The Next Prime Movers

Electric Drives are potential prime mover substitutes for I.C engines.

Mobile workability has made the development of I.C engines to this extent.

Burning of fuels for energy is the wrong concept which humanity is recklessly following with deliberation in spite of all it's negativities.

We seem to be used to a well known utility than attempting green alternates.

First, let's look at the reasons I. C. engines are predominant in transportation. The engines and fuels (considered together) have the best energy/mass and energy/volume ratios of any readily available technology. Likewise, nothing surpasses liquid fuels for speed and convenience of refueling and handling. Wind power fails on the convenience factor; becalming has always been a problem for sailing ships. Solar power fails both the convenience and energy density tests - solar cars are great toys, but they are range limited after dark and can't carry much. Nuclear power for ships has many advantages over I. C., but due to its high initial cost and specialized operational requirements is not considered "readily available." Muscle power cannot compete with the energy density, and animal excrement was a major environmental problem in urban areas before horses, donkeys and oxen were supplanted by I. C. vehicles. The disadvantages of I. C. technology are well-known: the efficiency of Carnot-cycle engines is limited by the maximum practically obtainable temperature difference. The maximum burn temperature in I. C. engines is limited not only by materials and combustion chemistry, but by laws restricting nitrogen oxides emissions. (Anyone who develops a cost-effective means of solving the NOx problem without limiting combustion temperature deserves fame and fortune; the solution will enable a significant improvement of efficiency.) Likewise, other emissions must be controlled to minimize environmental damage, but fortunately these are best mitigated by making the engine more efficient. A frequently cited concern about combustion-based engines is CO2 emission and purported greenhouse effects. This may be somewhat misplaced - the real concern should be over the failure of the biosphere to take up all of the restored carbon from fossil fuels. A greater limitation is the availability of suitable liquid fuel at a reasonable price. At present, bio-fuels are probably a losing proposition when their production comes at the expense of food and plant fiber production or environmentally necessary "wild plant" growth. In this respect, oil and gas are less harmful for the environment. Unfortunately, economically recoverable supplies of these are being rapidly depleted. This will be the fundamental limit of the liquid-fueled internal combustion engine: when the convenience and power density no longer outweigh the fuel cost, compared to the performance penalty of electrical energy storage or the difficulties of gaseous fuels. (Notice that I have shifted the topic a bit: liquid vs. gaseous fuels should be a key sub-thread to this discussion.)