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You can reduce the pulsating torque of a SRM using several techs. like: - Different number of stator winding poles and rotor teeth. You need a high number of winding poles for this, so I guess that's what they are aiming for. - Skewing. - Wave shape modulation. My pet tech. is the flux switching motor, which is closely related to the SR motor. Its has the same troubles (vibration due to irregular torque) and the same fixes.
I don't think FC are cost effective in any of those cases. Ship engines are cost sensible, fuel intensive, and lifetime intensive. Existing FC can't compete in those specifications. Train engines are less cost sensible, but the rest applies. Current LiFePo4 and LTO are cost effective and have long lifespans, plus you save a lot in fuel using batteries. I believe ships should bet in LNG as a way of reducing pollution and enhancing energy independence as sustainability (biogas can easily be produced if needed by any country, at quantities large enough to support shipping operations).
I don't get why the train industry is waiting so much to use modern batteries instead of expensive overhead lines... Batteries slightly bigger than this one are perfect for railroads. LiFePo4 or LTO chemistries will give you >10 year of constant operation and unlimited power. Exchanging batteries in the route end points should be trivial for the rail industry. And the "fuel" cost would be so low, charging the batteries at valley hours... That would make much more sense than electrifying ships, which is probably one of the most difficult applications for batteries.
What a pity, it seems BYD is going ternary lithium. I was hoping they would keep using LiFePo4 and I could buy one of their cars in my country in the future...No nickel, no Cobalt, that's what I understand as sustainable. Also, LiFePo4 is finally getting cheap and competitive in China. You can already ~$120/kwh in many products.
These guys are promising $150/kwh now, and $85 in 2020. I wish them well, but that's not cheaper than current li-ion ($100/kwh). Who knows what the cost of li-ion will be in 2020! This is highly reminiscent of many solar technologies which have died recently, because traditional silicon cells kept going down in cost fast.
Heterojunction cells are about 22% efficient, just a bit more than monocrystalline cells (which are dead cheap by now). And the voltage problem the claim have solved, is just silly. In nealy all uses, cells (electrochemical, solar or otherwise) are operated in series, and balanced if needed. There is no real advantage on coupling directly the solar cell with the electrolyzer to gain a few marginal points in efficiency. If you go "parallel" like these guys are doing, you end up needing huge copper bars for conductors. Plus, any change in solar radiation lowers the voltage & the model stops working. Much better to use a DC-DC device, which are 95% efficient today. The only new (to me) information I get from this article is that PEM electrolyzers are very efficient, about 65%. Cool, but it seems these devices have their own problems which remain to be solved (mostly related to lifetime). Seems like poor research to me.
Does "Cryogenic fluid" means they are using liquid air or nitrogen? If that's the case, how do you compute the efficiency? Producing liquid nitrogen is an energy-intensive proccess. I think this 60% efficiency does not account for energy spent in producing the cryogenic fluid.
These trucks have no traction battery. They don't charge from the wire. When the electric contact is lost, the diesel engine kicks in instantly Trolleybuses used to have big problems when electric contact was lost, but that's not the case for these trucks.
Sublime, I think you misread the article. It says: "specific energy of 152 Wh/kg". Barely better than LiFePo4, but half the energy density of modern Li-ion. Also, we don't know the chemistry, wyth all the components. Maybe nickel or manganese is used too...Lithium cells are usually complex beasts. BTW, manganese is really cheap an abundant. Nickel and cobalt are problematic, though.
What's the point of this chemistry? - It has low energy density. - No mention to power density. - Has a long life, but no longer than LiFepo4, currently used in China. - Good safety; ok, but current Li-ion systems are very safe too. - It has low voltage, not a good thing. So what's the point? Price maybe?
This is how the future of batteries looks like... - Common and dirt cheap materials: carbon, sulfur...and probably sodium will replace lithium. Hopefully copper will find a replacement too, because we don't have much. - Complex and precise microstructures. - Energy densities around 1 kwh/kg. - Probably having some self-repair capabilities? Li-ion is changing lot's of old technologies today. Tomorrow's batteries will change everything, including flight transport. But how could those organic-like system be mass produced? I have the feeling that genetically modified bacteria (or even viruses) could be the fastest way to reach this point. Put these things in a soup and teach them to build complex microscopic structures. As bacteria reproduce themselves, the technology becomes some kind of "software development". You only have to provide the original egg with the genetic code. Once you have the basic hw tools, development could grow really fast.
I understand with torque vectoring systems you can balance the torque as you wish, which seems a bit better than having two motors. But it looks quite complex mechanically. I read Tesla (but have no official confirmation) brakes the inside wheel to allow more torque to be transferred to the outside wheel when needed.
Maybe there is a fear of tires exploding due to malfunction or something similar... About differentials: I read in several places that Tesla and other car engineering firms prefer differential because you can use the full torque of your motor on curves. With two motors, the one closer to the internal part of the curve should not use full torque. I think this concept is interesting (electric torque vectoring):
$4000 for 4 kwh of used li-ion? Ok, I will buy a new one instead, is cheaper!
Engineer-Poet, the EV1 only had 1 motor, plus differential. There is one gadget in the EV1 that would be nice to have today: automatic tire inflation. Every wheel had a device which kept tire pressure at the optimum level. That saves a lot of energy, as many people use their cars with under inflated tires.
500 cycles is not referred to capacity under 80%. They just mentioned the cell was tested for 500 cycles and capacity loss was ok. There is also the question of how much cycles do yo need. That depends on battery capacity; 500 cycles on a 60 kwh battery means more than 100k miles. This technology is fascinating, but does not seem fit for production (3d graphene?). We need to develop nanoengineering to mass produce this kind of devices. But at least we get a glimpse about what is possible using common chemistries, when you can order the molecules at your will. :)
This chemistry uses significative quantities of Boron. Interesting technology, but does not fit traction battery requirements. Boron is scarce, VERY expensive.
Engineer-poet, the aluminium-ion battery from Stanford has an (estimated) energy density of just 40 wh/kg. You can check it in the Nature paper. I think we will be stuck with Litihium chemistries for a while...
If anybody is interested, you can take a peek at the paper at the nature journal: [url][/url] It seems to need just graphite, aluminium and clhoride...this thing is really intriguing. However, I don't think it shows potential to be cheaper than lead-acid. Energy density being similar, aluminium is more expensive. The graphite foam is another "unknown" factor for cost. It's not raw graphite.
Engineer-poet, you can do something close to that with 50KG of LiPo today. But life expentancy of the battery would be short, I think. However, the same could happen in this new chemistry; we heard it can charge/discharge at 60C, but we don't know about aging when used that way.
Davemart: yes, for grid levelling I guess it could make sense. When mahonj mentioned stationary, I just thought common stationary, wich usually have very low C ratings.
mahonj, common Chinese motorbikes use 60 kg of lead-acid. They work well and are immensely popular. 50-100 kg of batteries in an motorcycle is acceptable, most megascooters weight up to 200 kg. Stationary batteries does not benefit from fast discharge/charge speed, it would difficult to compete with stationary lead-acid. Another interesting use in the EV space would be trucks and trains. Both types of vehicle have used lead-acid with some success, so it's competitive. Fast charge would help there. Example: you could ran a city truck with 1 ton battery of 40 kwh, stop for 1 hour of fast charging and drive the rest of the day. Could be an interesting technology, especially it it's more recyclable than li-ion.
(On the second paragraph I was referring to cars).
The paper mentions 40 wh/kg. Too heavy for cars, would be acceptable for bikes (China electric motorcycles use lead-acid, 2 Kwh is OK for city driving). As an EV hobbyist, I consider 40 wh/kg (if real in driving conditions) acceptable if the prices is lower than lithium and cycling is as good promised. A good temperature range is algo important. However, does not seem a good technology for commercial EVs.
I have an electric vacuum pump in my hand (a Volvo one) and it weights 1 KG. So this Bosch pump "1 KG lighter than electrics" must weight 0 grams. BTW, I don't think my pump was designed for light weight. Mostly steel instead of aluminium. Could be lighter if designed for it. This thing is just marketing...