Adding CO2 to the air
is very good news for
"C3" green plants that
humans and animals
use for food.
Optimizing plant-based food
would best support life on
our planet.
That's why I favor much more
CO2 in the air -- doubling or
tripling today's CO2 level.
I know this is the opposite
of what you hear from
government bureaucrats
with science degrees, and
from the leftist politicians
who hired them !
That's because
I base my
CO2 conclusions
on real science,
while their
predictions of doom
from CO2
are self-serving
junk science.
Every prediction of environmental
doom in my lifetime -- 45 +20 years --
has been wrong.
Fool me once -- shame on me --
fool me every year -- shame on me!
I'm proud to say my conclusion,
that 100 year climate forecasts
were worthless, took only one day
of climate science reading,
back in 1997.
I've never been one to believe
predictions of the future,
so why would I believe climate
predictions ... that have been
wrong since the late 1950's,
with wrong comnputer game
forecasts for over 30 years ?
Let's consider what
greenhouse owners do
to optimize the growth
of their own plants:
Carbon dioxide
supplementation
means adding
more CO2
inside the greenhouse,
which increases
photosynthesis
in the plants.
This is also called
“CO2 enrichment”, or
“CO2 fertilization.”
With the development
of improved
lighting systems,
environmental controls,
and balanced nutrients,
the amount of CO2
is the only limiting factor
for maximum plant growth.
Without additional input
of pure CO2,
the CO2 content
inside the greenhouse
can be reduced to
less than 50%
of its normal content
in the outside air.
This shortage of CO2
would reduce
the efficiency
of photosynthesis.
Greenhouse growers who
seal up their greenhouses,
in an effort to control
their heating bills
during the winter,
reduce CO2 levels
even more.
Supplemental CO2
provides improved
plant growth.
Of course the plants still need
the correct temperature, water,
nutrients and light, that they
would get naturally
if they were growing outdoors.
An additional supply of CO2
can lead to earlier flowering,
higher fruit yields,
improved stem strength,
and flower size.
Supplementing CO2
at an early age
reduces the number of
days to maturity,
so plants can be
harvested earlier.
For flowers,
supplemental CO2
increases the number
and size of flowers,
making them
more valuable.
CO2 enrichment systems
are normally turned on
during sunrise,
and turned off
several hours
before sunset.
Additional
CO2 enrichment
may be needed
if supplemental lighting
is used at night.
The optimum level of CO2
depends on the crop,
light intensity,
temperature, ventilation,
stage of the crop growth
and the economics (value)
of the crop.
For most crops
the saturation point
will be reached at about
1,000 ppm to 1,300 ppm,
roughly triple of the ambient
410 ppm CO2 level outdoors.
The more practical sources
of CO2 include
the clean combustion
of fuels, usually propane
or natural gas
... or pure CO2 in tanks.
CO2 is heavier than air.
Therefore, distribution systems
should maintain enough turbulence
to keep added CO2 evenly mixed
with the greenhouse air.
Monitoring and control systems
should be able to measure
CO2 levels at several locations
inside the greenhouse,
compare concentrations
to a set point, and adjust
the concentration
by adding more CO2
when required.
CO2 generators
using hydrocarbon fuels
(e.g., natural gas, propane)
are common CO2 sources
in greenhouses.
The CO2 burner capacity
ranges from 20,000
to 60,000 Btu per hour,
and can produce 8.2 pounds
of CO2 per hour
by burning natural gas.
Alternatively,
a portion of the flue gas
from natural gas boilers
connected to
hot water
heating systems,
can be directed
into the greenhouse,
as a means of
supplementing CO2
to the crop .
The boiler
should be equipped
with a flue gas condenser,
to reduce the
flue gas temperature
and take the moisture out
of the flue gases,
avoiding their entrance
into the greenhouse.
Liquid CO2
is another alternative
for supplementation.
Liquid CO2 is stored
in pressurized tanks,
usually located
just outside
the greenhouse.
Pure liquid bulk CO2
is delivered by truck
to the greenhouse,
and stored in
refrigerated tanks.
The compressed CO2
is in a liquid state
and must be vaporized
through vaporizer units
before entering
the greenhouse.
The distribution system
for liquid CO2
in the greenhouse
is simpler to design
and install.
During the day,
the CO2 generator
is automatically
turned off
when the
ventilating fans
are on.
In the event of
roof ventilation,
mechanical switches
are installed
on the ventilators
to allow the
CO2 generator
to operate
only when
the vents
are closed.
More sophisticated
CO2 injection systems
usually consist of
a CO2 generator,
a control system,
and a “feedback”
monitoring system
for monitoring
CO2 levels
in the greenhouse.
The monitoring device
is usually an infra-red
gas analyzer (IRGA).