Transforming Sunlight with Quantum Greenhouses

What if we can make light itself better for growing produce? And not by special lighting rigs requiring energy, but passively through greenhouse glass?

A recent USDA-funded study at the University of California, Davis, looked at exactly that.

The study compared lettuce grown in a standard glass greenhouse and one with laminated glass roof panels made with spectrum-shifting “quantum dot” technology during January and February. The results, recently published in the peer-reviewed journal “Materials Today Sustainability,” found that the augmented glass boosted lettuce crop yields by almost 40% and increased nutrient concentrations.

“For glass greenhouse farmers looking to boost output while reducing energy inputs, this is a breakthrough,” says Hunter McDaniel, CEO of UbiQD, the company that produced the test roof panels.

“These results prove that the sun can be engineered passively through QD-infused glass to deliver more productive, resilient, and sustainable food systems,” McDaniel says.

Study and Findings

The test glass used in the study had a layer of quantum dots sandwiched between a pair of standard glass panes. UbiQD calls it UbiGro glass.

“Quantum dots (QDs) are vanishingly small nanoparticles of semiconductor material that are highly effective at manipulating color and light,” explains Eric Moody, UbiQD’s vice president of sales and marketing.

“If you filled a thimble with QDs, there are more QDs in the thimble than there are stars in the known universe,” says Damon Hebert, senior director of agriculture R&D at UbiQD and one of the report’s authors, trying to put QD’s size in context.

The effect of the QD-infused glass was to give the study’s lettuce plants more of the kind of light they need for growth.

“What this technology does is it shifts a small portion of the blue light and the UV light into the red light spectrum,” explains UC Davis’ Shamim Ahamed, lead researcher on the study. He notes that this is especially valuable when it’s cloudy or during the winter when red light is relatively low.

“This passive tailoring of the sun’s spectrum results in faster growth rates and higher yields,” summarizes Hebert.

According to the report, plants grown in the greenhouse with the UbiGro glass roof panels:

• Were 37.8% heavier, meaning more edible yield.
• Had more leaves (average 51 verus average 41 in the control greenhouse) and leaf area was increased by 38%.
• Had 38% longer roots, meaning more water and nutrient uptake.
• Had statistically significantly higher concentrations of nutrients (nitrogen, phosphorus, potassium, magnesium, zinc and copper).

Tech in Context

“It’s incredibly validating to see these spectral shifts result in measurable improvements in plant performance,” Moody says.

He notes that the company already produces plastic films for greenhouses using the spectrum-shifting QD technology targeting specific uses. But the study was the first deployment of quantum dot-integrated structural glass in agriculture.

“Our film products are already delivering strong results in commercial greenhouses around the world, and this new data supports our broader vision for integrating light-optimizing technologies — like our upcoming glass innovations — into agriculture at scale,” Moody says.

The UbiGro glass and film products are all examples of spectral engineering, Moody and Hebert explain. This includes everything from LED fixtures that can focus on specific light spectra to spectral netting and spray-on products that block specific parts of the spectrum.

“It is important to note that UbiGro Glass does not filter out parts of the sun’s rays but instead captures these UV and blue photons and converts them to red photons that spur photosynthesis in plants, pushing them to produce more fruit and grow faster,” Moody says.

Taking the Findings to the Future

Ahamed says that the most important part of the study’s finding is that, if light is an issue for greenhouse growers — such as during winter, on cloudy days, or during the early mornings or late evenings — the QD-infused glass can get more useable light to plants than standard glass.

“It really helps to reduce the overall cost of the production because of the increased production per unit area,” he adds.

Moody frames the findings in terms of efficiency.

“Just like the research we have done with our greenhouse plastics, growers should understand that our technology can help them produce more from their No. 1 resource — the sun,” he says. “While this research was conducted on a small scale it is basically the same technology we have had with our greenhouse plastics.”

However, he adds that growers will have to wait for the glass technology to be commercially available.

“For glass, Phase 2 R&D studies run through 2028, so we would expect to have commercial pilot trials running concurrently with Phase 2 in 2028,” says Hebert. “However, growers who want to try out the concept of QD spectrum control before glass is ready have the option of installing UbiGro Inner retrofit plastic films, as a proof of concept that this technology does work for their crop in their location.”

Ahamed sees more potential avenues of research for this kind of technology in the future.

“If this kind of spectral shifting is happening, is there any impact in terms of the indoor thermal environment, so in terms of heating costs or cooling costs?” he asks. “What could be the impact in terms of water use?”

He adds that there are other potential applications for this kind of spectral engineering that could be pursued in the future. If the glass could be designed in such a way as to allow only what is critical to the plant and reflect the rest, he offers as an example, “then you could significantly reduce the energy costs.”

‍

Read the original article from The Packer