Detergents

First the raw material to make soap are sodium or potassium hydroxide with animal fat or plant oil. The above answer mixes up animal & plant oils which are from different sources. Most people regard soap is most green detergent because it is made from renewable resources, it is completely biodegradable. However they forget the main purpose of using soap is to clean soil. If soap is so effective to do the work then we donot need other surfactants(thousands do exist!!!!). If you use a green cleaner to clean but turn out doesnot work, you need to use another cleaner to reclean again, you already waste the resouces , the energy and your time, it is not green at all ! Most people only consider the superficial effect not thinking the whole process of cleaning. A green cleaning process need the cleaner can perform effectively, with least energy to solve the whole problem. Soap does not work in many cases.

2009-01-02 09:18:54 補充：
In conclusion : keep place clean avoiding to use detergent, use soap only to clean what it can work well.

Pros:
-Soap is come from animal fat of plant oil, which a renewable resources while petroleum is non-renewable.
-Soap is bio-degradable. It cause less environmental problem
Cons:
-Soap is come from animal fat of plant oil, which can be used as food for people. So using soap would cause less food for people
-Soap cannot work well in hard water and acidic solution