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Steve Reynolds
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"...unless of course, it hits another 6,000 lb SUV." No, there is good data showing the additional crush space provided by a larger car makes a huge difference.
So Lad, you expect people to buy and put their families into dangerous small cars so you can be happy about reducing oil consumption? Talk about trading blood for oil. Let's have safe green hybrid or electric cars, not dangerous tiny cars.
"There is no practical way to meet the 54.5 mpg emission standards by 2025." But isn't the Prius there right now by that measurement?
"Passenger load factor (i.e., percentage of seats filled) and freight carriage are relatively less important drivers of fuel efficiency." "The impact of premium seating on emissions is substantial." Those two statements seem contradictory to me. What is the density difference between premium seating and empty coach seats?
Harvey, this seems like a good application of solar energy from a power tower. Avoid the conversion to electricity until needed late in the day. Then use the gas turbine.
Roger: "The concept of long cylinder for weight-optimization for containing high-pressure gas is well known in the industry. It is already validated via the tube trailer for transporting industrial gases. Please kindly look it up." I did look it up; spherical is optimal for minimum weight by 2x! Tubes (especially steel up to 600mm diameter) are cheaper. "Theoretically, a spherical pressure vessel has approximately twice the strength of a cylindrical pressure vessel with the same wall thickness,[3] and is the ideal shape to hold internal pressure.[1] However, a spherical shape is difficult to manufacture, and therefore more expensive, so most pressure vessels are cylindrical with 2:1 semi-elliptical heads or end caps on each end. Smaller pressure vessels are assembled from a pipe and two covers. For cylindrical vessels with a diameter up to 600 mm (NPS of 24 in), it is possible to use seamless pipe for the shell, thus avoiding many inspection and testing issues, mainly the nondestructive examination of radiography for the long seam if required." From: https://en.wikipedia.org/wiki/Pressure_vessel
"25 kg of H2 at 10kpsi would have a volume of 640 liters." While Roger's idea of extreme use of tank structure in the wing is interesting, if weight balance is the issue, it could be solved much more conventionally. How about: A near spherical (but somewhat egg-shaped) tank could be just over 1 meter in diameter, just behind the second row of seats and still contribute structurally. The COG of the tank contents could be just 70cm behind the COG of the plane. If 25 kg removed from that close to the COG is a problem, it could be balanced by pumping 2.5kg (less than one gallon) of water from a tank in the nose to a tank in the tail.
"...how do you get the energy out of that small space and turn it into electricity that can go onto the grid." Liquid Li2BeF4 salt at 900K (with heat capacity similar to water) carries the heat to where it is used to heat He gas. The He gas drives a conventional gas turbine.
Infrastructure is an issue for anything new, but unless oil stays cheap, long haul trucking is likely to switch to natural gas fairly quickly for the cost savings. When most truck stops have NG available, this blending could be practical. A 10% efficiency increase combined with the lower carbon content of NG seems worthwhile to me.
"California will increase from one-third to 50% its electricity derived from renewable sources..." Does this include imported electricity (like what they get from coal plants in Arizona)? I suspect they are only counting what is generated in CA, not what is used.
But Harvey, the global effect of what is done in Europe and North America is pretty small now. The cost issue is much more important to people of China, India, and Africa. It determines whether they drive anything at all and whether they even have electricity. They will choose to have a modern lifestyle (I don't blame them) whether you like it or not. R&D to reduce the cost of non-fossil energy is much more likely to be helpful than trying to force people to pay more for renewable energy.
Looks like an excellent phone or laptop battery, but discharge rate is too low for a car (unless you want a 500 mile range at 50 mph).
Looks to be presented in a biased manner against CNG to me. Seems they took as their CNG example an engine that did not work well. I also wonder what time frame was used to compare the GHG impact of the CH4 emissions to CO2. It is easy to get a large CH4 impact if you use a short time frame.
This looks like an excellent alternative to use in vehicles that Toyota is designing to use fuel cells. Then a version of essentially the same vehicle can be sold where hydrogen is not readily available.
Even liquid hydrogen is not very heavy. It seems a hydrofoil would work well (high speed, low energy use) for a ship like this.