Underground vertical farms repurpose disused tunnels, mines and basements into stacked, sunless growing space. Because there is no daylight, every photon plants receive comes from LEDs — which makes lighting the single biggest line item in both the energy bill and the capital budget. This scene shows a cutaway tunnel with racks of LED-lit crop trays and a closed-loop nutrient water system, the two systems whose sizing decides whether a facility pays for itself.
In a windowless facility, LED electricity can account for 60–80% of total operating cost, so a few tens of µmol/m²/s of "wasted" light — intensity above what the crop can actually use — is often the difference between a farm that pays back its capital in a few years and one that never does.
A tunnel-style underground vertical farm cutaway with stacked LED-lit crop racks and a closed-loop nutrient water system, driven by real lighting-energy and payback-economics formulas.
LED wattage scales with target PPFD and rack tier count, driving daily kWh and cost; photoperiod compresses a full day into a short visual cycle so you can watch racks switch on and off; water recirculation toggles between closed-loop and single-pass water use.
Adjust PPFD, photoperiod, tier count and electricity price to see the LED load, daily energy cost and estimated payback period update live. Toggle the closed-loop water system to compare recirculated vs. single-pass water reuse.
Because there is no sunlight underground, every micromole of light a plant receives is metered electricity — which is why lighting efficacy (µmol per joule) matters as much to a vertical farm's balance sheet as crop yield itself.