CO2 power Idea

I just wanted to toss out an idea. Don't know if it could work. Consider a led flashlight powered by a CO2 cartridge. The gas expands through a turbine which spins a generator to power a led. The expanded gas then circulates through the heat sink on the led cooling the led. The reheated gas then passes through another turbine attached to the same generator, for a little more power, and then vents to atmosphere. Thoughts?

ed

my guess.. waaaay to little energy stored in the Co2 cart.. it's a neat idea for ONE really interesting reason..

the POWER output capability is great!

you could probably generate 100W from such a setup.. just for a half a minute or something.. you can do the math to figure out what energy is stored if you know the volume and pressure. For low power lights the hydrogen fuel cell is the way to go.. though i'm partial to butane or lighter fluid myself.. both have many times the energy density of batteries.

One drop of gasoline could run an LED light for HOURS.

pressurized butane.. and a little burning cell exactly how the 'thermacell' mosquito repellents work.. put heat on one side of a peltier junction and generate some electricity.. the other side of the peltier is cooled by your skin to give you constant output. I think i will do some testing with the peltier and the thermalcell i have.. if i can figure out that i can get it to work.. i think i can get like 5-10W out of my peltier with maybe 200F difference in temp... not hard to achive with a FIRE on one side!

-awr

Whats wrong with batteries?

batteries are notoriously low energy density. My latest lights have runtimes on the order of 10 minutes because batteries are the 'weak link'.

examples of some energy density by mass: (WH/kg)

SLA: 25
Compressed air (Co2) 34
NiCD: 50
NiMH: 60
LiON: 120
LiPO: 140

Wood: 1600-4700!
Gasoline: 11,860

So.. as you can see.. compressed air.. lower than NiCD for energy density.. but almost certainly higher in POWER density.. an added bonus.. the chilling effect of the expanding compressed gas will naturally cool the ludicrous amount of heat certainly being generated from the 100-200W lamp on the other side

lemme think about this.. i had a C02 cart around here somewhere.. 16g..

so 0.016kg x 34 WH/kg = .544WH aka 32.64 Watt-minutes.

That means 1W for 32 minutes.. about what i can get from a AAA LiON cell.. however.. having some fun.. we could probably discharge that in under 1 minute and get 32W for a minute.

change to propane at 1atm.. you get nearly 14,000WH/kg.. i can see a little butane powered lamp that runs for 6 hrs from a charge.. i will make a tester unit.. i just discovered that my thermacell has a flat aluminum plate on the outside of the burning chamber used to heat the insecticide pad.. it will mate perfectly with my peltier junction, it's almost exactly the same size. I will see what kind of voltage/power i can get and will report back.

-awr

andrewwynn said:

For low power lights the hydrogen fuel cell is the way to go.. though i'm partial to butane or lighter fluid myself.. both have many times the energy density of batteries.

Click to expand...

Fuel cells for flashlights are a ways off, and although liquid fuels have greater energy density than batteries, converting them to electricity on a small scale (for a handheld device!) is typically so inefficient that you're better off with batteries.

A compressed-air generator that uses the "waste" air to cool the lightsource has some merits for a small, short-running, intensely-bright light ... but recovering energy from the heat it will gain strikes me as impractical at best.

disappointing news.. just tried one of my peltiers.. putting on a 10ohm load.. i was able to generate about 120mA at 1.2V.. 144mW.. with direct application of a torch! hardly an efficient method of generating electricity. I was also disappointed in the relatively low cooing when i put 10-15W into the thing.. i was able to feel a pretty chllly cooling surface but i was told it could do a lot better. I want to try to use it to cool a ludicrously overpowered LED light.. maybe put 10-15W into cooling so i can make a non-fanned cooling solution.

-awr

it would seem you are pretty spot-on with that analysis.. though that hydrogen light looks very promising.. 24WH of energy i think.. from a single recharge.. that's about the same as 12xCBP1650s.. but can only extract it 1W rate.. yowza! i woud like to see at least 10W.. i don't need a 24Hr light.. 2.4 at 10W sounds a lot nicer to me.

-awr