ABSTRACT
A reasonable clue in choosing paths would have to deal with energy availability, that is, developing a technology that impacts a scarce energy supply may not be a desirable path. The technology will impact the energy supply in direct proportion to its market penetration and in inverse proportion to its average efciency. The market penetration implies an acceptable initial price and a reasonable operating cost. The latter is again inversely proportional to the efciency. Hence, efciency appears as a rst-order consideration in choosing a path. Efciency also matters when it comes down to waste or undesirable byproducts, because the higher the efciency, the less of them will be produced.
