Archive for March, 2022

Mar 08 2022

Solid State Li-ion Batteries

Published by under Technology

OK, I’m a sucker for juicy battery news, even though I know these advances are all incremental and not the dramatic “breakthrough” they are often presented to be. But cumulatively these incremental advances are significantly increasing the energy per mass and energy per volume of high-end batteries. This is a critical technology for our low-carbon future, and so these advances are worth tracking.

As I always point out when I write about battery technology, an ideal battery needs to have many features simultaneously: good specific energy, energy density, lifespan in terms of charge-discharge cycles, rapid recharge rates, sufficient power, use of cheap, abundant, and non-toxic materials, a good temperature range of operation, overall cost-effectiveness, scalable manufacturing, and stability (it’s nice if they don’t spontaneously burst into flames). Li-ion batteries are the current state-of-the-art because they are reasonable to good on all these parameters, but there is a lot of room for improvement. One of the many lines of research looking into alternate battery design is solid state Li-ion batteries. These use a solid rather than liquid electrolyte for conducting charge between the electrodes.

A solid state design could have twice the specific energy (energy per mass) and twice the energy density (energy per volume) as current Li-ion batteries.  This is because the solid electrolyte requires much thinner separators between the electrodes, and also because the lithium-graphite electrode can be replaced with a lighter pure lithium electrode. Solid state batteries also will likely have a longer lifespan and are more stable and therefore safer. Imagine essentially doubling the capacity of a lithium battery, for your cellphone, laptop, or electric vehicle. You could increase the range of an EV by 50% while still decreasing the battery weight by 25% (which would actually increase the range a bit more). I own an EV with a range of 350 miles, and going to a range of 500 miles would definitely reduce range-anxiety on long trips. That might be the sweet spot for EVs.

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Mar 07 2022

Alcohol Is Bad for the Brain

Published by under Neuroscience

The dose makes the poison, so anything is potentially a poison in a high enough dose and safe in a low enough dose. But we generally refer to substances as poisons or poisonous if they cause significantly negative or dangerous biological effects at typically encountered doses. By this practical definition, alcohol is a poison. When you are tipsy or drunk what you are experiencing is alcohol’s poisonous effect on the functioning of your brain. The acute effect of alcohol is to inhibit neuronal firing, thereby depressing brain function. Even after one drink, these effects can be measured in reduced reaction time and cognitive function.

There has long been a scientific question, however, as to how much of a long term damaging effect alcohol has on the brain. It’s possible that it acutely inhibits neuronal firing, but once out of your system, function returns to normal and no harm done. There is a great deal of scientific research on this question, which has well-established that chronic heavy alcohol use causes damage to the brain. Even after we separate out damage caused by associated malnutrition (vitamin B1 being most relevant) there is a separate direct brain toxicity from heavy alcohol use.

While this is scientifically settled, there is still the question of – at what amount of regular alcohol use does this damage begin? The evidence for brain damage from light to moderate drinking has been mixed. This makes sense just from a statistical point of view. As we look at milder exposure, effect sizes should decrease and eventually be lost in the noise. So generally speaking, with any phenomenon, it should be easier to see with the strong effect size, then the scientific results should become mixed and ambiguous with smaller effects sizes, and then eventually disappear. This would be true even if the toxicity from alcohol were strictly linear with no threshold.

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Mar 03 2022

Exuviae and Frass for a Circular Farming System

Published by under General Science

What are exuviae and frass? These are terms I just learned and are probably new to you as well, but they may become more familiar in the future. Exuviae are molted exoskeletons from insects and are primarily made of chitin. Frass is undigested food from insects, so basically bug poop. Frass could make a good fertilizer for plants because it is high in nitrogen. Exuviae would not serve as fertilizer, but there are species of soil bacteria that can break down chitin for food. Adding exuviae to soil increases the population of these soil bacteria, which are beneficial to plants and make them more resilient to pests.

Exuviae and frass, therefore, can be extremely useful for farming. But where are we going to get the massive quantities of these materials that would be necessary to have any significant impact on our agricultural system? Well, we could farm insects for food and use the waste products of insect farming for plant agriculture. This could be the basis for a circular agricultural system. Organic matter from plant and animal farming can be used to feed insects which are also grown for food. The exuviae and frass from the insect farming can then be fed back into plant farming as fertilizer. This would not be a totally closed system, of course. Humans would be removing calories and nitrogen from the system to feed themselves, and human waste is typically not recycled as fertilizer (this is a separate issue – the risks and benefits of using humanure).

Insects are increasingly recognized as an important source of food. They have several advantages, the biggest being that they are small. This translates into a high food output to land use ratio. Raising insects also uses far less water than other food sources. Insects can also be easily farmed indoors, meaning they can be farmed year-round and in urban settings. Already there is significant farming of crickets, grasshoppers, mealworms, waxworms, and other insects for food. The insects are not generally consumed whole (although they can be), they are ground up and used as protein powder (such as cricket flour).

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Mar 01 2022

NASA Funding Innovative Projects

Published by under Technology

One of the themes in my upcoming book (that I wrote with my brothers, Bob and Jay) about future technology (coming Fall 2022) is the frequent disconnect between science fiction visions of the future and actual future technology. We can look at past science fiction about today and see how they did, but we can also look at current science fiction about the future to see how plausible their vision is. It’s a mixed bag, but one area where the disconnect is very strong is space travel. The problem is that space travel really sucks, and is going to suck for the foreseeable future. This is not only true for interstellar travel, but even travel within our own solar system. But science fiction authors want their action to take place in space and have their heroes travel to different worlds. So essentially they either need to just ignore major hurdles to space travel or make up sci-fi technology to solve those problems even if that means ignoring current science. Even hard science fiction has to allow 1-2 “gimmies” to make the storytelling work.

I think all of the challenges of space travel are potentially solvable. But I also think those solutions are going to be more complicated, involve more trade-offs, and take much longer than science fiction authors generally imagine. Toward that end, NASA is funding innovative research projects to chip away at the technological challenges of space travel. While these are early (phase I and phase II) research projects, they give a much more realistic glimpse into what space travel might look like over the next couple of centuries. Here are some highlights:

 

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