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Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Oil instead of lid? on 02/01/2009 17:15:05 MST Print View

There was a link posted on BPL sometime ago that showed using oil in your water was more fuel efficient than using a lid. I can't find it now, but thought it was a goof FYI for those who routinely use oil in their cooking. If you add it to the water at the start, you can leave the lid at home.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Oil instead of lid? on 02/01/2009 17:52:26 MST Print View

I think this is what you are looking for

Heat Losses in a Cook Pot at Constant Temperature Alan Berick, Aprovecho June 10, 2006

http://www.aprovecho.org/web-content/publications/pub2.htm

Tony

Scott S
(sschloss1) - F

Locale: New England
Wow on 02/01/2009 18:09:23 MST Print View

I would never have guessed that a little oil would make so much difference. How much oil would you need to create a film in a typical backpacking pot?

Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Re: Re: Oil instead of lid? on 02/01/2009 18:10:09 MST Print View

Yeah, that's it, thanks Tony

"Runs were also made to ascertain the results
in evaporation losses when 1) a thin layer
of olive oil was floated on the top surface of
the water and 2) a lid was placed on the pot.
..... The olive oil film was
100% effective in inhibiting the losses due to
evaporation while the pot lid was 92% effective.
The latter result was valid as long as the
lid was undisturbed during the entire run. If it
were lifted to examine the pot contents or to
stir the food, the loss due to evaporation would
be greater.
The effectiveness of the oil film in inhibiting
evaporative losses exceeded expectations. Apparently
the oil film forms a potential barrier
which the water molecules cannot penetrate.
Any cooking oil or viscous liquid would probably
have the same result.

For a 25 cm diameter pot:

*At typical cooking temperatures, evaporation accounts for the major portion of the total heat losses.

*At a temperature of 98° C evaporation accounts for approximately 78% of the heat loss for the blackened
pot and 85% of the loss from the shiny pot.

*A thin layer of cooking oil will entirely eliminate liquid evaporation.

*This not only saves approximately 80% of the fuel used and reduces air pollution by the same amount, but
will also save water.

*At a cooking temperature of 98° C with 5 liters of water approximately 22.5% of the
water is lost each hour.

*Using a lid while cooking will achieve roughly 90% of the above savings as long as the lid is not removed
during the cook time.

*The heat loss from radiation accounts for 16 % of the total loss for the blackened pot and 8% of the total
loss for the shiny pot.

*Convection losses only account for 6% of the total for both pots.

Jeff Antig
(Antig)

Locale: Pacific Northwest
wow on 02/01/2009 18:38:43 MST Print View

Wow, thanks for the info! I am totally ditching my lids

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: wow on 02/01/2009 20:03:11 MST Print View

Hi Jeff,

Think about poring off hot oil on top of boiling water, seems very dangerous to me, for the small amount of water we boil and the small fuel saving gain it would give, in my opinion it would not be worth the trouble.

It has been suggested that a silicone floating lid might be as good, I have yet to test this idea.

Tony

Piper S.
(sbhikes) - F

Locale: Santa Barbara (Name: Diane)
Re: Wow on 02/01/2009 20:35:33 MST Print View

Pouring off oil a hazard? You would eat it, wouldn't you? I mean, it's not much different than when you put some oil in your spaghetti water at home, right?

Kathleen Whalen-Burns
(rosierabbit) - M

Locale: Pacific Northwest
Authentic laboratory experiment in controlled environment for oil-type lid on 02/01/2009 20:54:11 MST Print View

I just poured 2 C of water into my 3C AGG pot and then started added oil to see how much it would take to get a full cover of oil. First attempt - 4 TB (2 oz.). Second attempt, and poking at the oil to try to make it spread out more - 3 TB (1.5 oz). I couldn't get it any thinner than that.

I brought the water to a boil and then tried to pour it off with either the oil or water coming first. No luck. There was no way to separate the oil from the water as I poured.

So if you are packing oil anyway, and want everything to have oil in it, it might work to skip the lid. However, if you don't always want oil in your water, for hot drinks, for example, you'll need a lid. Otherwise, you'd need about 1.5 oz of oil for every time you boil water. I'm keeping my foil lid.

But it was cool to watch the water covered in oil come to a boil without any steam rising at all until just as it boiled.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Authentic laboratory experiment in controlled environment for oil-type lid on 02/01/2009 21:02:35 MST Print View

Hi Kathleen,

thanks for your excellent test report, reaffirms my views.

Tony

Nia Schmald
(nschmald) - MLife
Re: Authentic laboratory experiment in controlled environment for oil-type lid on 02/01/2009 21:22:03 MST Print View

Thanks for trying this Kathleen. For me though, even though I always cook with oil, an extra 3 TB of oil seems a bit much to me.

I like the silicone floating idea though. I was testing my new 1 oz wood stove (shameless plug) and the Al foil lid started to burn on the edges not to mention the soot that collects. This solves both problems nicely.

Has anyone ever used an oven liner like this one? It looks fairly thin. Any one have a light weight, cheap source of silicone sheet?

Edited by nschmald on 02/01/2009 21:24:22 MST.

Sarah Kirkconnell
(sarbar) - F

Locale: In the shadow of Mt. Rainier
Re: Oil instead of lid? on 02/01/2009 21:23:05 MST Print View

While the oil/water would work great if you are cooking one pot style, remember if all you are doing is boiling water you will have a pot with oil traces in it ;-)

Personally....I like a lid for safety (and to bring a pot of water and food back to a boil after dumping in the dry food.)

Craig W.
(xnomanx) - F - M
Re: Re: Authentic laboratory experiment in controlled environment for oil-type lid on 02/01/2009 21:31:57 MST Print View

Kathleen makes a good point.
My first thought: Doesn't the weight of carrying oil and a container for it (something I never bring anyway) completely offset any minute gain in efficiency or the weight of a foil lid?

I think shaving your head might bring the same gains in overall perceptible efficiency on the trail.

I'd rather have the convenience of oil-free meals, less mess to clean, and a "normal" lid.

Kathleen Whalen-Burns
(rosierabbit) - M

Locale: Pacific Northwest
Lid instead of oil on 02/01/2009 21:44:50 MST Print View

Yeah, it's an interesting idea, but not very practical for backpacking.

Brett Tucker
(blister-free) - F

Locale: Puertecito ruins
Re: Authentic laboratory experiment in controlled environment for oil-type lid on 02/01/2009 22:02:38 MST Print View

The olive oil trick would make sense if you were packing oil already and intended not to waste it, meaning no pouring off of the water after cooking, but boiling all of it away or into the food. In that case, going lidless would remain entirely optional, unless camp happened to be wind-lashed.

Pamela Wyant
(RiverRunner) - F - M
Oil instead of lid on 02/09/2009 20:22:59 MST Print View

This might work well for thru hikers who have to worry about weight loss on a long trip. The extra calories from the oil would be a slight help. I've read many of them start carrying extra oil or butter to increase caloric intake. I think I read about some guy who ended up mixing bacon grease into peanut butter to try to offset weight loss.

Denis Hazlewood
(redleader) - MLife

Locale: Luxury-Light Luke on the Llano Azul
Re: Oil instead of lid on 02/11/2009 00:20:06 MST Print View

One might use a thin piece of silicone, or Teflon. Lots lighter than the oil. I float one on top of the water and use a lid too. It seems to hasten the boil a little, and weighs almost nothing.

Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Re: Re: Oil instead of lid on 02/11/2009 16:48:23 MST Print View

It would work best for people like me who cook in the pot and use oil anyway. It woud be best with a tall narrow pot so less oil is needed. Since we always carry a second smaller pot (with lid) for cuppas, we wouldn't have a problem there either. Oh well, back to the drawing board. I don't really think it is a practical alternative for most people.