One prediction on electric cars

[FionaZuppa]

Tesla electric car is superb example of good electric car that is pollution free. It is quite useful for providing more facilities to users. I think it will soon replace fuel cars.

but "pollution free"? nah, you need to account for battery construction, disposal, and the source of energy. all it does is shift things around so that while standing at the vehicle the apparent pollution seems to be zero.

post #96.... not sure where i was confused about the units of energy, i think i am spot on....

 

[Besoeker]

but "pollution free"? nah, you need to account for battery construction, disposal, and the source of energy. all it does is shift things around so that while standing at the vehicle the apparent pollution seems to be zero.

Well yes, it does shift things around a bit. Whether it is EV or IC powered, both have construction and disposal costs. The main differentiator is propulsion unit efficiency.

 

[mivey]

...Then the discussion turned to POCO charges, utility rates, and peak demand charges.

It may have been, but not by me. And really, it was something of a red herring in the context of the original post.

Actually you were the first in this thread to bring in the utility and supply grid which led to later discussions of the same. But no matter because you made some perfectly sound criticisms of the idea of a EV revolution because of grid and supply issues as well as good points about issues with renewables vs. current generation.

Maybe, but it doesn't change the fact that the watt is an instantaneous value.

If you use instantaneous voltage and instantaneous current you will get instantaneous watts, otherwise, not so much fact there. You can have instantaneous power and average power. "Instantaneous" refers to an instant in time: an infinitesimally small space of time...not what we usually consider.

With AC the power varies with time and is not really our primary interest so the average watt value you get by incorporating rms voltages and currents or energy quantities divided by time are average values. These are the ones we are usually interested in, not the power that varies in a sinusoidal pattern made up of a cyclical sequence of instantaneous watt values.

I'm not disagreeing with you for the sake of disagreeing - you're much too bright for that and show a lot of common sense.

The brightness is probably the light bouncing off my grey hair and I'm not sure the point you are making since we obviously have both instantaneous and average watt values. Is it the fundamental watt unit you are referencing or the values we are measuring?

 

[mivey]

If everybody in a street has an electric car, the supply would most likely have to beefed up. Roll that out nationwide and you can begin to see the scale of what would have to be done.

It would seem the only viable solution might be DG. We just haven't got there yet. Is the dream of widespread EV today sort of a cart-before-horse issue?

 

[mivey]

Of course kW is a rate and it's an instantaneous value.

Not that a rate value has to be instantaneous. Average rates are people too.

 

[mivey]

but "pollution free"? nah, you need to account for battery construction, disposal, and the source of energy. all it does is shift things around so that while standing at the vehicle the apparent pollution seems to be zero.

Hear! Hear! For some it would seem out of sight is out of mind. The details mess up the dream.

post #96.... not sure where i was confused about the units of energy, i think i am spot on....

What you typed must not have been expressing what you know. Easy enough to do in an informal atmosphere. If you are clear then :thumbsup:.

 

[Besoeker]

Actually you were the first in this thread to bring in the utility and supply grid which led to later discussions of the same.

Yes, in terms of capacity for EV charging. Not measurements or billing.

But no matter because you made some perfectly sound criticisms of the idea of a EV revolution because of grid and supply issues as well as good points about issues with renewables vs. current generation.

Thank you kindly.

If you use instantaneous voltage and instantaneous current you will get instantaneous watts,

Just watts.

 

[Besoeker]

It would seem the only viable solution might be DG. We just haven't got there yet. Is the dream of widespread EV today sort of a cart-before-horse issue?

Actually, EV's were around about a century before those the ICE powered units.
And with much the same limitations then as now. Range and recharge time.

In this country they were, and are, used for niche markets.
Milk floats is one such. It was customary for milk to be delivered to the doorstep in the early morning in urban areas. Electric vehicles were used. The quiet operation didn't disturb the residents. The well-defined short route suited the limited range as did the start stop operation.

Another application, and an odd one that we got involved in, was airport cargo. These were for provincial airports and for the same reasons as above. Local residents had complained about the noise from operations through the night and early hours. We were awarded the project of retrofitting electric drives and motors - we manufacture both.

 

[mivey]

If you use instantaneous voltage and instantaneous current you will get instantaneous watts

Just watts.

Is your position of fact that it is "just watts" for both "instantaneous watts" and "average watts"?

Is it just for the "watt" term or do you also apply this to the term "power" so that it is "just power" for both "instantaneous power" and "average power"?

 

[mivey]

Actually, EV's were around about a century before those the ICE powered units.

The scale and de-centralization makes it a whole different world today.

I can envision a future where the grid includes portable buckets of power (maybe the EV as one type) as well as DG resources scattered around the grid to support mobile load centers. It just has to happen one day. Today we build substations near load centers and bring power in from economies-of-scale large generation sights. This model is just not flexible enough to continue forever but I doubt we can pick the winning horse at this point because we don't know enough yet.

If we let it evolve naturally, it should cost less and if we over-force the issue on a national scale we add cost. You would think natural equilibrium would tend towards the lower cost point and a model that fits better.

 

[Besoeker]

Is your position of fact that it is "just watts" for both "instantaneous watts" and "average watts"?

It isn't.
My position is that a watt is an instantaneous unit. That what it is. So watt needs no qualification.It is just a watt.
Of course you can use a qualifier like average to get average power over a period.

 

[GoldDigger]

There is no formal difference in dimensions (units) between watts and watt-hours per hour.
Or watt-seconds per second for that matter.

 

[Besoeker]

There is no formal difference in dimensions (units) between watts and watt-hours per hour.
Or watt-seconds per second for that matter.

Very droll..........

 

[FionaZuppa]

There is no formal difference in dimensions (units) between watts and watt-hours per hour.
Or watt-seconds per second for that matter.

sure, s or h, doesnt matter

 

[FionaZuppa]

my edit time expired

i'll disagree in some regards.
there are unit diffs, W carries seconds as the units, not hours, thus you have mixed units in "Wh/h", you would need 3600 as a conversion factor to unify the units. in the mathematical procedure though. h cancels the h, thus you are left with just W with seconds or hours, depends on if you used the 3600 factor or not, you could end up with 3600J/hr or J/s, etc.

as written, Ws/s = W = J/s
this is why Wh is total power used, not an instantaneous rate

 

[GoldDigger]

my edit time expired

i'll disagree in some regards.
there are unit diffs, W carries seconds as the units, not hours, thus you have mixed units in "Wh/h", you would need 3600 as a conversion factor to unify the units. in the mathematical procedure though. h cancels the h, thus you are left with just W with seconds or hours, depends on if you used the 3600 factor or not, you could end up with 3600J/hr or J/s, etc.

as written, Ws/s = W = J/s
this is why Wh is total power used, not an instantaneous rate

No. Watt-hours uses mixed units. Watt-hours per hour unmixed them again. Hours per hour is dimensionless, as are minutes per minute and seconds per second. No conversion is required.
Now if I tried to use watt-hours per second to express a power (rate of energy over time) I would again have mixed units and a conversion factor based on the number of hours per second would come into play.

 

[FionaZuppa]

as written, Wh/h is mixed

Wh/h = Jh/sh
its only after you apply a mathematical function does it become J/s
but as written, mixed units.

ok, i am out of this debate....

 

[Besoeker]

this is why Wh is total power used,

Incorrect.
Wh is energy, not power.
It's an important distinction.

 

[Patrick_SF]

minor sidetrack back to an earlier topic? but this is something i've spent a decent amount of time contemplating.

How soon will EVs become mainstream to the point it ousts gasoline cars?
Not very soon in my opinion. Cost, range, and recharge times are obstacles at the moment.

I envision the best option would be a symbiotic relation with self driving cars acting as a taxi service.

cost is balanced across a large audience and probably balance out to equivalent of taxi prices?

With enough cars in place in a city/town, the balance of available cars while others charge.(only may become an issue during peak times). car can drive itself to charging stations. so only need a few key charging garages.

range could be interesting. coordination between different cars and switch vehicles? enter service station and robotics to pop the batteries out and input new batteries?
or for since we are talking long distances it will most likely be driving on major highways. induction charge only those, much more reasonable as an upgrade to infrastructure.

maybe a little too idealistic theories

 

[Besoeker]

minor sidetrack back to an earlier topic? but this is something i've spent a decent amount of time contemplating.



I envision the best option would be a symbiotic relation with self driving cars acting as a taxi service.

cost is balanced across a large audience and probably balance out to equivalent of taxi prices?

With enough cars in place in a city/town, the balance of available cars while others charge.(only may become an issue during peak times). car can drive itself to charging stations. so only need a few key charging garages.

range could be interesting. coordination between different cars and switch vehicles? enter service station and robotics to pop the batteries out and input new batteries?
or for since we are talking long distances it will most likely be driving on major highways. induction charge only those, much more reasonable as an upgrade to infrastructure.

maybe a little too idealistic theories

Replaceable battery packs are obviously an option and could effectively refuel a vehicle maybe even as quickly as replenishing a liquid fuel tank.
It's something I've seen suggested elsewhere.

A few points in no particular order.
It would need standardisation of the physical battery layout.
And you'd still need to get the power to such stations.
Imagine a dozen cars an hour pulling it to get a 30kWh replacement.