1. INTRODUCTION
MYUNG-MIN OH

2. Background
Unusual weather, water shortages, insufficient available land threat crop production
World’ population: 7 billion (2011)9.3 billion (2050)
Limited cultivation area and fresh water (sufficient but unevenly distributed)
A new form of agricultural cultivation is required
to feed the world, protect the environment, improve health, and achieve economic growth

3. Plant factory with artificial lighting
PFAL : a plant production facility with a thermally insulated and nearly airtight warehouse-like structure
Components: multiple culture shelves, electric lamps, air conditioners, air circulation fans, CO2/nutrient solution supply units, an environment control unit
Electric lamps
Fluorescent lamps : have been mainly used
Light emitting diodes (LEDs) : attracting great attention due to compact size, low lamp surface temperature, high light use efficiency, and broad light spectra
PFALs are not replacement for conventional greenhouses or open field
PFALs has creased new markets and business opportunities
Leafy greens, herbs, transplants : main crops in Japan, Korea, Taiwan, China
Indoor vertical farms : another term used in USA and Canada

4. Disadvantages of open field and greenhouse production
Open field production
Yield and quality are subject to weather condition  unstable and unreliable supply of plant-derived food
Greenhouse production
Not energy efficient due to unregulated incident light
(e.g. Too low at dawn, sunset, night, on cloudy and rainy days; too high around noon on sunny days)
Difficult to optimize the environment (solar light affect temperature and relative humidity)
Ventilation for lowering air temp. allows insect and diseases inside
Hard to keep high CO2 due to ventilation
Light quality and direction are not controllable
Excessive agrochemicals and fossil fuels are used

5. Potential advantages of PFAL
Can be built anywhere because neither solar light nor soil is needed
The growing environment is not affected by the outside climate and soil fertility
Production can be year-round and productivity is over 100 times that of field production
Produce quality such as concentrations of phytonutrients can be enhanced through manipulation of the growing environment, especially light quality
Produce is pesticide-free and need not be washed before eating
Produce has a longer shelf life because the bacterial load is generally less than 300 CFU/g (1/100 to 1/1000 that of field-grown produce)
Energy for transportation can be reduced by building PFALs near urban areas
High resource use efficiency (water, CO2, fertilizer etc.) can be achieved with minimum emission of pollutants to the outside environment

6. Challenges with PFALS
Challenges: High initial and production costs (cost of building = cost of PFAL)
Solutions
- better design : reduces initial investment
Operation and management experience : decreases production cost
Designing efficient lighting system : reduces electricity cost (lighting accounts for 70-80% of the electricity cost)
Other approaches: increasing the number of vertical tiers, shortening the culture period, designing the production schedule without time loss, increasing planting density, reducing produce loss