[MerrimanInd]

When one gets in the weeds on EVs or ICE cars two things become shockingly clear: internal combustion is hilariously inefficient YET gasoline is hilariously energy dense. Most people's intuition is wrong on both of these points but then they cancel each other out.

Edit: another important point is that the "cost" to acquire gasoline is only the very end of the process. The energy has already been gathered, stored, and most of the processing is complete. Our cost (in money and energy) to "make" gasoline is really just gathering it. This is why the comparison to renewables is often a hard sell, it's just apples to oranges. Gasoline started on third base, renewables are batting from the plate. Some of the internal combustion enthusiasts are holding up e-fuels or synthetic fuels as the solution but then we have to pay for the entire energy gathering and processing pipeline and still be using a conversion method that's not at all efficient. It's the worst of both worlds.

[oceanplexian]

> internal combustion is hilariously inefficient

It's inefficient but not hilariously so. Modern ICE are quite amazing technology.

Combined gas turbines (you know, the energy source that powers your electric car) are about 60% efficient for the really good ones, minus 5-7% transmission losses, minus 10-12% charging losses, minus 20% loss in cold climates, lands you at around 35-40% efficiency from fuel source to the wheel.

The Atkinson-cycle engine in the Toyota Prius gets around 40% give or take some losses in the drivetrain. Electric have plenty of upsides, but for some people with cheap gas+high electric costs+cold climate you would honestly be better driving a hybrid.

[sitharus]

> Combined gas turbines (you know, the energy source that powers your electric car)

Not everywhere. My car charges off an average of 80% renewables (mostly hydro and geothermal), right now it's 95%.

But it is definitely something you need to take in to account when purchasing, an EV isn't right for everyone.

[noosphr]

This is something that always gets lost in these conversations.

Whenever you do the real world calculation for what an electric cars CO2 profile looks like it turns out to be the same as a gasoline car unless your country is majority nuclear.

[ramidarigaz]

> Whenever you do the real world calculation for what an electric cars CO2 profile looks like it turns out to be the same as a gasoline car unless your country is majority nuclear.

Not at all true: https://www.carboncounter.com/

US-specific but you can even pick a state and it will use the generation mix of that state

[noosphr]

You charge your car at night.

At night the sun doesn't shine.

The mix is mostly coal or if you're lucky mostly gas.

This is the type of bullshit I mean by doing real world calculations.

[namibj]

Maybe today, but basically everywhere south of Canada solar is so high ROI that it's just a question of time before sunlight hours have electricity so much cheaper that the primary daytime parking locations become the favored (slow-)charging spots.

For you to prefer charging there your employer only has to charge you less during the day than your utility charges during the night, so the day/night rate arbitrage can easily pay for the metering hardware and installation (at the next opportunity to install without having to dig the parking lot up just for the chargers), with the rest being profit to incentivize the managers to install/offer this.

[lokar]

I charge during the day, from my rooftop PV panels. Over a year we are net negative on grid consumption.

[bethekidyouwant]

This means you don’t take your car to work, which isn’t typical

[cogman10]

The wind blows, water flows, nuclear glows. Further, demand's at lows.

In my state (idaho) at night the power mixture is primarily renewable/clean because of this.

[pcchristie]

This is wrong, and by a long way.

[sitharus]

Or majority renewable.

[Terr_]

The tyranny if the rocket/horse equation: You need energy to carry the energy you need to move.

There's a good reason so many sprawling civilizations of the past involve leveraging wind-power for transport.

[frankus]

Every single ICE car driving down the highway is throwing away enough waste heat to heat a small apartment building on a freezing cold day.

[OldSchool]

IF the joules of energy in your EV battery came from gas-fired or coal-powered generation, a similar amount (~60%) was simply dumped somewhere else.

[frankus]

I wish we did more e.g. district heating with that waste heat in the US.

[antisthenes]

That means relatively dirty combustion near where people live. The population density around fossil fuel power plants tends to be pretty low in wealthy countries.

You can't pump hot water the same distance you can transmit electricity on HVDC towers.

[groundzeros2015]

Exactly. The environmental/social burden isn’t just the energy used in the raw physical form, but the cost to acquire and make it useable.

The problem with gas is not that burning it doesn’t maximally capture all energy, but that there are externalities to doing so.

[dylan604]

Train locomotives have used diesel powered generators that then powers electric motors. Would this be less efficient than battery powered EVs? Or better asked, what would be the most efficient use of gasoline?

[csours]

> Would this be less efficient than battery powered EVs?

Measured in terms of mass * distance, trains with steel wheels will beat anything with rubber pneumatic tires.

Part of the magic of hybrid trains is that you can have multiple generation units that can be turned on or off as needed.

---

Efficiency is just one consideration for a power plant.

Historically, reliability has been more important than efficiency, especially for industrial applications like locomotives. In other words, locomotives are probably not as efficient as they could be. For instance, you could use a lower viscosity engine oil for lubrication, but that would reduce reliability as engines fail due to friction.

[ZeroGravitas]

Nissan makes a range of these under the e-power branding:

https://www.nissan-global.com/EN/INNOVATION/TECHNOLOGY/ARCHI...

[MerrimanInd]

In the auto industry these are usually called a series hybrid and there have been a handful. The Chevy Volt (though it had the ability to directly connect the engine to the wheels at highway speeds), and the BMW i3 and i8, the Fisker Karma/Karma Revero. The new Ram Ramcharger truck and the second gen Ford Lightning will also be series hybrids.

It's a really good drivetrain that was unfortunately made untenable for a long time by a combination of regulation and market forces.

[jfengel]

When it comes to the environment the most efficient use is to leave it in the ground.

Hybrids work for trains because they are so large and don't need big swings of acceleration or to climb steep grades. They can run the diesel generators at maximum efficiency.

Battery power would be better, because you can build even larger power plants running at higher heats and not have to haul them with you, but the costs of sufficient battery is too large, so far. That is changing.

[einpoklum]

Isn't it better for trains to just to draw from the electric grid?

[csours]

Do you have to run new electric transmission lines? Will you have to maintain those power lines?

[einpoklum]

Possibly, yes. But that seems to be worth it:

https://en.wikipedia.org/wiki/Railway_electrification

"Maintenance costs of the lines may be increased by electrification, but many systems claim lower costs due to reduced wear-and-tear on the track from lighter rolling stock. There are some additional maintenance costs associated with the electrical equipment around the track, such as power sub-stations and the catenary wire itself, but, if there is sufficient traffic, the reduced track and especially the lower engine maintenance and running costs exceed the costs of this maintenance significantly."

[mrguyorama]

We once dammed basically every river in the nation because it was in vogue at the time.

Maybe building overhead power lines for rail infrastructure should be the "hip" thing right now instead of AI. Maybe building oodles of solar power farms and batteries should be "hip"

We built electrical infrastructure to the most remote residences just because we could and because it was an investment in our people. We directly funded our massive and formerly world class rail network because we could, and because it would pay off. We built a world class road network half as a make-work project, and it still pays dividends. We purchased Alaska, with no obvious reason. We built a space program to have slightly better nuclear weapons, and it's part of the reason we were so dominant in computer chips for so long.

We have spent something like 40 trillion dollars over the past 25 years, and almost none of it on anything of real value. More than a little of that debt is just handouts to already rich people.

We can build new electric transmission lines and I'm so tired of things that we absolutely 100% can do if we just demand it be done being somehow treated as a problem. America can afford infrastructure.

[fragmede]

Someone could graph the cost/benefit ratio on putting the batteries on the trains vs putting wires up everywhere.

[MerrimanInd]

That's a complicated question that unfortunately has quite a bit of "well it depends" in the answer. I worked in the auto industry for a long time - both doing engine development and EVs - so my opinions here are well-informed but not world expert.

From a pure energy efficiency perspective you can't beat economies of scale. A stationary power plant (even ones that are just big gasoline engines) run at a constant load and RPM so they can be optimized for pure efficiency, they rarely have to start, warm up, and shut down, and they can use larger and more expensive exhaust aftertreatment systems. Most energy conversions grow more efficient with scale and this is no different. The locomotive powertrain works for a handful of reasons but one of them is you can build much more efficient engines that are optimized for a single constant speed and load. But most of the advancements in internal combustion engines over the last 20-30 years don't increase peak efficiency but increase the conditions in which they're efficient. Variable valve timing and lift are probably the most underrated and overpowered technologies that have transformed engines from having one narrow regime of high efficiency to running well over a huge range of the map. But turbocharging, variable intake geometries, 7+ speed transmissions, and mild hybrid systems like belt-starter-generators get honorable mentions here. However we're not talking about anything close to EV-levels of efficiency. I think the cutting edge research engines are running in the mid to high 40s for thermal efficiency (percentage of fuel energy captured as useful work), most passenger car engines probably peak in the mid 30s.

So while there is some efficiency to be gained by a more locomotive-style system it's not as much as you would hope. In the industry that's called a series hybrid system, vs a parallel hybrid system where either ICE or EV power can go to the wheels. The benefits of a series system are more emissions and product features. You can get the full torque and power of an EV, you can start and stop the IC engine in a more emissions optimized way, and and you can filter load spikes to use a small engine that meets average not peak load.

From a more pragmatic perspective, with the energy density of gasoline and other liquid fuels it's probably best to use it in applications for which you just can't use full electrification. Planes are currently the best example of this. It's also worth noting that passenger cars benefit massively from strong hybridization because of the uneven load cycles so that's a technology where you can deploy a gasoline engine but then claw back a lot of the efficiency losses with hybrids. That's not always true, for example boats don't really have a regen cycle so hybridization just doesn't get much.