[MainFrame65]

Are you certain that a diesel can run safely on light weight hydrocarbons? I would think that pre-ignition (knock) would be a terrible problem. And I seem to remember that using gasoline in a diesel engine can be very destructive, due to both knock and lack of lubricity because of the absence of higher weight (more like oil) hydrocarbons.

A pure-hybrid diesel electric car - a locomotive with tires, but smaller - would not need a transmission, and would operate at a much higher efficiency than a similar gasoline version. The diesel driven generator would operate only at its most efficient speed, and the electric motor(s) naturally produce an appropriate torque over a wide speed range.

I believe that the transportation fuel of the future is not very different from the transportation fuel of today - it will just come from different sources. After all, would you rather be rear-ended in a car with a 20-gallon tank of hydrogen gas compressed to 20,000 PSI, or a 20-gallon tank of gasoline, when BOTH contain the same amount of hydrogen? I consider this to be a very hopeful development, particularly if the process can use coal (carbon) as a primary input for hydrogenation.

The eventual solution would be to run most of our transportation on the electric grid, most of the time, using some kind of metered trolley or slot car type pickup in central cities and on major intercity routes. The hybrid I mentioned above, equipped with such a pickup device, could be the model private car - on the generator out of your garage and to the expressway, on the grid to (and within) downtown on the streets, and back to generator in the parking garage. Then the reverse going back home.

If we could do that, the Saudi's had better figure out how to run their economy on sand and salt water....

[alloysteel]

At one time, it was thought necessary to add tetraethyl lead to refined gasoline, to reduce the tendency of gasoline-powered vehicles to "knock" under load. When it was made legally impossible to buy leaded gasoline, the manufacturers of motor vehicles and refineries made the necessary compromises to develop fuels and vehicles that did not need tetraethyl lead.

The upper-end lubrication needs of Diesel engines can be similarly be engineered into the design. As will the capability to reduce preignition.

The rest of your points were very good.

[JAKraig]

Are you certain that a diesel can run safely on light weight hydrocarbons?

There are not many fuels that cannot run safely in a diesel engine. The major difference in diesel engines and spark ignition engines is that the high temperature needed for ignition come from different sources. In spark ignition engines it obviously comes from the electric spark. The fuel and air are mixed prior to the spark, when the spark fires it ignites the mixture, and you have power. In a diesel engine you heat the air first by compressing it, and compressing it at quite a higher pressure than in a spark ignition engine. After the diesel engine compresses the air the fuel is introduced. When the fuel is introduced to the high temperature air it ignites almost immediately and again we have power.

The problem is that some fuels ignite at lower temperatures than others. Gasoline, especially lower octane gasoline ignites at lower temperatures than say Diesel fuel. Because gasoline ignites at a lower temperature the compression used in a gasoline engine must be lower than in a diesel. Cheap gas (lower octane) causes knock because of pre-ignition. The problem is compounded when the engine and fuel are already hot as in hot city driving. When that happens the compression of the cylinder raises the temperature of the fuel-air mixture past the point of ignition and we have a premature ignition. Because the fuel is introduced prior to the compression it is difficult to use this pre-ignition, the only way to make it useful is to not premix the fuel and air and instead use real injection.

We hear a lot about fuel injection in our cars spark ignition engines but it is not the same as fuel injection in a diesel engine. A spark ignition fuel injection system usually injects fuel into an air stream where it mixes with the air and is then sucked into the cylinder is compressed and ignited. In a diesel engine the fuel is not injected until the air is nearly fully compressed and near the highest temperature it will get to prior to ignition, it ignites almost immediately upon injection. The engine timing controls when the fuel is injected and therefore when the ignition starts. No matter how hot the engine or fuel it does not change ignition. Since the diesel engine compresses the air to a much higher pressure than spark ignition engines the heat generated by the fuel ignition is converted into useful power at higher efficiency rate than spark ignited fuel engines. It also means that diesel engines produce very substantial torque in comparison to the spark engines.

The diesel has been much maligned in our culture. Using the proper fuel it can be a very clean burning engine. Nearly any fuel can be adjusted to raise it's ignition temperature. I expect that eventually the diesel will be the choice to replace gasoline engines. The fuel is much easier to make, it produces more power and can be 100% renewable, taking 1 part to make 4 parts. In other words if we decide to grow vegetable oil to fuel our diesel cars we can make 4 gallons with every 1 gallon we put into it.

We hear all this talk about hydrogen and fuel cells. It sounds good but we already have service stations that can easily adapt to handling more diesel fuel. We already have farmers that are willing to produce fuel crops. Why even think about hydrogen. In France 50% of all cars are diesel and they are running on a substantial amount of vegetable oil. In Germany the rate is approaching 50%. As oil prices go up it will be more and more economically advantageous to grow our own fuel. At that point we can tell the Middle East to take their oil and shove it, or leave it where the sun doesn't shine.


Diesel is the future and it's here now!