So where does the heat go? Judging from the FAQ my assumption is it's transferring it into the surrounding water? How many of these before it starts becoming a local ecological problem?
There is dramatically more heat capacity in the ocean than in the atmosphere. Many power plants reject heat directly to the ocean, and clearly they do produce a local hotspot, which is much argued over by ecologists.
There can be some valid local ecological concerns. If it emits into a spot which is particular important to some species it can become a problem. It can also create ecological activities, where some species congregate around the outlet because they want the hotter water. This isn't necessary good, but again, it's a local occurrence.
Globally, using ocean water for cooling is almost always ecologically better, simply because it's more efficient than alternatives that are either constrained in terms of the usable volume flow of water, or must use a less efficient medium for heat transfer. Eventually, all heat we produce will be radiated into space, but if an activity indirectly produces greenhouse gases, then it warms by a very large multiplier compared to its direct heat production.
You seem to have a good understanding of this subject. Could you explain to someone who is much less well-versed, why it matters if some species has an important area that it can't go to anymore and, say, stops producing in that area? (Goes somewhere else.) I mean is it some great tragedy not to have some species in some particular place?
I want to kind of add a disclaimer to my question. At the limits of course I am not questioning ecological conservation - the Earth would both suck if it only had humans and our crops and livestock in it, and be thrown completely out of equilibrium so that it would suck for humans too. But I assume that the effect you're talking about is where over time some tiny little place becomes bad for some species, so they stop going to just that one place. Likewise you mentioned the opposite effect where "It can also create ecological activities, where some species congregate around the outlet because they want the hotter water" but this doesn't seem like some objectively great thing - wow, we have all these fish hanging around what amounts to a thermal spa for them, fantastic - but more like just a neutral fact.
This is my impression, that it is what it is, so I'd just like an explanation of the strong moral component or why this is important - since you seem to understand this. (Again, I can do part of the reasoning myself since obviously I wouldn't choose a barren lifeless planet with only humans and stuff we eat, on it, I'm just having trouble extending this reasoning to tiny local perturbations.)
Not an expert by any means, but do dive some. I think one concern is that not all life can easily move or be recreated. Coral reefs probably being the biggest one there. They have huge biodiversity and are incredibly important in the health of the oceans but are also incredibly fragile and sensitive. It isn't hard to imagine a few degrees difference in water temperature affecting these and they don't just "pop up" again somewhere else, they are often thousands of years old.
Most of the ocean is pretty uninteresting though, so I would hope this project is looking at installing these datacenters in deeper waters (where as you said the life can more easily migrate) rather than the shallower waters that reefs inhabit.
I have no experience with data centers, but a little bit of experience with ecological impacts of pass-through nuclear cooling, i.e., water is pumped in from a body of water as cooling for a nuclear power plant, then pumped back to the body of water.
My guess would be that the heat diffusion system for the data center could be designed in such a way that you could have a very large installation without a large ecological impact, as long as a modular footprint like the one pictured is used (think of reef systems that spring up around shipwrecks). However, this will very much depend on the ocean currents at installation to quickly transport heat out of the area.
Most species can handle a couple degrees (Celsius) variation in water temperature, and given the pure huge heat sink that is available by being completely surrounded in water. Species that prefer slightly warmer temperatures would probably establish a new foothold in the areas around the datacenters.
As for the "why it is important" bit. My conservation stance comes down to the precautionary principle. We still know so little about the ecosystem of the ocean that has been working pretty well for millions of years. We should endeavor to change as little as possible because we don't want to disrupt the complex feedback system that exists. Despite all the environmental impact studies that would be performed, we don't know what the possible cascading effects could be, if any.
It makes more sense to heat things that need heat. For example we have a few public pools heated by datacenters [1]. Alternatively you can also heat homes like they do with the heat generated from burning trash. [2]
