Hi,
Quote:
Originally Posted by ken1784
Hi all,
I also don't agree the article contents 100%, but I would like to comment some.
http://www.eia.doe.gov/cneaf/electri...t/co2emiss.pdf
On the Table 1 of above material, it says coal power plant emits approx 2.1 pounds CO2/kWh (935g/kWh).
On the Table 3, it says some divisions, such as East North Central and West North Central, generate more than 70% from coal.
We know the base electricity is generated by nuclear, then the other electricity is generated on-demand by mainly the fossil fuels. Therefore, if number of plug-in/electric cars were increased, the fossil fuels usage will be increased.
http://www.eaa-phev.org/wiki/Prius_PHEV
A plug-in Prius requires 260 Wh/mile (162 Wh/km) from grid electricity, which means a plug-in Prius emits 151 g-CO2/km using coal generated grid.
http://www.hybridsynergydrive.com/en...emissions.html
The UK gas/electric hybrid Prius is rated as 104 g-CO2/km.
Of course, a plug-in car does not use 100% coal generated grid, but I would like to tell the plug-in car does not mean totally clean. |
I agree with the approach but would prefer to see the plug-in and Prius CO2/km normalized for the same speeds. I took the US EPA numbers of 4 tons of CO2 / 15,000 miles and my conversion figures came up with 150 g-CO2/km:
4 tons CO2 -> 8,000 pounds
8,000 pounds -> 3,628,738.96 grams
15,000 miles -> 24,140.16 km
3,628,738.96 / 24,140.16 -> 150.32 grams CO2/km
http://www.fueleconomy.gov/ (I used 2008 Prius)
I would observe that for USA drivers, the current EPA tests show a combined mileage of 46 MPG and GreenHybrid.com shows this model Prius having an average of 47.6 MPG.
It is true that coal fired plants have the ability to handle variable power demands better than nuclear or other base load generators. The best variable load supply is a hydro-electric dam. The problem is that our power demands are not steady but vary through out the day and even day of week. What plug-in hybrids do is give us new ways to manage power so more base load plants make sense. For source data, I would like to recommend this study:
http://www.acpropulsion.com/technolo...grid_power.htm
By giving a significant discount for off-peak electrical use, a growing fleet of plug-in vehicles will even out the power demand. This will encourage utilities to install more base power systems with less reliance on variable-demand coal plants. But the other advantage occurs to employers who put in 'plug-in' parking lot facilities.
A smart, parking lot gives employers a local, co-generation capability so power outages and brown-outs can be mitigated by paying the employees for access to their plug-in hybrid power plants. In fact, it moves co-generation closer to the employee and their families. This is the right way to go.
Plug-in vehicles also solve a problem of wind driven power systems, energy storage. But to abort plug-ins because of coal power plants exist is to cut off one's nose to spite one's face.
As a fuel, coal is pretty ugly but 'dirt cheap.' Ultimately it makes sense to use it as chemical feed stock but first we have to get there.
Bob Wilson