Plug-in hybrid: true comparison?
Created August 9, 2006, at 2:58 pm by Anonymous
Has anyone here ever tried (or read of someone trying) to compare the consumption of a traditional hybrid versus a plug-in hybrid or true electric car? In other words, that electricity is coming from somewhere, and what is the comparison between getting that power from your local utility versus burning a minimal amount of gas to do it. As a former mech eng I am famliar with the tradeoffs, etc....but a lot of work would go into such an analysis.
Has anyone done it?
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Its been done a lot. See:
http://www.evworld.com/blogs/index.cfm?page=blogentry&authorid=12&blogid=143
http://www.epri.com/programHigh.asp?program=249637&objid=286784
http://www.teslamotors.com/learn_more/white_papers.php
http://www.pluginamerica.com/faq.shtml (emissions summary)
Rough numbers to help you are:
- Power plant efficiency 60 – 80% (combined cycle gas turbine)
- Power-line transmission efficiency ~95%
- Charging efficiency – 90 – 95%
- Discharge/motor efficiency ~90 %
Basically, the BEV or plug-in portion of the Plug-in Hybrid are around twice the efficiency of the gas-only hybrid.
I would like to see one from a source that is completely objective.
It's kind of hard to define anyone who is 'truly objective' since something has to motivate someone to do the research. I suggest that if you trust yourself, you need to do your own basic research into each of the steps in the energy chain from well to wheel.
For the record, Plug-In-America is a non-profit organization composed of people who saw the light and have no financial interest in EV's (except that a lot have wasted a lot of $ buying the few RAV4EV's that exist on the market). EPRI is a government agency FWIW. Tesla Motors are a bunch of guys who have really put their own money where their mouths are to develop affordable, practical EV's.
You might want to start with some of this analysis that you question and then try to follow up the footnotes and sources to confirm for yourself that the fundamental science is pretty close. Don't worry about too much precision since EV's are so more efficient and clean than their pure ICE counterparts that there is significant tolerance to inaccuracies.
Happy number crunching.
I would like to see a more independent analysis also. Most power plants are not combined cycle plants, and only get about 35-40% efficiency.
It is good to lower our dependence on liquid fuels, i.e., those coming from countries that don't like us, but the ecological and health costs of the mercury, sulphur dioxide and particulates coming out of coal plants need to be taken into account also. We don't want to minimize a problem in one area only to increase our costs in another years down the road.
However, if we consumers just keep trying to buy the highest mpg vehicles we can, then we will do a lot to minimize all these factors.
Me too. Of course, it depends on how you define 'truly objective'. I doubt that anyone with nothing to gain from any outcome will go to the effort of doing the study. You should probably look at the footnotes in the sources provided and see the fundamental sources of the information are believable.
But then again, you could probably say that I'm not 'truly objective' either since I've done sufficient research and talking with people to have made my mind up about the electric drivetrain being the most efficient/feasible one known today.
I think this comes close to answering the questions. Popular Mechanics did a comparison of fuel costs. Down load the chart from the link at the bottom of this page:
http://www.popularmechanics.com/science/earth/2690341.html
Plug in electric appears to be about 1/3 the cost of using gasoline for fuel. Most other fuels other than natural gas cost more than gasoline.
I have solar electric panels (about 8KV system) on the roof of my house and generate most of my electric needs. Thus, if I added a few more panels and had a plug in hybrid rather than my hybrid Ford Escape, my hypothetical plug in hybrid would probably be fueled in a significantly more efficient manner than the gas hybrid.
It would take a major investment in solar panels and a low-latitude sunny climate to charge up a plug-in vehicle every night. Current Li-Ion based plug-in designs need a lot of energy to recharge.
Actually Li-ion batteries don't take any more energy to do a day's drive than any other battery type (maybe less since they are lighter).
For a typical 30 mile day, a Tesla, that can go 250 miles on 50 kWh would consume 50k/250=0.2 kW per mile driven so it would need 30*0.2=6 kWh per day. Assuming 6 hours of sunlight per day, it would take a 1 kW solar array to meet your daily driving needs. This isn't particularly tough except maybe for Helsinki or Fairbanks in December - but it would average out in June.
The current US average price for a 1 kW collector is about $5,450. If your figures and calcs are correct, that means investing probably $7,000 or more to install the collector and charging equipment for a tiny car that only travels near home and only 30 miles per day. And only when the sun shines.
Still needs work, unfortunately.
See:
http://www.plugsandcars.blogspot.com
for a comparison between the hassle of putting gas into a Prius versus plugging in an EV at home.
One aspect overlooked when comparing electric vs gas efficiencies is that only cost is being comparied because the cost of electricity is "normalized" to a gas cost. The bigger picture needs to include:
1) Gas is very finite and few power plants burn oil. (i.e. These comparisions are very misleading since they are changing as every barrel is consumed.)
2) Coal is very abundant but if all of it is burned, the CO2 pollution basically suffocates the planet. Believe it or not, the CO2 pollution problem is worrysome not because of the remaining oil, but because of the abundant coal. Most U.S. Power Plants burn coal. Any Gas vs. Electricity comparision ignores both sides of the pollution aspects.
3) Solar power is very reliable and makes electricity directly and LOCALLY on the roof of where you live (some day in the future).
I would go to the Teslamotors web site and read about Elon Musk's Secret Master Plan; http://www.teslamotors.com/blog2/?p=8 I hope he will be very successful. What his discussion makes clear is that the CAPITOL cost of making the electric car/home recharging system affordable is the direction to go. Comparision of the FUEL costs lures everyone away from the true issues to examine.
The thing I like most about the plug-in is that electricity can be generated from many sources and the electrical grid is a very efficient means of transporting it between sources and destinations. There doesn't appear to be any single solution to our planet's energy needs, therefore, there is a lot of merit to being able to use many different sources. If plug-in cars get out on the road, electricity can become sort of common currency that enables them to use the energy available.
In the south, they can use solar, hydro in the north, coal (although I don't really like it's side effects) in coal country, tidal near the coasts, sewage and trash in the cities, weeds, switchgrass, and biomass (without the need to convert to ethanol) in farm country, etc.
Tesla Motors truly does seem to have the best grasp of the big picture of any site I've seen. I highly recommend reading the blogs by their employees. http://www.teslamotors.com/blog2/?p=22 is particularly insightful on the power of solar.
http://www.teslamotors.com/blog2/?p=27
Essentially the point is that to have a car that is a good plug in EV you need a full electrical drivetrain and battery pack. To have a car that can do long road trips when the batteries die you need a full gasoline engine drive train. The weight of each compromises the range and efficiency of the other. The complexity of having two complete drivetrains is a potential maintenance nightmare. And, of course, with two drive trains there is little space for people and luggage.
You would be better off with a pure EV like a Tesla that can go 200 miles on a charge, and have a second car (diesel?) for long trips. Or even cheaper, rent a car for long trips. The few long trips most people go on, it is cheaper to rent.
I agree with the poster that said that installing a 7,000 solar panel to power a car "needs work."
However, I have an 8Kw solar system on my house and I am better than energy neutral (meaning I generate more power than I use).
In conjunction with eliminating my home bills and still being able to completely power my Tesla (perhaps the upcoming Whitestar, but if I can, the roadster), the 40K spent on the solar is pretty good (with the power company paying half and a 1k state tax credit and a 2k federal tax credit).
However, the investment is likely still to high for the average consumer (even though they buy 50k SUVs) and it does need a lot of roof space in a good open area (I am in AZ).
EV vs ICE car
Let's say what is the future of ICE car? Obviously that the oil is not sustainable. biofeul may be another option. however, the emission of car (Co2 only) make up of 15% of gloable warming gas. therefore, the room for ICE car is not bounderless.
So how about EV? Electricity have more sources. solar, wind, nuclear, water, not only coal. compared with ICE, it is more sustainable. This is the key point.
therefore, EV is worth a serious try, even though the risk exist.
www.howmuchenergydoesmycaruse.com
www.themanhattanprojectof2009.vom
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