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[–] MystikIncarnate@lemmy.ca 0 points 6 months ago (3 children)

So, I understand what Toyota is saying. I'm not sure I agree, but I get it.

Simply put, until we figure out a good solution to the battery problem, EVs are kind of at a dead end. They are about as good as they could be with current technology. There's a big push right now towards better energy storage tech, aka battery tech, for EVs and beyond (everything from cellular/mobile/device applications, to EVs, to "grid scale" storage).

The problem is basically twofold: first, limited energy storage. This is compounded by fairly slow charging... Second, current lithium tech used in EVs tends to be rather.... Flammable. Specifically, the most common chemistries are pyrophoric; aka, they burst into flames on contact with air. .... I'll emphasize that pyrophoric battery chemistries are commonly used in just about all consumer goods. This includes every Tesla, and every cellphone.

The only reason that your phone doesn't spontaneously combust in your hand is because the batteries are sealed so no air can get at the chemistry. The issue with Tesla's EVs is when one cell's seal fails, and it combusts, then the chances that adjacent cells will have their air seal compromised, dramatically increases. This can quickly lead to a chain reaction of failures.

Current research is ongoing into batteries. The golden battery for EVs will have, fast charging, high discharge capability (also known as the "C rate"), similar or better energy density to current cells, and longer charge/discharge cycle life. Since we're already comfortable giving pyrophoric batteries to the general public to carry around in their pockets, I don't think anyone is focused on eliminating that, but, if they can, while achieving the other goals, so much the better.

Other battery chemistries exist that are not pyrophoric, but they lack the energy density of their pyrophoric counterparts. One notable chemistry is LiFePO4, which, by sacrificing some energy density, you get much longer cycle life, and no pyrophoric materials.

Solid state batteries are being researched which should extend cycle life significantly if it can be achieved as a "commercially viable product" (which is corporate talk for something that can be mass produced). Thus far, while sold state batteries exist, they're either done in very small batches, and are very hard to produce, or, they simply don't have the same, or similar, energy density to the lithium/cobalt cells that currently dominate the market.

One alternative is hydrogen. Hydrogen fuel cell technology isn't perfect, with a loss of about 20-30% IIRC, from the energy in vs the energy out. The benefit to hydrogen is that it can be stored, highly compressed (a large volume of gas in a relatively small container), and it doesn't degrade or go bad, so it can be stored indefinitely, aka no significant loss over time. But hydrogen is a far more dangerous material than lithium/cobalt, and a tank rupture from a full tank of hydrogen in an EV, could create an explosion of significant size. It's far more dangerous than the pyrophoric batteries. For more information, see: Hindenburg.

Other alternatives exist, but generally are not being used in EVs for various reasons. Among these are RITEGs. An RITEG outputs a consistent and stable power flow indefinitely, even a relatively small unit could be used to power a vehicle, with a small buffer battery, for upwards of 40 years without needing to "refuel" so to speak. Possibly longer depending on the fuel used. The reason they're not considered is right in the name. The full name for an RITEG is "radio isotope thermal electric generator". Aka, nuclear. The unique thing about an RITEG is that the power output is dependent on the differential between the heating provided by the fuel, versus the temperature of the surrounding material (usually some sort of passive heatsink). They're very safe unless the seal is broken, in which case, you need Hazmat to clean up the mess. Their energy conversion is very very low. The power is stable, but only a small amount of wattage can be generated. It's constant, but it's a small amount. So the presence of a "buffer" battery for acceleration (and most driving) would be required, and often you can get more power from a small solar array, dependent on the weather. I like the idea of RITEGs, but more as a home generator type option, where you could bury one into the ground and dissipate the heat geothermally. No options exist for this and research into thermal electric tech has been stalled for many years. Nevertheless, I think it's awesome. The idea of having a mostly solid-state, base load generator in your back yard, seems like a really good idea, but nobody has done it, since IMO, the regulations would be a nightmare.

Anyways, the battery problem outlined here is what we're all waiting for... A commercially viable product that is on par with the current battery front runner, lithium/cobalt, for energy density, while having a much higher cycle life and a high "C rate".

[–] bad_alloc@feddit.de 0 points 6 months ago (2 children)

One alternative is hydrogen. Hydrogen fuel cell technology isn’t perfect, with a loss of about 20-30% IIRC

You don't recall correctly: The efficiency of Hydrogen, from solar cell to the wheels is 26%. Electrolysis is highly inefficient and compression and chilling of hydrogen is very energy intensive. Meanwhile, EVs are at 70%.

You are right that batteries kinda suck due to their energy density. However with EVs you can buy today you can still commute every day without noticing any major difference to an ICE car. You can also do long road trips, even in a small car, albeit slower. (Source: did both)

[–] MystikIncarnate@lemmy.ca 0 points 6 months ago (1 children)

I see I get to have this conversation several times.

I looked it up, hydrogen fuel cells can attain about 60% efficiency from the energy potential in hydrogen, when converting to electricity. So I'm not wrong, we're talking about different numbers.

You're referring to the efficiency of the whole system from generation (via solar panels) to conversion to hydrogen (I assume by electrolysis?) to conversion back to electricity by fuel cell (~50-60% efficiency), then any losses getting the electricity to the wheels. That's a very different number than what I was saying.

AFAIK, no real progress has gone into electrolysis for decades. But we can usually also do natural gas reclamation, which is the process of removing the carbon from CH4, and producing pure hydrogen, which, I believe is a much more energy efficient process.

It becomes an entire discussion to figure out how you're producing hydrogen for the system, which is not an easy topic to tackle in a limited written medium like this one. I decided to forego that and focus on the efficiency of the hydrogen fuel cell vs the energy potential in hydrogen directly. I was still off, I'll give you that, but not so far off to make ICE look like a good option compared to FCVs.

BEVs are great short trip vehicles, daily commuters and all around daily driver vehicles. Even with current battery technology, I'm not disputing that. The fact is that the batteries will cause the cars life to end long before anything else wears out that could potentially cause the car to get scrapped. It's cycle life which is the primary issue, but if we get super long cycle life at the cost of energy density, we generally won't switch (see LiFePO4). If the c rate is too low (significantly lower than current tech), then acceleration and charging time will suffer, and we will equally reject the technology as viable for the purpose. So it needs to beat out lithium/cobalt on cycle life, but come close to, or do the same or better than lithium/cobalt in terms of C rate and energy density.

If anyone finds something that is identical to lithium/cobalt for energy density, and C rate, and just has an improved cycle life while all other factors are the same.... Then IMO the entire industry would pivot so fast your head will spin.

Cycle life is the core of the battery problem. Other factors are nice, but the cycle life is where we need to improve before we can really get rolling on EVs. If that problem can be solved, I don't think that ICE cars will even be built anymore. It will end the consumer petrol market within a decade of such a breakthrough. Of course, there's more uses for gasoline and diesel than vehicles so there will still be gas stations, but there will be a LOT fewer of them, and many will likely be replaced by EV charging points.

[–] bad_alloc@feddit.de 0 points 6 months ago

I looked it up, hydrogen fuel cells can attain about 60% efficiency from the energy potential in hydrogen, when converting to electricity. So I’m not wrong, we’re talking about different numbers.

If you are looking at the pure engine efficiency, we are now looking at >97% for most EV motors (class IE4). However, the point of the entire transition away from fossil fuels is preventing or delaying climate collapse. For this purpose lowering emissions and reducing energy use go hand in hand, hence the overall efficiency is critical.

But we can usually also do natural gas reclamation, which is the process of removing the carbon from CH4, and producing pure hydrogen, which, I believe is a much more energy efficient process.

Hydrogen is less strongly bound to Carbon than Oxygen, however in this process we produce more CO2 again.

AFAIK, no real progress has gone into electrolysis for decades.

There is a theoretical upper bound for the efficency of water electrolysis, depending on the temperature. While current electrolyzers can surely be improved, since we are already making electricity, we might as well use it directly. Some applications (aircraft, rockets, ...) need the higher energy density of chemical fuels. But: Working with liquid or gaseous hydrogen is terrible: Cyrogenic liquids are not easy to handle, let alone store. Hydrogen will embrittle any metal exposed to it and when inadvertenly mixed with air forms a highly explosive gas. Even the rocket people try to avoid using hydrogen unless they really need the ISP.

The fact is that the batteries will cause the cars life to end long before anything else wears out that could potentially cause the car to get scrapped.

So far we have seen EV batteries not degrade a lot due to good BMS. For most cars the battery will last at least 10 years before performance is seriously impacted and even then the battery can be reused for storage (home or grid scale). Most EVs have >40kWh batteries, homes usually need 5-10kWh storage. So one chewed up EV battery could be reused for multiple stationary battery systems.

Cycle life is the core of the battery problem.

I do agree that current battery tech is... not great. Having less spicy cells that are easier to recycle or recondition would be a massive gain and more research needs to be a core focus. However Li-Ion and LiFePo are already good enough to work for most people most of the time. Pair this with a lot of wind and solar energy generation and you have mostly sustainable traffic. This can be done right now and it has to be done right now. I argue a lot against hydrogen because it seems like a technology that is not there yet and allows many old players in the energy market to delay a transition which is not beneficial to them.