How is the Oxygen Not Included self-powered oxygen (spom) worked out?

Oxygen Not Included

Self-Powered Oxygen (SPOM)

In Oxygen Not Included, the self-powered oxygen module (SPOM) is the go-to mid-game oxygen build — but it only breaks even on power when its parts are in proportion.

SPOM Oxygen Calc

Water (g/s)

Duplicant Trait

888 g/s

O₂ Output

112 g/s

H₂ Output

Dupes Supported

1.0 Electrolyzers needed

896 W

Gross Power

How the numbers are worked out

The build balances electrolyzers against the hydrogen generator feeding them power, plus the pumps shifting gas about. The calculator gives you the part counts that let the loop run itself instead of eating power.

The formula

electrolyzers = water ÷ 1000
oxygen = water × 0.888 · hydrogen = water × 0.112
dupes supported = floor(oxygen ÷ consumption per dupe)
power = (hydrogen ÷ 100) × 800

Common mistakes

An electrolyzer shuts off once the pressure around it climbs too high, so a module that is right on paper can grind to a halt because its output gas is not being moved away quickly enough. Pump capacity is what keeps the numbers holding up in practice.

A worked example

One electrolyzer splits 1,000 grams of water a second into 888 grams of oxygen and 112 grams of hydrogen. At 100 grams a second each, that oxygen covers 8 ordinary duplicants; mouth breathers need 150, so only 5 of them. Burning the hydrogen in hydrogen generators, at 800 W per 100 grams a second, gives 896 W.

Why the power is not free

Those 896 W have to run the system itself first. The electrolyzer uses 120 W, and the two gas pumps a typical oxygen module uses to separate oxygen from hydrogen draw 240 W each. That is 600 W, which leaves roughly 300 W spare from a single electrolyzer. It is a useful surplus, but small, and anything else on the circuit such as a gas filter or a shutoff reduces it further, so plan the layout before counting on it.

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