hardy oriole
While the Zapfish are the most obvious source of electric power in the Mollusc Era, they are far from the only one.
This is a brief rundown of known or implied sources of electricity used by the inhabitants of the world of Splatoon, based on official sources, background elements, and artbook excerpts.
(Now complete. Feel free to comment.)
The source of power most front-and-center, bioelectricity seems to be the primary source for the world's energy supply. There are two main sources for this type of power: Zapfish and Salmonid Eggs.
A type of electric catfish, presumably evolved from the various Common Era species of electric catfish that were exclusively native to Africa.
They serve as the level goals for Octo Valley, Octo Canyon, and The Crater.
It seems that electricity is conducted through their glowing-yellow whiskers; the Octarian "light bulb" containers used as goal points have clamps on each of the Zapfish's whiskers.
Mini Zapfish are juveniles, and seemingly have not yet grown their main whiskers—instead, the Octarians siphon it from the single "whisker" on the top of their head.
According to Marie Agent 2 of the New Squidbeak Splatoon, a Mini Zapfish's power output is about one-eighth that of an adult Zapfish.
hardy oriole
On rare occasions with unknown cause, Mini Zapfish will mature into a Great Zapfish instead of a regular adult. These titans are an order of magnitude larger than regular Zapfish, and seem to have the electricity output to match. They are also somehow capable of flight.
Two individuals are known, each providing a large amount of power to an entire city. It is implied that they support a large percentage of the power infrastructure, both by a sticky note drawn by New Agent 3 and how (relatively) seriously their squidnapping is treated.
Inkopolis' Great Zapfish is over 100 years old, having been born shortly after the end of the Great Turf War. The age of Splatsville's Great Zapfish is unknown. After the events of Return of The Mammalians, Splatsville's Great Zapfish has a single hair on its head, but is otherwise unharmed.
Inkopolis' Great Zapfish was used twice to power DJ Octavio's Octobot King mech and was rescued by Agents 3 and 4 on each occasion. Splatsville's Great Zapfish was used in addition to Golden Eggs in order to power the Spirit Lifter rocket in Alterna, and likely flew back home after the rocket's Steerage section (where it was contained) was decoupled during launch.
Great Zapfish, once rescued, are often seen coiled around the building that contains the multiplayer lobby. Perhaps these buildings are somehow capable of harmlessly siphoning power from the Great Zapfish?
Small, orange Salmonid eggs. They can somehow be refined into electrical power.
According to Page 203 of The Art of Splatoon 2, they are "the world's energy source".
The Octarians have a commercial agreement with the Salmonids, and trade technology for Power Eggs. This is why Power Eggs are found in abundance in Octo Valley and Octo Canyon. However many eggs the Octarians are getting, though, it clearly isn't enough to alleviate their energy crisis.
A special, extra-large kind of Salmonid egg. Described as a "potent energy source".
They are considered sacred/precious to the Salmonids, and thus are not traded to the Octarians. All known Golden Eggs are stolen from the Salmonids by Grizzco workers during Salmon Runs.
While many were privately hoarded by Mr. Grizz for the creation of Fuzzy Ooze and to power the Spirit Lifter, it is stated on Splatoon Base that at least some of the Golden Eggs collected by Grizzco do contribute to the Inkling world's energy supply.
While solar power is rarely mentioned, roof-mounted solar panels make occasional appearances in the background of certain stages in Inkadia, such as Arowana Mall, Inkblot Art Academy, and The Reef.
There are no locations in the Splatlands known to feature solar panels, not even Crableg Capital. This may be to emphasize the region's older age/architecture and implied relative poverty (see: Deep Cut's motives). Or maybe Nintendo will prove me wrong when Chill Season 2023 comes out, I don't know.
Wind turbines can be seen in the distance from Spawning Grounds and Marooner's Bay. It is unknown whether they are still operational.
However, there are functional wind turbines seen in the background of Kelp Dome (Thanks @finite glacier) and Port Mackerel, confirming the use of wind power in the modern day. (Not pictured, as new images cannot be added in an edit. Sorry!)
The Art of Splatoon 3 reveals that the "Gone Fission" Hydroplant, back when it was in operation, was meant to produce electricity from the tides and ocean currents in/around the coast of the Splatlands. However, it was abandoned for unknown reasons, and was later taken over by the Salmonids who apparently use it to purify/refine their eggs.
The Salmon-Jammer Dam, seen in the background of the Spawning Grounds, has a notable water flow coming out of it. It is possible, though not confirmed, that the dam generates hydroelectric power in addition to creating a border between Inkopolis and the Salmonid Swim Zone in Inkopolis Bay.
Saltspray Rig, fairly obviously, is an offshore oil rig. As of 2015, it seems to still be active. It seems to be operated by an unknown company whose logo appears on billboards, trucks, and blimps. One of this company's logo variations also bears loose resemblance to the logo of the real-life oil brand Esso.
This company also has unclear ties to the Octarian Army, as their logo can be seen on various Octarian aircraft, the thrusters for the Octobot King Mk. II, and the pelvis of the Octobot King L3.Gs.
The coal mine at Bluefin Depot, prior to its closure around the 1960s ME, was said to have flourished.
However, it is not known if coal is mined elsewhere or still used in the modern day.
(Heck, for all we know, the coal even back then could have been used only for things like steel and cement production.)
And that's everything, as far as I know.
@ornate scaffold I blame you for giving me the brainworms.
tropic anchor
Nice thread.
I honestly can’t also help but wonder if there’s any geothermal energy used in places like Brinewater Springs.
hardy oriole
I really don't think it would be very popular to build a geothermal plant right next to an onsen.
tropic anchor
Hm, fair
hardy oriole
In a fairly rural mountain village, no less.
tropic anchor
i once had to write a paper on the viability of geothermal energy in high school so it’s always stuck in my brain now
hardy oriole
If there's anyplace that runs off geothermal, it'd probably be Alterna or the Deepsea Metro.
I. I refuse to believe all of Alterna could be powered solely by half a dozen of those stupid windmills off the coast of Eco-Forest Treehills. No.
ornate scaffold
I love that NILS is solar powered because it just is Tartar doing its programming and learning from humanity’s mistakes with making it eco friendly! (It is ironic for the species annihilator 5000 to be eco friendly)
final flax
For some reason I thought at least one Salmonid map was a nuclear power plant
Do we have any indication that nuclear energy is present?
tropic anchor
To my knowledge, the only nuclear thing in lore whatsoever was the nukes that started this whole mess in the first place
finite glacier