A couple of points to make
First, Ethanol does require fuel input to make. Currently this process still yields about a 30% net energy gain from processing. Other materials are better suited to this process and bacterial or catalyst assisted conversion processes are in development and hope to improve this dramatically.
Second, the energy input required for conversion can be substituted with just about any system other than fossil fuels commonly used. Only heat is really required. Using solar heat or wind-to-electric energy is also possible for ethanol conversion. Other common farm processes can also be used to generate this heat which by the way themselves result in usable byproducts (charcoal)
Next, Ethanol production also yields material waste, which can be converted to charcoal (and provide heat in the process to make more ethanol!). This charcoal can be sold to power plats in place of coal. It's actually both cleaner AND more efficient for use in power generation than coal. The output of the coal power plants can be flushed through algae and other materials yielding a very powerful fertilizer which can be provided back to farmers for ethanol plant growth.
Ethanol can be used to power the vehicles that move the fuel and materials back and forth. More detailed explanations about how this all pulls together are found here: http://www.theoildrum.com/story/2006/11/27/0432/3533
OK, now onto Hydrogen. Not only is it less efficient for direct combustion, cost nearly 5 times as much to produce, and the fact that we have to worry about boil off, we're talking about giving people mobile bombs to drive around in!!! Fuel cells work OK for making electricity on large scale, but are almost worthless for small vehicles. We're 20+ years from sufficient battery and motor technology to work this out.
Nuclear?!? We have at best 30 years of nuclear fuel at our current rate of use. We'll be out of it before we're out of oil or natural gas. Even if we bring online a dozen condensers, we're still looking at maybe 75-100 years of fuel. Besides, making a nuclear generator small enough to go in a car is at least 50 years off.
Wind, water, and solar power backing up plugin/ethanol hybrid's using recyclic turbines for electric power instead of typical combustion engines will give us plenty of power to move even 18 wheeled trucks, will more than triple current fuel economy, and it CAN be done. In fact, we can do it at a PROFIT of about $400 per person per year vs current fuel technology, and we can start today. Lets get that start by making farmers plant ethanol crop in their empty fields that their currently being paid not to plant tobacco in...
Oh, 1 last thing. FORGET CORN! It's not good enough. There are crops that produce more ethanol per yield with more yields per acre per year, and they cost less to grow, harvest, and process than corn.