I wonder what the energy density of granite is, compared to a battery… ;-)
Thermal storage mass is around 5-10x higher (net) given that it is thermal and hence needs a heat engine
Great for heating and stationary applications, useless for transport
Pump water storage is a proven and widely deployed energy storage method, despite its energy density being very low. Nobody has suggested to use that to power cars
Turns out I was wrong… :-D
[ URL cleaned up to just the required bit ]
This is what I get, while driving at least 20% above any speed limit
Once more about the Manhattan Institute study and then I’ll shut up
Getting further into the document I see figure 7 which says that up to 50% of gain of fuel efficiency of ICE cars in the period of 2018 to 2030 is possible. I must have been living under a big dark rock, so someone please enlighten me. More important than enlightening me, please enlighten Lycoming, Continental, Austro and Rotax who seem not to have found the magic formula to make that happen.
I don’t think I’m going to be spending more time on this study. I continue to stumble on half thruths, deceptive data and a lack of a wider and longer view on the whole issue of BEVs.
It starts with figure 1 misleadingly leaving out population growth. Then no mention of the seemingly viable chemistry of Sodium which ‘mining density’ is three orders of magnitude bigger than Li (a factor 1.000) which undermines the study’s sums in a big way. Besides, isn’t is viable to extract Sodium from ordinary salt? Works nicely in my pool, NaCl plus a tiny bit of electricity gives me the Cloride I need and the rest must be….? No mining needed? And then the claim of a 50% increase of efficiency of ICEs.
And no mention of oil running out. The current estimate is 50 years, and the fact that they said the same thing 50 years ago does not mean that the current estimate is wrong.
It seems to be a document trying to sow doubts based on a purely political agenda.
@Silvaire in a couple of years you will tell us that you are retiring. I have to inform you that regretfully I will then tell you that will not be allowed 🙃 We need your excellent engineering skills and experience to push forward electric energy storage and propulsion!
@Airborne_Again my position is that man made climate change has been sufficiently proven. Interestingly I meet more and more people who were either deniers or doubters who start to change their minds. However, quite a few of these go into “we need to adapt” mode rather than go towards carbon neutral. I usually tell the ‘adapters’ to try and sell that idea to the people in countries that don’t have the means to prevent their land from flooding and are not welcome to move elsewhere, or to Californians who see their homes go up in flames.
aart wrote:
Getting further into the document I see figure 7 which says that up to 50% of gain of fuel efficiency of ICE cars in the period of 2018 to 2030 is possible. I must have been living under a big dark rock, so someone please enlighten me. More important than enlightening me, please enlighten Lycoming, Continental, Austro and Rotax who seem not to have found the magic formula to make that happen.
You can make ICEs in cars more efficient by adopting design methods and technologies that improve the ability of the engine to operate efficiently at a variety of speeds and under different loads, as is required of them. Things like variable valve timing and lift, much more adaptive ignition timing, really precise mixture control, etc. This is all stuff that’s made a big difference since it came in, and I don’t doubt there will be further developments.
It doesn’t have much application for piston aircraft engines because they spend nearly all their time at a single constant power level.
up to 50% of gain of fuel efficiency of ICE cars in the period of 2018 to 2030 is possible
I think this is a mixture (good pun) of things.
I absolutely do not believe a petrol car engine in 2018 will produce 1.5x more power for same fuel flow in 2030. Well, you can definitely do it if you remap an engine for best perf and ignore emission regs 
But diesel cars often do 60mpg, and even big ones like a big Merc estate were doing 50mpg 20 years ago (a friend drove one). Various reasons, starting with the higher compression ratio, and then details like not allowing coolant to flow into the cabin heater until the engine is fully hot (an irritating feature of diesels when used for short trips).
So if you take cars as a whole, I can believe it.
In GA, stuff doesn’t happen because of slow or nonexistent market acceptance, together with (as Graham says) mostly constant power running, at around peak EGT i.e. stochiometric. And the companies are old, stale and incapable of doing good R&D even if they had the volume to pay for it. Then we get onto the old Q of why car engines are not used in GA… well it is because if run at say 65% of max rated HP continuously, they would break very soon. The reason why car engines are very reliable is because they spend most of their life at 10-30% power.
go towards carbon neutral
This is for the climate change thread but surely there is no such thing – all the time you are burning hydrocarbon fuel somewhere.
When comparing petrol and diesel, you can’t just take the MPG and compare them because diesel is both denser (more kg/L) and more energy dense than petrol per kg. 36.9 MJ/litre compared to 33.7 MJ/litre for petrol (assuming the petrol hasn’t been adulterated with ethanol, which is less energy dense). Also be careful about MPG – American gallons are 3.8L, but UK gallons are 4.54L. It’d be better to stick to L/100km.
So a diesel that does 60 UK MPG is 4.7L/100km, or 173.4 MJ per 100km.
So a diesel that does 60 UK MPG is equivalent to a petrol car that does 5.15L/100km or 54.9 UK MPG. (My petrol Honda Civic will do that on a motorway journey, local journeys not so much).
Thermal storage mass is around 5-10x higher (net) given that it is thermal and hence needs a heat engine. Great for heating and stationary applications, useless for transport
In combination with a Brayton cycle and generator it’s not useless at all when you consider that the biggest problem with breaking the connection between fossil fuels and EVs on a world wide basis is the delivery of huge amounts of solar-sourced power at night. Otherwise it can’t and won’t happen. EVs have a lot of other problems too, but this is one of the bigger ones. It’s a stationary application.
Reducing the world population by 50% over 100 years would be a whole lot easier than stubbornly persisting in trying to make the world support an absurd number of people via technologies that won’t actually be effective in that regard. But nobody said people or politicians are rational – that’s the main issue, people are driven by instinct, apt to delude themselves with nonsense, and (worst) increasingly supportive of authoritarian rule to eliminate rational debate and effective choice. EVs have all that written all over them.
Peter wrote:
This is what I get
I used to keep track of car mileage by adding up fuel receipts and dividing by miles driven. The difference was small but noticeable, in that the car computer consistently displayed a few % better economy than reality. I don’t know what caused it, maybe it not counting fuel on low flow (idle), or batches of diesel at different densities, or possibly vapour loss. Not to mention VW mendaciousness
