Greenhouse - Revision history

Michel Lamontagne: /* Water usage */

2024-11-12T19:24:49Z

Water usage

Michel Lamontagne: /* Greenhouse development on Mars */

2024-11-12T18:57:27Z

Greenhouse development on Mars

Michel Lamontagne: /* Dust storms */

2024-11-12T18:56:29Z

Dust storms

Michel Lamontagne: /* Dust storms */

2024-11-12T18:47:31Z

Dust storms

Michel Lamontagne: /* Dust storms */

2024-11-12T18:44:07Z

Dust storms

Michel Lamontagne: /* Dust storms */

2024-11-12T18:38:11Z

Dust storms

Michel Lamontagne: /* Underground Greenhouse Concept (Grow room) */

2024-11-12T18:32:08Z

Underground Greenhouse Concept (Grow room)

RichardWSmith: /* Solid State Greenhouse */ Aerogels are light.

2024-11-11T23:48:29Z

Solid State Greenhouse: Aerogels are light.

RichardWSmith: /* Solid State Greenhouse */ formatting

2024-11-11T22:09:44Z

Solid State Greenhouse: formatting

RichardWSmith: /* Solid State Greenhouse */ grammar

2024-11-11T22:09:00Z

Solid State Greenhouse: grammar

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 == Water usage ==
-Plants require large amounts of water for evapotranspiration.  A typical value is 16 l/m2 per day<ref>https://ag.umass.edu/greenhouse-floriculture/fact-sheets/sizing-greenhouse-water-system</ref>. So plants to feed one person require about 16 l/m2 x 365 m2/person = 5 840 liters per day.  This water can (must) be recycled.
+Plants require large amounts of water for evapotranspiration.  Peak values can reach 16 l/m2 per day<ref>https://ag.umass.edu/greenhouse-floriculture/fact-sheets/sizing-greenhouse-water-system</ref>. So plants to feed one person can require up to 16 l/m2 x 365 m2/person = 5 840 liters per day.  This water is evaporated and must be recycled.
 ==Nutrition and Energy Calculations==

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 ==Greenhouse development on Mars==
-For early missions, enough food will be sent to avoid needing greenhouses.  However, for future growth of the Martian settlement local food production is an eventual requirement.  Therefore, some early experimental greenhouses will be built.  They may be used to provide a more varied diet.
+For early missions, enough food will be sent to avoid needing greenhouses.  However, for future growth of the Martian settlement local food production is an eventual requirement.  Therefore, some early experimental greenhouses will be built.  They may be used to provide a more varied diet and may prove essential depending on long term nutritional requirements(ref).
 ==Radiation damage==

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 ==Dust storms==
-Greenhouses will be affected by dust storms.  For greenhouses with reflectors and no artificial lighting a large dust storm will be catastrophic, possibly reducing lighting levels bellow the survival level of the plants.  Dust storms which block 90% of the sunlight occur irregularly, and Mars gets less sunlight than Earth.  If the light on Mars is halved, then low light crops can barely survive.  More than that and artificial lights are needed. During dense dust storms (which can last up to 1 to 2 months) power may be diverted from industry to lighting & heating the greenhouses. Alternatively, the greenhouses may be shut down to reduce energy demand if sufficient food is stored to last this period.  As Mars has a significant axial tilt, greenhouses at higher latitudes will shut down for winter anyway, as do greenhouses in Northern latitudes on Earth. So the summer months must create enough surplus to last the 11 month winters, adding more area to the greenhouses.  Eventually, a planet wide civilization would be able to source produce from different locations, but would still be sensitive to planet wide dust storms.
+Greenhouses will be affected by dust storms.  For greenhouses with reflectors and no artificial lighting a large dust storm will be catastrophic, possibly reducing lighting levels bellow the survival level of the plants and freezing the greenhouses.  Dust storms which block 90% of the sunlight occur irregularly, and Mars gets less sunlight than Earth.  If the light on Mars is halved, then low light crops can barely survive.  For lower ambient  light levels, additional artificial lighting is required. During dense dust storms (which can last up to 1 to 2 months) power may be diverted from industry to lighting & heating the greenhouses. Alternatively, the greenhouses may be shut down to reduce energy demand, and sufficient food must be stored to last for these recurrent periods.  As Mars has a significant axial tilt, greenhouses at higher latitudes will shut down for winter anyway, as do greenhouses in Northern latitudes on Earth. So the summer months must create enough surplus to last the 11 month winters, adding more area to the greenhouses.  Eventually, a planet wide civilization would be able to source produce from different locations, but would still be sensitive to planet wide dust storms.
-The only energy source that can support continuous and reliable food production is nuclear reactors.  This is true for all types of greenhouses.
+The only energy source that can support continuous and reliable food production is nuclear reactors.  This is true for all types of greenhouses.  Any greenhouse food production system depending on solar will require overproduction to be able to store food, and therefore will be significantly more expensive to build and operate.
 ==Greenhouse development on Mars==

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 The only energy source that can support continuous and reliable food production is nuclear reactors.  This is true for all types of greenhouses.
-Any greenhouse food production system depending on solar will require overproduction to be able to store food, and therefore will be significantly more expensive to operate.  During the rare dust storms that block 80% or more of the light from the sun, industry may have to be slowed or even shut down, to provide enough light to keep the plants alive.  It will be an important practical concern if 80% or 90% of the light is blocked.
+Any greenhouse food production system depending on solar will require overproduction to be able to store food, and therefore will be significantly more expensive to build  and operate.  During the rare dust storms that block 80% or more of the light from the sun, industry as well as food production, may have to be slowed or even shut down.
 ==Greenhouse development on Mars==

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 ==Dust storms==
-Greenhouses will be affected by dust storms.  For greenhouses with reflectors and no artificial lighting a large dust storm will be catastrophic, possibly reducing lighting levels bellow the survival level of the plants.  Dust storms which block 90% of the sunlight occur irregularly, and Mars gets less sunlight than Earth.  If the light on Mars is halved, then low light crops can barely survive.  More than that and artificial lights are needed. During dense dust storms (which can last up to 1 to 2 months) power may be diverted from industry to lighting & heating the greenhouses. Alternatively, the greenhouses may be shut down to reduce energy demand if sufficient food is stored to last this period.  As Mars has a significant axial tilt, greenhouses at higher latitudes will probably shut down for winter anyway.  (Providing the summer months can create enough surplus to last the 11 month winters.)
+Greenhouses will be affected by dust storms.  For greenhouses with reflectors and no artificial lighting a large dust storm will be catastrophic, possibly reducing lighting levels bellow the survival level of the plants.  Dust storms which block 90% of the sunlight occur irregularly, and Mars gets less sunlight than Earth.  If the light on Mars is halved, then low light crops can barely survive.  More than that and artificial lights are needed. During dense dust storms (which can last up to 1 to 2 months) power may be diverted from industry to lighting & heating the greenhouses. Alternatively, the greenhouses may be shut down to reduce energy demand if sufficient food is stored to last this period.  As Mars has a significant axial tilt, greenhouses at higher latitudes will shut down for winter anyway, as do greenhouses in Northern latitudes on Earth. So the summer months must create enough surplus to last the 11 month winters, adding more area to the greenhouses.  Eventually, a planet wide civilization would be able to source produce from different locations, but would still be sensitive to planet wide dust storms.
-Note that huge amounts of energy are needed to artificially light plants.  During the rare dust storms that block 80% or more of the light from the sun, industry may have to be slowed or even shut down, to provide enough light to keep the plants alive.  It will be an important practical concern if 80% or 90% of the light is blocked.
+The only energy source that can support continuous and reliable food production is nuclear reactors.  This is true for all types of greenhouses.
 ==Greenhouse development on Mars==

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 [[Image:Underground Greenhouse.png|thumb|right|300px|Underground Greenhouse Concept]]
-If geothermal energy or [[nuclear power]] is not available the [[heating]] will consume large amounts of electrical energy. In this case the sum of energy used for [[lighting]] and heating must be considered. An underground greenhouse is easier to insulate to hold warmth inside. On the other hand the effort of lighting is higher, since no direct sunlight is used. This concept has some additional advantages: It is [[meteorites|meteorite]]-safe and [[radiation]]-safe.
+Underground greenhouses are interesting if they require less energy overall for the same biomass production levels.  The artificial lighting required for an underground greenhouse is more than sufficient to provide all heating needs for the greenhouse.  In fact, underground greenhouses will require active cooling since the insulation from the soil, an any additional insulation, reduces heat losses well bellow heat gains from the lights.  This concept has some additional advantages: It is [[meteorites|meteorite]]-safe and [[radiation]]-safe.
-[[caves|Natural caves]] and [[artificial cave]]s can be utilized to build such an underground greenhouse, which requires a preparation with high effort in either case. The maintenance may be less that for a surface greenhouse, for the ambient temperatures are steady and the radiation levels are low.  A combination of greenhouse and living space for the settlers might be possible, but high productivity greenhouses will be warm, humid, rich in CO2 and with very high lighting levels.  These are not necessarily the best conditions for humans, so grow rooms will probably be build as separate environments from the general habitat.
+[[caves|Natural caves]] and [[artificial cave]]s can be utilized to build an underground greenhouse, which requires a preparation with high effort in either case. The maintenance may be less that for a surface greenhouse, for the ambient temperatures are steady and the radiation levels are low.  A combination of greenhouse and living space for the settlers might be possible, but high productivity greenhouses will be warm, humid, rich in CO2 and with very high lighting levels.  These are not the best comfort conditions for humans, so grow rooms will probably be build as separate environments from the general habitat.
 The [[Mars One]] concept for the initial settlement was an inflatable greenhouse with a thick cover of [[regolith]].
-Artificial lighting equivalent to the average illumination level on Earth is 600 W/m2 and more.  With an insulated grow room, this energy must be removed from the grow room to avoid overheating.  However, the lighting is required for proper growth.  Therefore a grow room will need to be cooled using mechanical cooling, as is the case on Earth.  Plant also evaporate a large quantity of water by evapotranspiration for their normal growth.  The water must be removed by cooling or some other method from the air, as saturated air will no longer allow evapotranspiration and the plants will not survive.  Compression work required to cool the air and remove the water is usually in the order or 50 to 80% of the light load to the area, as compressors operate in low efficiency ranges for grow rooms<ref name=":0" />.  So beyond the 600W/*m2 of lighting at an efficiency of about 80% for LEDs, up to another 4-500 W/m2 may be required to power the cooling of the grow rooms for a total peak load of 12-1500 W/m2.  Alternatively, water cooled in the Martian regolith or through surface radiators might be used to cool the grow rooms without the added energy of compression.
+Artificial lighting equivalent to the average illumination level on Earth is 600 W/m2 and more.  With an insulated grow room, this energy must be removed from the grow room to avoid overheating.  However, the lighting is required for proper growth.  Therefore a grow room will need to be cooled using mechanical cooling, as is often the case on Earth.  Plant also evaporate a large quantity of water by evapotranspiration for their normal growth.  The water must be removed by cooling or some other method from the air, as saturated air will no longer allow evapotranspiration and the plants will not survive.  Compression work required to cool the air and remove the water is usually in the order or 50 to 80% of the light load to the area, as compressors operate in low efficiency ranges for grow rooms<ref name=":0" />.  So beyond the 600W/*m2 of lighting at an efficiency of about 80% for LEDs, up to another 4-500 W/m2 may be required to power the cooling of the grow rooms for a total peak load of 12-1500 W/m2.  A more interesting solution for cooling underground greenhouses would be to use chilled water cooling to the Martian regolith or through surface radiators.  This would cool the grow rooms without the added energy of compression.
-Underground greenhouses will require a vast amount of power, see the calculations in the "Nutrition & Energy Calculations" section below.
+Underground greenhouses will require vast amounts of power, see the calculations in the "Nutrition & Energy Calculations" section below.
 ==Water-shield Greenhouse Concept==

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 Imagine a pebble in Antarctica made out of quartz.  This is translucent to light, blocks [[Ultraviolet]] radiation, prevents winds from drying out the area under it, and acts as a thermal buffer.  This suggests that the ground under this pebble is friendlier to life than above it.  This in fact happens; algae and lichen can grow under such pebbles but not above them.
-A thin layer of material, laying on the ground could have a similar effect on Mars.  This is the idea of a 'solid state greenhouse'.  A large flat plate of a material that is translucent enough to transmit light, but is opaque to [[Infrared]] (heat) would warm up a large area of soil.  This paper <ref>https://www.sciencedirect.com/science/article/abs/pii/0019103589900079#:~:text=Subsurface%20heating%20by%20sunlight%20can,the%20study%20of%20planetary%20surfaces.</ref> suggests that a 2.5 cm thick layer of [[Aerogel]], many meters in diameter, could warm the sub-soil to above the melting point of water down to a depth of 5 meters in about 8 years.
+A thin layer of material, laying on the ground could have a similar effect on Mars.  This is the idea of a 'solid state greenhouse'.  A large flat plate of a material that is translucent enough to transmit light, but is opaque to [[Infrared]] (heat) would warm up a large area of soil.  This paper <ref>https://www.sciencedirect.com/science/article/abs/pii/0019103589900079#:~:text=Subsurface%20heating%20by%20sunlight%20can,the%20study%20of%20planetary%20surfaces.</ref> suggests that a 2.5 cm thick layer of [[Aerogel]], many meters in diameter, could warm the sub-soil to above the melting point of water down to a depth of 5 meters in about 8 Martian years.
 This could be of great use for those who want to [[Terraforming|terraform Mars]].  However, the solid state greenhouse would have to be in an area where it won't be covered by [[Dust]] most of the time, or it must be cleaned.
 ==Multiplying Sunlight==