Subscribe Contribute Advertise Facebook Twitter Instagram Forums Newsletter
Electric cooking in the wilderness – a rough analysis
Display Avatars Sort By:
Rex Sanders
(Rex) - M

Locale: Central California Coast
Electric cooking in the wilderness – a rough analysis on 08/13/2013 23:38:30 MDT Print View

I know what you are thinking – Are you crazy? Who would cook with electricity in the wilderness? Why?

I'll run the numbers, so we'll see how crazy that might be.

But first:

– Most backpackers use a battery-powered flashlight or headlamp, instead of a candle or no light. Are they crazy?

– Some backpackers use a battery-powered GPS instead of a compass, paper maps, and navigation skills. Are they crazy?

– Some backpackers use a battery-powered cell phone, satellite phone, or satellite messenger, instead of developing more self-reliance, and more tolerant families. Are they crazy?

Why would someone want to cook with electricity in the wilderness?

– Fire bans, which are becoming more common because of the left-wing global warming conspiracy.

– Some people are afraid of cooking over a flame. Don't laugh, I have friends who grew up with electric stoves and are afraid of cooking with flames.


Important concepts

Energy is potential work. The energy in a battery is like the gasoline in a car's tank. Electric energy can be measured in Watt-hours.

Power is how fast you spend energy. Some batteries can push out energy faster than others. The power of a battery is like the engine in a car. Electric power can be measured in Watts.

Some cars have large tanks (high energy) and small engines (low power); some have small tanks and large engines; most are in between. Batteries are similar.


So how could we cook with electricity in the wilderness?

Caveat: I am not an engineer. If you are, please be kind in your comments!

Goal: Bring 2 cups of 1° C (34° F) water to a boil in about 10 minutes.

That's a a little slow, but tolerable.

To raise 2 cups of water by 99° C takes about 55 watt-hours of energy.

Delivering 55 watt-hours in 10 minutes takes 330 watts of power.

... assuming we have 100% conversion of electricity to heat (good assumption), and 0% heat loss from the stove and pot (bad assumption).

Assuming our stove and pot are 67% efficient, we need about:

83 watt-hours of energy
500 watts of power

How do we deliver 500 watts to a pot holding 2 cups of water?

Four 120-watt immersion heaters would be close enough:
immersion heater

Crammed into a pot with a cozy:
pot with cozy

Someone could make a better setup, these are off-the-shelf.

Where do we get 83 watt-hours and 480 watts of electricity?

Option 1: Lithium AA batteries

One Energizer Ultimate Lithium AA battery can supply 4.5 watt-hours at 4.5 watts (being generous).
AA battery

We need to supply 12 volts to the immersion heaters. We could use an 8-battery pack like this:
battery pack

We need 4 battery packs running in parallel, for each heater, to get enough watts.

128 batteries total cooks almost 7 meals, weigh about 1856 grams (4 pounds), about 265 grams (9.3 ounces) of "fuel" weight per meal. At $2 per battery, that's about $37 per meal.

Total weight about 2600 grams (5.7 pounds) for batteries, cases, wiring, and immersion heaters.

This particular setup might have other problems. A custom design could be a little lighter and more efficient.

But almost any backpacking stove on the market will be much lighter and much cheaper, even this one:
Stansport stove

Option 2: Alkaline D batteries

Consumers cannot easily buy Lithium D batteries, so we'll try Alkaline D batteries.
D battery

Alkaline D batteries have more energy than Lithium AA batteries, but D's are much less powerful (bigger gas tank, smaller engine).

We need about 640 Alkaline D-cells weighing over 200 pounds to deliver 480 watts. I won't do the rest of the math.


Rechargeable batteries

We can choose from many different rechargeable battery chemistries – Lead Acid, AGM, NiCad, NiMH, several varieties of Lithium, and more. Lithium batteries are clear leaders in power and energy per gram, though rechargeable Lithium batteries store much less power per gram than single-use Lithium batteries. For more than you really wanted to know about batteries, try Battery University at http://batteryuniversity.com/learn/.

We want rechargeable Lithium batteries that yield 480 watts and 83 watt-hours for the lowest weight – assuming we can recharge completely every day.

There are hundreds, if not thousands of different rechargeable lithium batteries available. After about one hour of searching, I settled on this lightweight motorcycle battery:
Shorai battery

Each battery yields 240 watts and 252 watt hours, and weighs 1,370 grams (about 3 pounds). We need two of these batteries to supply enough power, but we can cook about six meals before requiring a recharge.

That's 6 pounds of batteries, and we don't have a way to charge them yet.

With more research, we might find batteries that yield 480 watts and 83 watt-hours.

But the total battery weight is likely to be at least 2 pounds, and we still need a charging system.

I'll stop here.


Super Capacitors

Super capacitors sound sexy, but their energy density is 20x-40x lower than lithium batteries, their voltage drops linearly with discharge, and they have other engineering challenges. Not analyzed.


Conclusion

Surprise! Electric cooking in the wilderness is not very practical. But if you really need to, you can.

I'll stick to Esbit tablets in a Trail Designs stove.
Trail Designs stove with Esbit

-- Rex

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Electric cooking in the wilderness – a rough analysis on 08/13/2013 23:45:56 MDT Print View

I can envision that it might happen someday, but it would need a super efficient solar panel, and that might be too large to be practical for now.

--B.G.--

Rex Sanders
(Rex) - M

Locale: Central California Coast
Re: Re: Electric cooking in the wilderness – a rough analysis on 08/13/2013 23:52:20 MDT Print View

Unless you brought rechargeable batteries (see above), you could use the super efficient solar panel only during the sunniest parts of the day.

Might as well use a solar cooker, probably more efficient. And just as useless on a cloudy day or in a forest or deep canyon.

-- Rex

Rex Sanders
(Rex) - M

Locale: Central California Coast
Portable generator on 08/14/2013 00:06:28 MDT Print View

The lightest portable generator I could find with a few minutes of searching generates 450 watts continuous (about right), but weighs about 11 kilograms (24 pounds) with fuel and oil (not good):
generator

On the other hand, you could cook 20 meals with a full tank, using only 51 grams (1.8 ounces) of fuel per meal!

-- Rex

Edited by Rex on 08/14/2013 00:16:41 MDT.

Richard Reno
(scubahhh) - M

Locale: White Mountains, mostly.
Simple. on 08/14/2013 05:16:38 MDT Print View

Just run a long line of windmills all along the Pacific Crest Trail(it's on the crest, right? it must get a lot of wind!), and then you can just plug in your little immersion heaters whenever you feel the urge for a nice warm cuppa!

For the CDT you might need some of those huge solar mirror thingies instead.

The AT, regrettably, is not all that sunny and in many places under the canopy of the forest for long distances. Little mini one-cup hydros at every stream crossing, or maybe a series of small nuclear power plants. You could disguise the cooling towers with cute little trees like on the cell phone towers, though, and nobody would ever notice.

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Simple. on 08/14/2013 06:20:56 MDT Print View

Hey, ha...plugging in to the local stump has always been a life long ambition.

spelt with a t
(spelt) - F

Locale: SW/C PA
scary on 08/14/2013 07:37:35 MDT Print View

– Some people are afraid of cooking over a flame. Don't laugh, I have friends who grew up with electric stoves and are afraid of cooking with flames.

I discovered this a while ago and it still bemuses me. Not only is fire amazing and lovely, electric stoves are the pits!

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Electric cooking in the wilderness – a rough analysis on 08/14/2013 08:54:04 MDT Print View

Using your numbers, lithium AA has 4.5 Watt-Hrs and weighs 1/2 ounce = 9 Watt-Hr/oz

Energy of combustion for butane = 49.5 MJ/kg = 390 Watt-Hr/oz (if I can calculate correctly : )

Butane has 43 times more energy density than Lithium Battery

That'll never work - you're crazy : )

Michael Ray
(thaddeussmith) - F
Re: Electric cooking in the wilderness – a rough analysis on 08/14/2013 12:21:59 MDT Print View

>>Fire bans, which are becoming more common because of the left-wing global warming conspiracy.

Are you serious? And here i though it was those pesky forest fires raging through much of the south/west, destroying wildlife and property. no no, it's because of the liberal agenda. *roll*

Michael K
(chinookhead) - F - M
Re: Re: Electric cooking in the wilderness – a rough analysis on 08/14/2013 15:59:07 MDT Print View

Michael......you have it all wrong.....the bans are b/c of that pesky anti-Christ Obama and his satanic servants.....duhhhhh :)

Edited by chinookhead on 08/14/2013 15:59:54 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Re: Electric cooking in the wilderness – a rough analysis on 08/14/2013 16:35:13 MDT Print View

When are we going to look back on this with amusement like the McArthey "anti-communist" era?

R K
(oiboyroi)

Locale: South West US
Re: Electric cooking in the wilderness – a rough analysis on 08/15/2013 00:54:58 MDT Print View

How about using the new hydrogen battery technology seen at outdoor retailer?

Edited by oiboyroi on 08/15/2013 00:56:47 MDT.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Electric cooking in the wilderness – a rough analysis on 08/15/2013 01:09:29 MDT Print View

"How about using the new hydrogen battery technology seen at outdoor retailer?"

They must be trying to use a hydrogen atom with the nucleus stripped off.

Geez, I thought we went to the moon in 1969 using fuel cells.

--B.G.--

Rex Sanders
(Rex) - M

Locale: Central California Coast
Re: Re: Electric cooking in the wilderness – a rough analysis on 08/15/2013 10:10:56 MDT Print View

>How about using the new hydrogen battery technology seen at outdoor retailer?

Most portable fuel cells are designed to recharge small electronic devices over USB, supplying 5 to 10 watts.

You need 48 of those fuel cells to boil 2 cups of water in 10 minutes.

You can buy larger portable fuel cells, like this one:

Hydropak fuel cell

but you need 10 of them, and they weigh 3 kilograms (6.6 pounds) each with fuel cartridge.

-- Rex

Rex Sanders
(Rex) - M

Locale: Central California Coast
How Many Batteries Would It Take to Cook a Turkey? on 11/27/2013 21:22:17 MST Print View

I'm not the only one ...

http://www.wired.com/wiredscience/2013/11/how-many-batteries-would-it-take-to-cook-a-turkey/

-- Rex

Spoiler alert:
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
263 D-cells

Hiking Malto
(gg-man) - F
Re: Simple. on 11/28/2013 05:37:37 MST Print View

"Just run a long line of windmills all along the Pacific Crest Trail(it's on the crest, right? it must get a lot of wind!), and then you can just plug in your little immersion heaters whenever you feel the urge for a nice warm cuppa!"

You may be on to something. There were plenty of windmills in SoCal that are becoming more plentiful by the day. There should be a congressional mandate to put a 4 plug 110 outlets at every windmill within half a mile of the PCT. cooking, electric blankets, device recharge, the possibilities are endless.

Doug I.
(idester) - MLife

Locale: MidAtlantic
Re: Re: Simple. on 11/28/2013 06:05:50 MST Print View

"Hey, ha...plugging in to the local stump has always been a life long ambition."

I've seen many a marriage get broken up because of that kind of thinking....

scree ride
(scree)
Lightning pack... on 11/28/2013 06:27:56 MST Print View

1and a microwave.

Edited by scree on 11/28/2013 06:42:13 MST.

Matt Dirksen
(NamelessWay) - MLife

Locale: Mid Atlantic
Re: Electric cooking in the wilderness – a rough analysis on 11/28/2013 20:57:06 MST Print View

I'm still waiting for the day that someone invents a scalable induction stove for the outdoors. That's probably the only technology that might allow for electric stoves to be feasible at a small scale.

Matt

Rex Sanders
(Rex) - M

Locale: Central California Coast
Re: Lightning pack... on 11/28/2013 23:37:00 MST Print View

http://www.scientificamerican.com/article.cfm?id=sciam-50-see-through-tech

One version even generates electricity—more than seven watts, enough to recharge phones.

You need 72 packs wired together to generate 500 watts to boil two cups of water in 10 minutes.

Under ideal conditions, you could provide 2 cups of boiling water to each of those 72 backpackers every 12 hours of hiking.

Maybe we should wait for version 2.

-- Rex