of the advantages of the saved fuel costs. You seem to use small unrepresentative countries Switzerland and Denmark to make your points. How much heat recovery could New Orleans use? BTW, electric motors are 90+% efficient in every case I can think of. Gasoline ICE motors 0% to 30% (actual US average @ 15% if you include the vehicle mass. &gt;1% if you consider the mass of the passenger). The CHP for the University of Texas at Austin is 68% efficient and could be higher with new equipment, purposely designed. Low grade heat produces chilled water with absorption cooling. CHPs can be throttled between heat and electricity production, depending upon the demand. A good thing ! Since the C/R ratio drops you need more R to get more C. Yes, lowering EROI accelerates depletion of lower grade materials but not all that much. In the hypothetical example, a world running on 75 mbpd of sweat crude would be equivalent to a world running on 99 mbpd of tar sands and shale oil. The world only have 37 years left of conventional oil 1000 Gb/ 27 Gb/a). Unconventional oil alone would last 50 years(500 Gb Canada, 250 Gb Venezuela, 600 Gb Colorado=1350/27) but derating for EROI it would last (another)37.5 years. EROEI matters because we can't do anything without energy and putting in more energy, into anything, than you get out gets you on a perilous downward slope. Of course, some low EROEI might be of benefit, because of the form