Sustainable Bioenergy Use

The DOE billion ton study says that roughly 1 billion tons of biomass can be used sustainably in the United States. This bioenergy can be used for building heat (either through direct combustion or through conversion to electricity) and for passenger vehicles (either through conversion to biofuel or electricity). Determine the most efficient use of limited bioenergy resources.

Assumptions:

• efficiency of converting biomass to electricity is 30%
• efficiency of converting biomass to biofuel is 60%
• efficiency of battery electric vehicle is 85%
• efficiency of biofuel combustion vehicle is 25%
• efficiency of heat pump is 300%
• efficiency of wood furnace is 70%
• 1 ton of biomass contains 13*10^6BTU
• Question: If the total energy required for building space heat in the U.S. is 7*10^18J and total energy required for passenger vehicle transport is 16*10^18J, then what percent of building space heat and passenger vehicle transport respectively could be met by bioenergy?