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.
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