| |
Biodiesel |
Hydrogen |
| Technological Readiness |
Can be used in existing diesel engines, which have already been in use for 100 years |
At least ten years away |
| Fuel source |
Algae farms or other vegetable crops, or waste conversion. Completely renewable process, with no net CO2 emissions. |
Electrolyzing water (most likely using fossil fuel energy) or reforming fossil fuels. Most likely non-renewable methods with large net CO2 emissions |
| Fuel Distribution System |
Can be distributed with existing filling stations with no changes. |
No system currently exists, would take decades to develop. Would cost $176 billion to put one hydrogen pump at each of the filling stations in the US. |
| Overall Energy Balance (each unit of energy put in yields....) [higher is better] |
3.2 units (soy)
4.3 units (rapeseed) |
0.5 units (electrolyzing water into hydrogen with renewable sources) |
| Large scale fuel development cost analysis |
For an estimated $1691 billion, enough algae farms could be built to completely replace petroleum transportation fuels with biodiesel |
To produce enough clean hydrogen for our transportation needs would cost $2.5 trillion (wind power) or $25 trillion (solar) |
| Safety |
Flash point of biodiesel is over 300° F (considered "not flammable") |
Highly flammable |
| Time scale for wide scale use |
5-10 years |
30-50 years optimistic assumption |
| Cost of engines |
Comparable to existing vehicles |
Currently 50-100 times as expensive as existing engines. The cost of the fuel cells themselves will come down significantly – the cost of the infrastructure and making the hydrogen will not |
| Vehicle performance |
Significantly better range than gasoline vehicles, comparable power (roughly 700 mile range for Volkswagen Jetta TDI) |
Significantly smaller range than gasoline vehicles (180 mile range for Toyota’s FCHV) |
| Tank capacity required for 1,000 mile range in conventional sedan |
20 gallons |
268 gallons |
