The same logic applies to other forms of alternative energies as well, not just ethanol.

It is going to be extremely difficult to replace gasoline as an energy source. The energy content of gasoline is very great and there simply aren't any viable alternatives that even compare, much less exceed the amount of energy contained in a liter of gasoline.

Per liter, gasoline has 1.48 times the energy of ethanol.
Per kilogram, gasoline has 1.72 times the energy of ethanol.

Hydrogen has nearly 2.9 times the energy as gasoline per kilogram, but because it is so light, it's too difficult to get enough hydrogen in one place to matter. Even if it was liquified to cryogenic temperatures, gasoline has nearly 3.5 times more energy per liter. And who's going to drive around in a car with a tank of highly explosive liquid hydrogen? Remember the Space Shuttle Challenger? That was liquid cryogenic hydrogen exploding.

Another nail in the coffin for hydrogen is that it takes FAR more energy to produce hydrogen than you can extract from it's combustion. In fact, the number one most viable method of producing hydrogen in mass quantities is extracting it from crude oil.

Propane has a slightly higher energy density per kilogram than gasoline, about 3 %. Though like hydrogen, but not as bad, it's difficult to contain in sufficient quantities to matter. The energy density of gasoline per liter is 1.36 times that of propane.

More energy comparisons can be found in the following document.

"Some Energy Fundamentals" - http://www.tinaja.com/glib/energfun.pdf

Also of interest is the Gasoline FAQ, where you can learn more about gasoline than you ever thought you might even hint at contemplating about wanting to know.

"Gasoline FAQ" - http://www.faqs.org/faqs/autos/gasoline-faq/part1/

I personally feel, based on the knowledge I have, is that the only answer is nuclear power. Solving the issue of nuclear waste disposal is a far easier task than solving the oil/CO2/greenhouse/pollution problem. It's a simple engineering problem that is largely solved. The only impediment is the political NIMBY attitude.

But that is assuming using currently used nuclear reactor technology. There are designs for reactors that produce far less waste and are much safer if not fail safe. Some of these designs have already been tested.

There are even designs for reactors that use for fuel what current reactors generate as waste. These designs basically 'recycle' the nuclear fuel to extract the maximum amount of energy from the uranium.

Did you know there is a sort of uranium shortage? If we built enough reactors to supply our energy needs there isn't enough uranium to go around. Hence the design of the waste recycling reactors. Normal reactors only extract a few token percent of the total energy content in uranium fuel pellets. The new reactors could exceed 50% extraction of energy.

In addition to nuclear, there are other electric generation sources such as solar and to a lesser degree, wind. Can you imagine if every building and home had at least a minimal solar panel on it? Why, that distributed energy generation capacity would be the equivalent of several nuclear reactors. Even if the building or home still needs some electricity from the grid, it wouldn't be as much.

Finally, for transportation, if we could build enough electrical generation capacity, we could all drive rechargeable electric cars. Then that would solve the issue of electric vehicles requiring more energy than it replaces, because the energy is derived form powerful, efficient, and cleaner nuclear and solar sources rather than dirty smoggy polluting fossil fuel sources.

Ah....but human nature being what it is, it won't happen unless somebody can get rich off it.

One can only dream....

Brian