Oxyfern

Oxyfern is a plant that converts Carbon Dioxide into Oxygen when it is domestically grown. It can be planted in a Planter Box, Farm Tile, or Hydroponic Farm, and it grows only in a Carbon Dioxide atmosphere at temperatures between 0 °C and 40 °C. Unlike many crops, it has no growth cycle, so it continuously processes gas as long as its requirements are met.

A domesticated Oxyfern consumes 4 kg of Dirt per cycle and 19 kg of Water per cycle. In exchange, it converts a small amount of Carbon Dioxide into a much larger amount of Oxygen, producing 18,780 g of Oxygen per cycle while consuming 375 g of Carbon Dioxide per cycle. A wild Oxyfern runs at one quarter of the domestic rate, producing 4,680 g of Oxygen per cycle and consuming 93.78 g of Carbon Dioxide per cycle, but it requires neither Water nor Dirt. Because of this 4:1 difference in speed, wild plants are useful as a low-maintenance source of Oxygen, but they are much less productive than farmed ones.

Oxyferns are often compared with Duplicants because their gas conversion closely tracks Duplicant breathing. A domesticated Oxyfern slightly overproduces Oxygen relative to one Duplicant, making it impossible to match them perfectly one-to-one without either Oxygen or Carbon Dioxide gradually building up. The practical ratio is about 3.2 domesticated Oxyferns per Duplicant. Wild Oxyferns follow the same ratio on a larger scale, at about 12.8 wild plants per Duplicant.

Their gas conversion is also very efficient. Domesticated Oxyferns turn about 98% of their Water input into Oxygen by mass, which is better than an Electrolyzer's 88% conversion, though the Oxyfern also requires Dirt. This makes them especially attractive when Water is available but power use and infrastructure need to stay simple.

Oxyferns have a very high pressure tolerance and multiply the mass of their input gas by 50, so they can operate in fairly dense Carbon Dioxide pockets. In open spaces, this means nearby Oxygen production can shut off first if pressure rises too high, since Oxyferns work at higher pressures than standard vents, Oxygen Diffusers, and Electrolyzers. In a sealed room, that same high expansion can eventually overpressure the area if input and output are not managed. A sealed setup can avoid uncontrolled pressure buildup, but it requires pumping Carbon Dioxide in and Oxygen out continuously.

They also have some heat-management value. Because they transform a small amount of gas into a much larger amount at their own body temperature, they can absorb or release heat depending on the temperature of the surrounding gas. A cool Oxyfern fed very hot Carbon Dioxide can delete a noticeable amount of heat while producing cold Oxygen, although its overall effect is modest compared with dedicated heat-deletion plants.

Oxyfern seeds are rare. They can sometimes appear in a Care Package, and there is no normal way to increase their number on the map except through seed splitting exploits.