Friday, August 15, 2008

vertical farming lighting efficiency





One thing that seems to be overlooked by most people when they look at indoor plant growing is the property of light and how it losses its intensity over distance. When you set up an indoor growing facility without sunlight, you create a small version of a solar system of sorts. The light source depending on what type of lamp you use can be compared to the sun in several ways. Too close is too hot, too far away and is too well Pluto I like to call it.

In a traditional flat or tiered garden setup some seats are better then others and your plants that are closest to the light source without being too close (you can light a smoke off a 600 or 1,000 watt bulb) as too burn, will perform the best. The reason for this is that as light spreads from the source it quarters with every increased foot of distance, for eg if you have a measurement of 100,000 lumen (1 lumen is the amount of light that lands on 1 sq ft of area, 1 ft from a candle) at 1 foot distance, when the light is 2 ft from the source the measurement is 25,000 lumen, at 3 ft is only 6,250 lumen, at 4 ft is just over 1,500. So you can see that there is a sweet spot for the plants with an artificial light source, and that is arguably between the 1 and 2 ft range from the light. Not too close to burn and not so far away that it doesn't grow well. A pretty simple concept that you recognize when you actually have the experience of growing plants this way.

If you consider that we here on planet earth are in the sweet spot, not too hot so we don't burn, and not so cold that the water isn't frozen, and the plants seem to like it too.

Utilizing a cylindrical shape with the light source int he center maximizes the light to plant ratio. Rotating that same cylinder oriented horizontally makes watering all the plants with a tray at the base that the roots are pulled through provides the most simple and effective way to provide moister and nutrients to the plants, and also keeps all of the plants perpendicular to the light and the surface of the section of the cylinder that each plant is secured to.

The supplemental lighting used in green housing has no growth relationship with the plants in the greenhouse. The relationship is one of annoyance meaning that the light keeps the plants awake. If there was no sunlight nothing decent would grow from the amount of light used and the distance of the light from the plants.

The Omega Garden needs no sunlight and uses less power to grow the same amount of plant material as the power used to supplement sunlight in a greenhouse.

If you overlay the lumen pyramid chart over a flat land garden compared to the Omega configuration you can figure the mathematical increase efficiency of the cylindrical system. There is also an increase in the rate of growth of a plant rotated in this fashion as plants predominate growth direction of the trunk and the stems are away from the pull of gravity, and I will post to this phenomenon in a future post.

When comparing these two ways to use light it can be argued that the Omega model is tens to hundreds of time more efficient light use. The fact that the Omega model needs no sunlight means that it can be expanded vertically for greater efficiency, and there are more places to find further energy savings.