Bishop Hill Why electric cars are really coal cars
Apr 6, 2011 Energy An interesting look at arguments for electric cars by a Professor of Chemistry:
It is claimed in a Royal Academy of Engineering (RAE) report on electric cars that they are in any case cleaner because 80 - 90% of the energy put into them in terms of electricity is recovered in terms of useful power at the wheels, to be compared with 20 - 30% in a conventional oil-powered car. Well, that sounds good, but the reality is that only about one third of the energy in the coal or gas actually ends-up as electricity because of the Second Law of Thermodynamics and the Carnot Cycle limit - the other two thirds being thrown away as heat. Thus the electric car is harvesting in terms of well-to-wheel miles only about 27% of the original fossil fuel energy, so not that much better than the standard car running on petrol or diesel. The difference is merely whether about the same quantity of waste heat energy is thrown away at source or in the vehicle.
Reader Comments (63)
most cars are underutilised: 2h out of 24h in service max.
compare that to airplanes 14h out of 24h
now the write off of the cost price of a car certainly is important part of its energy budget (30-50%).
automated driving and pooling of the rolling stock would bring this time and be a much higher saving than all batteries ideas smacked together.
and (probably mentioned already) that waste heat can no longer be used to heat the passengers, so additional coal will be required on cold days!
Never mind the lack of ability to refill in 2 minutes to allow me to drive all day (800km on one refill).
phinniethewoo
Agreed. But people like their own cars, right or wrong. I can't see a politically workable route from this reality to the rational alternative you propose.
Curt: yes, coal plants are at least 36% in UK currently, which is better than in many parts of the world, except brand new build for example in China which might top 40%, but that would be in the mix with smaller, older plant with ghastly efficiencies. The average for coal generation across the world is 31%, and I believe USA is still only around 33% on average.
In some parts of USA electricity is all coal generated, so electric cars there really are 100% coal powered cars. IEEE did a study a while back showing that CO2 emissions for electric cars were considerably higher than CO2 emissions for gasoline-powered cars in states that used a large proportion of coal fired generation. They concluded that if reduction in CO2 was the aim then switching to electric vehicles was totally misguided.
There are other unintended consequences. If we start using electric vehicles in a widespread fashion the grid transmission losses will increase considerably unless we install a whole load of new infrastructure at higher voltage, or heavier cables. Resistive losses increase with the square of the current, so the percentage increase in losses in the existing infrastructure due to the additional charging loading can be considerably greater than the percentage increase in loading itself.
At least when a diesel/petrol powered car is turned off, there are no emmissions. With an electric car, the base load power stations that charge their batteries are running 24/7. Even when not supplying any power to the grid, the base load power stations consume considerable amounts of power (and hence are emitting CO2), just to run their own processes.
Then when everyone gets home after their day of driving and plugs their car in to re-charge, the electricity grid will need to be designed to carry this peak load. This has the unintended consequence that ScientistForTruth describes above. The electricity network will need to be beefed up, which is not without an environmental cost.
Trickle charging overnight may help flatten this peak, however I'm sure most people will want to charge their electric cars in the shortest time possible, which will add to the peak demand problem.
Perhaps small, home based gas powered generators for charging these cars may help solve this problem. Personally, I think they should be made to re-charge their cars from renewable sources. That should wipe the smile off their smug faces!
The author of the piece, Prof Chris Rhodes, is author of a book called "University Shambles"
http://universityshambles.com/
Blair’s educational reforms of the 1990’s. Where glittering new universities arise from the ashes of mediocre former polytechnics; and where egos don’t just run departments – they run rampant.
Enter Charles Rae, a young, rabidly ambitious particle physicist who is offered a professorship at the newly fledged Evergreen Epstein University (EEU), making him the youngest professor of physics in the world.
His elation chills as he rapidly finds himself drawn into a twilight-zone scenario that appears to have been deliberately engineered for his destruction.
Sounds like a good read!
@ simpleseekeraftertruth (Apr 6, 2011 at 6:30 PM):
"A fairer comparison for the electric car would be the horse & carriage: limited range, long recharge time, ..."
As Viv Evans points out, there are a few snags.
But don't forget that when the horse & carriage breaks down you can do like the Belgians and eat the horse. Quite tasty!
You can't do that with a Pious. Or a Leaf.
@ScientistForTruth
If you took ten minutes to actually read the paper in the link and check the sums that are provided on the same page you'd realise that the study is based on real calculations rather than your approach of plucking numbers out of the air and presenting them as fact. If anyone has an agenda here, it's you.
SighGroan "If you took ten minutes to actually read the paper in the link and check the sums that are provided on the same page you'd realise that the study is based on real calculations rather than your approach of plucking numbers out of the air and presenting them as fact. If anyone has an agenda here, it's you."
You are obviously impressed by arithmetic and numbers rather than reality. Obviously you didn't read the paper very carefully, for the author states:
"This is NOT an analysis that qualifies for an actual scientifically rigorous analysis, and is meant to simply provide some overall insights regarding what happens to the heat created inside a standard engine."
Not a rigorous analysis, chum.
Here's something to think about.
Supposing we do as the government wants - all drive electric cars.
So, then we have the following situation:
No road tax.
No fuel duty, and the VAT on it.
No Congestion Charge being paid.
Goverment/London Mayor billions short in their calculations - does anyone REALLY think that they won't invent a nice crippling tax regime to replace that lot..??
As for the charge of "plucking numbers out of the air and presenting them as fact" I have referred to the readable IEEE article (http://spectrum.ieee.org/energy/the-smarter-grid/how-green-is-my-plugin/0) and here you can see for yourselves the g/km for electric driving. In UK, Germany and USA it falls between 100-125 g/km on average, but in some US states is worse than 175g/km. In France, because they are a little over 80% nuclear generation, it is less than 50 g/km. In Norway and Brazil (which are blessed with hydro power) it is between 50 and 75g/km. In Australia, India, South Africa and China it is over 125g/km. European diesel engines already do better than 100 g/km, and keep improving.
http://spectrum.ieee.org/image/61915
If anyone wants a few sums from the article:
"In most places, grid power is for many decades going to come from the burning of fossil fuels, which generate their own emissions. So the question becomes: If you power a vehicle with electricity from the grid rather than with fuel from the tank, is that better or worse for the environment, particularly with respect to greenhouse gases like carbon dioxide?..To figure out the amount of CO2 that might result from running on grid power, the first thing you need to know is how much electricity a plug-in car uses.Tesla Motors has claimed that its sporty Roadster consumes just 110 watthours per kilometer, although some real-world measurements show its usage can be more than twice that...For something like a plug-in version of a Toyota Prius, a more reasonable number to use might be 150 Wh/km...The next key factor is how much carbon dioxide is released while the electricity is generated. For that, the U.S. electric grid provides a convenient benchmark. According to the U.S. Department of Energy, roughly 600 grams of CO2 were emitted for each kilowatt-hour of electricity generated in the United States in 2006. The transmission and distribution of electricity is thought to incur losses of about 9 percent, and charging a car’s battery pack is about 90 percent efficient. So the actual amount of carbon dioxide emitted is probably closer to 700 grams—or 0.7 gram for each watt-hour in an electric vehicle’s battery pack. The plug-in’s 150 Wh/km therefore translates to 105 grams of CO2 per kilometer, assuming the car is charged on the U.S. power grid, averaged across all its many different generating sources...European diesels emit less than 100 g/km."
As the article points out, for some states in USA (e.g. Wyoming, North Dakota) power station CO2 emissions exceed 1000g/kWh, which translates to over 175g/km for electric vehicles used there.
A caveat is that there is some additional overhead to add the cost of bringing fuel from the well to the vehicle, but there is also cost in bringing fuel from the mine/well to the power station. And, heck, what about the overheads and environmental damage in producing all the rare earths and all the batteries in electric cars (compared to a simple block of cheap steel for an internal combustion engine)?
The long and the short of it though is that while fossil-fuelled cars will continue to reduce their g/km (partly due to commercial pressure because of the sheer cost of fuel), electric cars are not going to able to improve significantly on their g/km CO2 without a massive rollout of nuclear power generation (though gas-fired generation would help somewhat) because so-called 'renewables' will never be more than a tiny fraction of generating capacity those many countries that are not blessed with abundant hydroelectric power.
@ David
does anyone REALLY think that they won't invent a nice crippling tax regime to replace that lot..??
It has been established empirically that someone who drives 6,000 miles a year in a 30mpg car is prepared to pay £1,200 for fuel and about £300 for tax and MOT. It's what European motorists are doing now,
It follows that if there were a way to run a car for a year on a gallon of water, that gallon would be chemically marked and taxed at £1,500 a gallon. An internet-connected device fitted to the engine would analyse the exhaust and automatically disable the car and direct debit you a large fine if the car were found to be running on unmarked water.
I'm not sure whether it has been mentioned here, but companies including VW are working on thermoelectric heat recovery for petrol or diesel cars thus reducing the engine load from the alternator and increasing the end to end efficiency of the fuel used.
http://www.greencarcongress.com/2009/02/volkswagen-show.html