30th March 2022

Orange is the New Green, for Greenhouses

By Jay Stein on March 30, 2022

Greenhouse agriculture is far more water efficient than open field, at the expense of greater energy consumption. New technology is enabling drought-stricken growers to move more crops into greenhouses with a smaller energy penalty. As climate change dries out the American West and much of the rest of the world, farmers are responding by growing more crops in greenhouses. In Colorado, where I live, from 2012 to 2017, the total number of greenhouse farms increased by 47%. Crops grown in greenhouses may require as little as one-tenth of the water used in open-field agriculture, but those water savings come at a cost: increased energy consumption. Per unit of crops produced, greenhouse growers may consume anywhere from two to four times more energy than open-field growers, with most of that energy going for heating and cooling. That additional energy consumption contributes to climate change, one of the factors driving growers into greenhouses in the first place. While greenhouse agriculture will likely never consume less energy than open-field (even including transportation), there’s growing demand for technologies to reduce the energy penalty. One young company getting into the game is UbiQD (pronounced “ubiquity”), which enables greenhouse growers to convert some of the sunlight that plants don’t make much use of into light that they love. That additional beneficial light enables growers to increase yields without increasing energy consumption. The more yield per unit of greenhouse space, the less energy it takes per bushel to put tomatoes, lettuce, strawberries, and peppers on our plates. So far, UbiQD is finding that its new product, UbiGro, increases greenhouse crop yields by 10-20%, and that it pays for itself in about a year. UbiGro has the potential to be widely adopted by greenhouse growers, and it’s not alone. More technological innovation is on the way to mitigate the additional energy consumption that’s surely coming from greenhouse agriculture. Making quantum dots ubiquitous Founded in 2014 by a scientist from Los Alamos National Laboratory, UbiQD makes quantum dots, which are microscopic semiconductor crystals. At about 5 nanometers across (one nanometer is a billionth of a meter), you could pack billions into the period at the end of this sentence. The main job of quantum dots is to absorb light photons in one wavelength and re-emit them in another. They’re mostly used in televisions and monitors. UbiQD’s breakthrough was to develop copper-based quantum dots that can be used in agriculture. So how can quantum dots help greenhouse growers? Just like the protagonist in the song Raindrops Keep Falling on My Head, greenhouse growers don’t like the way the sun gets things done. It puts out too much light in parts of the spectrum that plants don’t absorb much of (like UV and blue), and not enough in the parts plants need to grow (like red and orange). UbiQD makes quantum dots that absorb UV and blue light, and re-emit it as red and orange. The company incorporates these quantum dots into a product named UbiGro. How UbiGro works To make UbiGro, UbiQD sandwiches quantum dots between two plastic sheets. Growers suspend those sheets between the greenhouse cover and the plants. When sunlight passes through, UbiGro suffuses the plants underneath in an orange glow, improving chlorophyl absorption and photosynthetic efficiency. In tests, crops grown under UbiGro produced yield increases ranging from 5% to 20%. For example, in a hydroponic tomato greenhouse in New Mexico, installing UbiGro increased yield by 20.5%. UbiQD is also testing out UbiGro in greenhouses growing lettuce, strawberries, basil, bell peppers, and cucumbers. There are two different ways to think about how UbiGro saves energy. One, it enables more crops to be produced in a greenhouse without any additional energy consumption. As a result, the amount of energy required to grow a bushel of tomatoes, or any other crop, goes down. Alternatively, greenhouse growers often install lights to boost plant growth. UbiGro offers similar yield improvement as grow lights, but without the typical 22 kWh per square foot of annual electricity consumption. UbiGro accomplishes such yield improvements at just $3 per square foot. According to Hunter McDaniel, UbiQD’s CEO and founder, growers can easily recoup that cost in a year or less. Given such favorable results and economics, it appears that the future is bright for UbiGro. Greenhouse energy efficiency technologies are growing UbiGro is not the only energy efficiency technology coming down the pike for greenhouses. Others include better LED lighting fixtures, heat pumps for both heating and cooling, robots and artificial intelligence for monitoring plant health, conveyors to eliminate unproductive walkways, and light transmitting solar panels integrated into greenhouse roofs (UbiQD is developing such a product). All these technologies are bound to reduce the energy penalty associated with greenhouse agriculture, but not eliminate it. As climate change continues to diminish freshwater sources, humanity will trade off increased energy consumption for increased access to potable water. Expanded greenhouse agriculture is just one example, and desalinating sea and brackish water is another. Incremental technological advancements will enable us to mitigate the consequences of these tradeoffs, but they’ll never be enough to eradicate the underlying problem. For that, ultimately, we’ll have to find the collective will to do what it takes to tackle climate change. Read the original blog post here.