrier is going to work,” predicts Brian Looney, senior advisory engineer at the U.S. Department of Energy's Savannah River National Laboratory in South Carolina and co-author of an independent assessment of TEPCO’s frozen barrier. The report, produced in collaboration with researchers at Looney's lab and at Pacific Northwest National Laboratory, was completed in February but only released late last month; it found the system’s design to be sound and within the bounds of prior practice. 

Since the 2011 meltdowns at Fukushima, TEPCO has been fighting a losing battle with groundwater that flows downhill towards the sea, permeates Fukushima’s fractured reactor buildings, and contacts their melted-down nuclear fuel. Until recently, TEPCO was sucking 300-400 tons of contaminated water out of the buildings every day, adding continuously to the site’s ballooning fields of radioactive water storage tanks. The frozen barrier is one of a suite of measures intended to stem that tide. 

In September, TEPCO started operating a system of ‘subdrains’ to capture groundwater around the reactors before it enters the buildings. After months of negotiations, fishermen’s groups agreed to allow TEPCO to treat the lightly contaminated water and then discharge it to the sea. The subdrain could cut groundwater inundation of the reactor buildings in half, leaving “only” about 150 tons per day according to World Nuclear News.

The frozen barrier is a more definitive solution, intended to completely isolate the reactor buildings from groundwater by encircling them with a 1.5-kilometer-long, 30-meter-deep wall of frozen soil. It was designed by Japanese engineering and construction firm Kajima Corp., which began piecing together its infrastructure in June 2014. Since then, Kajima has perforated the ground surrounding Fukushima’s four reactors with 1571 bore holes, lined them with chiller pipes, and hooked up those pipes to refrigeration plants that pump out brine at an icy -30 degrees Celsius.

This groundwater isolation technology has been applied hundreds of times since the 1950s at mines and at deep excavations for tall buildings. But at Fukushima, it has been a magnet for scorn. The negativity stems from an understandable dearth of confidence in TEPCO and misreporting by media outlets. 

Many news outlets accidentally conflated Kajima's frozen barrier with a distinct and ill-fated TEPCO effort to freeze 5,000 to 6,000 tons of contaminated seawater in a utility trench adjacent to one of the reactors. CleanTechnica’s August 2014 report, "TEPCO Concedes Failure of Fukushima Ice Wall”, was one of many to describe the failed trench freeze as a section of the frozen barrier. 

And this confusion persists. Al Jazeera opined in March that the frozen barrier had “turned out to be another of the cleanup’s dramatically costly and utterly ineffective schemes.” It is also one of many new outlets to erroneously assert that Kajima's design was beyond the scale or applications of prior frozen walls.

The U.S. national labs’ analysis is as complimentary of Kajima’s design as the media’s opinions have been skeptical. According to Looney, their report found that Kajima’s design is “within the envelope of experience for successful barriers.” The team identified installations larger than Kajima’s design, such as a 3.66-km-long freeze wall at an open pit gold mine in Ontario that was four times deeper than Fukushima's, as well as urban projects that had more buried structures to work around (or through) than is the case at Fukushima. 

Site-specific analysis by Looney et al, meanwhile, projects that the freezing energy to be deployed by Kajima’s system will be equal to the task of managing Fukushima’s hydrological conditions. That finding is affirmed by initial testing of about 60 meters of the barrier in May 2015; the ground chilled as predicted.

The national labs study did identify small areas that could potentially resist freezing. But it also identified 10 to 12 available fixes, and also concluded that small leaks would be of little consequence given the suite of other groundwater control systems TEPCO has in place. “The goal of the barrier is to minimize flow to the reactors. You don’t actually need 100 percent effectiveness to reach that goal,” says Looney. 

While skepticism over the barrier’s water-stopping capability reigns in the popular media, Japanese regulators have been fretting over whether it might prove overly effective. Japan’s Nuclear Regulation Authority (NRA) has been holding back TEPCO from beginning the freeze while it assesses the risk of groundwater levels plummeting within the perimeter as the freeze kicks in, drawing highly radioactive water out of the reactors and contaminating the soil below.

Looney argues that this scenario is unlikely. It will take 1-2 months of refrigeration to establish each section of the barrier and at least six months of refrigeration before it has a measurable impact on groundwater levels within the frozen wall's perimeter, according to Looney. He adds that extensive monitoring should give TEPCO several months' notice of potential groundwater imbalances. 

But to minimize the risk of a groundwater crash, the NRA has requested that TEPCO first freeze the barrier’s side and downhill segments, saving the uphill segment (which Kajima finished first) for last. According to Looney and recent media reports, the final piping should be complete and the system should be ready to switch on within weeks.

If the barrier kicks in next year, concluding what will have been a five-year battle against groundwater, TEPCO will then be in a position to attack a still-tougher foe: its shattered reactors’ melted fuel. Naohiro Masuda, president of TEPCO’s cleanup subsidiary, Fukushima Daiichi Decommissioning Company, told Japanese state broadcaster NHK in March that TEPCO has “no idea” what the physical state of the fuel is (though it's got robots on the hunt) and no idea how to get it out. As Masuda put it: “We have to remove it remotely from 30 meters above. But we don’t have that kind of technology yet. It simply doesn’t exist.”

Photovoltaic panels near some palm trees

Only 15% of California's Big Solar Projects Are on the Right Kind of Land

The real estate agent’s mantra is well known: location, location, location. But location is important, too, when considering where to site utility-scale solar projects, and most of California's projects or planned projects are in less-than-ideal spots, according to a new study. As a result, these projects may have negative impacts on the environment and will not be as cost-effective or as carbon neutral as they could be.

Researchers from Stanford University and the University of California’s Riverside and Berkeley campuses identified 161 planned or proposed large-scale utility solar and applied an algorithm to determine how compatible they are with their location.

The results, which were published today in the Proceedings of the National Academy of Sciences, found that only 15 percent of sites were on compatible land.

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Batteries Running on Shrooms

Mushrooms have energized many a marinara sauce, not to mention a few vivid hallucinations, but soon the fungi may be powering your Prius or getting your Galaxy phone to run longer. Engineers at the University of California have shown that mushrooms can create long-lasting, environmentally friendly anodes for lithium-ion batteries.

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Nuclear Cybersecurity Woefully Inadequate

The risk of a major cyberattack on the nuclear industry is rising, potentially leading to blackouts or even meltdowns, researchers say.

The 2010 Stuxnet worm's infiltration of Iran's nuclear program was the most dramatic cyberattack the nuclear sector has ever seen. But it was not the only one. In one case in 2003, the Slammer worm infected the Davis-Besse nuclear power plant in Ohio, leaving reactor core safety data unavailable for nearly five hours. In another example from 2014, hackers stole blueprints of at least two nuclear reactors and other sensitive data from Korea Hydro and Nuclear Power Co., then demanded money from the company in exchange for not releasing potentially important files.

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Arizona Utility Blinks in Bitter Battle Over Rooftop Solar

Arizona’s biggest utility, Arizona Public Service, is withdrawing its bid to jack up monthly fees for rooftop solar users in its territory. The retreat, tendered last week to the Arizona Corporation Commission (ACC), capped an eventful month in the high-stakes battle between utilities and solar advocates that's raging across Arizona rooftops. The party with the most bruises is not Arizona Public Service (APS), however, but the ACC itself. The elected body referees the state's power markets, but all five of its commissioners now face accusations of bias that challenge their ability to fairly adjudicate the rooftop solar dispute.

Arizona’s solar dispute is hot, but not unique. Across the United States utilities are fighting to contain or eliminate “net metering” policies that pay rooftop solar users retail prices for the surplus power that their panels export to the grid (thus offsetting retail charges for power they consume at night). Utilities argue that solar customers rely heavily on the grid but, under net metering, pay little or nothing to maintain it. Over the past year all of Arizona’s utilities levied or proposed new fees for customers installing rooftop solar systems. APS’s proposal worked out to about $21 per month.

Solar advocates argue that rooftop solar provides a variety of benefits to the grid—such as reducing consumption of fossil fuels and lessening reliance on distant power plants. They see fees from utilities such as APS, which owns fossil-fueled and nuclear power plants, as unfair competition. 

In August, ACC staff sided with solar advocates’ call to defer consideration of proposed fees so they could be reviewed in the broader context of the utility’s overall business. When the ACC commissioners voted to overrule, calling for immediate hearings on solar fees, San Francisco-based solar installer Sunrun and two former commissioners filed challenges with the ACC, alleging bias

The bias filings allege that the two commissioners elected in 2014 allegedly benefited from $3.2 million in secret campaign donations to independent groups by APS. The filings also cite a third commissioner elected in 2012 for inappropriate public comments about rooftop solar users. (Earlier challenges accuse the remaining two commissioners of bias based on lobbying activities prior to their election in 2012.)

APS presents these attacks as a bid by solar advocates to avoid debating the proposed utility fees on the merits. APS writes:

They have retreated to procedural tactics and character attacks designed to discredit elected officials and undermine the integrity of the Arizona Corporation Commission.The obvious goal is to paralyze the Commission.

However, allegations of improper campaign contributions by APS have been swirling in the Arizona media for over a year. APS acknowledges that it is politically active, and has refused to confirm or deny the allegations. 

Under state law independent groups financing political advertisements in Arizona are not obligated to reveal their donors, so tracking such “dark money” spending is difficult. The Arizona Republic, Phoenix’ leading daily newspaper, reported last month that two commissioners are seeking ACC staff advice as to whether the ACC can compel utilities such as APS to reveal their political contributions

According to the Republic the commissioners elected in 2012 benefited from contributions from the Arizona Chamber of Commerce and Industry, including money from Arizona Public Service. And it writes that the two commissioners elected last year benefited from "independent political campaigns widely believed to be financed with so-called dark-money from APS.” 

In March 2015 an organization tracking campaign finance contributions revealed that a foundation led by a former APS chairman and CEO that is normally dedicated to supporting Arizona State University had inexplicably given $100,000 to a "shadowy" nonprofit called Save Our Future Now. That group spent $2.4 million on TV ads attacking pro-solar ACC candidates in 2014. 

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Green Flow Battery Based on Cheap, Nontoxic Reagents

Flow batteries are an interesting alternative to conventional batteries because they can store charges in the form of a liquid electrolyte that can be kept in tanks. Only the size of the tanks limits the amount of energy that can be stored. Utility companies and energy engineering firms have been eying these devices because they might replace storage batteries, devices that: have a limited lifetime; are known to be fire hazards; require metals such as lithium, that are limited in supply; and can only store energy in the electrode material, which has a fixed volume. What stands in the way of the wide implementation of flow batteries, in spite of the fact that they are commercially available, is that the compounds they use are expensive, toxic, and corrosive. Additionally, the energy storage capacity per unit volume of the electrolyte is low, typically just squeaking past 20 watt-hours per liter.

Recently IEEE Spectrum reported on a flow battery that has a better performance and uses a basic electrolyte instead of an acidic one, keeping a zinc compound in solution.  Now a team of researchers at Harvard University have reported in the 25 August issue of Science that they’ve created a version that uses two alkaline electrolytes that contain quinone and ferrocyanide—both widely available and non-toxic compounds—in solution. The researchers reported that after 100 charge-discharge cycles, the battery’s stored energy capacity had degraded less than 1 percent.  

Michael Aziz, who led the research group, realized that if the negative points of today’s flow batteries—cost and toxicity—could be overcome, the flow battery could become a commercially viable alternative for the storage now badly needed for intermittent energy sources such as solar and wind.  

“This looks like a compelling value proposition if you can find inexpensive chemicals that work well,” says Aziz.  “We noticed that there is a molecule in plants that takes the electrons from chlorophyll, and it forms an electron shuttle in photosynthesis that ports electrons over and over, without any sign of degradation. That is exactly the functionality you want for the battery,” says Aziz.  

However, the molecule did need some work; it was not soluble, and the reduction potential was not the right value.  “All these things can be changed,” he noted. “We found ways to render the molecule soluble, and change the voltage, so we have something that works and that is highly soluble.” 

The team made it clear that it was headed in this direction last year, when the researchers published a paper in Nature describing how they paired up this compound with bromine, which is a toxic substance. Aziz explains that, “We switched to alkaline chemistry because of the availability of a positive electrode material that is stable and soluble in base, but not in acid, and that is ferrocyanide.” Ferrocyanide is a widely available compound, used as a food additive and which, paradoxically, is not toxic because the cyanide groups are so strongly bonded to the iron atoms already present that they cannot attack the iron atoms in hemoglobin. “So now we have fulfilled our promise by coming through with non-toxic molecules on both sides [of the ion-selective membrane],” says Aziz. “We now have an entirely non-toxic chemistry.” 

Flow cells need electrolytes that keep these compounds in solution with extreme pH values so that electrons and ions can flow easily.  Most current flow batteries use acids, but the use of a base has other advantages. “Base is just less corrosive than acid, and this allows us to contain these electrolytes with much less expensive materials,” says Aziz.

At this point, about 95 percent of stored energy in the United States is in the form of water pumped up into a reservoir, which can be released to generate power by driving turbines when flowing back down. But in flat or arid areas, this storage option is not available, and it is here that flow batteries could play an important role, argues Aziz. “We are looking at a technology that can be used where pumped hydro cannot—in the middle of a city, on rooftops, near windfarms and solar farms,” he says.  However, reaching this goal will require further work.  “We need to prove that these molecules can last many thousands of cycles of oxidation and reduction, without doing anything else.” 

Is industry interested? When they published their first paper in Nature last year, there was a lot of interest from companies. According to Aziz, “Most of them said, this is really interesting, call us as soon you get rid of the bromine.”

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