Win a copy of Compost Teas for the Organic Grower this week in the Composting forum!

Russell Graves

+ Follow
since May 17, 2019
Russell likes ...
hugelkultur solar
Southwest Idaho
Apples and Likes
Apples
Total received
0
In last 30 days
0
Total given
0
Likes
Total received
6
Received in last 30 days
0
Total given
0
Given in last 30 days
0
Forums and Threads
Scavenger Hunt
expand First Scavenger Hunt

Recent posts by Russell Graves

Chris Kott wrote:Russell, it's good to have a fresh voice contributing to these forums. Welcome.



Thanks.  I hold less "techno-utopian" views than many, so some of the tech forums and I don't get along quite as well.  Off-grid (and even on-grid) power systems are an interest of mine, but my views don't line up quite as well with the mainstream on those points.  I'm far more on the side of, "You know, these problems get an awful lot easier if you don't demand as much power as you want, 24/7/365, regardless of the environmental conditions outside."

I meant my statement as a wishlist, as you insinuated. I urge you to remember all the things once considered impossible, including human flight, landing on the moon, getting bananas in North America in winter, or at all, and having any control at all over epidemic disease.

The impossible is simply an indicator of our level of progress and understanding.



That's not a particularly useful way of scoping the problem, though.  First, I don't care too terribly much about what may or may not come down the road, maybe, at some point in the future, if it can manage to escape the lab (see graphene).  I'm more interested in practical energy storage designs with today's proven technology.  If one goes by press releases about battery tech, I should be able to propel an ocean liner across the ocean at hydrofoil speeds with a battery roughly the size of a dorm fridge.  Very few of those advances ever make it out of the lab.  I pay enough attention to that realm that I'm regularly asked about them, and my response is always the same: "I bet it won't."  I'm almost always right.

With the exception of diseases, all the things you list are simply a matter of being able to throw more energy at problems.  We knew how to fly (glide) long before we could get an energy dense enough solution to sustain flight.  I'm less than convinced that throwing yet more energy at the problem is going to be a good solution for energy, going forward.

We've also done a pretty complete job of exploring the problem space for many varieties of reactions, batteries included.  There are remarkably few secrets left in chemistry.  The book "Ignition!" is a fascinating (and occasionally horrifying) read on the history of the liquid rocket propellant program.  It was a massive amount of work during the 50s and 60s, but has largely tapered off because we found just about every combination that works, depending on conditions.  If you eliminate stuff that's an unholy nightmare to work with, is liquid and stable at workable temperatures, and has good performance, there are only a few combinations one ends up with - and if you look, modern rockets are using just a handful of propellant combinations these days.  It's because they're the best set of compromises - and, importantly, they're affordable.  You could build super expensive exotic propellants, but they don't tend to perform enough better to justify the costs.

Batteries are similar.  We know what works, we know what might work (see lithium sulfur for one that's having a hard time getting out of the lab with more than a couple hundred cycles worth of lifespan), and we iterate on the previous ones (the last decade or two of lead acid has actually been fairly exciting).  But there just aren't that many chemical combinations you can get good energy/power density out of, and a lot of the ones battery engineers look longingly at are stubbornly resistant to actually working.  Metallic anodes are an example of one that we know will improve density, but they simply don't work well in practice - you get dendrite buildup, and shorting out a lithium cell is the sort of excitement best left to other people on YouTube.

Instead of suggesting that such is impossible, maybe you could suggest what form of energy storage is best for each stated goal, and where each fall down. Perhaps hybridisation within systems is the answer, as opposed to a more panaceic option.



I did just that.  Does it move?  Use lithium of some variety.  Is it stationary storage?  Use a modern lead acid chemistry.  I could go deeper into the variants of lithium, but they don't matter for stationary storage because I don't think it's the best set of compromises.  Flooded lead acid, in particular, is quite tolerant of abuse, is easy to monitor (a voltmeter and something to measure specific gravity will tell you just about anything you want to know), and lacks the energy density to be exciting.  If you really abuse them hard, you might manage a hydrogen explosion - but even that's difficult.  And that tends to rapidly disassemble things, not light them on fire with toxic fumes (see a lithium runaway - ideally from far upwind).  If you have halfway decent venting, you don't even manage a hydrogen explosion.  The chemistry simply lacks the energy density needed to be exciting.

Plus, it's nearly 100% recyclable.  Reprocess the containers, smelt the lead, purify the acid, replace a couple bits of separator, and you've got a brand new battery for fairly little energy.

http://www.trojanbattery.com/pdf/TBSALES_recycling.pdf is an overview of the process.  Lithium recycling is far from that well established.

And on another note, does anyone have information on the new cryonic hydrogen fuel cell technology? I will try to find the article I was just perusing.



It's almost certainly not useful for small scale.  Anything involving cryogenics, or high pressures (or both) doesn't tend to scale down very well at all.

Marta Meengs wrote:This is a great discussion.  I just watched this video and nickel-iron batteries sound good but also some drawbacks (mining of nickel?) and space/weight?   Nothing seems perfect that's for sure but I appreciate learning the possibilities that are being tried and proven.        



Space and weight don't matter much for stationary storage.  Round trip energy efficiency matters somewhat, and nickel iron is dreadful on that front.  Maintenance also matters, and they come up quite short on that front.  They operate as quite effective oxygen/hydrogen generators, though!
2 months ago

Kate Downham wrote:Is there a way to make ex-telco batteries last? A certain percentage we shouldn't let them get below?



Keep them above, say, 90-95% and they should last a short while - though the telco presumably got rid of them for a reason.  If they were still perfectly good batteries, it's unlikely they'd be tossed out.

There are a wide range of design parameters you can tweak while building a battery, and the UPS/telco batteries simply aren't designed for cycling.

You see it in how lead-acid batteries are rated.  A typical car starter battery is sized and rated by cold cranking amps - they're designed to put out a ton of amps for a very short period of time, then be fully recharged.  They will have a large number of very thin plates (the surface area is how they generate current), but if you drain them significantly, they're damaged.  I've found that a typical car battery can handle being fully discharged about once and recover, but the second time you do it, the battery is shot.

A deep cycle battery (like I have in my office) will be rated in capacity - amp-hours.  They can be deeply discharged without much damage, though it's best to avoid it when possible.  But, because they have large, thick plates designed for cycling, they don't provide nearly as many amps.  Despite being the same size as my truck batteries, I seriously doubt my office batteries would start my truck in the winter.  They're just not built for it.

The "marine deep cycle" batteries live somewhere in between, but good luck finding a datasheet other than a price tag for them.  I won't consider buying anything for energy storage without a very nice datasheet to tell me what I can expect.

Telco/UPS batteries are far closer to starter batteries than deep cycle.  They're designed to bridge an outage, and (depending on the facility) may be running at a very high discharge rate for a short period of time while the generators spin up.  They're just not deep cycle batteries, and you can't expect much life out of them if you ask them to do it.
2 months ago