Electric car news ...

[ltiu]

http://news.cnet.com/8301-11128_3-10049104-54.html?tag=rtcol;txt

" ... By purchasing V2Green, GridPoint intends to add the capability for utilities to manage an anticipated wave of electric cars being plugged into the electricity grid. ... "

" ... The company's software also lets utilities draw power from many electric cars' batteries--another potential method for easing the load on the grid during peak times. ... "

Huh!?

On a hot day, you plug in your car to be charged ... but the power company drains your car batteries to power your neighbor's A/C?

 

[Fallingwater]

So what kind of diode would one need on the charging lead to make sure power only goes one way?

 

[Resqueline]

OMG.. Microsoft mentality on the grid..
At first I thought it had to be an april-fools joke, but now it makes sense..
Big brother's watching you? You aint seen nothing yet..

 

[ltiu]

At the very least, it would be helpful during a power outage, you run the car to power the house. Same rule applies when running a generator, make sure to cut the breaker going out to the neighborhood to keep your power in the house and not bleed into the grid.

 

[ifor powell]

Covering the peaks and troughs of usage on the grid is an expensive business you have to have a lot of capacity to cover everyone putting the kettle on at the same time after the soap opera finishes on TV. Most of the generating systems do not do a quick start.

The one exception is hydro where you can get it all going in 10 seconds. It's such an issue that pump storage stasions exist. They pump water up hill to a resovior when there is over suply and the electricity is cheap and then generate from it at the moments of peak demand when the price is high.

If this differentail pricing was avalible for electric cars I would not be too unhappy selling back to the grid at high price points and charging up at low price points. The interesting question is of course cycle life on the batteries but I think we still need some advances there for electric cars in general before you add this into the mix.

Ifor

 

[ltiu]

I have an interesting scenario.

What if at peak demand, we burn gasoline in our cars and sell the electricity generated back to the grid and actually make a profit??? Provided electricity generated from gasoline is cheap(er) than generating electricity from coal/gas/hydro/nuke at peak demand times.

If this is the case, then we are defeating the purpose of the electric car!

 

[jtr1962]

What if at peak demand, we burn gasoline in our cars and sell the electricity generated back to the grid and actually make a profit??? Provided electricity generated from gasoline is cheap(er) than generating electricity from coal/gas/hydro/nuke at peak demand times.

Just doing the numbers, a gallon of gasoline has 5.72 kW-hrs of chemical energy. However, an internal combustion gasoline engine in a car is at best 20% efficient at converting this to mechanical energy. A generator hooked up to the engine might be 90% efficient converting work to electricity. So you end up with 0.2*0.9*5.72 = 1.03 kW-hrs of electricity per gallon off gasoline. Even if gas was $1 per gallon you couldn't make a profit selling electricity given that rates are typically 10 to 25 cents per kw-hr.

Source

 

[ltiu]

Just doing the numbers, a gallon of gasoline has 5.72 kW-hrs of chemical energy. However, an internal combustion gasoline engine in a car is at best 20% efficient at converting this to mechanical energy. A generator hooked up to the engine might be 90% efficient converting work to electricity. So you end up with 0.2*0.9*5.72 = 1.03 kW-hrs of electricity per gallon off gasoline. Even if gas was $1 per gallon you couldn't make a profit selling electricity given that rates are typically 10 to 25 cents per kw-hr.

Source

So the issue here now is, if you plug your car in and the power company draws power from your car to even out peak demand, how much money is the power company paying you? The actual cost of the gasoline of the peak power price which is less than the price of gasoline?

 

[jtr1962]

So the issue here now is, if you plug your car in and the power company draws power from your car to even out peak demand, how much money is the power company paying you? The actual cost of the gasoline of the peak power price which is less than the price of gasoline?

They're not paying you anything when they draw power from your car. What's happening instead is that your electricity meter is running backwards. Let's say you used 600 kW-hr for the month and the power company took 200 kW-hr from your car during peak times. You would only be billed for the difference (400 kW-hr). Effectively, you're being paid for electricity at the same rate you're paying. If you generated more than you used over the month then the power company would cut you a check in theory. In practice however most won't, and once your meter zeroes out for the month they wouldn't accept any more electricity from your car. Anyway, what this means is generating electricity via a gasoline engine will mean a loss as it would cost well over $1 per kW-hr to generate but you would only be paid your kW-hr rate. Besides that, generating power from a stationary gasoline-engined car is a horrible idea even if the economics weren't against it. The fumes building up near your house will make life unpleasant for you and your neighbors.

 

[BB]

Regarding how much energy is in a gallon of gasoline... It is around 115,000 BTU.

The conversion from BTU to kWhrs is:

115,000 BTU/gallon * (1/3.414 BTUperWHr) * (1kW/1,000 W) = 33.68 kWhrs per gallon of "heat"

A reasonably efficient gasoline generator can get between 5kWhrs and 6kWhrs per gallon of gasoline.

5.5 kWhrs per gallon of elec / 33.68 kWhrs per gallon of heat = 16.3% efficient

$2.00 per gallon (swag) / 5.5kWhrs per gallon = ~$0.36 per kWhr (excluding capital cost, wear and tear, other taxes and fees)

My current Net Metering Rate (PG&E, E7 Time of Use, note E1 is flat rate residential), but basically (because I have grid tied solar), I pay/receive:

off-peak rates; from $0.09 to $0.37 per kWhr (more I use, more I pay)
on-peak Summer rates; from $0.30 to $0.58 per kWhr

Because I don't use a lot of power, my kWhr rate is $0.09 / $0.30 and I generally consume power at $0.09 per kWhr and I get "Credits" at $0.30 per kWhr... The credits are good during one calendar year... If I use more than my minimum $6 per month electric bill, I pay the utilty. If I generate more than I use during the year, the credit is reset back to Zero dollars.

So, It is close, based on my current (very high) California power rates--if you end up needing to burn gas to make up the power costs...

Not to mention that most long term rechargeable batteries do wear out faster the more, and deeper, you cycle them.

In theory, your car could just sit in the driveway and the electric company could wear out your $10,000+ battery without you ever driving your car.

Generally, batteries have on the order of 100's to thousands of cycles before wear-out. Whether that wear is from driving or utility cycling, it does not matter.

Of course, batteries also fail over time (years of storage), even if they are not cycled.

For the price per watt of storage, it would probably more cost efficient if the utility made purpose built storage sites (batteries, pump, compressed air, whatever)... These storage systems (other than pumped hydro) are still at the initial testing stages and all pretty much have 20-50% (or more) energy losses for charging/generating AC. And depending if you wish to store the energy for a few minutes or days-months--each offers it own advantages/disadvantages. And there is not (that I have heard of yet), a lot of these plants being rolled out at this time.

In any case, having a function to disable charging if needed (for lower cost of kWhrs), would not be difficult or expensive to implement.

-Bill

And I should add, Utility controlled switching of heavy loads, even residential (such as hot water heaters and A/C) is already available and used in many places.

 

[Steve K]

The basic scheme seems plausible, but the details would need to be worked out. I can't imagine that anyone would agree to allow the utility to pull as much charge out of one's battery as they wanted, even if they did get credit for the power.

I would assume that an intelligent charging port would be required that could track the net flow in and out of the car's battery. I should also mention that I'm assuming that this is a system that might be in use in a large parking lot at a place of employement, since that's where many cars spend the daytime hours when utility demand is the greatest.

The car owner should be able to program the limits for allowed battery discharge. If you have a long commute, you might not want to allow any discharge. If the commute is short, or downhill, maybe you'd want to allow 10% to 20% discharge? A shallow discharge produces little wear on a battery. If the utility compensated me appropriately for this wear, both the utility and I might profit.

Steve K.