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Confused about PHEV, Hybrids, etc...
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nctnico:

--- Quote from: bdunham7 on August 03, 2022, 06:02:27 pm ---
--- Quote from: nctnico on August 02, 2022, 01:07:54 pm ---If you use less fuel with a hybrid, then you'll need less non-fossil fuel as a replacement. In turn this means that 1) synthetic / organic fuels may be significantly more expensive compared to fossil fuels while you can still get from A to B for the same price. 2) you'll need to produce less fuel in order to replace fossil fuel consumption.

--- End quote ---

It is unfortunate that nobody developed an E85-only hybrid, since an E85-only engine can be made even more efficient than the gasoline Prius engine by using even higher compression.  E85 is typically much cheaper (32% on average IIRC) but has 25% less thermal energy per gallon.  The increased efficiency would probably make up for about half that, meaning a slight reduction in range or increase in fuel tank size along with lower operating costs and an 85% non-fossil fuel.  Sadly E85 isn't common enough for this to be a viable product.  An E85 only Prius Prime would really slash fossil-fuel usage.

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The problem is that ethanol production needs to make a lateral move towards more sustainable production first (2nd and 3rd generation bio fuels) before production can be increased significantly. There really is a lot going on where it comes to making ethanol from agricultural and other plant based waste instead of growing crops specifically for ethanol production (see https://ethanolproducer.com/). But making this move likely takes another decade as the whole chain from harvesting until production needs to be build up.
Miyuki:

--- Quote from: tom66 on August 03, 2022, 06:07:45 pm ---There are a couple of diesel hybrids, which theoretically could run on some forms of biodiesel if well refined.

Examples include the Mercedes "BlueEfficiency Diesel" PHEV and Citroen DS5 Hybrid.

I don't know of any North American examples -- maybe in trucks.  Ford has some hybrid F150 but it's petrol powered.

There are issues with diesel hybrids due to the short-cycling of the engine, so they didn't seem to gain much market share compared to petrol hybrids.  I think it's telling that VW didn't attempt to make any given they liked to pretend they were well ahead on diesel tech (or at least the cheating part)

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Modern emission system in diesel engines needs at least 20 minutes of running time to work
This is why they fail in city traffic
And with highway traffic is no benefit to a "normal" hybrid
You need to have PHEV to use a diesel engine only for long ways
Those Mercedes PHEVs look with decent parameters, but the price is crazy.
nctnico:
You can never get good control over emissions on a diesel engine. A diesel engine works with excess air which also contains a lot of nitrogen. So you get a lot of NOx. Now you can try to control that by additives and reducing the amount of air by mixing exhaust gasses into the inlet but that causes the formation of sooth (fine particles consisting of half burned fuel) and reduces engine efficiency.
Miyuki:

--- Quote from: nctnico on August 04, 2022, 10:13:07 am ---You can never get good control over emissions on a diesel engine. A diesel engine works with excess air which also contains a lot of nitrogen. So you get a lot of NOx. Now you can try to control that by additives and reducing the amount of air by mixing exhaust gasses into the inlet but that causes the formation of sooth (fine particles consisting of half burned fuel) and reduces engine efficiency.

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You can deal with emissions relatively easy when you keep exhaust gasses hot enough, which means you are using at least 20-30% of engine power/keeping within an efficient region (typical engine example, dark blue line area and better)
But you cannot reach that in a common passenger car with engine side, they uses. As city traffic requires 1-5kW of power with short peaks to lower tens of kW.
It works kinda Ok in things like busses where the engine size is well suited for city speeds
And of course, highway traffic is the best for them
And with today's efficiency of over 40%, they can beat batteries with the current energy mix in CO2 easily, especially when we will talk about cargo transport for long distances
But for cities it is terrible and I understand why dense cities are trying to push them from centers
And the start-stop system won't help it either as it lets catalytic converter cool even more
tom66:
And then we have bizarre vehicles like the Nissan e-Power Qashqai (I hate this car so much in any form, but maybe I have an irrational hatred towards SUVs.)

https://www.autoexpress.co.uk/nissan/qashqai/357617/new-nissan-qashqai-e-power-2022-review

This car features a 1.5cyl petrol engine driving a generator which charges either a 2.1kWh battery or powers a regular 187 hp electric motor then driving the wheels.  So it's a series hybrid.  But it has no option to recharge the battery - all energy comes from combustion.   There are very few series hybrids in use, as I understand it the concern is double conversion losses from generator to motor are notable enough to avoid this design in most cases.

I can't imagine this offers any benefit on the highway but maybe in the city the ability to keep the petrol engine at high load all of the time is of some benefit.  Still, it does seem like a rather odd design. 

Edit - typo
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