A Supplemental Lighting Control Approach in Controlled Environment Agriculture to Reduce Peak Power Consumption

Abstract

Global population growth requires efficient food production, especially with food security concerns due to natural resources limitation and climate constraints. Supplemental lighting is an effective means of increasing productivity in greenhouses. However, supplemental lighting electricity cost can be high, and systematic lighting strategies are required to reduce lighting electricity cost. Prior research has focused on minimizing electricity use or cost, while maintaining adequate crop growth. However, in addition to being charged for electricity consumption, US greenhouse growers also pay a demand charge that is based on the peak electricity use during a 15-min period within each billing cycle. This demand charge is in the same order of magnitude as the charge for the used electricity, but has been ignored in prior lighting optimization research. This paper presents a lighting strategy for controlled environments (like greenhouses) equipped with dimmable light-emitting diodes (LEDs) to minimize supplemental lighting electricity cost and peak power consumption of supplemental lighting. Markov-based sunlight prediction is employed to develop a realistic control strategy and improve its efficiency. Moreover, the impact of shifting the time of day during which supplemental lighting is used on peak power consumption is investigated. Compared to a heuristic method, the proposed method illustrates an up to 51% mean peak reduction.