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Plants produce oxygen, we know.

This might make plants useful in the supply system of possible colonies on other planets or moons. But how efficient they are?

Which is the maximum amount of oxygens can be produced by a single entity and what is it enough for?

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source:space.com

There are certain plants that are more efficient in removing and adding Oxygen to the surrounding environment, but the main disadvantage is that they need soil with comfortable acidity otherwise the roots of the plants would die. That prevents them from being used on other planets where the acidic contents in the soil is more (but there are a few exceptions). Also, plants add water to the surrounding environment through transpiration which helps to cool atmosphere.

So the other option would be microbes with chlorophyll (green pigments which helps photosynthesis) what we call as algae and suspend them in suitable way in certain liquid (mostly water) and exposed to light so that they may carry out photosynthesis.

Source

Scientists at the Hydrology institute of China have developed a system that sees 1.5 cubic metres of algae produce enough oxygen for a man, weighing 70 kilogrammes, to survive in an enclosed space for one day.

External source

http://wiki.answers.com/Q/What_plant_produces_the_most_oxygen#page1

http://www.mnn.com/health/healthy-spaces/stories/best-air-filtering-houseplants-according-to-nasa

http://news.softpedia.com/news/Top-15-NASA-039-s-Plants-That-Can-Save-Your-Life-78345.shtml

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  • $\begingroup$ I'v heard about that plants can grow if their roots are in water (with right amount of elements they need) instead of soil. It may make transporting easier. $\endgroup$ – Zoltán Schmidt Sep 29 '13 at 12:28
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    $\begingroup$ True, or semi-true. It depends on the kind of plant. Plants also need oxygen (They use it all day and night, they just produce more oxygen than they use during daylight.). The roots also need oxygen. If there is not enough oxygen in the water for that plant then the roots will die. How much is enough obviously varies per plant species, but many plants want airy soil. When we immerse the root from these plants in water we need to bubble air though it. Or even grow the roots in air and continuously spray them with water mist. Both are done in earth side hydroponics. $\endgroup$ – Hennes Sep 29 '13 at 12:39
  • $\begingroup$ What time it takes to produce this amount of oxygen? $\endgroup$ – Anixx Dec 14 '13 at 15:19
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The higher plants are less efficient, so the entity will probably be not a bush, but a jar of algae.

30-40 liters of Сhlorella suspension

enter image description here

could provide for a gaseous exchange of a single person.

Grishin Yu. I. "Artificial Space Ecosystems" Cosmonautics, Astronomy 7/1989

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    $\begingroup$ doesn't this assume some kind of specific CO2 concentration and available sun light? $\endgroup$ – user6972 Sep 29 '13 at 3:44
  • $\begingroup$ @user6972 I think artificial light is enough for plants to grow. $\endgroup$ – Zoltán Schmidt Sep 29 '13 at 12:25
  • $\begingroup$ @ZoltanSchmidt My point is this estimation has to be based on some parameters...or were the numbers lifted directly from the article? $\endgroup$ – user6972 Sep 29 '13 at 17:54
  • $\begingroup$ Yes, that's almost direct quotation from the article. Google translation is quite understandable btw. $\endgroup$ – horsh Sep 29 '13 at 19:31
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Well it is not as easy as it seems, it needs a suitable environment to grow in. First of all it itself need some oxygen to grow. And you cannot just give oxygen to the plant directly, the oxygen would escape into the atmosphere.You need CO2. You need the right amount of sunlight. You need nutrient specific soil. You need bacteria to fix nitrogen into the soil. You need a thick atmosphere like earth has to prevent harmful UV radiation from the sun. This is just the basic conditions you need to grow a plant in other planets. rain forest plants produce the most oxygen. Algae also is a good oxygen producing plant but need more specific conditions to grow in. A single grown rain forest tree can produce oxygen required needed by 4 to 5 people. 100 liters of algae can produce oxygen for 2 to 3 people

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  • $\begingroup$ I asked about using plants in closed colonies instead of on surfaces of planets. $\endgroup$ – Zoltán Schmidt Sep 29 '13 at 12:29
  • $\begingroup$ @ZoltánSchmidt, Even on closed colonies some of these problems apply $\endgroup$ – Shreesha Hegde Sep 30 '13 at 9:13
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This TED talk addresses the issue, but not from the standpoint of space habitats, just looking at oxygen in indoor environments:

http://www.ted.com/talks/kamal_meattle_on_how_to_grow_your_own_fresh_air.html

He gives estimates of number of plants needed per person. You might want to look into the biodome projects as well:

http://en.wikipedia.org/wiki/Biosphere_2

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    $\begingroup$ Welcome to Space Exploration! If you could try to summarize or paraphrase the applicable portions of your links in your answer, it will make this answer more readable and protect it from the possibility of dead links or changes to the linked pages. Thanks! $\endgroup$ – called2voyage Dec 10 '13 at 20:04

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