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Doctorate in Mechanical Engineering, entreprenuer
Interests: diesel and gasoline engines, cars, aircraft, railroads, electric drives
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I should add that fuel cell research has been going on since 1838 and we still do not have practical fuel cell vehicles.
I expect that Lithium-Sulfide will be the next breakthru in battery technology. There are a number of people working on the problems and they seem to be making good progress. It is also good to see a major automotive company seriously working with Li-Sulfide. Lithium-Air might render the IC engine to dustbin of history but that is an much harder problem. I agree with SJC and Treehugger on most people not understanding how much time and effort it takes to get a new technology to market. I remember attending a seminar 45 years ago when I was a ME graduate student at MIT. The speaker had a new magnetorheological fluid and demonstrated some of the properties but stated that he had no idea what it could be used for. At the time it was just a laboratory curiosity. It took 30 years or so but now some of the Cadillacs and Corvettes have tunable magnetorheological shock absorbers along with a host of other applications. LED's have been around since 1962 but only in the past few years have they made major inroads in lighting.
Roger Pham I work as an engineer and am also a principal of a small company that builds a relatively high tech agricultural harvester. We use a hydrostatic transmission which is what you are describing for the wheel drives. Electric would be more efficient but a relatively small amount of the total power is used for traction. We also use some hydraulic motors and cylinders for other functions such as conveyor drives and lifts but where we are different is that all of the high speed positioning is done with 375 V electric servo motors. The use of the electric drives gives us a substantial efficiency and maintenance advantage over our competitors. As we go forward, we will be electrifying more of the functions and may add ultracaps to recover some of the available power from deceleration.
Engineer-Poet Your are right in that power is pressure * flow rate and with a variable displacement motor, it is possible to reduce power without throttling losses by changing the flow rate. You do need a variable speed transmission as the pressure gives you torque and the displacement gives you rotational speed. No matter what you do, you will have a less efficient system with hydraulics than you would with electric. However, the hydraulics may have a lower initial cost but would probably require more maintenance.
Would this work? Yes, but. I tried make some reasonable (maybe even generous) estimates and then do some calculations. If you do like my estimates put your own in but no fair ignoring physics. I assume that is a hydraulic accumulator type hybrid but it does not really matter. Anyway, energy is change in Press * Volume. I assumed that change in pressure is about 2000 PSI or 14,000,000 Pa (Newtons/m**2) and the tank volume is 50 liter or 0.050 m**3. Multiplying the two, yields 700,000 Nm or 700,000 Joules. Remembering that a watt sec is a Joule, so a watt hour is 3600 J and a kilowatt hour is 3,600,000 Joules. Anyway, with my assumptions (which may even be generous), you end up with about 0.2 kilowatt hour equivalent. OK, so this would work if you were doing most stop and go but you are not going to get far on just the stored energy. One other fly in the ointment and that is efficiency. With electric power, you can chop the current or use pulse width modulation to control the power. Full on for a few micro seconds and then full off for a few micro seconds. You can not do this with hydraulics. You have to throttle the flow. Even if the system was 90% efficient at full power (which I doubt), it would only be 45% efficient at half power. And we have not even worried about the heat that is lost if we do not immediately use the power. Anyway, this might work OK for mail delivery or trash collection where you start and stop every 50 meters but, even then, my money would be on electric power with ultra caps. This is also how John Deere and Caterpillar bet with their hybrid excavators. Bottom line -- I do not think that this is break-thru technology.
The US Tier 4 Final and the Euro 6 compliant engines are quite clean. In some places, the exhaust make actually be cleaner than the intake air. The real problem is the older engines especially the engines that predate common rail electronic injection. Also, until recently, the EU standards were more lax than the US standards.
HarveyD According to the CIA, the estimated 2014 birthrate in Canada is 1.59/woman. This is well below replacement which needs to be about 2.2 - 2.3 to account for those that die before reproducing. The US is about 2.01 which is still below replacement. Even Mexico is down to 2.29. Most of the countries with really high birthrates are in Africa and the Middle East. Even India is down to 2.51. Anyway, I will stick with my PC suggestion for more education for women. War is so messy. I could suggest getting rid of religion but that is probably not PC. On your other comment, the US is not likely to have high speed rail any time soon except on the coasts as the population density and the distances traveled will not support it.
HarveyD I more Politically Correct (PC) approach would be to support women's education. With education, the population growth rate would fall, the demand for resources would fall in the long term and we might even have fewer wars.
Not sure what this has to do with sustainable mobility but it is interesting. I suppose if I had mounted on my truck, I could eliminate those old smoking vehicles that cross my path. I actually worked briefly on a predecessor to this vehicle almost 45 years ago. It was a tracked vehicle designed to destroy aircraft with a lot power for the laser but the technology was not well enough developed for it to be practical.
There is an interesting commentary in the current New York Times concerning a test drive of a VW Diesel Golf. "But no crossover, and no hybrid for that matter, can do what I managed in the new diesel-power Golf TDI: 60.6 miles per gallon over 75 highway miles along the Jersey Shore. That’s my personal highway m.p.g. record for any American-market car I’ve tested, including the Toyota Prius." "In stark contrast to a Prius, a car in which I feel my life force oozing away with every mile, the VW isn’t a sluggish chore to drive."
I have no idea if Lux knows what they are talking about or not. I have not taken a Tesla Model S out for a test drive It looks like a nice vehicle but is not what I currently need. I do hope that Tesla makes it in the market place but I would not buy their stock as there is no way that their current market capitalization of $35.4B (number of outstanding shares * share price) makes sense when Ford has a maket cap of $68.3B and GM is $55.8B. Tesla as a company is just not worth half of Ford or 5/8s of GM despite what you might think of Ford or GM. By the way, I am not an anti-EV troll and worked on an Electric Vehicle as far back as 1968 when I was a grad student at MIT.
HarveyD I wish you were correct and it was so easy. However, the largest on-shore wind turbines, I could find were 3.2 MW from GE and 3.3 MW from Vestas. There are limits to how large a blade can be and still be transported and how large the diameter of the tower can be and still be transported. Vestas has built a 8 MW off-shore wind turbine and that apparently is the largest to date. Most commonly, the on-shore wind turbines that are presently being installed are about 1.5 MW. These numbers are the rated power and for on-shore wind farms, you are doing very well to average 20% of the rated power. So if you take 1000 MW for a new nuclear plant and 2.5 MW for a very large on-shore wind turbine and then take the average output to be 20% of that or 0.5 MW, it will take 2000 of these wind turbines to equal the power of the nuclear plant and I think that I am being generous with the numbers. I would like to see a verifiable reference for wind turbine power being produced at 2.0 cents to 2.5 cents per kWh As I said in a previous post, about a month ago I flew in a private plane from Utah to Wisconsin and back. We flew low enough so that it was easy to see the wind turbines on the ground in Wyoming, north western Nebraska, and southern South Dakota and Minnesota. Almost none of the turbines were rotating and I think I could have counted the turbines producing power on my fingers.
I have a hard time understanding why some many people fear nuclear power and favor wind turbines. If you throw out the Chernobyl disaster, there have been more fatalities involving wind turbines than nuclear power. It takes several thousand wind turbines to generate the power developed by a nuclear power plant. The rotating equipment has to be maintained at a height that is often 100 m (~330 ft) or more above the ground. There have been numerous nacelle fires and blade failures and even some complete tower failures. For more information on this than you ever wanted, see The main problem with nuclear power has been the spent fuel and now there are a number of newer designs that will essentially burn the waste and the so-called depleted uranium. There is nothing that is truly safe but I would rather live near a nuclear power plant than a wind turbine farm.
HarveyD If, by this small firm, you mean Sakti3, Tesla would be about 4 years late.
HarveyD The 1.4 liter turbocharged Ecotec engines for the North American Market are made in Flint, Michigan. I am not sure where the automatic transmissions are made but I am reasonable certain that they are either made in the US, Canada, or Mexico. A few parts are probably imported from other countries including China but most of the car for the North American Market will be manufactured in North America. These are global cars and are designed for a global market. It was introduced in China but as the article notes most of the testing was done in Germany. I am glad to see GM is using a dual clutch transmission as I believe that this will be the most efficient type of transmission both for economy and driving performance.
HarveyD I am quite sure that the sedan as shown will be built in the US for the US and Canadian markets. The US Cruze is manufactured in Lordstown, Ohio. The Cruze is also manufactured in Australia, Brazil, China, India, Kazakhstan, Russia, South Korea, Thailand, and Vietnam. In some markets there are also hatchback and wagon versions. The current Cruze is a nice car but the new version looks to be quite a step up.
ai_vin F(drag) = CD * Area * Air Density * Velocity * Velocity / 2 and if you SI units, the force will be in Newtons. The point that I was trying to make is that these cars are not aerodynamically efficient and that our understanding of aerodynamics has increased dramatically in the past 50 years. A Chevy Cruze would have less aerodynamic drag than these cars.
I can not believe that anyone with a knowledge of engineering and/or physics can believe that we can realistically generate hydrogen from wind or solar power. Just to provide the electric power that we now require using wind power would require covering the area twice the size of Wyoming with wind turbines using the recommended spacing (I picked on Wyoming because it is a neighboring state with wind turbines and I had seen a pro-renewable energy presentation that showed that it would take an area at least the size of Utah but Utah has really bad wind conditions and when I did the calculations using what I considered reasonable assumptions and the recommended spacing between the turbines, I got about twice the area). Simply put, we will not have excess wind power (or solar) to waste on electrolysis. If you do have renewable electric power, it makes far more sense to use it to replace some electric power now being produced using hydrocarbon fuels. As an aside, I recently made a low level round trip flight from Utah to Wisconsin and went over quite a number of wind farms. Almost none of the turbines were turning. I think that I could have counted the number of turbines that might have been producing power on my fingers. All I could think of was, "what a waste of capital equipment".
"physics doesn’t change much over time." The physics does not change at all but our understanding of aerodynamics has changed dramatically. I was stunned to see that the CD (coefficient of drag) of an E-Type Jaguar was 0.44 while most current street cars have a CD of about 0.30 to 0.33 and some practical cars are even less than 0.30 and a few semi-practical cars have a CD less than 0.20. Beautiful cars -- both the E-Jag and the LeMans Cobra but they are not efficient either as race cars or street cars. This car was made to be looked at.
Fuel cells are so early 19th century technology (1838 to be exact - ). Talk about a technology that has taken a long time to mature. Seriously, the real problems are with generating and storing hydrogen. Probably, the only practical clean source of hydrogen is high temperature disassociation or high temperature electrolysis using nuclear power and even then you are probably better off just using the electric power for other needs.
Short of some magic lithium air batteries, this is probably the most practical way to electrify heavy trucking. I would rather see electrified railroads but the shuttles they are talking about are moving the containers from the ports to the railroad yards.
@Otis The aircraft diesels will run on Jet A or on the common #2 diesel and should also run on the military JP-8. The US military tries to run everything (trucks, tank, aircraft) on JP-8
Amazing. An aircraft engine that does not use 1930's technology and does not require 100 LL (100 Octane Low Lead) which contains a know neural toxin. I attended the Oshkosh airshow earlier in the week and looked at some of the Continental Diesels. I am building a light sport STOL aircraft and have a 115 HP Rotax 914 engine which is a liquid-cooled turbo-charged spark ignition engine that will run the higher octane automobile fuel. I would rather run a diesel but the ones currently available are too large and too heavy for my purposes.
I will echo Herman's "Well Done" comment.