Sodium-Air Fuel Cells, the Search for Planet 9 and Cutting Onions with less tears
June 5
This week we kick off with a story suggested by one of my longest and most loyal readers. We investigate a new refuelable sodium-air fuel cell that may enable faster refueling of electric vehicles and the possibility for short hop electric planes. We also discover how to read a book from over a kilometer away. We examine the latest discovery in the quest to locate Planet 9 in the solar system. Finally learn how to cut onions without causing a flood of tears.
Sodium- Air Fuel Cell
One of the most important factors in battery performance for mobile applications is the power to weight ratio. For example current battery technology does not carry enough power per unit of weight to be able to power electric planes. This is also an issue for long haul electric trucks and ships.
A team at MIT has developed a new type of fuel cell which is similar to a battery however it can be quickly refueled rather than recharged. The fuel is a liquid sodium metal which is inexpensive and widely available. The other side of the fuel cell is air which acts as a source of oxygen atoms.
A solid ceramic material serves as the electrolyte. This material allows sodium ions to pass freely through. A porous air facing electrode helps the sodium react with the oxygen to produce electricity. The prototype device can carry three times as much energy per unit of weight as lithium-ion batteries used in nearly all electric vehicles.
The minimum threshold for electric aviation is 1,000 watt hours per kilogram. Current lithium-ion batteries top out at 300 watt hours per kilogram. Tests on the single stack prototype yielded nearly 1,700 watt hours per kilogram. This translates to over 1,000 watt hours per kilogram for a full system.
The fuel cell would release sodium hydroxide into the air which would then react with carbon dioxide to form sodium bicarbonate. The sodium bicarbonate is a white crystalline powder which is not harmful in small quantities in the environment. In the ocean it helps to de-acidify the water, countering one of the effects of greenhouse gases.
The system would use a refillable cartridge which would be filled with liquid sodium metal and sealed. Sodium melts at 98C so it is easy to heat the metal to melting point. The team have formed a company to commercialize the technology. A demonstration prototype should be ready within a year.
Reading a Book from a Kilometer away
A team at the University of Science and Technology of China have developed a device that can read letters on a page, which are millimeters wide, from over a kilometer away. This was achieved in real world urban conditions (not in a lab).
The team used a method called active intensity interfermoetry. This allowed them to bypass the common limits of optics and atmospheric interference. The system uses several lasers to create psuedothermal illumination. Laser beams are sent towards the target and two telescopes record the reflected intensity. The data is then run through an algorithm that can reconstruct the original image in high detail.
To test the system the letters USTC were cut out of aluminium with each letter no more than 1.5 millimeters wide. The target was placed 1.36 kilometers away. the imaging system captured the letters at a resolution 14 times higher than the theoretical maximum of a single telescope.
The system does not zoom into an image like other spy tools. It reconstructs the image with super resolution, even when the signal is weak or distorted. The technology has potential for applications like long distance sensing, non-invasive imaging in hazardous environments and high precision surveillance.
Planet 9
We have mentioned Planet 9 previously however it is still waiting to be found. Planet 9 is the mysterious planet that is thought to be hidden in the Kuiper Belt way beyond Pluto. We have not found this lost planet however another clue to its’ existence has been discovered.
The speculation about Planet 9 stems from the strange orbits and clusters of icy rocks beyond Neptune. Something big must be influencing these objects and causing them to move as they do.
A team in the US has stumbled upon a new dwarf planet in the outer reaches of the solar system whilst searching for Planet 9. Named 2017 OF201 (I preferred the old way of naming planets after Roman Gods) the new dwarf planet is roughly 700 kilometers across. That is 1/3 the size of Pluto.
Currently three times further away from Earth than Neptune, 2017 OF201 has an extremely elongated orbit which swings out more than 1,600 times the distance between the Earth and the Sun. This orbit sends 2017 OF201 deep into the Oort Cloud (the massive area beyond the Hydropause before we reach deep space).
During its 25,000 year orbit 2017 OF201 is only within view of Earth for 5% of the time or about a century. It is currently moving away from us. The team has applied for time on the James Webb Telescope to study the object.
A new telescope, the Vera Rubin Observatory, which opens in Chile later this year may also tell us more. The great hope of astronomers is that the Vera Rubin will answer the question about Planet 9 and the strange clustered orbits in the Kuiper Belt.
Cutting Onions
Some physicists spend their days pondering the structure of the Universe, some discover new laws that govern our existence whilst a few others spend their days trying to work out how to cut onions so that they cause less tears. I am sure that many a home cook will be grateful for their work.
A team of physicists, biologists and engineers at Cornel University in the US has discovered some of the factors that lead to more or less spray when cutting onions. Prior research has shown that eye irritation from cutting onions is caused by the release of syn-propanethial-S-oxide into the air.
The team used a special guillotine fitted with different types of blades to cut samples. They cut onions that were with paint to allow for better viewing of the cutting process. Trials included different knife sizes, sharpness and cutting speed. An electron microscope was used to examine the knives before use.
Slow motion video revealed that the amount of spray released was due to the sharpness of the knife and the speed at which it cut the onion. The sharper the knife and the slower the cut, the less spray. Dull knives tended to push down on the onion forcing layers to bend inward. As the layers sprang back more spray was released.
As the juice droplets were flung into the air they broke into smaller particles. This meant that they persisted in the air for longer. Faster cutting lead to more juice and thus greater chance of eye irritation.
The lesson here is to use a sharp knife slowly. If you can’t do that, go out to dinner where someone else will cut the onions for you.
Paying it Forward
If you have a start-up or know of a start-up that has a product ready for market please let me know. I would be happy to have a look and feature the startup in this newsletter. Also if any startups need introductions please get in touch and I will help where I can.
If you have any questions or comments please comment below.
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