Energy storage issues

[MC.STEEL]

Who doesn't know the old faithful lithium ion battery,The thing that provides power to your super slick new flashlight that provides 800 lumens +.Or what lets you watch this post on your mobile phone or laptop.

The problem is that energy density is not exactly peachy.

Well thats depressing.What are our alternatives?

Searching for "future energy storage devices" didnt show much except an article for Graphene/water battery that does not explain how it stores its energy.So no cake for that!

After some searching i found the lithium/sulfur battery.

As you can see its density rivals that of gasoline!But judging from its wikipedia article the device suffers from degradation issues and also seems to be in an experimental phase.

Fuelcells dont scale down very well (atleast to my understanding) and I am no expert in capacitors and super capacitors so i wont budge in anything.

Any one care to share some information?

[Kryten]

The first graph doesn't exactly seem reliable. 'Watts per cubic liter', seriously? A litre is already volume, and even just 'watts per litre' wouldn't actually give energy density.

[MC.STEEL]

The first graph doesn't exactly seem reliable. 'Watts per cubic liter', seriously? A litre is already volume, and even just 'watts per litre' wouldn't actually give energy density.

Then by that logic watts/kg would sound funny. (never been very good with measurements,forgive my idiocy)

Also i forgot to mention miniature RTGs would be useful if they didnt emit that pesky radiation.Is there fissionable material that emits easy to stop Helium nuclei and next to none of the harder to block stuff?

[Nuke]

some of the lithium polymer packs i own scare me. they certainly have discharge rates high enough to kill me. ive even seen youtube videos where you can use several of them in series as an impromptu welder.

i also dont like the lack of other storage methods. for example molten salt storage i hear is really effective, though not something you want in a car. flywheels are also a thing. the navy wants to reprocess environmental carbon back into fuel. im also somewhat curious about antimatter as energy storage. making antimatter to burn antimatter doesn't make a lot of sense, unless it turns out to be hyper efficient as an energy storage medium, when compared to other storage means. id love to see a side to side for all the energy storage numbers.

Edited April 20, 2014 by Nuke

[andrewas]

Then by that logic watts/kg would sound funny. (never been very good with measurements,forgive my idiocy)

Watts/kg does sound funny. Watts are a measure of power, not a measure of energy. You wants joules or watt hours or some other energy unit.

[rkman]

That graph looks about right.

Yes we've still got a long way to go with improvement of batteries.

http://en.wikipedia.org/wiki/Energy_density

[Dwayne_Knight]

If I had the resources I'd do research on rechargeable molten carbonate fuel cells right now with some kind of co-generation. I think energy storage in carbon, methanol and dimethyl ether would either for use in the cell or as more traditional fuel use be beneficial.

I also wonder if flywheels have long term prospects with future materials improvements in tensile strength and higher temperature superconductivity.

[cantab]

Watts/kg does sound funny. Watts are a measure of power, not a measure of energy. You wants joules or watt hours or some other energy unit.

Watt-hours per kilogram being what the second graph shows.

Though Watts/kg is also important. It's all very well having a small battery capable of storing masses of energy, but you also need it to deliver sufficient power for the device. Likewise for large-scale energy storage you need to consider charge, discharge, and self-discharge rates, along with overall efficiency. Oh and throw cost into the mix.

Also important in practical applications is the whole system. For an electrically-powered device, it's not valid to compare a battery that gives the current directly to a liquid fuel for a fuel cell and ignore the mass of the fuel cell hardware.

Of course sometimes the simple solutions are the best. When it comes to storing energy for load-balancing electricity grids, pumping water uphill is far and away the dominant method, despite the energy density per kg of water being abysmal. A typical pumped storage station can generate upwards of a gigawatt of electricity for several hours before running out.

[Tommygun]

One near term solution in some application could be micro internal combustion engines.

http://phys.org/news9823.html

[MC.STEEL]

One near term solution in some application could be micro internal combustion engines.

http://phys.org/news9823.html

O_O a combustion engine that small...

Interesting, but yet i see this as a niche component as the thing still spews out the most dreaded CO2.And the heat and noise coming out of this thing are not quite what i would call convenient.

[Tommygun]

From what I have heard, because it is so small, the emissions coming from it are too little to be dangerous.

I have only seen them in videos, but they didn't sound any worse than maybe a noisy cooling fan on a computer.

Although sound is hard to judge because you don't know where they put the microphone.

[MC.STEEL]

Still i wouldnt want my stuff to smell of burned hydrocarbons.However the one place this will be invaluable is in mini drones like those quadcopters the size of your palm, miniature buggies and maybe even robotic spiders .Search and rescue drones will encounter a giant leap in effectiveness.

[Thiel]

CO2 emmisions scales linearly with fuel consumption. The size of the engine doesn't have anything to do with that.

About the power density graph you have to remember that so far we're only capable of accessing 40% of it at most.

[m4v]

Lithium-air battery is another contender, albeit one that faces many technical problems.

http://en.wikipedia.org/wiki/Lithium%E2%80%93air_battery

Even so batteries might never be as convenient as gasoline, is not just about the energy densities, there's also the charge/discharge rates. Put it in perspective think about the power you're delivering to your car when you fill its tank, assuming gasoline energy density of 36MJ/l, that a car has a 50l tank and it takes 2 minutes to top it off, then you're "charging" your car at a rate of 15 MW. That's a lot of power, I don't think that there's a copper wire that is small enough so you can plug and unplug it capable of withstanding that.

In the end I think we will have to accept it and go by with cars with less autonomy and long charge time, instead of holding off migration because they aren't as good.

[Idobox]

Other metal-ait batteries are being studied. Zinc air is easy but not very good, aluminium air is very promising but requires something else than water to work.

http://en.wikipedia.org/wiki/Metal%E2%80%93air_electrochemical_cell

[Thiel]

Heat management is also going to be a major issue for micro engines. Lithium-Ion batteries can get pretty hot when charging and discharging at high rates and they're about 80-90%. AFAIK the thermal efficiency of those micro engines hasn't been established yet, but your average gasoline powered car engine has an efficiency of about 25-30% when running under optimal load. That means you've got at least seven times as much heat you need to dissipate.

Another issue is that the engine needs air to work. What's going to happen if you stuff it in a pocket?

Noise and vibration are also going to be an issue. Who is going to buy a noisy phone even if it does have a fabulous "battery" life.

[m4v]

Noise and vibration are also going to be an issue. Who is going to buy a noisy phone even if it does have a fabulous "battery" life.

The military.

[Nuke]

hydrocarbon fuels are horribly inefficient. i want nuclear-reactor-on-a-chip type devices!

Edited April 21, 2014 by Nuke

[Thiel]

The military.

Actually, they're kinda picky on that subject. Aside from the obvious stealth issues, having an engine droning in your ear is less than helpful when using a radio.

And they're going to be even more wary of the heat issues since they're likely to operate them in really hot climates. They're also going to be very worried about stuff like dust ingestion and how to get the fuel cannisters out to the troops. Despite their drawbacks, Lithium-Ion batteries does have the advantage that mil-spec chargers will accept just about any combination of voltage and frequency and they're built into just about every vehicle in their arsenal.

[m4v]

Actually, they're kinda picky on that subject. Aside from the obvious stealth issues, having an engine droning in your ear is less than helpful when using a radio.

And they're going to be even more wary of the heat issues since they're likely to operate them in really hot climates. They're also going to be very worried about stuff like dust ingestion and how to get the fuel cannisters out to the troops. Despite their drawbacks, Lithium-Ion batteries does have the advantage that mil-spec chargers will accept just about any combination of voltage and frequency and they're built into just about every vehicle in their arsenal.

And phones aren't the only thing that needs batteries, nor you have to pick one type of battery for every use. Everything has some utility in some situations while none in others, Li-Ion batteries aren't used in space for example.

[sgt_flyer]

hydrocarbon fuels are horribly inefficient. i want nuclear-reactor-on-a-chip type devices!

That's betavoltaics (and yes, they fit on a chip ^^) although each chip only gives out a few nanowatts of power, it can run for 25+years

[Nuke]

That's betavoltaics (and yes, they fit on a chip ^^) although each chip only gives out a few nanowatts of power, it can run for 25+years

ive heard of those but i was thinking of something a little bit more ambitious.

micro actuators moving control rods a few micrometers thick between banks of fissile material. i dont think these would work because physics has its limits on what size a critical mass need to be. but unlock the island of stability and it may become feasible.

Edited April 21, 2014 by Nuke

[Dwayne_Knight]

hydrocarbon fuels are horribly inefficient. i want nuclear-reactor-on-a-chip type devices!

I wonder if nanofactor level nanotech will stumble across the source of all the cold fusion confusion and maybe come up with just such a device.

[Seret]

Hmm, first graph is of power density, second is of energy density. Not exactly the same thing. However, the OP does have a point. The reason hydrocarbons are so useful for transport fuels is their high energy density. Despite this, we don't use it as our only energy storage solution, trying to compare it to electricity storage is really only relevant when you're looking at electrification of transport.

There are a few different challenges when it comes to energy storage:

• Grid-level storage
  
• Local or domestic
  
• Transportation fuel (road/air/maritime)
  
• Mobile electric/electronic devices
  
• Storage for heating/cooling (which may or may not be electric)
  

We've got solutions for some of these, but not others, and they all could do with improvement. No one technology is going to be useful for everything.

Edited April 22, 2014 by Seret