“Please, Allow Me to Dunk Your Food Underwater…”
~ delicious, energy-efficient cooking by diving to pressurize air ~
TL;DR — Submerge an air-bubble 60m (200ft) deep to HEAT it, and cook food fast. Better yet, the water boiling within that underwater grub is actually *browning* through the thick of it! Called the “Maillard Reaction” after its discoverer, that browning makes food tasty — and you normally can’t get the reaction to BEGIN until the water is driven-off by the skillet or oven. (THAT is what makes good cooking take SO LONG!) With a 200ft deep well of water to cook things, the kitchen can simply dunk & hoist, for reliable, instant pot roast and soft yams, lightly browned. Sound like a place you’d visit?
The Science of Tasty
“Bake until golden brown.”
“Sear in pan until browned on both sides.”
“Continue to de-glaze until it takes on a deep, reddish hue.”
“Slice the sprouts and lay them down in the pan this way — you’ll need those centers to get soft and brown to taste sweet… instead of like ear-wax!”
It’s always the same. You want delicious? Brown your food! Heck, toast those grains, to make malty beer! It’s everywhere — the “Maillard Reaction.” Every cracker company is diligently cracking their crisps, surveying the surface with a palette of beige, seeking that warm honeyed brown which defeats snack-legions! How do we get it? To do so, first: we have to DRY the surface of the food.
Why? Because water in the food will keep the surface from rising above 100c (210 Fahrenheit, for those with the King’s Measures) — boiling! So, that slab of eggplant will refuse to brown, until you’ve hammered it with enough heat to push the water away from the surface. And then? ONLY the surface can brown. The insides remain untouched by the Maillard seasoning. Dastardly!
Yet, we have a sort of magic trick. One you would never show your friends — it would require scuba gear, or a pressure vessel that might explode as you heat it. We need to raise the pressure of the air around our food to seven atmospheres. As air is compressed, it *increases* water’s boiling-point. So, at seven atmospheres, water boils at 165c, instead of 100c here at sea-level! That temperature, 165c, is when the Maillard magic happens. [Well, technically, some foods brown at lower temperatures, such as fruit, which becomes candy…but 165c is the tippy-top temp!]
With seven atmos to heat as they compress, we can cook in a flash. And, that Maillard Reaction can occur wherever water is boiling — even deep within the thick of the foods. A golden brown, forming all the way down! That meal is unique — and unique on its own is usually enough to inspire a few visitors. Uniquely delicious? I’ll book our flight…
Now, trying to get seven atmospheres of pressure around a catering-rack and cooking it… that’s asking for explosions. And, it would require immense energies, especially to run the compressor! How do you have a kitchen serve such succulent dishes? There is a better way…
Adiabatic Heat-Transfer
“Adiabatic” means that the air around your food is NOT given a chance to cool-off into its surroundings. We’ll need a thick layer of insulation for this oven. That’ll keep our process “adiabatic”. And, we can think of the cooking-vessel like a piston… When a piston pumps a chamber of air, that air’s temperature rises; when the piston is released, the air expands and cools BACK to the original point. So long as no heat was lost to the walls, then 100% of the energy is recovered! This back-and-forth is called an “adiabatic process”. That 100% efficiency (minus heat-loss) lets us recover and re-use the heat from ONE oven, feeding it into the NEXT oven. Let’s see how:
A bubble of air under a bowl is squeezed as you push it lower in the water; you are working on it, and the squeeze is heating the air inside. That bowl, a decent insulator, isn’t absorbing much of the air’s heat; when you release the bowl, the air “springs-back” and is cooled back to its original temperature. So, when you want the bowl-bubble to heat, you do WORK pushing it down; yet when you want the bowl-bubble to rise, you let-go and it DOES work to get back to the surface! Might we combine the two stages, to cancel the effort out? No work?
Yes! We form a loop of cable between a pair of gears (one at water-level, the other at the very bottom) and hook each bowl-bubble onto the conveyor-cable in turn. When the conveyor is fully-loaded with bubbles in a row, then the effort required to pull one bubble lower is being “paid for” by the upward force of the ascending bubbles! The bubbles headed deeper are teeter-tottered in balance with those rising to the surface. (Though, the conveyor will experience some friction, and there’s also that pesky heat-loss I’d mentioned. We get to that in a lower section…)
With good insulation and machining, on a large bowl & pipe shape (for minimal surface-area, to reduce heat-loss & structural costs) then we might expect 90% of the oven-heat to be regenerated adiabatically into the ovens that follow them — cooking food for 1/10th the energy budget! That would be enough efficiency to allow solar reflectors to pre-heat rocks. By placing a few of those heated rocks with your food inside the bowl-bubble, you add enough heat to compensate for insulation’s loss, as well as ensuring that your food’s surface is still hot after the de-compression. (De-compressing a bubble which was allowed to cool will cause the air to flash-freeze — sorbet and gelato come to mind!)
Numbers?
A pulley-system, tugging clay & insulation jugs underwater 60 meters, with a few rocks aboard, should cook food significantly faster than normal. A normal kitchen pressure cooker only increases the pressure to 2 atmospheres, not SEVEN! That high through-put, and large batches, mean that only a few workers are needed to process an immense amount of food from a single well of water 60m deep. If the bubble-chambers are 4m diameter and 5m height interior volume, then they can cook about 8kg of food each, in less than 15 minutes. A cable-conveyor hauling each bubble in a 15 minute-loop, each bubble 8m apart from the last, tugs 15 bubble-loads to the surface every 15 minutes. One bubble per minute, with 8kg of food on top!
If your dinner was a full 1kg of food (Maillard really is that scrumptious…), then this diving-kitchen is serving 8 plates a minute… or 1,440 dinners over the course of 3 hours. If you can take $1 per plate to pay for the excavation and construction of the diving-kitchen, that’s $4,300/day, or $6.5 MILLION over 5 years. Does this sound like a tourist destination, yet?
And you’d only need a well-shaft that’s 5m by 10m for the bubbles and conveyor assembly, 60m deep — that’s going to be at least 3,000 cubic meters to cut and haul, which is drudgery… but it’s well-known and do-able drudgery! To excavate 3,000 m3 with a budget of $6 Million, you’d have to be spending a whole $2,000 per cubic meter —about ten times more than standard prices. I’m sure you can do it for less. Building a resort around that submersible kitchen, with room for 1,400 eco-foodie-visitors and staff? Priceless.
