Design of a plant factory suitable for Okinawa

Abstract

A "Plant factory" is one of the advanced facilities for vegetable cultivation in an artificially controlled environment, i.e., temperature, humidity, and CO₂ concentration are controlled. Recently, it has become popular in Japan, USA, China and others. However, there are some problems to overcome before they become widespread. A project to develop a specific plant factory called the "Okinawa-type plant factory" has been funded by the Okinawa Prefecture. It addresses the severe environmental and social conditions of Okinawa. The main goal of the project was to reduce energy consumption by 30%. To achieve this, three methods were investigated using solar energy and LED lamps, since this plant factory used artificial illumination. Forty foot reefer containers were employed for the cultivation room, and insulation panels were partially used. Solar energy was used for lighting and air-conditioning. Solar energy was converted to thermal energy for air-conditioning using heat collecting panels. Hot water of 75-85 ^oC obtained by the collector was used for adsorption refrigeration. Sunlight was introduced in the cultivation room from the skylight windows. DC to DC system was also employed for photovoltaic utilization. The use of solar energy and LED lamps are effective to reduce energy consumption. A 30% reduction in energy use was achieved.