The U.S. war on non-smokable hemp hurts the environment and the
economy, according to a new report from the free-market-promoting
Reason Foundation. To wit: Hemp fiber requires six times less
manufacturing energy on average than polyester fiber, and requires less
pesticides and water than cotton. Hemp can be used to make paper,
fiberglass, and cement, generally with less energy use than alternative
materials. It could make a lovely cellulosic biofuel, were cellulosic
ever ready for the big time.
And in case you needed a reminder, says the report: “Marijuana
cultivated for drug value contains between 3 and 10 percent of the
active ingredient, tetrahydrocannabinol, or THC. Industrial hemp
typically contains 0.3 percent or less of this active ingredient — as
a result, it has no value as a drug.”

source: 

The Reason Foundation


straight to the report: 

Illegally Green: Environmental Costs of Hemp Prohibition [PDF]


see also, in Grist: 

Umbra on hemp fabric