Comments by "Engineering the weird guy" (@engineeringtheweirdguy2103) on "Donut" channel.

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  3. actually most modern EV's have ranges between 250 miles to 400 miles. The computers on them are smart enough to realise your destination is outside your battery range and will divert you to the nearest charger. it is also smart enough to know you dont have enough charge to get home and will again, warn you and set a navigation to the nearest charging point. If it is a super charger, it would only take around 20 minutes to get to full. Hydrogen cant get much further than BEV's though, and need significant sacrifices just to do that. People always froth at the mount about hydrogens gravimetric energy density (kWh/kg) but completely ignore its volumetric energy density (kWh/L) which is less than half that of BEV's. That means you cant actually fit enough fuel into the car to drive significant distances. Even if you had the refuelling infrastructure. which you dont. Look at the Mirai, it only slightly larger than the Model 3, but has so little cabin space you cant fold the rear seats to extend the boot which is a big deal since the boot is almost 100L smaller than a Toyota Yaris half its size, and has no front boot. Making it extremely impractical as a taxi or family car especially when compared to BEV's. why? because they tried to stack so much fuel into it to only get 400 miles of range whilst the model 3 gets 325 and the model S gets 412. It also meant they had to sacrifice their speed, with the Mirai taking a whopping 9.1s to get to freeway speeds whilst the model 3 does it in 3.1s. So you are paying almost 20x more per mile for something that doesnt get much further, on a tank, and is significantly slower and has an impractical amount of room, just because you might be able to fill up faster on the road, at some point in the future maybe if fuel stations decided the $1.2 million upgrade to hydrogen is worthwhile. As opposed to just charging every night at home and never needing a fuel station.
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  16.  @mightyweapon  the production of an EV only produces 15% more emissions than the production of a similar ICE car. To give you context on how little that is, and how much better they are for the environment. To make up for that 15% more emissions on a coal only grid, the EV only has to drive 20,000 miles before it’s even with emissions to an ICE car. That’s around 1-2 years of driving. And that’s BEFORE you include the emissions produced by fuel refineries for every litre of fuel you burn. As for disposal, even a basic google search shows that more than 95% of an EV battery is recyclable. Infact the end of life impacts between EV’s and ICE have been stated as being roughly equivalent to each other almost unanimously across the auto industry. Lastly, yes, there isn’t really a country today on 100% renewables… yet. However why is that a bar from entry? Firstly, EV’s still produce less emission on even a coal only grid. Infact if I were to charge an EV using a cheap, small, portable generator, I’d get more range than if I had used that same fuel in even a modern conventional engine. But you think large Powerplants purpose built for efficiency would be worse than a cheap $100 pocket generator from the hardware store? Ok bud. Calm down. Besides, even while produce less emission on dirty grids, why do they have to wait for a 100% green grid when EV’s are already cleaner than ICE and just get cleaner as the grid does, like a damage multiplier in a game reducing the emissions of TWO industries at once? You should probably think this through more.
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  46. I would disagree with some of this. Does the 145kj/kg include compression of hydrogen to 700 bar? But the crux of what I wanted to say was that hydrogen does have a high gravimetric energy density kWh/kg. Objectively that is true. However there is a slight problem people often overlook. Which is Volumetric energy density, kWh/L. Hydrogen itself as a gas does have a high volumetric energy density at around 1.4kWh/L at 700 bar, much higher than a BEV's 0.3 kWh/L. However that isnt the full story. The space consumed by the gas isnt the only constraint. The fuel tanks are designed as an edgeless cylinder to avoid stress concentrations and such high pressures. Looking through the cross section of the fuel tank its soon clear than you cannot neatly stack circles, especially in to a mostly rectangular geometry such as a car. hydrogen fuel tanks also have about 1 inch thick walls, adding 2 inches to its diameter. So when you work out the volumetric energy density taken up by the hydrogen, inclusive of the tank walls and wasted space around the fuel tanks (imagine the empty space fitting a circle inside a square for example). The Practical Volumetric energy density is less than 0.16kWh/L. Much less than a BEV. Not including additional space required for the fuel cells, larger cooling system and exhaust water discharge system and the small battery packs required. This can be seen in hydrogen cars today. Lets compare two similar sized vehicles, Both mid-sized sedans. The Tesla Model 3 BEV and the FCEV Toyota Mirai. The Mirai is 1 inch taller, 1 inch wider and 11 inches longer. Similar sizes but the Mirai is ever so slightly larger. The Tesla Model 3 has a HUGE boot, with another boot inside it where a fuel tank would traditionally go. It has 425L of rear boot space, with another boot in the front engine bay. The Mirai however, well... the Mirai has 361L, a full 272 L of boot pace. Less than a Toyota Yaris half its size and not front trunk and its entirety is taken up by the fuel cell. In addition, unlike the Model 3, the Toyota has so little cabin space that you cant actually fold the rear seats down to extend the boost space for longer items. Whilst the model 3, you can. This bears out a very impractical amount of cabin and cargo space for the hydrogen vehicle which only gets an additional 75 miles of range over the Tesla. Unfortinately for heavy hauling, this needs to be considered. A larger truck would need bigger fuel cell or more fuel cells to generate the power to drive the truck. A larger Lithium Battery pack to provide enough torque to the wheels through the electric motor, and more hydrogen for the increased consumption. But the Mirai, even being a mid-sized sedan has 149L of hydrogen on board, more fuel storage than a Ford F150. Building a truck with an acceptable range and towing power would be very difficult to fit in. For reference with towing power, the Mirai has an engine sized Fuel cell, which produces only enough power to drive the car when cruising and not enough power to adequately accelerate the car, so the Mirai has 1.6kwh of batteries to provide the power to the electric motor to accelerate it at a whopping.. 9.2s 0-60mph. I would imagine that a truck would require far more torque and power, meaning bigger battery pack and much bigger fuel cells and bigger hydrogen tanks to boot. All in all, hydrogen freighting doesnt look like it would be a good idea.
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