Vertical farming is undergoing a "dark" revolution. 
Imagine a vertical farm where plants thrive not under the purple glow of LEDs but in complete darkness. This is the essence of Electro-Ag—a system where crops are nourished not by photons but by little more than air, water, and electricity. 

What is Electro-Ag? 

Plants naturally use light to convert CO₂ into sugars for growth. Electro-Ag takes a different approach—CO₂ is converted into acetate using renewable energy, which plants can use directly to grow without light Crandall et al. 2024; Hann et al. 2022. 

Growing plants with acetate requires modifying plant metabolism. Plants normally use the Krebs cycle to process sugars for energy and growth. However, Krebs cycle does not work well with acetate. Because acetate has only two carbon atoms (unlike sugar's five or six), the Krebs cycle releases both carbons as CO₂, leaving no carbon for growth. 

Plants possess an alternative pathway—the glyoxylate cycle—that prevents this carbon loss. Normally active only in germinating seedlings, this cycle becomes inactive during photosynthesis. Through CRISPR gene-editing, this cycle can be kept active throughout a plant's life, enabling continuous growth using acetate. 

In essence, Electro-ag bypasses photosynthesis by feeding gene-edited plants with electrochemically produced acetate, allowing them to grow in darkness. 

Why Electro-Ag Matters 

LED lighting, while fundamental to vertical farming, is also its greatest limitation. Lighting accounts for the biggest operation cost, consuming up to 80% of the total energy budget of a vertical farm Graamans et al. 2018. These energy costs makes vertical farms viable only for leafy greens, not staple crops Asseng et al. 2020. Lighting also contributes the most carbon emissions in vertical farming. 

Electro-Ag advances vertical farming by eliminating the need for lighting, which leads to several benefits: 

1. Energy Efficiency: Eliminates energy use and costs associated with lighting. 
2. Environmental Impact: Reduces CO₂ emissions by removing the largest source of carbon emissions in vertical farming.  
3. Expanded Crop Variety: Lower production costs without light could enable cultivation of high-calorie and longer-duration staple crops like potatoes and grains, moving beyond just leafy greens 
4. Resource-constrained farming: Makes crop cultivation possible in regions with limited energy and even in space environments 

Challenges

While electro-ag is a promising technology, three main hurdles must be overcome before it becomes commercially viable: 

1. Energy efficiency uncertainty: Energy required for acetate-based lettuce production remain unknown. Electro-ag should demonstrate energy-use lower than required for LED lights, i.e., 103 mega joules per kilogram of lettuce 
2. Complexity of metabolic engineering : Modifying plants to utilize the glyoxylate cycle is challenging. Redesigning plant metabolism requires extensive testing to ensure no unintended effects on plant growth and development. 
3. Plant development under dark : While acetate can support plant growth, the absence of light could stunt plant development. Though genetically modifying light-sensing photoreceptors could address this issue (as demonstrated in rice by Hu et al. 2020, implementing this across different crop species is challenging. 

Conclusion

Electro-ag offers an innovative solution to vertical farming's energy challenges, yet hurdles block its path to commercialization. The technology's benefits of lower energy costs, broader crop options, and reduced environmental impact make electro-ag a compelling avenue for research.  

Through ongoing research in acetate production, genetic modification, and plant development under dark, electro-ag could reshape vertical farming and enable sustainable food production in resource-limited environments, urban centers, and space colonies. 

For now, though, the lights remain on.