If diesel has higher energy density than petrol, is that per litre? per kg? (what's the relative density - any difference?) per kg of original crude? (might be that petrol has lower energy density but takes less of the original crude to produce). Is it useful energy potential after combustion? i.e. taking into consideration available combustion efficiency. Any of these could make diesel a more or a less wasteful use of the original crude, than petrol.

At any rate, the problem is it's all explosion-based (the method by which nature disintegrates spent material, ready to be recombined into fresh stuff) rather than implosion-based (how organisms handle their energy transactions other than the above) according to Viktor Schauberger, and as he told Hitler in 1938, any society that relies on that is doomed.

Posted By: fostertomAt any rate, the problem is it's all explosion-based (the method by which nature disintegrates spent material, ready to be recombined into fresh stuff) rather than implosion-based (how organisms handle their energy transactions other than the above)

It's the same reaction - Hydrocarbon (or carbohydrate) plus oxygen = water and CO2. Diesel has a higher energy density than petrol because it uses longer chain molecules (which have more carbon per unit mass) - this is partly why ethanol has a lower energy density than petroleum products. In an internal combustion engine, the higher the compression ratio, the more efficient the engine is. Note that diesel engines and gas turbines are not much different in efficiency - they're both basically heat engines and are governed by the same thermodynamics equations - basically the higher the operating temperature, the higher the efficiency.

Hybrids are more efficient in stop-go traffic because of the regenerative braking. At higher speeds, the efficiency is about the same as a regular IC car, possibly lower due to the extra mass of the batteries. Now a diesel-electric hybrid would be interesting. Except that was done decades ago - anyone remember the Class 55 Deltic locomotives that were introduced in 1958? Of course, this technology is being rediscovered again :)

Paul in Montreal.