Leaf C02 versus Prius C02

But the Prius is an atypical A/C, it is electric, not belt driven. A Prius uses energy based on A/C load, most cars use A/C energy based on the rotation speed of the engine, as well as load.

http://www.crtech.com/docs/papers/C599-061.pdf This hints the Electric A/C either is twice as efficient as Belt driven, or could be.
http://www.nrel.gov/docs/fy00osti/28960.pdf This hints that the more efficient the rest of the car is, the worse A/C sticks out.

 

Is this for the Prius specifically, or passenger cars in general?

For the 2010 Prius AC, which has a thermal capacity of 5-point-something kW and was introduced with the best energy efficiency of any passenger car AC to that date, your figure seems horribly overstated.

Could that figure instead be for a typical pre-2008 non-hybrid car, when AC energy efficiency was not reflected at all in EPA stickers?

 

Of course this atypical electric AC of the Prius is perfectly typical of what EVs have had in the past, are being made with today, and will have in the future.

 

Fuzzy1,
I think it is clear that the wiki reference is not Prius specific. I brought it up to try and sort out a range of AC load for context, because Darell had said that slowing down 1-2 mph is enough to make up the AC load drain.

Look at this data from Wayne Brown: Prius Palm Mileage Simulator
This is Prius I data I think. 250 wh/mile at 70 mph, 233 wh/mile at 65 mph. In that speed range, a drop in speed 5 mph saves about 7% of 17.5 kw = 1225 watts, or 245 watts/mph assuming quasi-linearization for that small range.

Is this 1-2 mph drop enough load savings to offset AC use ? In my experience -- yes, sometimes. But it is likely close to a best case scenario of gentle AC use in a dry climate, and the initial cooling to steady state has been done. Slowing down 5 mph looks more realistic, and I still think we are talking dry climate. I am only talking about cooling AC.

 

All I can offer is my direct experience - and in my current location in Northern CA - with driving three production EVs for many miles (80,000 on the current one, over 100,000 EV miles total).

The more aero the car, the more you'll have to slow down to make up the difference. Look at that, an advantage to driving a barn-door shaped EV. I don't have to slow down as much to make up the AC energy difference!

 

Saw a license plate today "NO CO2". It was on a tesla, I hadn't seen one before with the top up, it was too cold to drive the car as it was designed. I thought of this thread. I wonder how many of you would have shaken your fists at the driver and called him a lier. I mean the can only has 2 seats, definitely not as good as the 5 in the prius. And even though the driver probably pays the local utility for wind, I'm sure you would point out that it took CO2 to build those turbines and the grid to get the power to his garage. And Sometimes he must be filling up with the coal power on the grid ;-) And where is the room for luggage, I mean he paid a prium and the car isn't nearly as good as a prius.

 

Nope, not much room for luggage in a Tesla. I could probably carry more on a bicycle, though with considerably less panache. And even less CO2, but still not zero...those bananas this monkey eats don't grow in the backyard.

 

Having said that, if you're going to count bananas per mile for cyclists and include all the costs - financial and environmental - of growing and shipping the bananas, then the same must be done for gasoline. We might think a Prius gets 50mpg, but that figure ignores the very real and significant costs involved with making the gas and getting it to the tank. In comparison, "NO CO2" on a Tesla seems fair.

Where's the common measurement for all energy forms, and what are the comparative figures?

 

... one can only hope the driver recognizes the green-washing.

 

paying to support wind ins't greenwashing. It sends a signal to utilities that there's demand for wind power, even when the price of wind is higher than coal or NG.

 

A signal is not the same as a decrease in CO2. It is not more clean energy for the higher price.

I call that green-washing.

 

A signal causes there to be an increase in capacity. Same goes for solar. Without the price signal here in CO, Xcel energy wouldn't be 10 years AHEAD of schedule on the wind component of our renewable energy mandate.

 

Hi Tripp,

Unless you are telling me that green energy purchases outstripped the *already* existent 'green' portfolio of Xcel energy (whether local or imported), I'll remain at best skeptical until you can prove the capacity addition was not regulatory or subsidy driven.

 

it was regulator (by referendum) but the pace at which it was installed was not driven by the mandate, it was driven by the market (NG prices were high back then). CO has installed about 1 GW of wind capacity over the last decade. The mandate was for 10% by 2015. That mandate has since been increased (20% by 2020?) and Xcel made no objections to it (the first time they did when amendment 37 passed back in 2004). That's not RECs from elsewhere, that's local energy mix, so it represent new installations.

 

^^ Thanks.
So it sounds like you agree with me that in this case, prices (NG spot and wind subsidy) was the cause of new clean capacity, not well meaning greenies who pay more for clean energy already on the grid.

 

Both because the people of CO mandated the increased wind capacity via referendum (when the lawmakers wouldn't pass a bill, the people voted it in via a constitutional amendment).

 

Different plans have different impacts. I would say green choice in Austin had a multiplier effect. Everyone that signed up seemed to cause more wind power on the grid than their contribution. The wind sucess led to adoption of programs in Texas. Those buying wind in the state programs led to increases in the mandates, so much so that wind is driving improvements in the grid so that more wind can be added. Texas is unique in that it opted out of the federal grid and has a grid within its own state. This allows the brand of deregulation and improvements that other states don't have control over. Right now there is a 2 cent/kwh subsidy for wind, so it only costs the customer about 1.5 cents/kwh more than other power. It is not subject to wind swings in price with natural gas. By 2020 there should be surplus wind power at night in texas, and with the subsidy, the utility can charge the customer nothing and still pocket 2 cents from the government for night charging of cars. No wonder the big texas utilities are building charging stations and encouraging electric cars.

Some programs in other states are shams where there is a mandate for more power than people want to buy, or reusable energy are sold multiple times. Not all programs are as bad as the one in NM sagebrush, and its the regulators that have made it that way.

 

Here is one attempt at trying to calc all CO2 sources (Well to wheel & US avg CO2/kWh) for 100 miles by Wayne Gerdes:

This shows that it is significantly better CO2-wise for the Leaf over the Prius using the emissions of the avg US electricity.

http://www.cleanmpg.com/chat/showthread.php?p=291024