Fluoride-based batteries have the potential to last up to eight times longer than today’s lithium ion technology.

An illustration of the electrolyte solution used in the new study, on the atomic scale. The fluoride ion (pink) is surrounded by a liquid of BTFE molecules. Image Credit: Brett Savoie/Purdue University. Click image for the largest view.

In a new study appearing in the journal Science, chemists at several institutions, including Caltech and the Jet Propulsion Laboratory, which is managed by Caltech for NASA, as well as the Honda Research Institute and Lawrence Berkeley National Laboratory, have hit on a new way of making rechargeable batteries based on fluoride, the negatively charged form, or anion, of the element fluorine.

Imagine not having to charge your phone or laptop for weeks. That’s the dream of researchers looking into alternative batteries that go beyond the current lithium-ion versions popular today.

Study co-author Robert Grubbs, Caltech’s Victor and Elizabeth Atkins Professor of Chemistry and a winner of the 2005 Nobel Prize in Chemistry explained, “Fluoride batteries can have a higher energy density, which means that they may last longer – up to eight times longer than batteries in use today. But fluoride can be challenging to work with, in particular because it’s so corrosive and reactive.”

In the 1970s, researchers attempted to create rechargeable fluoride batteries using solid components, but solid-state batteries work only at high temperatures, making them impractical for everyday use. In the new study, published in Science, the authors report at last figuring out how to make the fluoride batteries work using liquid components – and liquid batteries easily work at room temperature.

Simon Jones, a chemist at JPL and corresponding author of the new study said, “We are still in the early stages of development, but this is the first rechargeable fluoride battery that works at room temperature.”

Batteries drive electrical currents by shuttling charged atoms – or ions – between a positive and negative electrode. This shuttling process proceeds more easily at room temperature when liquids are involved. In the case of lithium-ion batteries, lithium is shuttled between the electrodes with the help of a liquid solution, or electrolyte.

Co-author Thomas Miller, professor of chemistry at Caltech explained, “Recharging a battery is like pushing a ball up a hill and then letting it roll back again, over and over. You go back and forth between storing the energy and using it.”

While lithium ions are positive (called cations), the fluoride ions used in the new study bear a negative charge (and are called anions). There are both challenges and advantages to working with anions in batteries.

Jones, who does research at JPL on power sources needed for spacecraft lays out the situation with, “For a battery that lasts longer, you need to move a greater number of charges. Moving multiply charged metal cations is difficult, but a similar result can be achieved by moving several singly charged anions, which travel with comparative ease. The challenges with this scheme are making the system work at useable voltages. In this new study, we demonstrate that anions are indeed worthy of attention in battery science since we show that fluoride can work at high enough voltages.”

The key to making the fluoride batteries work in a liquid rather than a solid state turned out to be an electrolyte liquid called bis(2,2,2-trifluoroethyl)ether, or BTFE. This solvent is what helps keep the fluoride ion stable so that it can shuttle electrons back and forth in the battery. Jones says his intern at the time, Victoria Davis, who now studies at the University of North Carolina, Chapel Hill, was the first to think of trying BTFE. While Jones did not have much hope it would succeed, the team decided to try it anyway and were surprised it worked so well.

At that point, Jones turned to Miller for help in understanding why the solution worked. Miller and his group ran computer simulations of the reaction and figured out which aspects of BTFE were stabilizing the fluoride. From there, the team was able to tweak the BTFE solution, modifying it with additives to improve its performance and stability.

“We’re unlocking a new way of making longer-lasting batteries,” said Jones. “Fluoride is making a comeback in batteries.”

Fluoride chemistry was almost forgotten in the face of so many other alternatives. It does offer some potential now for consumer products. So there needs to be a massive “Thank You!” sent to Victoria Davis, the sharp razor edge of the research. And a “Thank You!” to Simon Jones for listening to her and taking her idea seriously.

The USGS announced last week a very large oil reservoir in Texas and New Mexico. Located in the Permian basin the Mass Media picked it up and it is good news.

For quick background the USGS has been evaluating oil reservoirs for decades and has a pretty good reputation lacking political bias and scientific extremism. If there is a criticism to be made one could say they underestimate the totals. But in actuality, the USGS access to oil companies’ latest and greatest technology isn’t likely available. Thus the USGS work is pretty good, reliable and consistent. Pretty much what public policy making needs.

Perhaps the best headline is at Anthony Watts site, “Watts Up With That”. Written by Davis Middleton the posting titled ‘Peak Oil Postponed Again: “USGS Identifies Largest Continuous Oil and Gas Resource Potential Ever”… And it’s in the Permian Basin’ covers the topic quite well.

The reality is this isn’t a new discovery. Rather its a reassessment of a highly explored basin. Two rock formations in the last assessment, the Wolfcamp Shale and overlying Bone Spring Formation have now been deemed technically recoverable resources.

In short, hydraulic fracturing has now vastly changed the reality of oil reserves. There are some very big numbers in the USGS assessment. 46.3 billion barrels of oil, 281 trillion cubic feet of natural gas and 20 billion barrels of natural gas liquids. At 9 million barrels a day of imports to the U.S. the reserve would be over 14 years of alternate supply.

In summary, the U.S. has immense energy reserves. Oil and natural gas reserves have been building for decades while much of the rest of the world has dwindled. This reality has a nearly total basis in technology, research and development – an enterprise that continues to get better. There are more basins that the USGS has yet to re evaluate, an effort that will continue for decades.

Lastly while technically recoverable, the economics have to work. Can an oil and gas company put a dollar in and wind up with more than a dollar? Probably soon in some locations and as the price of crude gradually works up, more and more will come on line.

Meanwhile, Mr. Middleton and his fellows in the comment section of the posting offer a great deal of excellent information to those of us looking for deeper understanding. These guys know their stuff. Its a few minutes well spent. Head on over!

Ruhr-University Bochum researchers have combined two concepts that make a biofuel cell as efficient as precious metal catalysts.

Fuel cells that work with the enzyme hydrogenase are, in principle, just as efficient as those that contain the expensive precious metal platinum as a catalyst. However, the enzymes need an aqueous environment, which makes it difficult for the starting material for the reaction – hydrogen – to reach the enzyme-loaded electrode. Researchers solved this problem by combining previously developed concepts for packaging the enzymes with gas diffusion electrode technology.

The researchers carried out biofuel cell tests in this electrochemical cell. Image Credit: Marquard, Ruhr-Universität Bochum. Click image for the largest view.

The system developed in this way achieved significantly higher current densities than previously achieved with hydrogenase fuel cells.

In the journal Nature Communications, a team from the Center for Electrochemical Sciences at Ruhr-Universität Bochum, together with colleagues from the Max Planck Institute for Chemical Energy Conversion in Mülheim an der Ruhr and the University of Lisbon, describes how they developed and tested the electrodes.

Gas diffusion electrodes can efficiently transport gaseous raw materials for a chemical reaction to the electrode surface with the catalyst. They have already been tested in various systems, but the catalyst was electrically wired directly to the electrode surface.

Bochum chemist Dr. Adrian Ruff, describing a disadvantage said, “In this type of system, only a single layer of enzyme can be applied to the electrode, which limits the flow of current.” In addition, the enzymes were not protected from harmful environmental influences. In the case of hydrogenase, however, this is necessary because it is unstable in the presence of oxygen.

In recent years, the chemists from the Center for Electrochemical Sciences in Bochum have developed a redox polymer in which they can embed hydrogenases and protect them from oxygen. Previously, however, they had only tested this polymer matrix on flat electrodes, not on porous three-dimensional structures such as those employed in gas diffusion electrodes.

“The porous structures offer a large surface area and thus enable a high enzyme load,” said Professor Wolfgang Schuhmann, Head of the Center for Electrochemical Sciences. “But it was not clear whether the oxygen protection shield on these structures would work and whether the system would then still be gas-permeable.”

One of the problems with the manufacturing process is that the electrodes are hydrophobic, i.e. water-repellent, while the enzymes are hydrophilic, i.e. water-friendly. The two surfaces therefore tend to repel each other. For this reason, the researchers first applied an adhesive yet electron transferring layer to the electrode surface, onto which they then applied the polymer matrix with the enzyme in a second step. “We specifically synthesized a polymer matrix with an optimal balance of hydrophilic and hydrophobic properties,” explained Adrian Ruff. “This was the only way to achieve stable films with good catalyst loading.”

The electrodes constructed in this way were still permeable to gas. The tests also showed that the polymer matrix also functions as an oxygen shield for porous three-dimensional electrodes. The scientists used the system to achieve a current density of eight milliamperes per square centimeter. Earlier bioanodes with polymer and hydrogenase only reached one milliampere per square centimeter.

The team combined the bioanode described above with a biocathode and showed that a functional fuel cell can be produced in this way. It achieved a power density of up to 3.6 milliwatts per square centimeter and an open circuit voltage of 1.13 volts, which is just below the theoretical maximum of 1.23 volts.

This is progress. So far there isn’t a mass market scalable technology for fuel cells that can launch using fuels the early adopters will use. The alcohol units died out from disinterest, so one has to wonder if a true hydrogen gas unit, with all its challenges in fueling, will ever get to market.

A Massachusetts Institute of Technology team of researchers has taken the first three-dimensional images of kerogen’s internal structure, with a level of detail more than 50 times greater than has been previously achieved. The images should allow more accurate predictions of how much oil or gas can be recovered from any given formation.

The fossil fuels that provide much of the world’s energy orginate in a type of rock known as kerogen, and the potential for recovering these fuels depends crucially on the size and connectedness of the rocks’ internal pore spaces.

Using a high-resolution system called electron tomography, researchers probed a tiny sample of kerogen to determine its internal structure. At left, the sample as seen from the outside, and at right, the detailed 3-D image of its internal pore structure. Image Credit: MIT. Click image for the largest view.

These new images should allow more accurate predictions of how much oil or gas can be recovered from any given formation. But this wouldn’t change the capability for recovering these fuels, but it could, for example, lead to better estimates of the recoverable reserves of natural gas, which is seen as an important transition fuel as the world tries to curb the use of coal and oil.

The findings have been published in the Proceedings of the National Academy of Science, in a paper by MIT Senior Research Scientist Roland Pellenq, MIT Professor Franz-Josef Ulm, and others at MIT, CNRS and Aix-Marseille Université (AMU) in France, and Shell Technology Center in Houston.

The team, which published results two years ago on an investigation of kerogen pore structure based on computer simulations, used a relatively new method called electron tomography to produce the new 3-D images, which have a resolution of less than 1 nanometer, or billionth of a meter. Previous attempts to study kerogen structure had never imaged the material below 50 nanometers resolution, Pellenq said.

Fossil fuels, as their name suggests, form when organic matter such as dead plants gets buried and mixed with fine-grained silt. As these materials get buried deeper, over millions of years the mix gets cooked into a mineral matrix interspersed with a mix of carbon-based molecules. Over time, with more heat and pressure, the nature of that complex structure changes.

The process, a slow pyrolysis, involves “cooking oxygen and hydrogen, and at the end, you get a piece of charcoal,” Pellenq explains. “But in between, you get this whole gradation of molecules,” many of them useful fuels, lubricants, and chemical feedstocks.

The new results show for the first time a dramatic difference in the nanostructure of kerogen depending on its age. Relatively immature kerogen (whose actual age depends of the combination of temperatures and pressures it has been subjected to) tends to have much larger pores but almost no connections among those pores, making it much harder to extract the fuel. Mature kerogen, by contrast, tends to have much tinier pores, but these are well-connected in a network that allow the gas or oil to flow easily, making much more of it recoverable, Pellenq explained.

The study also reveals that the typical pore sizes in these formations are so small that normal hydrodynamic equations used to calculate the way fluids move through porous materials won’t work. At this scale the material is in such close contact with the pore walls that interactions with the wall dominate its behavior. The research team thus had to develop new ways of calculating the flow behavior.

“There’s no fluid dynamics equation that works in these subnanoscale pores,” he said. “No continuum physics works at that scale.”

To get these detailed images of the structure, the team used electron tomography, in which a small sample of the material is rotated within the microscope as a beam of elecrons probes the structure to provide cross-sections at one angle after another. These are then combined to produce a full 3-D reconstruction of the pore structure. While scientists had been using the technique for a few years, they hadn’t applied it to kerogen structures until now. The imaging was carried out at the CINaM lab of CNRS and AMU, in France (in the group of Daniel Ferry), as part of a long-term collaboration with MultiScale Materials Science for Energy and Environment, the MIT/CNRS/AMU joint lab located at MIT.

“With this new nanoscale tomography, we can see where the hydrocarbon molecules are actually sitting inside the rock,” Pellenq said. Once they obtained the images, the researchers were able to use them together with molecular models of the structure, to improve the fidelity of their simulations and calculations of flow rates and mechanical properties. This could shed light on how production rates decline in oil and gas wells, and perhaps on how to slow that decline.

So far, the team has studied samples from three different kerogen locations and found a strong correlation between the maturity of the formation and its pore size distribution and pore void connectivity. The researchers now hope to expand the study to many more sites and to derive a robust formula for predicting pore structure based on a given site’s maturity.

This is highly interesting work. Of all the oil and gas discovered so far less than half has been recovered and marketed. Those reservoirs are found, infrastructure installed and connected to markets. Secondary and tertiary recovery are already very big businesses indeed.

So one has to wonder if the big private petroleum firms may or may not be at this point or beyond. These firms hire the best petroleum engineers in the world and petroleum engineers are all very bright folks indeed.

But the research is offering, out in the open, real basic information and importantly, perspective.

Dr. Daniel Puyol of King Juan Carlos University (KJCU), Spain said, “One of the most important problems of current wastewater treatment plants is high carbon emissions. Our light-based biorefinery process could provide a means to harvest green energy from wastewater, with zero carbon footprint.”

Purple phototrophic bacteria which can store energy from light, when supplied with an electric current, can recover near to 100 percent of carbon from any type of organic waste, while generating hydrogen gas for use as fuel.

 

Experimental set-up of the foto-bio-electrochemical H-cell device. Image Credit: Frontiers. Click image for the largest view.

Organic compounds in household sewage and industrial wastewater are a rich potential source of energy, bioplastics and even proteins for animal feed – but with no efficient extraction method, treatment plants discard them as contaminants. Now researchers have found an environmentally-friendly and cost-effective solution.

The team’s paper published in Frontiers in Energy Research, is the first to show that purple phototrophic bacteria – which can store energy from light – when supplied with an electric current can recover near to 100% of carbon from any type of organic waste, while generating hydrogen gas for electricity production.

When it comes to photosynthesis, green dominated the limelight. But as chlorophyll retreats from autumn foliage, it leaves behind its yellow, orange and red cousins. In fact, photosynthetic pigments come in all sorts of colors – and all sorts of organisms.

Cue up purple phototrophic bacteria. They capture energy from sunlight using a variety of pigments, which turn them shades of orange, red or brown – as well as purple. But it is the versatility of their metabolism, not their color, which makes them so interesting to scientists.

Puyol explained, “Purple phototrophic bacteria make an ideal tool for resource recovery from organic waste, thanks to their highly diverse metabolism.”

The bacteria can use organic molecules and nitrogen gas – instead of CO2 and H2O – to provide carbon, electrons and nitrogen for photosynthesis. This means that they grow faster than alternative phototrophic bacteria and algae, and can generate hydrogen gas, proteins or a type of biodegradable polyester as byproducts of metabolism.

Which metabolic product predominates depends on the bacteria’s environmental conditions – like light intensity, temperature, and the types of organics and nutrients available.

Co-author Professor Abraham Esteve-Núñez of University of Alcalá, Spain said, “Our group manipulates these conditions to tune the metabolism of purple bacteria to different applications, depending on the organic waste source and market requirements. But what is unique about our approach is the use of an external electric current to optimize the productive output of purple bacteria.”

This concept, known as a “bioelectrochemical system,” works because the diverse metabolic pathways in purple bacteria are connected by a common currency: electrons. For example, a supply of electrons is required for capturing light energy, while turning nitrogen into ammonia releases excess electrons, which must be dissipated. By optimizing electron flow within the bacteria, an electric current – provided via positive and negative electrodes, as in a battery – can delimit these processes and maximize the rate of synthesis.

In their latest study, the team analyzed the optimum conditions for maximizing hydrogen production by a mixture of purple phototrophic bacteria species. They also tested the effect of a negative current – that is, electrons supplied by metal electrodes in the growth medium – on the metabolic behavior of the bacteria.

Their first key finding was that the nutrient blend that fed the highest rate of hydrogen production also minimized the production of CO2.

“This demonstrates that purple bacteria can be used to recover valuable biofuel from organics typically found in wastewater – malic acid and sodium glutamate – with a low carbon footprint,” reported Esteve-Núñez.

Even more striking were the results using electrodes, which demonstrated for the first time that purple bacteria are capable of using electrons from a negative electrode or “cathode” to capture CO2 via photosynthesis.

“Recordings from our bioelectrochemical system showed a clear interaction between the purple bacteria and the electrodes: negative polarization of the electrode caused a detectable consumption of electrons, associated with a reduction in carbon dioxide production. This indicates that the purple bacteria were using electrons from the cathode to capture more carbon from organic compounds via photosynthesis, so less is released as CO2,” said Esteve-Núñez.

According to the authors, this was the first reported use of mixed cultures of purple bacteria in a bioelectrochemical system – and the first demonstration of any phototroph shifting metabolism due to interaction with a cathode.

Capturing excess CO2 produced by purple bacteria could be useful not only for reducing carbon emissions, but also for refining biogas from organic waste for use as fuel.

However, Puyol admits that the group’s true goal lies further ahead.

“One of the original aims of the study was to increase biohydrogen production by donating electrons from the cathode to purple bacteria metabolism. However, it seems that the PPB bacteria prefer to use these electrons for fixing CO2 instead of creating H2.

“We recently obtained funding to pursue this aim with further research, and will work on this for the following years. Stay tuned for more metabolic tuning.”

This is progress. Lets hope a replicating scientists get on board to follow up because the potential is huge and the problem addressed is abundant. This is worthwhile work with grand results.


css.php