Cooking Efficiency: Leave the lid at home, bring oil

[Mitch Chesney]

We bring lids because we know heat is lost in evaporation. But the following research article seems to explain using a thin layer of oil on the water is more efficient than a lid!

(pdf) http://www.aprovecho.org/lab/rad/rl/perf-stud/doc/61/raw%E2%80%8E

What do you all think?

[Greg Mihalik]

This article is about losses associated with boiling.

If you are simmering for any length of time, it would make a difference.

It is not applicable to bringing your water up TO boiling, which is all I do for "freezer bag" meals.

[Justin Baker]

Why not both?

[Stephen Barber]

Interesting.

The question is, would the energy saved in grams of fuel between the lid- and oil-topped boils be greater or less that the weight of the oil expended vs. the weight of the lid?

One boil, likely yes. But the longer you're out, the more oil you'd need to take….

[Greg Mihalik]

"Why not both?"

When water boils the escaping molecules take energy with them. Oil prevents their escape.

When the water is not boiling, it is only conduction losses to the air, which is small, per the article.

[Ben C]

Very cool. And oil is good to have for extra calories anyway, so it's no net extra weight at all.
It seems pretty clear that the evaporative losses will be significantly less on the lower temperature range of of reaching a boil, so on a normal backpacker boil the effect will not be as large. But, assuming that containment of evaporative losses is the main purpose of a lid, this may be as effective as a lid, unless the lid does a lot regarding convection losses.
Worth some experiments on a boil from cold water.

[Charley White]

Brilliant. I love it. I was thinking how the only drawback–enhanced quantity of woodsies in the water when boiling over a wood fire–was an actual boasting challenge & gnar opportunity, but then the other hit (pretty much always & only think winter camping.) I keep by boil pot pure. Water only in it, all foodstuffs confined to the "cooking" soak-bowl. I certainly wouldn't mind the flavor of oil in my drinking water–wood smoke and funky snowmelt don't bother. But getting the oil sheen in the water bottle would be a drag. Would lose the chance to experience a pure freshet.

Didn't study…will later…pdf, but other items pop out. Notable, black vs shiny pot. Shiny less radiation loss. Working hypothesis for my science review will be: facility of loss = facility of gain. Here, heat was electric and ~ all via bottom conduction, so benefit of radiation absorption via flames licking up sides of black pot doesn't arise. Still there's a principle bearing minding: easy come easy go. Didn't see mentioned, but suspect a culprit with a lid is the steam covecting between surface & lid. No steam convection with oil.

Thanks!

[Mitch Chesney]

Right, we need to ignore the sooty vs shiny pot measurements because the researcher is heating via conduction and we would be, in the field, by radiation so the worst thing the soot would do is absorb a small amount of heat which would then xfer into the pot. The electric range, however, is only efficient if all of the coil comes in contact with the pot directly.

A study was done using flames on the first version of the FourDog pot (designed in part by Mors Kochanski) and it was found that anodizing, or blackening, the aluminum yielded a faster boil.

[Bob Gross]

I'm not getting good results with the oil on the water. I used 10W30.

–B.G.–

[Stephen Barber]

"oil is good to have for extra calories anyway, so it's no net extra weight at all."

Maybe, maybe not. If the oil is absorbed into the cooked food, yes. Or if the hiker drinks the hot oily water, yes. If the hot oily waters gets tossed on the dirt, no.

Difference in heating (electric vs. pack stove vs. wood) is certainly a consideration. I've never enjoyed ash particles in my food, so a lid on a pot over a wood-burning stove or fire should definitely have a lid, in my book!

[Greg Mihalik]

"…the researcher is heating via conduction…"

Direct contact is good, but if you hold you hand over that element you will realize that radiation plays a big part is electric heating.

"…we would be [heating], in the field, by radiation …"

I don't think it's that simple.

Hot gases bumping (convection) into a metal pot are heating by conduction as well. A hand held to the side of a burner will get hot, but not nearly as hot as if it where in direct contact with the flame.

[Mary D]

I like olive oil, but definitely not in my tea, thanks!

[Franco Darioli]

That is the problem with leaving the lid at home.
What you may gain by using oil you will lose when just boiling water for tea/coffee or chocolate.
Mind you I have added olive oil to my hot chocolate to boost the final calorie intake for the day…

[Kathleen B]

This idea was discussed in 2009 at http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=18456

I tested the idea and made this comment in that thread:

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.

[Robert Blean]

The oil may have a good effect when cooking in a confined area (e.g. tent) if it reduces steam. I can see it now … best cold weather practices being to use enough oil with a meal to prevent steam, even if you are using a lid….

[James Marco]

It really doesn't matter what the oil is. You can use butter, for cocoa/tea. It's good in either. Parified butter is just the butter fat, without the liquids/salt. But I think I would rather have my coffee black.

[Anonymous]

"Mind you I have added olive oil to my hot chocolate to boost the final calorie intake for the day…"

???

Coconut cream! So very yummy.

[Charley White]

The '09ers like Kathleen probably got this back then, otherwise, like me, you got it overnight. The KEY to the heating superiority of the oil is that it floats; it's edibility is a pure BPL amenity. The floating lid I'm testing is a cutout from a thin silicone cutting sheet. Small irregularities in cutout allow trace bubbling. Only one test so far, but rose without explosion. Let me know how the baking-sheet parchment, and saran wrap work. ;)

EDIT: to add I went & read whole thread you linked, Kathleen B. I see I wasn't the only one to think up silicone disks (which doesn't diminish the pleasure of conceiving a good idea! :). Did hidden problems emerge? Surprised this isn't up there with cotton-bad and windscreens-good.

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