LEDs Magazine - May/June 2017

32 MAY/JUNE 2017 LEDSMAGAZINE.COM
life science | HORTICULTURAL LIGHTING

The Earth’s population is projected to reach 10 billion by 2050, and there are growing concerns about water, energy, and food availability for such a high number of people. To maintain our current water supply and produce enough food to feed our fellow human residents, several different practices must be adopted within the agricultural sector. One potential solution to the problem is growing vegetables in water through hydroponics, aquaponics, or aeroponics. LED-based horticultural lighting works as an excellent companion technology to enhance crop production for indoor applications, especially in warehouses — in what is known as vertical or urban farming — versus greenhouses.

The three water systems are soil-less methods of agriculture that can produce 5× the amount of food in the same space as typical outdoor agricultural methods. Furthermore, these practices utilize at least 90% less water than the irrigation practices used in outdoor agriculture. With food and water availability possibly being the greatest future challenge facing humankind, these systems will provide significant relief to those concerns.

One common question with such agri-
cultural systems is how the yields compare
to soil-grown harvests. As stated earlier,
these systems provide the ability to grow
roughly 5× the amount of food in the same
space compared to outdoor agriculture. The
ability to stack the water and lighting sys-
tems in shelves allows for a condensed and
efficient use of space. Along with that, uti-
lizing LED grow lights designed to deliver
appropriate light spectra for each crop, pro-
vides more photosynthetic active radiation
(PAR) than what most plants receive from
the sun (Fig. 1). For instance, Mount Ver-
non, which is one of the most notable farm
towns in Iowa, receives a maximum of about
14 hours of photosynthetic light a day in the
summer, but in the winter it can drop to as
low as eight hours of light. When equipped
with horticultural solid-state lighting (SSL),
plants reach their maximum photosynthetic
potential every day. Growers just need to be
careful about giving their crop too much of
the heat energy that comes with the any light
source. Therefore, periods of no light expo-
sure must be set aside each day for plants.
The reduced heat and the lower electricity
operating costs of LEDs have opened a whole
new chapter in agriculture.
Reaping the economic benefits
With greater yields than the common out-
door methods of agriculture, the next con-
cern is whether these horticultural systems
are economically efficient. The quick answer
is “yes” — with an asterisk — based on three
key factors: type of plant; sales region; and
cost of electricity

People outside of the agriculture industry might assume that cannabis, with medical and recreational marijuana, is the only “cash crop.” Since cannabis takes multiple months to grow and grows multiple feet tall prior to harvest, it uses up more real estate — horizontally and vertically — than other crops like lettuce and micro-greens. Indoor farmers can “rack and stack” leafy greens four or five high and turn the crops more than once a month. California lettuce is shipped