2010-12-28 22:05:17Solutions: Electric cars don't save CO2
MarkR
Mark Richardson
m.t.richardson2@gmail...
92.15.45.64

2 common criticisms of electric cars are that they take more energy to build and that you have to run a power station anyway. Scientists and engineers look at how much energy is used from the factory to the junkyard including the energy to make the car & battery plus the energy to run it. Figure 1 shows the results of Samaras & Meisterling who looked at plug in hybrids (‘PHEV’), hybrids and ‘normal’ petrol cars. Plug in hybrids have a battery that can run the car for a distance before a petrol engine takes over.

 

This is a pretty common result: electric cars take more energy produce but most of the energy used is from driving and here they make big savings.

Other studies have looked at combinations of electric cars versus hybrids versus hydrogen versus normal cars powered with petrol or fuel made from coal. Ou, Yang & Zhang found that an electric car charged by a coal power station is 3-36% less polluting than an average petrol car (the range is from the efficiency of the power station).

The picture is a complicated as petrol cars improve efficiency, polluting oil sands are used, battery technology improves etc. The biggest difference is the efficiency: the 1.6L DuraTec 2011 Ford Mondeo on average needs almost 0.7 kWh of fuel energy to drive a kilometre. By contrast the Nissan Leaf, Chevrolet Volt, Tesla Roadster and Mitsubishi iMiEV all require less than 0.14 kWh of battery energy.

This is where electric cars have the advantage; even accounting for power station & electricity transfer/storage an electric  car is usually more efficient than the petrol alternative and they can run on any fuel from uranium to wind to oil. An electric car charged up in France produces around 2-3 g CO2 per kilometre, compared with the best Prius at 90 g and an average new British car at 150 g.

 

Electric cars take more energy to produce, but this is more than made up for by their greater efficiency. They reduce total energy used, but since coal is more CO2 intensive than oil they might only have small effects on CO2 emissions in some countries. In the US they offer significant CO2 savings and in France an electric car produces under 5% of the CO2 of a ‘normal’ car in use. Electric cars are capable of CO2 savings that it’s thermodynamically impossible for oil to match.

 

 

 

 

 

Bit messy at the moment. I have a handful of Life cycle analyses and generally they agree on the results, but battery capacity is the problem for long range driving.

2011-01-08 04:06:56summary study
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.252
Plug-in America did a nice summary of studies on the subject to debunk this myth too.
2011-02-08 10:06:23
Paul D

chillcast@googlemail...
82.18.130.183
There is also the case of electric buses which are beginning to be used.
I would imagine the co2 per passenger km is tiny once you get rid of coal.
2011-02-08 12:16:18Status of this rebuttal
John Cook

john@skepticalscience...
123.211.149.21
Mark, any update on this rebuttal and the missing pics?
2011-02-25 11:57:50
Agnostic

mikepope_9@hotmail...
118.208.63.19

Surely production of electric vehicles is, in terms of greenhouse gas emissions, cheaper than production of hybrids, the most expensive product since it has all the fittings and fixtures of both electric and petrol vehicles. 

 

Purely electric cars have, at most, 4 electric motors (one on each wheel) and may only have one, plus a bank of batteries, compared to a petrol vehicle with its internal combustion engine, radiator, exhaust system, fuel tank and pump.  Prima facie I can not believe that production of electric cars could be more expensive than conventional ones.

 

Operating cost in terms of pollution requires a comparison between greenhouse gases emitted by to produce and combust petrol used per km. and emissions required to generate electricity used per km.  Again, prima facie, it is difficult to imagine electricity used being more polluting.  But that is based on current technology.

 

Future technology is likely to involve production and use of batteries with much higher storage capacity and durability (based on nano technology) which are cheaper to produce than present day batteries.  Base load electricity will increasingly be produced from renewable sources such as hydro and geothermal as Australia transits to a “low” then a  “no” carbon economy.

 

Some technological aspects are considered here and economic ones here

2011-02-25 12:08:20
nealjking

nealjking@gmail...
91.33.108.242
I would think that the most important thing to focus on is the battery. Batteries are heavy, big, dangerous, short-lived, nasty, and well, chemical.
2011-03-03 00:26:20
perseus

owlsmoor@googlemail...
78.143.200.99
2011-03-03 00:33:13
perseus

owlsmoor@googlemail...
78.143.200.99

Mark

There is a great deal of contradictory information on this subject.  In general, trials have not yielded the carbon savings suggested by calculations, probably due to overestimating the energy efficiencies of the various electrical components, particularly the battery.  There was a comprehensive series of tests carried out in Germany about a year ago. I will try to find it.

Obviously, the carbon saving will depend upon the generating mix for the relevent grid. I understand due to the dominance of coal generation in Germany, electric vehicles were shown to produce more carbon than their petroleum equivalents. 

I have generated spreadsheets for vehicle range and CO2 emissions if you are interested. You can enter parameters based on various inputs such as speed, generating mix etc. but these are only for highway running (constant speed). Of course it's a lot more complex for city driving, but electric vehicles should generate far less carbon than IC engines in this mode. 

Most of these reports are recent. The Smart trial was an unusual battery from what I recall so not sure how much to read into these results.  The low carbon transport innovation strategy does the work for you by calculating the carbon equivalent for a move from petroleum to electric for cars. This is for the UK generating mix, it might be possible to convert to a global mix from this. 

The Smart Move trail, initial results.  

Electric Vehicles Charged with potential

Electric vehicle Operating and Production Costs

From hype to reality - How to avoid an electric shock

Life cycle analysis

pathways to a low carbon economy Life cycle assessment: Toyota's comprehensive analysis of vehicle C[O.sub.2] emissions over the life of the vehicle reveals some surprizes

 

 

Low Carbon Transport Innovation Strategy DfT May 2007; Section 9.7 C emissions from replacement of the UK car and taxi fleet under 3 grid mix scenarios.  
 
Some of this information is summarised here.