Shining light on vertical farming

In vertical farming crops are grown indoors in stacked layers under electric light. This allows for production of fresh food near or even in cities with a high land, water and nutrient use efficiency. However, electricity use for lighting and climate control is high, making it costly and energy intensive.

This PhD study first reviews vertical farming technologies and their environmental and economic potential. Then a meta-analysis on lettuce experiments is conducted which shows that adding 1% more light increases biomass by about 1% at low light levels, gradually decreasing to 0.6% at high light levels. Experiments conducted with young tomato plants show that, at the same total amount of light, both frequency of alternating between light and dark periods as well as the order of light colors during the day affect growth. An economic analysis further shows that smart lighting strategies aligned with variable electricity prices could reduce lighting costs by 10–23%.