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Tesla Reveals High-Profile Electric Roadster; Calculates EV is More Than 3x as Efficient (WTW) as Fuel Cell Vehicle

Tesla3
The Tesla Roadster.

Tesla Motors unveiled its much-anticipated all-electric two-seater roadster. The lithium-ion battery powered sportscar features a 248hp (185 kW) electric motor that accelerates the car from 0 to 60 in four seconds.

Built by Lotus for Tesla, the Roadster has a range of about 250 miles and a top speed of 130 mph. The price for the Roadster will be around $100,000.

The custom-designed battery system (Energy Storage System) weighs in at close to 1,000 pounds and uses commodity lithium-ion cells. The system addresses thermal balancing with a liquid cooling circuit.

The 3-phase, four-pole motor uses a low resistance “squirrel cage” with large copper end rings. This allows the rotor to develop high current flows and torque, with low resistance losses. The use of a small air gap allows tight inductive coupling which, combined with low loss magnetic materials, enables the development of high torque at high rpm. Together, these factors allow the induction of large currents, even at high rpm, producing much flatter power and efficiency curves from approximately 2,000 rpm to 12,000 rpm. The motor redlines at 13,500 rpm.

(Devising a cost-effective method for the production of copper motor rotors has been under investigation for years. Siemens introduced three motors with die-cast copper rotors to the US market in April.)

Tesla4
Comparing Well-to-Wheel Efficiency and GHG emissions. Click to enlarge.

In a white paper (The 21st Century Electric Car) published on the Tesla Motors website, the company calculates the tank-to-wheel (actually, the “electrical outlet to wheel”) energy efficiency of the Roadster to be 2.18 km/MJ.

Assuming electricity supplied from a combined-cycle natural-gas-fired generator, and accounting for transmissions losses over the grid leads them to calculate the “well-to-wheel” efficiency of the Roadster to be 1.14 km/MJ—double the efficiency of the Toyota Prius.

Tesla then tackles the question of hydrogen fuel-cell vehicles (FCV) fuel cars, deriving a theoretical efficiency for an FCV fueled with hydrogen produced by steam methane reforming of 0.85 km/MJ.

Tesla2
Theoretical efficiency of battery-electric and fuel-cell vehicles. Click to enlarge.

This is impressive when compared to a gasoline car, though it is 32% worse than our electric car. But real fuel-cell cars do not perform nearly this well.

...The best fuel-cell demonstration car measured by the EPA is the Honda FCX, which gets about 49 miles per kilogram of hydrogen, equal to 80.5 kilometers per kilogram. We know that the energy content of hydrogen is 141.9 MJ/kg, so we can calculate the vehicle efficiency to be 80.5 km/kg / 141.9 MJ/kg = 0.57 km/MJ.

...When we calculate the well-to-wheel energy efficiency of this Honda experimental car, we get 0.57 km/MJ x 61% = 0.35 km/MJ, not even as good as the ordinary diesel Volkswagen Jetta, let alone the gasoline-powered Honda Civic VX or the Honda Insight hybrid car.

However, some proponents of hydrogen fuel cells argue that it would be better to produce hydrogen through electrolysis of water. The well-to-tank efficiency of hydrogen made through electrolysis is only about 22%, and the well-to-wheel energy efficiency of our theoretical fuel-cell car would be 2.78 km/MJ x 50% x 22% = 0.30 km/MJ, and the well-to-wheel energy efficiency of the Honda FCX would be 0.57 km/MJ x 22% = 0.12 km/MJ, even less efficient than a Porsche Turbo.

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Comments

Neil

More importantly than economics and security. We can't keep burning gas and turning our world into a desert.

The reasons for reducing the weight of a vehicle is to improve energy efficiency and performance. In performance this car is competative. In energy efficiency gasoline ICE cars can't touch it. So who cares if it weighs 500 lb more.

marcus

Anitgravity, I really think it is quite preposterous and offensive to be denigrating all Arabs for the US's fuel dependency. Firstly and most importantly its only the Arab elite that are in control of the oil by and large and they are not the terrorists! Secondly it takes two to tango. Is it their fault you are so dependant on their oil ? What if the shoe was on the other foot? Do you think the US would be giving it away for free? Thirdly, in many cases OPEC have done a reasonable job of keeping oil prices as low and steady as they have (supplying the addict with cheap dope!). The Saudi's themselves have said they would like gas prices much lower than they are. I believe them since as we can see, a change over is starting to occur. What this also means however is that if oil prices get a lot worse very quickly there is little spare capacity get things back to normal.

My only complaint for the Saudi elite is, LET US IN TO AUDIT YOUR RESERVES!!

Neil

Marcus: Here,Here ... Racism is just plain ugly. Re: audit ... Does the JODI come close?

antigravity

you are quite correct it is not the arabs alone who are to blame for the US oil dependency the blame lies with the american people, the american government and the american car companys
OPEC of which the arabs play a large part likes to keeps the cost of oil lower so alternatives to oil will not be able to compete on cost, this is called the price collar
the arab elite are not the tererists
was that a joke OBL was belived to have between 100-300 million dollars if that not the elite what is, his second in comand was a doctor and also part of the elite, the saudi elite spend hundreds of millions of dollars very year exporting their brand of islam all over the world. but you are right it is mostly poor people who will die on both sides, poverty is not the cause of arab terrorism if you think it is you fail to understand the problem and its cause
Racism
i am not a racist and i think anyone who uses the word too much ends up debasing the word, you end up like the boy who cried wolf no one will listen in the future
by the way i love the fact that the price of oil is high now, i check it every day, i hope it will go a lot higher, the sooner it goes over 100$ the better
oh and i have traveled to more than one arab country and to other muslim countries have you

marcus

The point is that the people supplying you oil aren't the same people trying to blow you up. This is also not a competition for who has been to the most Arab countries. When you post comments like "dirty arab scum" on the web you can hardly blame people for calling you racist.

marcus

Ok, we agree on the Tesla!

antigravity

sound, knew we would

Neil

time to edit the thread Mike. We're a little off topic.

Neil

Thanks Mike

antigravity

neil, mike if you want to change or edit one of my posts please don't, it would be better if you just delete the post in full
thanks

Vito

It does look interesting but when I took a closer look the numbers seem a little off. The corvette's
well to wheel CO2 is 57 g/km, which is very low considering Europe is struggling for 140g/km tank
to wheel...unless I am missing something.

Mike

done.

Walt

I realize it's a big if, but if the price and weight of batteries comes down or ultra-caps become viable, I can see where we might make these cars fit our pattern and maybe offer some flexibility. Assuming it's possible to design the cars this way, the gas station would be the place to fast charge, with the necessary fat cables and high current equipment (maybe a quick disconnect coolant hose),and the slow charge can be done at home overnight. If the fast charge is fast enough, it would allow trips of any distance. A small, portable battery system, good for maybe 10 miles can serve as the equivalent "gas can" for emergencies.

I think if people are given this type of flexibility, they might accept a slightly shorter range for the occasional long trip.

I'm wondering also if the hydraulic hybrid concept can be employed here, if cost effective, to extend the in town range.

A . R . E . C

If you want to stop all the crap on engine then coming soon by a company is the all new auto recharge electric car, reaching speeds of 250 MPH and 300 HP, and heres what is going to confuse you.... you never stop and recharge, it is not solar, nuclear, gasolone, no PURE ELECTRICTY and coming soon Joel Oliva will come on the national news and address the biggest relief in the history in the world because not only can he make Cars, in production is the New Airplanes of the future because they are pure electricity and rehcarges internally like the vehicle. now back to the vehicle, you basically in simple terms, start the car and begin and never stop until you want to, not because your running out of gasoline. Coming soon, This is no joke, just wanted to let you know, And heres the best part of all. He is not interested in making big Profits like all these greedy pricks, no hes going to sell the vehicles starting at $9,000, yes in american dollars. Finally the Americans have a made the best reliable vehicle with only once a year maintenance. better than any comapny in the world because it never needs anything, and everything has a backup, event even the lightbuld, they automatically, this is not a dream this is a reality and YOU deserve it, Email me at Joel305239@aol.com and address the Title as A.R.E.C and your name, thanks again for your time, and this is on the way, so now where are the industries going to take your money this time, think about that but welcome to the properous year of 2006 and 2007. Inventor and future Leader: Joel Oliva

A . R . E . C

If you want to stop all the crap on engine then coming soon by a company is the all new auto recharge electric car, reaching speeds of 250 MPH and 300 HP, and heres what is going to confuse you.... you never stop and recharge, it is not solar, nuclear, gasolone, no PURE ELECTRICTY and coming soon Joel will come on the national news and address the biggest relief in the history in the world because not only can he make Cars, in production is the New Airplanes of the future because they are pure electricity and rehcarges internally like the vehicle. now back to the vehicle, you basically in simple terms, start the car and begin and never stop until you want to, not because your running out of gasoline. Coming soon, This is no joke, just wanted to let you know, And heres the best part of all. He is not interested in making big Profits like all these greedy pricks, no hes going to sell the vehicles starting at $9,000, yes in american dollars. Finally the Americans have a made the best reliable vehicle with only once a year maintenance. better than any comapny in the world because it never needs anything, and everything has a backup, event even the lightbuld, they automatically, this is not a dream this is a reality and YOU deserve it, Email me at Joel305239@aol.com and address the Title as A.R.E.C and your name, thanks again for your time, and this is on the way, so now where are the industries going to take your money this time, think about that but welcome to the properous year of 2006 and 2007. Inventor and future Leader: Joel

Burtt

I'm late in this but: this is a three phase 4 pole ac motor. not dc.. Speed is determined by frequency not voltage. and there is a problem with low end torque.this is corrected by a regulator.

as for the obivo and the like If I can get 240mile per charge at 49 k I will make the sacrifice. these cars should live longer, hold resale, goood for the enviroment, does not finace terror, less maitance, and a lot of neet tech stuf is onboard these things. you need to go to zap's web site.

Andy

One thing I’m amazed that no one has picked up on is battery lifecycle costs.

All I see on forums like this (and similar) is that electric cars are being suppressed by major car cos etc etc.

Bollocks I say. The reason no one wants them (with the exception of rich philanthropists) is that the economies don’t make sense.

I’d be interested to see the real life expectancy of these batteries along with the replacement costs.

Consider that if the car is used daily the batteries will be charged daily. Assuming the car does the average mileage (say 15,000 miles/yr).
If the car can withstand 2000 cycles before major battery degradation then at 356 charges a year (a pessimistic assumption) then you’re looking at approx 5.5 years of use from the batteries.
Now at a rough guess approx 50% of the costs of this car will be embodied in the battery pack (again a conservative estimate)

So $50,000 for a replacement pack after 5.5 years equates to an annual “battery cost” if you like, of $9,090.

And that’s before you charge it. At, say 12 kWh per charge, that’s 4,380kWh a year.
So at say, 9 cents a kWh you’re annual power cost is a mere $394. By the way the assumption that you can drive 15,000 miles on 4,380kWh is extremely optimistic. It’s roughly the equivalent to 130mpg on gas.

Your $9,484 will buy you approx 2,700 gallons at $3.50/gal.
Hey, even in Euro land at $6.20 it’ll buy you 1,529gal.

At 30mpg you could drive 81,000miles a year for the same cost.
Or in Euro land you could drive 45,800 miles a year.

To put it bluntly its simply far too expensive for you’re average joe.

The next most predictable excuse is that a smaller (lower powered car) will have less batteries. As posters in this thread above have alluded, this is a fallacy. The range of an electric car is determined by its battery storage capacity. The high power is merely a useful by-product of having so many batteries. Even a smaller powered car is going to need approx $40,000 of batteries to give decent range. (Yes I know the Rav 4 battery pack is cheaper than this but it’s range sucks)

Next fallacy is that as production volume of batteries ramps up the costs will come down. This always makes me laugh.
Duracell etc have been making millions of AA cell batteries for years, and I’ve yet to see costs fall significantly.
The main problem with batteries is not the manufacturing costs it’s the material content costs.
Complaining that batteries are expensive due to manufacturing is like complaining about high gas prices being due to high refining costs. It ain’t, it’s the cost of the raw material.
Oh, and as every man and his dog, rushes out to but an EV, what do you think that will do to the supply and demand curve for Lithium? Doubt it’ll get any cheaper. Repeat for any (semi scarce) material that batteries can be made from.

Of course the holy grail of battery designers is to increase power density while reducing material content. Unfortunately you do eventually run into the limits of what is possible as defined by the laws of physics. Much like hydrogen, its limited not by our technology but by fundamentals of physics, which cannot be changed.

The do believe that EV’s have a future, but not as full size cars. (except as toys for the rich)
I reckon that EV’s will be small highly aerodynamic devices with possibly a max speed for 50mph for urban runaround work. They will be small and light, to maximise the utility around the smallest (read: cheapest) battery that can possibly do the job. For longer range transport CTL/BTL fuelled aircraft and electrified trains will do the job.

In smaller countries (like the UK where I live) its even possible that the main highway network could be electrified to allow freight trucks to keep running. It may be cheaper to do this than rebuild our old railway network. (The existing network is running at capacity)

Neil

Andy: the 2000 cycles they are talking about is a deap discharge limit. Even after the 2000 deap discharges, batteries like the Valence still have 90% capacity. So unless you are driving 240 miles a day you won't be replacing the batteries every 5 years.

antigravity

most people drive less than 50 miles a day so i don't think people will charge the car 365 times a year, but if they did then the batterys may need to be replaced in five years, is that a bad thing, the batterys you buy in 5 years will prob cost less, hold more charge and be a little lighter, so 5 years from now the car you drive actually gets better and better, more range, faster, maybe even faster charge times, can you think of any ICE car that woks like that
this is wht GM dont want electric cars most people would just buy new batterys every few years and not new cars, good for drivers bad for GM ect

Andy

antigravity, if someone drives their electric car every day, then they will charge it every day just to ensure the charge remains "topped off"

I'm afraid I'll still want some proof that those batteries are still good after 2000 deep cycle charges and 5 years daily thermal cycling. Even the effect of aging on them could be significant.

What about a 6 year battery/powertrain warranty that guarantees free battery replacement if there is less that, say, 85% capacity remaining after 5 years.

Is the manufacturer really that confident in their batteries.

I'd bet they aren't.

Andy

Andy

Antigravity, see my first post about WHY people don't want to replace battery packs every 5 years.

The per annum depreciation cost (on batteries) is horrendous. It is far too much for mere mortals to buy.

If I had an electric car and the batteries died after 5 years, I'd be livid. Not to mention hugely out of pocket.

Andy

Neil

Andy:

2000 may very well be a conservative number for the newer technology battteries. Altair got 9000 cycles out of this battery:

http://www.greencarcongress.com/2006/05/altair_nanotech.html

Calendar life may still be an issue.

I think you're being a tad pessimistic about battery costs in the future. If you are going to be pessimistic then what happens if you apply that pessimism to the price of gasoline in 5 years?

The tesla engineers are confident they can get 100,000 miles out of the batteries.

I suspect that the batteries that go into the production car will be better than the ones they have been using so far.

anti gravity

the battery pack in the tesla is made up of thousands of small cells if one cell or many has a problem it not hard or expensive to replace, Li batterys can be recycled if you trade in your old pack when you need a new one this may bring down the cost
yes it is true that Li batterys are very expensive, but i think that will change in the future, if not I'm not that worried there are a number of different people working on other solutions
do a google search on firefly batterys lead acid but almost as good as Li
do a search on EEStor capactor
there are others working on other ideas it only takes one to make the difference
to bring the cost down and at the same time you have to remember that the oil peak is very close now and the only way is up for gas prices
Andy you don't like the idea of electric cars thats ok they are not for everyone if ICE is best for you stay with it who knows you may change your mind some day
you said you live in the UK do you live in london if you do you know that if you drive in the centre of london you have to pay £8 a day but if you have an electric car there is no charge

Nick

re battery charge cycling: From the FAQ on the Tesla website:

"Li-Ion batteries are good for 500 charge/discharge cycles. With 250 miles of range this works out to 125,000 miles, but our estimate is a conservative 100,000 miles. However we believe that we will get better life from our batteries due to temperature control of the batteries and intelligent charge/discharge cycling."

I take it that 'intelligent charge/discharge cycling' means cycling the discharge load through different banks of batteries so as to minimize the number of times a particular bank or battery needs to be cycled. I'm no expert on this, but clearly a (conservative?) limit of 500 cycles would be very limiting if daily driving implied 1 cycle/day for the complete set.

Neil

How many people drive 250 miles per day?

I also suspect that by the time they produce these cars in a year they will be using updated batteries with a much higher cycle number. How much would you spend on maintenance on a car that had gone 125,000 miles?

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