Redefining Sustainable Agriculture for the 21st Century
In the race to build a more sustainable, resilient, and efficient food system, one technology is standing out above the rest: the Plant Factory with Artificial Lighting (PFAL). These advanced indoor farms offer a controlled environment where crops grow on vertically stacked shelves under optimized artificial lighting, independent of external weather, pests, or seasons. PFALs represent not only a leap forward in food production but also a transformation in how we think about farming in a resource-constrained world.
But what makes PFALs truly revolutionary isn’t just the ability to grow lettuce indoors—it’s their unmatched sustainability. When designed and operated correctly, PFALs can achieve extraordinary levels of resource efficiency, productivity, and reliability—the very benchmarks of sustainable agriculture.

The Three Indices of Sustainable Food Production
To evaluate the sustainability of any fresh food production system, researchers and engineers focus on three key indices:

1. Resource Use Efficiency (RUE):
This refers to the ratio of the amount of a resource (e.g., water, nutrients, energy) that is fixed in the harvested product to the amount originally supplied. A high RUE means minimal waste and maximum efficiency.

2. Cost Performance (CP):
This is the ratio of sales revenue to production costs. A high CP indicates a profitable, economically sustainable system—critical for long-term adoption.

3. Vulnerability (V):

Defined as the yearly deviation of yield and product quality, this index measures how consistently a system can produce high-quality food under changing conditions.
PFALs score exceptionally well on all three, particularly when compared to traditional field or greenhouse farming.

The Essential Components of a PFAL
The success of a PFAL hinges on its ability to create a precise, controlled environment for plant growth. This includes several technical design elements:

• Airtight Construction
PFAL buildings are nearly airtight, with air exchange rates below 0.015 h⁻¹, ensuring contaminants are kept out and energy efficiency is maintained.

• Thermal Insulation
Walls and roofs are highly insulated, with a heat transmission coefficient below 0.15 W/m²/°C, minimizing energy loss.

• Clean Access Systems
To maintain hygiene and avoid contamination, culture and operation rooms include air showers or hot water showers for personnel and equipment.

• Multitier Vertical Cultivation
Plants are grown on shelves equipped with LED lighting and hydroponic beds, maximizing space usage.

• Advanced HVAC Systems
Air conditioning systems serve dual purposes—cooling and dehumidification—while ensuring proper air circulation.

• CO₂ Enrichment
Indoor CO₂ is maintained at around 1000 ppm to boost photosynthesis and accelerate plant growth.

• Hygienic Flooring
Epoxy-coated floors make cleaning easy and help maintain the sterile environment.

• Water Reuse Systems
Condensed water collected from cooling coils is sterilized and reused in the nutrient supply, conserving water.

• Closed Nutrient Loop
Drained nutrient solution is filtered, sterilized, and recirculated, drastically reducing nutrient waste.

Water and Nutrient Efficiency in PFALs
One of the standout sustainability features of PFALs is their remarkable water efficiency. Here’s how:

• 95% of transpired water from plants is captured via condensation on cooling panels.
• This water is sterilized and reused, with net consumption reduced to about 2% of what greenhouses require.
• Nutrient solution is also recirculated, with over 90% nutrient use efficiency.

On top of that, because PFAL-grown produce is pesticide-free and hygienic, it doesn’t require washing. This eliminates the need for water used in conventional post-harvest cleaning—often involving tap water, electrolyzed water, or disinfectants.

Overall, when combining irrigation and post-harvest processes, PFALs can cut water use by up to 99% compared to greenhouse-grown vegetables.

Expanding the Crop Portfolio: New Opportunities
While leafy greens dominate today’s PFALs, trial production is expanding into small-rooted vegetables and medicinal plants such as:

• Turnips
• Mini carrots
• Panax ginseng
• Angelica acutiloba

These crops are compact, mature quickly, and offer added economic and culinary value. Many can’t be grown efficiently in open fields, giving PFALs a niche competitive advantage in specialty markets.

Tuberous vegetables in particular thrive in PFALs under high CO₂ and controlled conditions. With enhanced carbohydrate movement from leaves to roots, photosynthesis is maximized, and growth accelerates.

The Economic Case: Toward Commercial Viability
PFALs were once criticized for being too expensive to scale. But this is rapidly changing. With smart design and efficient operation, the economic outlook is improving:

• Production cost per kg can be reduced by up to 30%
• Market value per kg can be increased by 15% through premium quality
• Initial capital costs have dropped by 30% in recent years

Additionally, if PFAL-grown vegetables expand beyond fresh salad markets and enter processed food or nutraceutical sectors, market size and profitability could multiply—ushering in a new era of urban food industries.

Conclusion: PFALs as a New Pillar of Urban Agriculture
Plant Factories with Artificial Lighting are no longer a futuristic concept—they’re a present-day solution to many of the food system’s toughest challenges. With their ability to drastically reduce water and nutrient use, eliminate pesticide needs, and produce consistent, high-quality crops year-round, PFALs are laying the groundwork for a more resilient, localized, and sustainable agricultural future.

As technology continues to advance and urban food demand rises, PFALs are poised to become a core component of global food systems—growing more with less, closer to where people live.