There is a lot of energy and resources being wasted in a fraudulent war on drugs. The military consumes a large amount of energy, without wars and fraud against people there would be a lot less energy consumed.
USA consumes somewhere around ~19,150,000 barrels of oil per day (bbl/day)
CIA removed the information from their website so here is the archived link. 1800 gallons of hemp ethanol per acre=42 barrels hemp fuel (42 gallons in a barrel)

Half of the arable land in USA 235 million acres
19,150,000 x 366 days* = 7,008,900,000
235,000,000 x 42 = 9,870,000,000 barrels hemp fuel
USA consumes ~ 7,008,900,000 barrels every year
Projected world oil consumption by 2030:
104,000,000 barrels per day x 366 days* = 38,064,000,000
Worlds total arable land 13,805,153km²
half of the total arable land in the world 6902576km² x 247 acres in 1 km² = 1,704,936,272 acres
1,704,936,272 x 42 (1800gallons) = 71,607,323,424 barrels hemp fuel
* 366 days are counted instead of 365 days in a year.
So there is math proving that more than enough hemp fuel can be made to supply far more than the demand covering one of the major energy sources, so obviously not all hemp biomass should be converted into just ethanol, diesel, gasoline, pellets, I guess the markets would adapt because what if diesel cars get more popular? There might be undiscovered ways to use ethanol, diesel and other forms of hemp energy more efficiently.
Even if hemp can only produce 300 gallons of hemp fuel per acre, hemp can still provide the energy needed with more land needed.
and yes arable land could be left alone, diesel is more efficient than gas.
Anyone who does not think there is enough land to grow hemp for fuel and still grow food crops need to take a serious look at all the waste land that can be converted into arable land. Hemp and mushrooms are a great resource to convert land into arable land good for growing food crops.
Energy for future -- HEMP
Erdem Ulaş