On earth ordinary sunlight is freely available and effective for growing plants. But in space there are problems with excess heat production from plant-growth lighting, and the vacuum of space makes it difficult to shed this heat. The key to the problem is finding an efficient light source, one that converts as much of the electricity it consumes into light that plants use for photosynthesis.
I have compared the performance of numerous lighting systems and discovered some very interesting things. First of all sunlight is the best choice especially in space. However as a spacecraft orbits the earth the sun is frequently rising and setting every 45 minutes, and this makes it impossible to utilize. This may change for space platforms orbiting the sun, or on mars. Besides sunlight I have discovered that the next-best source of "white" light is the Sulfur Microwave Lamp. This light can be used both for growing plants and for ordinary illumination. The next best alternative are orange or green light-emitting diodes. These are not as good for general illumination (people can't see well under orange or green light) but they are extremely efficient for plant growth and produce less heat than any other light.
For more detailed info visit the "Agricultural Lighting" section of the Starship Generations website:
http://www.geocities.com/womplex_oo1/StarshipGenerations.html
I have compared the performance of numerous lighting systems and discovered some very interesting things. First of all sunlight is the best choice especially in space. However as a spacecraft orbits the earth the sun is frequently rising and setting every 45 minutes, and this makes it impossible to utilize. This may change for space platforms orbiting the sun, or on mars. Besides sunlight I have discovered that the next-best source of "white" light is the Sulfur Microwave Lamp. This light can be used both for growing plants and for ordinary illumination. The next best alternative are orange or green light-emitting diodes. These are not as good for general illumination (people can't see well under orange or green light) but they are extremely efficient for plant growth and produce less heat than any other light.
For more detailed info visit the "Agricultural Lighting" section of the Starship Generations website:
http://www.geocities.com/womplex_oo1/StarshipGenerations.html