Ask the Best and Brightest: Wave Disc Engine?

Robert Farago
by Robert Farago

Next big future? How many times have we heard that before? [Thanks to MMH for the link]

Robert Farago
Robert Farago

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  • PeteMoran PeteMoran on Nov 08, 2009

    What the good Professor says (I think) is you can go 3.5 times further than a "regular" hybrid vehicle or 5 times further than an otherwise normal SUV (which I guess means hybridising the SUV first, then the 3.5x rule applies). In other words; 20MPG turns into 100MPG. Anyway you look at it, that's a very big claim.

  • Udham Udham on Nov 08, 2009
    True. A gallon of gasoline contains about 33 kilowatt hours of energy. The Lotus Elise gets about 25 miles per gallon. That’s about 0.75 miles per kilowatt hour. The Tesla Roadster goes over 3 miles per kilowatt hour. That’s about 4 times more efficient. Seems like a lot of low-hanging efficiency fruit for us to pick. The problem with this analysis is - how do you define efficiency? Something like the Telsa Roadster moves the Carnot efficiency hit upstream. Assuming that the efficiency of the coal plant combined with the efficiency of the grid is 50% (sounds reasonable), the efficiency multiplier of the Tesla just dropped to 2 instead of 4. Driven conservatively, the elise can hit 30+ mpg on the highway. That makes the efficiency gain of the Tesla even smaller. Obviously if the upstream plant is nuclear/wind/solar, then from a carbon standpoint, the Tesla is much much better. Wind/Solar with the current state of the art will not be able to generate the energy the world requires. Nuclear suffers from a serious case of NIMBY.
  • PeteMoran PeteMoran on Nov 09, 2009

    @ udham In my day-to-day work on and around energy projects we normally work with the "local" efficiency. It's an extremely complex task otherwise. People attempt it in the form of "Carbon Accounting", but that's a controversial subject (for some). In your rebuttal of the Tesla example, you could also make the same argument about MPG not taking into account the upstream energy costs of drilling, transporting and refining the fuel in a car. People don't (can't?) sit down to work that out. The only indicator as to what is going on, and it's highly distorted for ALL forms of energy, is the price per unit.

  • Udham Udham on Nov 09, 2009

    @PeteMoran I appreciate your response. I am not sure if my response was a "rebuttal" of sort. I was just trying to point out that there is more to what meets the eye as far as "efficiency" goes and that qualitative blanket statements are almost bound to be off. I agree that with oil, there is probably a relatively big added carbon cost of converting dino juice into the ground into something you can put into your tank. Of course, for coal/natural gas/oil fired plants, there is an added carbon cost of getting the carbon out of the ground and getting it to the power plant. So you are right, people are not going to want to figure out the intricacies of where their energy comes from, and exactly what their carbon footprint is. Maybe regulation is the answer, or maybe regulation leads to controversial and in my opinion asinine decisions like corn based ethanol being added to fuel.