You need an enormous, full sun greenhouse just for one person’s CO2: “An active person exhales about 1 kg of CO2 per day. So, you would need 1000 square meters

You need an enormous, full sun greenhouse just for one person’s CO2: “An active person exhales about 1 kg of CO2 per day. So, you would need 1000 square meters of grass to absorb one person's CO2. That's a square about 32 meters on a side, or in archaic units, a quarter acre. A one-square-kilometer park could support 1000 people, just with the grass.“ (Or: Need about 16 trees per person.) http://highfrontier.com/forum/showthread.php?tid=20 http://highfrontier.com/forum/showthread.php?tid=20