Yes, you're right. The "40 acres of wheat per gallon of gasoline" was sensational enough that I stopped there. However, my conclusion stands: biomass is not a scalable option for renewable energy.
The article goes on to say, "we would need to harvest 22 percent of all land plants just to equal the fossil fuel energy used in 1997". This calculation is for using plant material directly, not as prehistoric biomass.
The 22% is roughly the fraction of arable land in the US -- and that assumes the US only uses energy at the average global rate, which we know isn't true. The US uses far more. So to produce the necessary biomass, the Americans would have to use up more than all the arable and farmable land they have, leaving nothing left for trivial things like growing food.
Only 7% of China's land is arable, so using valuable farmland to grow biomass is even less feasible. What's more, China's energy needs will probably grow four or five times in the next century. This makes biomass utterly insufficient.
Conclusion: biomass is not a scalable option for renewable energy.
Solar power is enough for Earth, many times over, if we use solar power satellites (SPSs). However, the satellites are probably several decades in the future. If we're stuck on terra firma, we need to store the solar energy for nighttime, which means either batteries or hydrogen. Batteries have a problem: there may not be enough resources to make enough batteries for terawatts of power storage. That leaves us with hydrogen, which should work.
ok, it seems that you did not understand my argument, which is from a chemical thermodynamics perspective.
your statement about biodiesel is not relevant to the response to "where does the carbon for methanol come from" because in my proposal, the biomass is a renewable source of carbon, not of energy.
The energy comes from the enthalpy of formation of the methanol from the hydrogenation of the products of biomass gasification. It is a scheme for the utilization of hydrogen with renewable carbon.
It is not a biodiesel scheme. I never used the words biodiesel. biomass usage as carbon source in a gasification process is not biodiesel.
Again, from a chemical perspective, here is how the gasification + hydrogenation process looks:
plants (CxHyOz in general) + O2 + heat -> C + CO + CO2 + H2O + some energy of combustion
C + H2O -> CO + H2 (syngas formation, +181.33 kJ/mol)
CO + 2H2 -> CH3-OH (methanol formation, -127.9 kJ/mol)
CO2 + 4H2 -> CH3-OH + H2O (
Net enthalpy change: -111.57 kJ/mol. You are free to check my work and calculate the enthalpy of reaction for each reaction yourself.
This is thermodynamic proof that for gasification and hydrogenation of generic carbon containing plant material, there is net energy gain as long as the H2 in the equations are "free".
The H2 from renewables is "free".
This is actually a hydrogen power scheme, not a biodiesel scheme.