Solar Energy

Batteries are a hot topic for SPARRCI researchers

Published

3 years ago

March 2, 2021

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Batteries are a hot topic for SPARRCI researchers

If you have flown commercially in recent years, you may have noticed that certain items with large lithium-ion batteries can’t be checked. Instead, they must be in your carry-on and turned off.

Objects with these batteries, such as hoverboards or even cell phones, have been known to spontaneously combust, especially if they are physically damaged somehow. The resulting fire presents a danger to people in their vicinity.

So, if these batteries aren’t allowed on airplanes unsupervised, using them to propel the fully electric aircraft of the future may come with some challenges and questions about safety.

Exploring the feasibility of predicting and preventing battery fires before they happen is the idea behind a NASA research activity called SPARRCI, or “Sensor-based Prognostics to Avoid Runaway Reactions and Catastrophic Ignition.”

The big goal is to create a “smart” battery system that would self-monitor, learn about itself as it goes, and if needed say “hey, I’m developing a problem, shut me down” well before it endangers the safety of its aircraft.

“Batteries are a hot topic. Pun intended,” said Brianne DeMattia, lead researcher for SPARRCI at NASA’s Glenn Research Center in Cleveland.

One of the safety threats posed by batteries in electrically propelled aircraft is fire. These larger batteries, like those needed to power hoverboards and cars, have been known to catch fire because of an effect called “thermal runaway.”

Large batteries are basically many cells of small batteries packaged together. If one cell has a malfunction and starts to heat up in temperature, it causes the neighboring cell to do the same. Eventually, the whole battery overheats and could start a fire.

Battery sensors like the ones used by our phones and computers only measure the temperature outside the battery. SPARRCI is designing batteries with sensors inside them to identify the conditions that lead to thermal runaway, then alert the aircraft’s operator to the potential trouble.

The operator would then be able to correct the problem or replace the battery before the dangerous overheating ever occurs. This new, fine-tuned view of the inside of a battery could lead to safer and better performing energy storage – a new generation of batteries.

“With current batteries, we just try to contain fire so it doesn’t spread. But the best approach is to try and prevent the overheating and fire entirely. That’s what we’re trying to do with SPARRCI,” DeMattia said.

Size Matters

Another research area of SPARRCI is battery size and power storage.

A typical remote control for a television uses a couple of AA-sized batteries. A small electric aircraft such as the X-57 Maxwell, NASA’s first all-electric aircraft, may need a battery with the equivalent power of more than 5,000 AA-sized batteries.

Currently, large batteries providing that kind of power must be packaged in bulky containers to make sure that if something gets hot or catches fire, the heat is insulated, protecting other battery cells and the vehicle.

The size and weight of these containers could be reduced in the future with SPARRCI’s ability to show what’s going on inside the battery.

If the aircraft’s pilot or maintenance crew know that thermal runaway could occur, the battery can be replaced and never have a chance to catch fire.

If fire isn’t a threat anymore, extra insulation isn’t required, and the battery’s overall size and weight can be reduced. This would allow more space inside the vehicle to be dedicated to energy storage, improving its range and available power.

Since the activity began in 2020, SPARCCI researchers have successfully begun working out how to install sensors inside batteries. The next step? Identify what conditions the sensors inside the battery should look for to detect imminent battery problems or failures.

The View Inside

SPARRCI is part of the Convergent Aeronautics Solutions (CAS) project, which is designed to give NASA researchers the resources they need to determine if their ideas to solve some of aviation’s biggest technical challenges are feasible and perhaps worthy of additional pursuit within NASA or industry.

One of the things that makes CAS activities like SPARRCI unique is the requirement for researchers from different technical disciplines and NASA field centers to collaborate and bring their unique expertise to bear on the problem.

For SPARRCI, that collaboration led to some memorable moments for battery and sensor researchers at NASA’s Langley Research Center in Virginia, who have been working with their counterparts at NASA Glenn.

The Langley researchers evaluated batteries from Glenn using a Scanning Electron Microscope (SEM), a device similar to the ultrasound machines used in doctors’ offices and hospitals.

“Our goal was to collect images of the guts of the battery during a test without having to open them up post-mortem. This allowed us to see conditions changing in real time and run non-destructive scans to get a sense of the ‘topography’ of the internal surfaces as they morphed during operation,” DeMattia said.

What they saw during the scans was, well, out of this world.

“As we used the SEM to scan images of these lithium metal surfaces inside the battery they sometimes looked like the surface of the Moon! It was one of the coolest things. We spent hours around the computer, ‘oohs’ and ‘ahs’ often thrown around, with an occasional ‘What on Earth is that?’ thrown in for good measure.”

“It’s not something that any of us have done or seen before, but the images did help us tie together the data we collected,” DeMattia said. “”We couldn’t have done this without the different disciplines coming together. It has been really exciting.”

SPARRCI was selected to be a two-year activity that began on Oct. 1, 2019. Interruptions in the pursuit prompted by the COVID-19 pandemic might lead to an extension, although nothing has been decided yet.

Once completed, information gathered, and experience gained during SPARRCI will be shared with others within NASA and the broader aviation community.

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Solar Energy

3D-printed microstructure forest enhances solar steam desalination

Published

3 days ago

July 24, 2024

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3D-printed microstructure forest enhances solar steam desalination

by Clarence Oxford

Los Angeles CA (SPX) Jul 24, 2024

To address the global freshwater scarcity issue, researchers in Singapore have developed advanced solar steam generators (SSGs) for seawater desalination. This method, powered by renewable energy, mimics the natural water cycle by using solar energy to evaporate and purify water, offering a potentially cost-effective solution compared to traditional, energy-intensive desalination techniques. However, current SSG technologies face limitations due to the complexity of fabricating designs that maximize surface area for optimal water evaporation.

Drawing inspiration from nature, the team utilized 3D printing to create innovative SSGs. Their findings, published in Applied Physics Reviews, highlight a novel technique for manufacturing efficient SSGs and introduce a groundbreaking method for printing functional nanocomposites using multi-jet fusion (MJF).

“We created SSGs with exceptional photothermal performance and self-cleaning properties,” said Kun Zhou, a professor of mechanical engineering at Nanyang Technological University. “Using a treelike porous structure significantly enhances water evaporation rates and ensures continuous operation by preventing salt accumulation – its performance remains relatively stable even after prolonged testing.”

The technology works by converting light to thermal energy, where SSGs absorb solar energy and convert it to heat to evaporate water. The porous structure of the SSGs aids in self-cleaning by removing accumulated salt, ensuring sustained desalination performance.

“By using an effective photothermal fusing agent, MJF printing technology can rapidly create parts with intricate designs,” Zhou added. “To improve the photothermal conversion efficiency of fusing agents and printed parts, we developed a novel type of fusing agent derived from metal-organic frameworks.”

The SSGs feature miniature tree-shaped microstructures that mimic plant transpiration, forming an efficient, heat-distributing forest.

“Our bioinspired design increases the surface area of the SSG,” Zhou explained. “Using a treelike design increases the surface area of the SSG, which enhances the water transport and boosts evaporation efficiency.”

In both simulated environments and field trials, the SSGs exhibited a high rate of water evaporation. The desalinated water consistently met drinking water standards, even after extended testing.

“This demonstrates the practicality and efficiency of our approach,” Zhou said. “And it can be quickly and easily mass-produced via MJF commercial printers.”

The team’s work shows significant potential for tackling freshwater scarcity.

“Our SSGs can be used in regions with limited access to freshwater to provide a sustainable and efficient desalination solution,” said Zhou. “Beyond desalination, it can be adapted for other applications that require efficient solar energy conversion and water purification.”

Research Report:3D printing of bio-inspired porous polymeric solar steam generators for efficient and sustainable desalination

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Solar Energy

Renewables overproduction turns electricity prices negative

Published

3 days ago

July 24, 2024

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Renewables overproduction turns electricity prices negative

By Nathalie Alonso and Catherine Hours

Paris (AFP) July 24, 2024

With the proliferation of solar panels and wind turbines an unusual phenomenon is becoming more and more frequent: wholesale electricity prices turn negative.

While that may brighten the mood of consumers whose power bills have surged in recent years, it could undermine the further development of renewables, a key element in the fight against global warming.

The increasingly frequent phenomenon is “extremely problematic” for the wind and solar sector, said Mattias Vandenbulcke, strategy director of the renewables industry group France Renouvelables.

“It allows some to have harmful, even dangerous rhetoric which says ‘renewables are useless’,” Vandenbulcke said.

In southern Australia, wholesale electricity prices have been negative some 20 percent of the time since last year, according to the International Energy Agency.

The share of negatively priced hours in southern California was above 20 percent in the first half of the year, more than triple from the same period in 2023, the IEA said.

In the first six months of the year in France, there were negative prices around five percent of the time, beating the record set last year, according to the electricity grid operator RTE.

In Switzerland the price tumbled as far as -400 euros (-$436) per megawatt hour on July 14. The lowest prices are usually recorded around midday during the summer when solar production is at its peak.

– ‘A warning signal’ –

The trend has been accelerating for the past three years as demand in Europe has unexpectedly dropped since the Covid pandemic and the war in Ukraine.

Prices turn negative on the spot wholesale electricity market when production is strong while demand is weak.

Around a fifth of the total is traded on this market, where electricity is bought for the following day.

Negative prices help reduce the bills of consumers, said Rebecca Aron, head of electricity markets at French renewables firm Valorem, but the impact is delayed and difficult to discern among the other factors that send prices higher and lower.

Large, industrial consumers that can shift production to times when prices are negative and buy on wholesale markets can reap the biggest rewards.

Negative prices are “a warning signal that there is way too much production on the electrical grid”, said energy analyst Nicolas Goldberg at Colombus Consulting.

Electricity grids need to be kept constantly in balance. Too much can lead to the electricity to increase in frequency beyond norms for some equipment. Too little can lead to some or all customers losing power.

There are currently few options to stock surplus electricity production so producers have to reduce output.

Many renewable producers stop their output when prices are set to turn negative. It takes one minute to stop output at a solar park, two to three minutes for a wind turbine.

But not all stop their production.

– Tripling renewables –

“Renewable energy can be controlled, but depending on production contracts, there might not necessarily be an incentive to stop,” said Mathieu Pierzo at French grid operator RTE, which has the responsibility for balancing the electricity load.

Some producers are paid a fixed price under their contract or are compensated by the state if prices fall below a certain level.

Fossil fuel and nuclear power plants can adjust their production to some extent, but halting and restarting output is costly.

In the future, solar and wind will also have to “participate more in balancing the electricity system”, Pierzo said.

Solar and wind production is set to rise further as nations agreed at the COP28 climate conference last year to triple renewable energy capacity by 2030 as part of efforts to limit warming to 1.5 degrees Celsius compared with pre-industrial levels.

“Rising frequency of negative prices sends an urgent signal that greater flexibility of supply and demand is needed,” the Paris-based IEA warned last week.

“The appropriate regulatory frameworks and market designs will be important to allow for an uptake in flexibility solutions such as demand response and storage,” it said.

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Solar Energy

NREL explores long-term strategies for sustainable perovskite solar panels

Published

3 days ago

July 24, 2024

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NREL explores long-term strategies for sustainable perovskite solar panels

by Clarence Oxford

Los Angeles CA (SPX) Jul 24, 2024

Researchers at the National Renewable Energy Laboratory (NREL) are examining the future of perovskite solar panels, focusing on scaling, deploying, and designing panels to be recyclable.

Perovskite solar panels could play a key role in global efforts to reduce greenhouse gas emissions. With the technology still in its developmental stages, researchers are emphasizing the importance of designing these panels to minimize environmental impact.

“When you have a technology in its very early stages, you have the ability to design it better. It’s a cleaner slate,” said Joey Luther, a senior research fellow at the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) and coauthor of the newly published article in the journal Nature Materials. “Pushing perovskite PV toward enhanced sustainability makes more sense at this stage. We’re thinking about how we can make sure we have a sustainable product now rather than dealing with sustainability issues toward the end of its practical life.”

The article highlights the PV research community’s influential position to prioritize remanufacturing, recycling, and reliability efforts, aiming to make perovskite PV one of the most sustainable energy sources available.

“Perovskites could unlock the next evolution of high-efficiency PV, and it is our responsibility to assure they are manufactured, used, and recycled sustainably,” said the lead author of the study, Kevin Prince, a former graduate researcher at NREL who now researches perovskites at Helmholtz Zentrum Berlin in Germany.

While silicon solar panels dominate the industry and cadmium telluride (CdTe) panels have established recycling programs, perovskites are at a critical point where sustainability issues can be addressed from the start.

The most effective circular economy begins at the design stage, considering materials sourcing, product lifetime, and end-of-life management. Researchers suggest assessing environmental impacts by looking at carbon emissions during production, embodied energy, sustainable material sourcing, and module circularity.

The journal article identifies critical sustainability concerns for each component of a perovskite solar panel. For instance, lead can be diluted with metals like tin to reduce lead content, though this may affect PV efficiency and durability. Expensive precious metals such as silver and gold could be replaced with cheaper alternatives like aluminum, copper, or nickel. Fluorine-tin oxide is recommended over the scarcer indium-tin oxide for front electrodes.

“We want to have the lowest amount of embodied energy in the fabrication,” Luther said. “We want to have the lowest amount of emissions in the fabrication. At this stage, now is the chance to look at those components. I don’t think we have to change anything. It’s more a matter of what decisions should be made, and these arguments should certainly be discussed.”

The authors discuss various ways to improve the circularity of perovskite panels. Remanufacturing involves reusing parts from old modules to make new ones, while recycling converts waste materials into raw materials for reuse. Attention is needed for the specialized glass used in perovskite modules, which is crucial for structural support and protection while allowing maximum sunlight penetration. Establishing a recycling pathway for this glass will be essential as PV deployment increases.

Silvana Ovaitt, a PV researcher and coauthor of the paper, noted that cleaner electricity grids will lead to cleaner manufacturing processes, further reducing emissions.

“Another concern is the transportation of the final modules and the raw glass because those are the heaviest items,” Ovaitt said. “Local manufacturing will be a great way to reduce those carbon impacts.”

The researchers explain that increasing the durability of PV modules, thereby extending their useful life, is a more effective approach to reducing net energy, energy payback, and carbon emissions than designing for circularity alone. A longer lifespan means panels won’t need to be recycled as often.

“Ultimately, we want to make them as durable as possible,” Luther said. “But we also want to consider the aspects of whenever that time does come. We want to be deliberate about how to take them apart and to reuse the critical components.”

Research Report:Sustainability pathways for perovskite photovoltaics