ElI5: Why can’t we use a renewably powered, industrial sized ice machine to replenish and cool the arctic?


ElI5: Why can’t we use a renewably powered, industrial sized ice machine to replenish and cool the arctic?

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I’ll take a swing at this as an ELI5:

Without getting into too much detail, you can’t make or remove energy from the universe. Temperature can kind of be though as a measurement of “energy” of an item. When you cool something down (to make ice) you’re removing energy from the water, but that energy needs to go somewhere.

Think of a refrigerator. It’s cold inside, right, but have you ever felt a warm current of air coming from the back of it? That’s the excess “energy” that is being removed from the inside. The fridge takes the warmth from inside the fridge and punts it to the outside.

So in your scenario assuming we can sustainably power this massive ice machine. We still have the issue that you’re not solving climate change. For every ice cube you make (by reducing the energy of the water), your machine is exhausting the equal amount of energy as hot air out the back (plus extra as the machine probably will produce extra heat itself just by functioning) so you net at best assuming a lot of things 0 temperature change of the earth as a whole, but more likely much worse because we made a lot of assumptions that aren’t practical to begin with (sustainably powered, 100% efficient)

Anything that produces cold will produce an equal or greater amount of heat as a waste byproduct. The heat has to go somewhere.

Our cooling systems are all designed around the concept of moving heat away from somewhere. When you run an air conditioner, the exterior gets hot. When you run a refrigerator, the coil on the back gets warm.

If you just put a window shaker air conditioner in the middle of a room and turned it on, the average temperature of the room would not change. It might push cold air out the front, but it’s pushing an equivalent amount of warm air out the back.

So we can never really cool a large open thing like the arctic. We can only ever cool closed off small boxes, like houses or fridges.

To make water cold enough to freeze you have to take all of the hot out until all that’s left is cold. But if you take all the hot out, you have to put it somewhere. So even if you make one place colder, you’ll just end up making somewhere else warmer

ok, so 2nd law of thermodynamics and can’t destroy/create energy issue aside, let’s do some quick back of the envelope math for this. Google says we’re losing about 1.2 trillion tons of arctic ice per year. That’s 38.6 million kilograms per second. Obviously, that means the ice is above the melting point, but due to salt, that may be closer to -5⁰C or lower. So let’s start there. We’re not looking at cooling the Arctic yet, that would take even colder temperatures and/even more ice. Just to replenish the ice.

Let’s say we’re taking water at 20⁰C about room temp and cooling it by 25 degrees. Water takes about 4.186 kJ per kg per degree to cool. So that’s 4000 gigawatts of power just to cool that much water (assuming 100% efficiency). But we’re still not done, the energy of fusion is also required. That’s another 333 kJ/kg.

That’s a grand total of 16,800 gigawatts or just over 5 Chernobyl reactors dedicated entirely just to replenishing the lost ice of the Arctic. And all assuming no losses. Not to mention, this isn’t a profitable venture, so who’s paying for the engineers to design, construction workers to make, and scientists/engineers/staff to run them?