Algae Photobioreactor Life-Support Simulator

Photobioreactor Controls

LED light intensity I₀ 700 μmol/m²/s

Dilution rate D 0.30 /day

Crew size 3 astronauts

CO₂ sparge rate 100%

Culture State

Biomass density X

0.00 g/L

Growth rate μ

0.00 /day

O₂ output

0.0 L/hr

CO₂ scrubbed

0.0 L/hr

Crew O₂ Balance

Reactor supplies 0.0 L/hr against a crew demand of 0.0 L/hr.

DeficitbalancedSurplus

How it works

Microalgae (e.g. Chlorella vulgaris) in a sealed photobioreactor photosynthesize under LED light, splitting water and fixing CO₂ into biomass while releasing O₂ — a real candidate technology for closed-loop spacecraft/habitat life support (studied by ESA MELiSSA and NASA). Growth is light-limited by a Monod-type response, but light itself is attenuated through the culture by self-shading (Beer–Lambert law), so denser cultures starve their own interior of light:

I(depth) = I₀ · e^(−k·X·depth)     (Beer–Lambert self-shading)
μ(I)     = μ_max · I / (I + K_s)   (Monod light-limited growth)
dX/dt    = (μ_avg − D) · X          (biomass mass balance, D = dilution/harvest)

μ_avg is μ(I) averaged over reactor depth, so a slider that raises I₀ helps less once X is high — the culture shades itself. O₂ production and CO₂ uptake are tied to biomass growth through the photosynthesis stoichiometry (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, roughly 1:1 by volume), scaled by CO₂ availability from the sparge rate.

Light intensity I₀ — LED panel output reaching the reactor wall.
Dilution rate D — continuous harvest/replenishment; too high washes the culture out (μ < D ⇒ decline), too low lets it self-shade into stagnation.
Crew size — sets O₂ demand (≈0.55 L O₂ per astronaut per hour) shown against reactor output in the balance bar.
CO₂ sparge rate — how much CO₂ (from crew respiration + injection) is available to fix; below ~100% it becomes the limiting substrate instead of light.

Algae cells (density-shaded) O₂ bubbles rising LED light panel

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