Will plug-in-hybrid vehicles solve anything?

[Disbelief]

The volt seems rather poor compared to the Nissan leaf.

Except for the fact that you do not have the limited range. When you run of of battery power, you switch to gas instead of sitting on the side of the road.

 

[davefoc]

The volt seems rather poor compared to the Nissan leaf.

The Volt is a plug-in hybrid and not an electric car and as disbelief noted when the batteries are discharged it is still possible to run on gas.

If there is only one car in your family you might select a plug-in hybrid over an electric vehicle because you plan to use the car for mostly short trips like commuting to work or buying groceries but occasionally you need a car with longer range.

If your daily commute is longer than 50 miles or so you might be better off with a Prius that gets better gas mileage but doesn't have a significant all electric range.

If you are a two car family the Leaf might make perfect sense. It can be used for all the short trips and when a longer trip is needed the other car can be used.

 

[DavidS]

It might be and it might not be.

That's my point. Whether one fuel burns more cleanly than another is but one of many, many considerations determining which will result in more pollution. The operations and constraints of distributing power from a "few" stationary consolidated generation facilities are vastly different from distributing fuel to "many" smaller mobile generation facilities. Deciding on fuel selection alone which would pollute less (as implied by lionking's first post) is overly simplistic (as his later post seems to acknowledge).

The point is that its real easy to figure out some qualitative benefit of a particular approach.

That's very much not my point. Deciding which of two very different approaches is even qualitatively better isn't as easy as some folks seem to want it to be. Even given agreement on an objective (e.g. "pollution"), there can be lots of things to consider; smelling a fuel sample isn't enough. Just reaching agreement on those objectives is hard enough; changing the goalposts to bats, birds, and hilltops may change the qualitative ranking.

But for wordsmithery details we may be in violent agreement here...

 

[davefoc]

...

But for wordsmithery details we may be in violent agreement here...

I noticed that.

ETA: Even more so, since I realized after I made the post in question that it wasn't exactly an appropriate response to what you wrote.

 

[davefoc]

Supposedly if you charge it overnight, it uses energy that would have just been wasted otherwise.

....

Have you heard about the unavailability of the free lunch?

Perhaps what you meant is that there is unused generating capacity that could be used to charge electric vehicles overnight. This is probably true and is put forth as an argument for all electric vehicles and plug-in vehicles.

An add-on to this scheme is that the storage capability of the electric fleet becomes tied into the electric network and electricity flows from from the electric vehicles back to the network to help balance the load.

 

[Sati1984]

The Volt is a plug-in hybrid and not an electric car and as disbelief noted when the batteries are discharged it is still possible to run on gas.

The gas is not used to gain propulsion in that case, the gas engine only powers the generator which produces electricity, thus making the Volt even more efficient. And since it's full range (electricity + gas) is some 610 km, I think that's sufficient for most of the longer trips too...

 

[Disbelief]

The gas is not used to gain propulsion in that case, the gas engine only powers the generator which produces electricity, thus making the Volt even more efficient. And since it's full range (electricity + gas) is some 610 km, I think that's sufficient for most of the longer trips too...

Bolding mine. That's true until it goes above 70mph, then the gas engine does run the vehicle. It was found in testing that this is more efficient at these higher speeds.

 

[davefoc]

Bolding mine. That's true until it goes above 70mph, then the gas engine does run the vehicle. It was found in testing that this is more efficient at these higher speeds.

This is true, but GM misrepresented the situation while the Volt was under development. The power train on the Volt seems to be somewhat more complicated than even that of the Prius.

There is a large electric motor that is the principle source of motive power when the car is being driven. However a second smaller electric motor can also be used to supply motive power when the load goes above a certain level. And then as disbelief noted the gas engine can also be used to supply power under certain situations.

The second electric motor normally functions as the generator and is directly connected to the gas engine. When the gas engine supplies motive power it does so by spinning the motor/generator which provides the direct mechanical connection to the transmission to supply the motive power to the car.

Despite all the fanciness the gasoline only mileage of the Volt seems to be significantly less than that of the Prius but of course the Prius doesn't have any substantial electric only range which is probably a huge advantage for a person who makes mostly small trips.

 

[aggle-rithm]

I saw a documentary last night where a guy was working on a gasoline substitute that was "carbon-neutral". Instead of digging up carbon from long-dead plants and spewing it into the atmosphere, this would make use of plants currently growing, which meant that they are still around to take in CO2 and release oxygen.

Reading between the lines, I decided that what he was saying was: The gas substitute pollutes the air just as much as petroleum-made gasoline does, but that's OK because the plants are absorbing the carbon.

Which means that if we completely replace fossil fuels with this "clean" gasoline, we would have to have a HECKUVA lot more plants growing than we do now, since what we have now is hardly sufficient to absorb all the carbon.

Which furthermore means that we could get the same result by just planting a HECKUVA lot of plants and continue to burn fossil fuels.

I notice a lot of this sort of "emperor's new clothes" logic in the Clean Energy movement.

 

[davefoc]

...
Which furthermore means that we could get the same result by just planting a HECKUVA lot of plants and continue to burn fossil fuels.
...

Well, kind of. You would need to sequester the carbon from the plant material so that it doesn't return to the atmosphere through decomposition.

The ethanol program is a huge scam, but it seems like some biofuel generating schemes might eventually be good enough that they could be a useful source of energy in the future I think.

 

[daenku32]

Bolding mine. That's true until it goes above 70mph, then the gas engine does run the vehicle. It was found in testing that this is more efficient at these higher speeds.

If you are doing 70mph you aren't exactly concerned with fuel economy.


Other than that, I'm hoping to see more hybrid technology in heavier vehicles. That is where the most benefit comes from. You don't gain much by putting hybrid technology in 2400 lbs car, but stick it on 7000 lbs SUV and you start seeing a lot of gain.

 

[daenku32]

When we all have plug-in hybrids, the problem they'll solve is what to do with the massive overcapacity in power generation we expect to have in the near future.

Oh. Wait.

Grid tied gasoline engine? After all, there will be that oversupply of gasoline once we all have plug-ins.

 

[JoelKatz]

Supposedly if you charge it overnight, it uses energy that would have just been wasted otherwise.

So even if the energy is coming from coal, it's cleaner if you charge it in the "off-peak" hours in the dead of night.

ETA: One could imagine however that if plug-in hybrids ever become really popular, those off-peak hours might no longer be off-peak hours if everyone is charging their cars during those hours.

It uses capacity that would have been wasted otherwise. However, the energy would not have been.

Coal and oil plants run at night too, burning coal and oil to make energy. If the demand is lower, the plants shut off one by one. If the demand is higher, the plants turn on one by one.

If you flip on a light switch at any time day or night, 99.999% of the time you're not having any effect on the grid. But 0.001% of the time, you make the difference between a plant running and a plant not running or your energy provider buying a megawatt hour or not buying a megawatt hour and have a hugely disproportionate impact.

By this same argument, buying an electric car has no environmental benefit, since it's just one car. If you're going to look at the benefit in aggregate, you have to look at the harm too. Enough electric cars to make a difference will mean enough more oil and coal generator running hours to make a difference.

Again though, the hope is that the grid will get cleaner over time.

 

[daenku32]

Again though, the hope is that the grid will get cleaner over time.

The grid on average is cleaner than your ICE.

 

[Modified]

If you are doing 70mph you aren't exactly concerned with fuel economy.

I'm concerned with fuel economy on the freeway. Only the northeast, Ohio, Wisconsin, Illinois, and Oregon have freeway speed limits below 70.

 

[redwards]

If you plug into a coal fired power station, I can't see any less pollution.

Even a coal-fired power station is more efficient than an internal combustion engine.

 

[redwards]

I think this is a good topic, but I don't know the answer.

Scientific American ran a small article a few years ago that suggested that plug-in hybrids could reduce US oil consumption by 70%. If that is true, there are at least four potential benefits to the US just because of that:
1. Reduced possibility of disruption of US economy by interruption of fuel supplies from overseas suppliers.
2. Economic benefit by the use of US produced instead of foreign produced fuels.
3. Most fuels that are used to power electric plants are cheaper per joule than gasoline.
4. Increased reliability of US transportation fleet because of the diversification of transportation fuels.

And even without the plug-in aspect of hybrids, hybrids are somewhat fuel efficient so just changing over to hybrids reduces fuel consumption somewhat.

An important question in all this is whether there would be a net environmental benefit as a result of the change. In large cities, there would be a significant improvement in quality of life because of reduced noise and reduced pollution in the city itself. But would there be an overall environmental advantage as a result of the changeover? That seems like the most difficult question to answer.

One idea that is put forth is that the unused capacity of nuclear power plants at night could supply the electricity so the added electric demand would be particularly clean. I suspect this argument is wrong because nuclear power plants generally run flat out and at night output from non-nuclear plants is reduced. I am not sure about this however.

In the end the only way to get a good idea about the environmental question is to do analysis using facts and math and then make a guess about how the future changes the analysis. I look forward to reading links or analysis posted by others on this.

Honestly, I think the most important aspect of the switch is the move to a system in which power is simply stored in battery. Whether efficiency is immediately improved or not seems sort of beside the point. Moving to a system in which we can obtain the power we use for transportation from the grid allows us to generate that power any way we want. This means that an electric fleet can automatically take advantage of any future advances in efficiency of energy generation.

It also means you're already set up to take advantages of little improvements in the vehicles themselves. You might be able to gain efficiency in regenerative breaking or reduce drivetrain losses by simply attaching one electric motor to each wheel hub and eliminating all of the traditional drivetrain components. Maybe future advances in solar cell technology will make it worthwhile to cover the roof in solar cells. I've already seen some prototypes for systems which would recharge batteries in electric vehicles not just through regenerative breaking, but through the resistance in the suspension.

Once your energy is simply stored in a battery, the potential for improvements on vehicle design opens up dramatically.

 

[davefoc]

Even a coal-fired power station is more efficient than an internal combustion engine.

I guess you are saying something like a higher percentage of the chemical energy in coal is turned in to kinectic energy in a coal plant than the chemical energy of gasoline is when burned in an internal combustion engine?

Which if any of these various energy losses does your statement take into account?

Coal
1. Energy to mine the coal
2. Energy to transport the coal to the plant
3. Energy to mitigate the environmental destruction caused by the mining of the coal
4. Energy to maintain and operate the plant
5. Energy to remove and dispose of the waste from the coal plant
6. Energy for pollution control at the plant
7. Energy lost when the chemical energy in coal is converted to kinetic energy
8. Energy lost in the generators when the kinetic energy is converted to electrical energy
9. Energy lost for voltage conversion during the transmission of the electricity
10. Energy lost from transmission line impedance
11. Energy lost when the car batteries are charged and discharged
12. Energy lost when the chemical energy in the batteries is converted to kinetic energy by the motors in the car.

Gasoline
1. Energy cost of drilling for crude oil including energy wasted on drilling dry holes.
2. Energy lost from transporting the crude to the refinery
3. Energy lost from converting the crude oil to gasoline and other products.
4. Energy lost from transporting the gasoline to the service stations
5. Energy lost when the chemical energy is converted to kinetic energy by the internal combustion engine in the car.

And if part of the justification for electric cars is to reduce the production of CO2 have you taken into account the fact that per joule of energy produced the burning of coal produces more CO2 than gasoline?

 

[Furcifer]

ETA: One could imagine however that if plug-in hybrids ever become really popular, those off-peak hours might no longer be off-peak hours if everyone is charging their cars during those hours.

That's not what I've heard in the industry. They figure there is enough capacity to handle the load even if everyone owned an electric vehicle. It may require intelligent chargers that you pug in and only charge when the load is lightest. So you might plug it in at 7PM and it not start charging until 4AM. That's a ways down the road and they figure the peak load will grow in proportion anyways.

Coal and oil plants run at night too, burning coal and oil to make energy.

Large power plants are much more efficient at getting energy out of oil than small cars are and have much more elaborate pollution controls.

Oil fired generation makes up 1% of the generating capacity and have almost nothing to do with baseload or peak. They're essentially back-up for coal and gas plants or off grid use in remote locations. Oil is a non factor in this issue.

 

[This is The End]

I'm concerned with fuel economy on the freeway. Only the northeast, Ohio, Wisconsin, Illinois, and Oregon have freeway speed limits below 70.

I see what you did there, you said "limits below". Trying to exclude all of the states with 70 mph speed limits, which are also not "above 70 mph"? If you go above the speed limit you are breaking the law, plain and simple.

Last time I checked, only a small percentage of total miles driven in the US are legally "above 70mph".

That's even assuming that the Volt switches at exactly 70, which I doubt.