Biofuels are unlikely to alleviate to any significant extent the current dependence on fossil energy…
Studies find that to produce 10% of US energy via ethanol would require 37 times the commercial livestock feed production. They say that providing US food plus energy via biomass would require 15 times the existing cropland, 30 times the agricultural water consumption, and 20 times present pesticide use.
If 8 billion people were to have the current Australian 128GJ/y oil plus gas consumption from methanol, the area of land that would have to yield 7 t/ha/y would be 22 billion ha. World crop land totals only 1.4 billion ha, world forest and pasture 4 billion and 3.5 billion ha, and total world land totals about 13 billion ha.
If we take the extremely optimistic project sketched by Hall at all, i.e., 890 million yielding 15 t/ha/y, then for a world of 9 billion this would yield energy per capita equivalent to a mere 5.6% of the present Australian oil plus gas consumption.
It estimates that 2.2 ha of forest would be needed to yield the 10,000kWh of electricity used by one person in a rich country per year. Thus per capita liquid fuel plus gas plus electric energy production from biomass would require 5.9 ha. To meet US oil plus gas demand would require a footprint of 6.5 ha.
If we assume methanol equivalent to 150 liters of petrol, 4.95GJ, can be produced net from each tone of biomass, then to meet the Australian oil plus gas demand of 2562PJ would require an input of 518 million tons of biomass pa.
If we assume an average yield of 7 t/ha, 76 m ha would be needed, which is almost 4 times all cropland and twice all good forest area. Such an average yield is highly unlikely from such a large area of Australian soil.
