Me, selling can gardens in Montréal - Summer 2012
Last week, the three scientists who invented blue light emitting diodes received the Nobel Prize. It was certainly well deserved, as this was nothing short of a revolution for lighting.
That revolution began with their invention 20 years ago and has brought us the newest in efficient light emitting diode (LED) lighting. These lights are so efficient that they have taken vertical farming from the pages of eco-utopian manifestos to tangible reality.
Navigant Research modeled a 63% adoption rate of LED lights for retrofitting projects by 2021. The numbers speak for themselves.
This is the first of a two-part piece that will explain what LEDs are in a way that anyone can understand. First, I’m going to look at what ‘efficiency’ means for LEDs, and the implications of increased efficiency. Then, in part two, I want to show you the companies breaking new ground on the vertical farming applications of LEDs right now.
Why is this so critical to vertical farming?
Before diving into the basics of LED lighting, let’s touch on why vertical farms require such a massive amount of light. Though a simple problem to understand, there is no universal lighting solution to efficiently illuminate multi-level farms because higher levels shade lower ones. Essentially, any move to intensify the number of seedlings per square foot, a primary function of vertical farming, is going to increase the shade over seedlings already in place as in the image from VertiCrop below.
As a result, prominent critics cite lighting as the main limiting factor any successful vertical farm would have to overcome. One such critic is Dr. Ted Caplow.
I first ran into Caplow’s work after learning about the Science Barge experiment he was running in New York. Caplow and his team were trying to figure out exactly what it would take to reach efficient, sustainable production in the middle of a city. The barge was a success, but it hinted at failure for vertical farming.
Based on his experience, Caplow came up with a rough estimate for roughly calculating lighting requirements for hydroponic growing facilities fueled by solar panels (like vertical farms). Basically, he estimates that to light a single layer of plants using energy exclusively from solar panels requires an area 20x larger than the square footage of that layer.
With improvements in LEDs and solar panels, Caplow’s estimates may soon be wrong if they aren’t already.
LED lights have become increasingly efficient and their energy requirements are declining rapidly. I want to explain what LEDs are, what ‘efficiency’ even means, the implications of increased efficiency, and finally in the next part, I want to show you the companies innovating existing lighting technologies even more.
First things first: LEDs?
LED stands for light emitting diode. So what’s a diode?
A diode, pictured below, is an electronic component with two points of opposite charge. In between those two points is a semiconductor. The semiconductor acts on the electric current as that current passes across the two points of the diode, dropping down the energy levels of the electrons in the current. It may help to think of the semiconductor as a permeable surface that allows the electrons to fall down out of their normal orbits, much like a sieve. The energy released in that reaction is what produces light, and in more wasteful systems, heat. The differences between semiconductors will produce various colors of light like the blue ones the scientists who won the Nobel Prize discovered.
What really matters more than the explanation is why that technology is better. The answer to that question lies in its efficacy.
These vegetated surfaces don’t just look pretty. They have other benefits as well, including cooling city blocks, reducing loud noises, and improving a building’s energy efficiency. What’s more, a recent modeling study shows that green walls can potentially reduce large amounts of air pollution in what’s called a “street canyon,” or the corridor between tall buildings.
For the study, Thomas Pugh, a biogeochemist at the Karlsruhe Institute of Technology in Germany, and his colleagues created a computer model of a green wall with generic vegetation in a Western European city. Then they recorded chemical reactions based on a variety of factors, such as wind speed and building placement.
The simulation revealed a clear pattern: A green wall in a street canyon trapped or absorbed large amounts of nitrogen dioxide and particulate matter—both pollutants harmful to people, said Pugh. Compared with reducing emissions from cars, little attention has been focused on how to trap or take up more of the pollutants, added Pugh, whose study was published last year in the journal Environmental Science & Technology.
That’s why the green-wall study is “putting forward an alternative solution that might allow [governments] to improve air quality in these problem hot spots,” he said.Compared with reducing emissions from cars, little attention has been focused on how to trap or take up more of the pollutants, added Pugh, whose study was published last year in the journal Environmental Science & Technology.
That’s why the green-wall study is “putting forward an alternative solution that might allow [governments] to improve air quality in these problem hot spots,” he said.
Evan Bromfield is a research assistant at the Centre For Food Safety in Washington D.C. and a vertical farming enthusiast and blogger. Read this recent article from his blog that considers what most don’t consider when thinking about vertical farming.
Designers love to praise vertical farms’ sustainability and combating climate change is a huge part of that, but there’s a lot more nuance than most other articles go into.
Sustainability is not just a measure of how much water your system recycles or how many solar panels it uses, and these resources are not the only things that affect climate change.
Not only that, but also there isn’t just one type of vertical farm: there are farmscrapers, farms that float, rooftop gardens, converted warehouses, and tricked-out greenhouses just to name a few.
The kicker? Each model is going to have entirely different measures of sustainability, especially when it comes to a carbon footprint.
Let’s take the obvious example. The original farmscraper envisioned by Dickson Despommier, whose name everyone should know, is a 30-story building bearing a tremendous amounts of water and carbon-rich plant weight. What is such a structure’s carbon footprint?
Looking at one emblematic skyscraper (1 Penn Plaza for the purposes of this exercise), we can calculate the estimated square footage of such a farmscraper.* Once we have an estimated square footage, we can use a carbon footprint calculator to see where it falls. In New York City, the carbon footprint of one of Despommier’s vertical farms is 63,360 metric tons of CO2 just in construction.** This means that for every floor built, 2,112 tons of CO2 are released into the atmosphere. To put that into perspective, the average American produced 19.8 tonnes from 1980-2006 (much higher than the average Chinese citizen who only produced 4.6 tonnes).
Loving the little built-in planter for micro-greens.
Edibles for an Espalier:
- Malus: Apple/Crabapple
- Pyrus: Pear
- Prunus: Stone fruit (peach, nectarine, plum, almond, etc.)
- Ficus carica: Fig
- Citrus: Lemon, orange, tangerine
- Vitis: Grapes
Ornamentals for an Espalier:
- Ginkgo biloba
- Fagus sylvatica culivars ( i.e., tricolor beech)
- Acer palmatum cultivars
- Pyrus calleryana (Callery pear)
- Tilia (linden)
- Cedrus atlantica (Blue Atlas cedar)
I “harvested” potatoes from my tower experiment today, and goddamn, was it depressing!! I legitimately got 5 potatoes from the entire bin. That was a lot of effort for nearly zero return.
Other takeaways: there were dozens of worms in the bin that resembled snakes in composition. They were thick and muscular ( versus your standard filmy night crawler ), moved as fast as snakes across the top of the soil and were iridescent in color, not dissimilar from a rubber fishing lure.
I imagine their color was from the soil I used and am still hoping it was the organic potting soil it claimed to be—not that it even matters with this many potatoes to eat.
I’m so sorry that this didn’t work out for you. What do you think happened? These potato towers are my favorite method and has produced well for me consistently.
Were you using commercial soil? Sometimes it is too much in the way of humus for potatoes, and you need to add sand or other inorganic matter to improve drainage and soil mobility. They grow best in a sandy, well-drained, cool loam soil.
Potatoes also require cooler weather to produce tubers: were they in a warm location, or did you have an unusually warm year? I can also theorise that the decomposition of the raw straw mulch heated the soil too much: I’ve seen potato towers done with newspaper, and this might be a lower heat solution.