<2003 model cars show steadily declining fuel economy

I ought to point out, especially since I know so much about the subject, how exactly we can achieve renewable energy for transportation on a national scale....

Hydrogen is bullshit. In spite of the high efficiency of hydrogen fuel cells, the most compact hydrogen storage method are compressed gas cylinders with 4 - 11 weight-percent storage capacity. In other words compressed gas tanks weigh 10-20 times more than the fuel stored inside them, and this technology is not expected to improve in the next 20 years. As a result a hydrogen-fueled car will have either non-existent passenger/cargo carrying capacity, or very short range. Via the fundamental equation for kinetic energy the increased weight of the car due to the hydrogen fuel tank will mean more fuel is consumed just to get the car up to highway speeds, and the heavy car will experience more rolling friction. A hydrogen fuel cell car will cost as much as a house (can you say "mortgage"?). The reciprocating compressor used to refuel the car with compressed hydrogen will run you an extra $5000 plus tax, and the least expensive source of hydrogen will be natural gas, a non-renewable fossil fuel (OH YEAH! that's the bitch!!!).

In contrast a featherweight container will store gallons of liquid fuel, such as ethanol. Ethanol is the way to go, since the fuel tank does not contribute to increased weight of the car. Ethanol can be made at home by fermenting sugars and starchy plants. It is made on an industrial scale by converting whole plants (composed of cellulose) to fermentable sugars in a process called hydrolysis, where the long fiber chains are broken down into glucose using a weak acid solution.

Most plants consist of up to 98 percent cellulose. In fact cellulose is the most abundant substance made by living things. Originally petroleum came from cellulose, but it has been rotting under the earth for millions of years. Freshly grown biomass can be made into ethanol, which is cleaner burning anyway in internal combustion engines. And as a pure fuel, ethanol can be used in fuel cells as well should they ever become affordable.

But how do we grow enough biomass to fuel the transportation industry with ethanol without competing with food production? See my essay entitled "Benthic Energy", found near the bottom of my starship generations website:

Starship Generations