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Posted by: crabbsaline Jul 10 2006, 11:57 AM

I'm not sure when the countdown page went up, but looks like the first peek will come on July 20:

Random thoughts:

• I wonder how similar the batteries are to those used on the MERs.
• I wonder what the replacement costs of the batteries will be.
• I wonder what the best disposal of the batteries will be.
• I wonder when they will reach a price range that I can purchase one.

As a related matter, check out the competition:



I'm glad that Doug has this chat section. This seems far enough from the subject matter of UMSF that I worried about posting it. Five degrees of separation on this topic, I suppose...UMSF : Launch Vehicles : Falcon : Elon Musk : Tesla Motors.

Posted by: Cugel Jul 10 2006, 01:04 PM

Well, I have an electrical car myself. A Toyota Prius hybrid.
It goes from 0 to 60 in 4 as well. 4 minutes that is, but...
In total silence!

The good news is that replacing the battery of a Tesla will be millions of times cheaper than replacing the battery of a MER rover!

Posted by: DonPMitchell Jul 10 2006, 08:01 PM

If you factor in the efficiency of generating and distributing electricity from power plants, is it more efficient to have an electric car, or to power a car directly by gasoline?

Posted by: Richard Trigaux Jul 10 2006, 09:54 PM

That depends on the energy source.

From oil, we gain the much better efficiency from power plants, and we lose the efficiency of the power lines and batteries. The balance must be positive I think. On environment, power plants pollute much less than car engines, and the better energetic efficiency also saves carbon dioxyd emissions.

But electricity can be produced from clean energies or dirty energies (such as nuclear). In these cases, it is more difficult to compare the overal efficiency (as we cannot do a car which would work with hydro power, for instance) but, I think, analyses show that, with any clean energy, electric cars make us win in both economic, environment, social or energetic sides.

Posted by: helvick Jul 10 2006, 10:57 PM

We do but it's not as clear cut as we might think. An oil fired station running on petrol (gasoline) would be very efficient but they burn crude (or very lightly refined crude) and their overall energy conversion efficiency is not much better than a car's engine.

The energy conversion efficiency of a standard oil fired power station is around 38%. The power transmission and distribution losses in delivering that power to consumers are around 9.5% in the US, best case 5% elsewhere. The conversion efficiency of the best electric storage and delivery mechanisms (conversion to energy store, reconversion and transmission to the motors and efficiency of the motors) is around 80%. Say 90% just to be safe. Overall energy delivery efficiency of an electric car using oil generated electricity is around 31%. Best case that would be around 37% for an advanced Oil Generator running at 44%.

Current petrol (gasoline) car engines have around a 30-40% energy conversion efficiency range while diesel versions hit 44% at the really high end. Transmission (gearing, oil drag, bearing friction etc) losses chew up around 10-20% depending on the car. So we have an efficiency range of 24-39% for normal internal combustion engine vehicles. Overall they are not that different and a good Internal Combustion engine could match a good electric only system if you wanted to build it.

The above calculation is a bit misleading though because when you fractionate crude oil you get only about 45% of the volume of petrol(gasoline) from the base fuel but you can basically burn the whole lot in an oil fired generating station. Still there is nothing stopping you burning the remaining 55% in a generator if you want so it's unfair to ding the internal combustion totally for that.

Things get more tricky when you compare the relative cost of generating power. The numbers have changed a bit over the past few years but from a few years back the relative cost of various electricity generation sources was:
Nuclear 0.33
Coal 0.33
Gas 0.82
Oil 1.00
(based on 2001 data in the US)
Since Oil and Gas have recently surged in price their relative cost has approximately trebled since then.

So an electric car powered by coal or nuclear generated electricity probably is arguably 8 or 9 times more cost efficient overall than a petrol(gasoline)\diesel internal combustion unit but you need to be clear about the fact that if the electricity is generated by oil (or gas) then that's not the case at all.

Coal and Nuclear power both have serious problems and alternative sources are still mostly more expensive than anything including oil at $75 per barrel..

Posted by: crabbsaline Jul 11 2006, 12:39 AM

Part of the beauty of it is the flexibility of choice of where the energy originates, as stated by Martin Eberhard in a http://www.redherring.com/Article.aspx?a=17178&hed=Q&A:+Tesla%25e2%2580%2599s+Martin+Eberhard:

"We’re changing the way cars are. Ten years from now, it’ll be obvious that electric cars are the way to go. They are more efficient than any other car on the road, and they are the ultimate multi-fuel technology, because you can make electricity with whatever comes along. If we want to free ourselves from our addiction to oil, it’ll be through electric cars."

Digressing a bit here, but I've been wondering about the direction of the following article, concerning capacitor batteries:

Interesting to note, the above capacitor research is sponsored by Ford Motor company. Would the realization of this "new" technology by Ford-MIT prevent a competitor such as Tesla Motor's from using it?

I wonder how much longer a capacitor can hold a charge, as compared to a lithium-ion battery?

Posted by: tty Jul 11 2006, 06:09 AM

You need to include another factor up here in the cold North. Half the year the car must be heated. With a combustion engine this is done by the 60-70 % waste heat, while for an electric car this heat is dissipated (or just possibly used) at the powerplant, and thus unavailable. Also batteries badly lose performance in cold conditions.

Power needed for A/C in the summer would be comparable in the two cases I think.

tty

Posted by: DonPMitchell Jul 11 2006, 08:53 AM

Helvick makes the good point that power plants can burn cheaper fuel. But I'm still skeptical that an electric car is efficient enough to be practical. A gasoline car is driven directly from the chemical energy of fuel. Let's look at the numbers again, for energy efficiency.

Gasoline Motor - 33%

Power Plant Efficiency - 40%
Transmission - 100 - 7.2%
LeadAcid Battery Efficiency - 80% (75 to 85)
Charging Circuit Efficiency - 80% (60 to 80)
Electric Motor - 95%
------------------------
Total Efficiency - 23%

Oddly enough, a good friend of mine owned a company that builds power lines. They built a big DC high tension line across Canada. He claims if we had it to do over again, all the high tension lines would be direct current, and the local exchanges would run at 133 Hz or higher. The Russians pioneered long distance DC transmission in the 1930s. My friend toured Soviet power plants in the 1970s.

I'm still skeptical about the electric car. If it were practical, it would be available I believe. I think there are a lot of other negative issues, battery weight, poor performance, short driving range, cost of buying and replacing batteries, etc. The market place is good at picking winners, and I don't see any electric cars on the road.

Posted by: djellison Jul 11 2006, 09:27 AM

The real advance will be the electric car using fuel cells. GM have one working already that produces so much power you don't plug it into yoru house....you could plug your house into IT. Just fill it with Hydrogen at the station, and it pulls the Oxygen from the atmosphere to do the fuel-cell reaction ( not burning ) and thus you have range, zero emissions etc.

Doug

Posted by: edstrick Jul 11 2006, 09:55 AM

What we want is cars that run off zero-point energy... or perpetual motion engines... or wishfull thinking...

The pure-electric's not going to hack it despite wacky agenda-full documentaries from people who's science and engineering grasp is the average level of a sociology student at the Peoples University of Berkeley <I'm being nasty> Pure electric autos will require battery technology (or supercapacitor... or... or) that can hold humongous charge safely and recharge FAST.

Fuel cells have a way to go but are a real candidate for a solution to replace the infernal-combustion engine for most uses. They're still "fussy" and I think tend to deliver low currents for practical systems, but could be used in fuel-cell/battery-electric hybrids.

The big question is the fuel. Hydrogen is not an energy SOURCE, it's an energy STORAGE MEDIUM... like a battery. Hydrogen storage technologies are lousy, and we've only had incremental improvement. Methane/Propane fuel cells are better, but then we're back to carbon containing fuels.

We'll get there, but it's going to take serious engineering, and time. And politically driven engineering like the big 1990's push to the pure electric car won't get us there any more than the space shuttle gave us the future we expected it to.

Posted by: jrdahlman Jul 11 2006, 04:35 PM

Carefull... any debate over alternative energy could quickly overwhelm this forum until Doug stamps down on it!

The best comparison of current alternative energy sources is Don Lancaster's lively
http://www.tinaja.com/glib/energfun.pdf paper.

By comparing "volumetric energy density in watthours per liter and gravimetric energy density in watthours per kilogram" for gasoline, hydrogen, lithium batteries, etc, you can see what's currently efficient and what's not. While hydrogen is ideal "for deep-space aps" it has many disadvantages on Earth. Don's mostly cynical against homebrew designs--using solar cells to run an electolysis of water into hydrogen "is pretty much the same as 1:1 converting US dollars into Mexican Pesos." In fact, he's pretty cynical about silicon PV, period.

I've been raving about this to other people ever since I read it.

Posted by: jrdahlman Jul 11 2006, 04:48 PM

Edit: I should have said I've been raving about this paper ever since I read it. As in showing it to everybody.

Posted by: Richard Trigaux Jul 11 2006, 05:32 PM

as edstrick says, hydrogen is not an energy source (unless we crack oil to use only its hydrogen fraction, saving greenhouse gas emissions, but not saving the oil price increase).

An important fact to understand is that, whatever the energy storage medium, it contains an amount of energy which is at least equal to that of a gazoline tank. And when a gazoline tank catches fire, it is the hell for the car occupiers, and so it is for any other energy storage method. On the reverse, there was a fuss about sodium-sulphur batteries, because sodium is a hell of an incendiary substance. But a car battery using sodium is not worse than a gazoline tank...

With any hydrogen storage method (metal hydrides, liquid hydrogen, chemical combinations like methane or ammonia...) you still run the risk of a fire if the storage breaks. The same goes with any other fuel, whatever it is burned into a battery, a fuel cell or any kind of thermal engine.

The only way to avoid the fire hazard is to use a fuel which cannot burn in the conditions of an ordinary fire: metals like aluminium, zinc, iron, etc (magnesium would be better, but it can burn). So with my opinion the best choice would be an aluminium-air battery, or at least a zinc-air battery.

Also the problem with batteries is that they often degrade with charge-discharge cycles. A solution would be to use one-time batteries and exchange them at the station.

Fuel cells have an advantage on internal combustion engine: there is no theoretical efficiency limit, like the Carnot theorem in combustion engines. So we can hope to have one day batteries or fuell cells with a near 100% efficiency.

Posted by: helvick Jul 11 2006, 06:08 PM

This is a wonderful piece of popular science with much more reality in it than anything else I've read on the subject - I absolutely love it. Thanks for the link it's going to provide me with tons of entertainment and material for throwing into discussions in the pub.

However even though I agree almost entirely with his assertions there are some points I'd disagree with. For example while he is perfectly correct in saying that PV is a net energy sink at the moment he says two things that are wrong. Firstly he says that PV has an inherant 30% conversion efficiency limit, that is not precisely true as 35% efficiency cells are now available and mid 40% is now believed possible. These types of cells are woefully uneconomic right now though (ie consume hundreds of gallons of old energy in order to produce one gallon of new energy) but that could be dramatically changed by creative application of semiconductor manufacturing techniques. Secondly he seems to think that diffuse sunlight is generally useless for PV generation - that is true for very low efficiency cells but as the MER's have proven repeatedly (to bring us somewhat back into the focus area for UMSF) you can convert more power from diffuse light than from direct light if you have high efficiency cells and you get the added benefits of a) that capability is available for a far higher percentage of time than direct light and PV cells that convert diffuse light effeciently do not need to be pointed at the sun. The difference is noteworthy in the following MER examples:

If you can only use direct insolation you are limited in this case (where atmospheric opacity is 0.904 which is slightly hazy by earth standards) then your maximum efficiency is limited to 30% of the theoretical maximum power potentially available if there was no atmosphere unless you have a sun tracking (ie expensive and energy hungry) mount. If (as the MER's can) your PV cells are good at converting diffuse light then your limiting efficiency rises to 76%. Now that's in terms of usable sunlight only so you still have the PV cells own conversion efficiency to deal with and storage\conversion losses but it does mean that the technology exists today (unlike all the other solutions) to power an average house in most places on earth with a 5x5m solar panel (assuming you get 0.5kWh from each 1m^2 or about half what the MER's get when clean). They are too damn expensive in terms of manufacturing to be practical today but that is a manufacturing challenge that could be met if sufficient focus was put into it. IMO at any rate.

Posted by: MizarKey Jul 11 2006, 06:54 PM

Maybe not as wishful as it used to be...

http://www.edge.org/3rd_culture/krauss06/krauss06.2_index.html

Of course, after reading an account of http://www.keelynet.com/energy/teslafe1.htm, it would be nice if this experiment had been better documented..even by 1931 standards.

Let's skip cars and go straight to Transporters ala Star Trek...

Posted by: Richard Trigaux Jul 12 2006, 10:36 AM

There is no theoretical limit about the efficiency of a solar cell. It is not like a thermal engine, which has a maximum allowed efficiency (Carnot theorem) given the temperatures of heat source and heat sink. Nothing such for solar cells, which can theoretically reach 100%. The much poorer practical efficiency is due to a number of factors which are difficult to overcome, so that nobody can say if we will really have one day a near 100% efficiency.

About the cost in energy to produce solar cells (the energy required to manufacture them, versus the energy they produce during their lifetime) I don't think it is so bad. Anyway the worse case is for high efficiency solar cells like those used in space. Cheaper solar cells have a much lower efficiency (5 to 10%) but they are energy positive, not energy sinks. To give an idea, paving a railway with such cheap solar cells would allow to circulate several high speed trains per day. This is just too costy for today solar cells.

The main energy cost for solar cells is the purification of silicium, which requires several cycles of melting and solidifying. Such ovens were intended for producing integrated circuits, where energy is a little part of the total cost. To produce solar cells for energy purposes would use more economic ovens (with heat recycling) and less cycles.


Anyway the smartest way to use solar energy on earth would rather be large solar ovens used to dissociate water and produce hydrogen. This is possible at 950°C with a catalytic cycle using sulphuric acid. This temp is of easy reach for solar ovens. After the hydrogen could be associated with CO2 to produce methane or gazoline, without the need to change anything to our industrial habits.

At a pinch, a smaller version of this could be used on space stations to produce energy. It would be perhaps more efficient than solar cells.

Posted by: djellison Jul 12 2006, 10:48 AM

Get this - on a trip to Coniston a few weeks back...we went in a Solar-Diesel hybrid boat. The boat ran on an electric motor, and for about half the trip ( in fairly good sun ) it ran purely on the batterys, with the solar arrays topping them up and the diesel augmenting it when appropriate.

Doug

Posted by: jamescanvin Jul 12 2006, 11:02 AM

In Sydney we can go one better.

Solar powered ferry whose movable 'wings' can also also be used as wind 'sails' - looks cool too.

http://www.solarnavigator.net/solar_sailor.htm

Posted by: DonPMitchell Jul 13 2006, 10:49 AM

Very interesting. Does it have to charge up for a while, or can it generate enough power on the fly to run continuously?

Posted by: jamescanvin Jul 14 2006, 01:46 AM

Here's a better web link - http://www.solarsailor.com

From the technology FAQ:

Posted by: crabbsaline Jul 20 2006, 07:37 AM

The car was unveiled at Midnight, California time:

The car looks great . The website design is nice too. Lots of info.

...just no price, yet.

Posted by: Richard Trigaux Jul 20 2006, 08:24 AM

Hmmm...

Yes, nice car for car lovers.

The problem I see in several other recent instances of electric cars, is that they are luxury cars or sport cars. perhaps this is the best market niche for cars which are anyway still expensive, by lack of mass production.

But, I think, electric cars will really take up when there will be family cars, small economic cars to go to work, and other models of common use.

We don't really need cars able to run at high speed (the speed limits are here and they are here to stay) and even not very nervous cars, which may be dangerous in town. And unused powelful motors add weight. Not to speak of eight wheels in place of four, as a recent japanese model has.

Cheap cars for everybody. Cheap at buying, cheap to use. (By the way 1 cent per mile is not bad).


In a general way, electricity is not an energy source. So that electricity simply offsets the nuisances, costs and problems of producing energy. In a general way, we gain on this (provided that electricity transportation and storage is efficient) but the silence and absence of exhaust must not hide heavy problems which may occur at the energy source.

By the way, solar cells on a car a far not enough to run it, but they could add some help, especially on small individual cars. Imagine a small car loading its batteries all day long on a parking, for someone just doing a short run to go to work.

Posted by: crabbsaline Jul 20 2006, 01:44 PM

Richard,

I've thought about solar panels. This car comes with an optional hard top. Understanding that the overall design of the car has omitted solar, it would be nice if they made a solar hardtop for this. I'm wondering how much further than 250 miles you could get then? How much more would this weigh, than the normal hardtop option? What would the longevity of the cells be, as compared to the overall longevity of the car?

Also, cheap electric vehicles would be a good thing. But I think much of public opinion is led by popular fashion. By making a sports car, I wonder how much more popular EV's will be to those who normally would not purchase it for frugal, environmental, or political reasons. I'm not fond of "keeping up with the Jones" motivation. But if this type of car becomes a status symbol, then an untapped section of society supports this technology. And that would be a step toward mass production, which would bring the price of this down further. "Keeping up with the Jones" worked with SUV's (yes, there were practical reasons too, but my opinion is that SUV's were partially status oriented"), maybe it can work here.

Posted by: Richard Trigaux Jul 20 2006, 03:42 PM

perhaps solar cells are not very interesting on cars, because a car is small but with a power much larger than the one it receives from the sun. But perhaps it would be interesting in some cases, or with better cells than available today. Anyway the cells must be sedigned to fit an aerodynamical shape, not just add a solar panel of the top of the car.








Alas...

Worse than than, it may be that some still think that electric cars are things for hippies.

Posted by: djellison Jul 20 2006, 04:08 PM

It might make sense if you could have an intelligent charging system using the solar arrays.

A 30 minute drive to work...

The car sits in the carpark for 6hrs+..at the best time of the day for charging...and then 30 minute drive home.

Allowing for inefficiency in the system - if you could have an array that chucked out power at say, 1/6th of that during driving, you could drive to work - park up, and then when you were ready to leave, your car would already be fully charged again.

Doug

Posted by: helvick Jul 20 2006, 05:40 PM

OK say you have 3m^2 of surface area to put cells on, live in a reasonably sunny climate and get ~4 hours of peak sun every day (ie 5 kw hours of insolation per m^2 which is close the the continental US annual average) and have pretty good commercial grade solar cells (~12% conversion efficiency), then you get ~2kw hours of energy from a full days charge. That's about 50cents worth of juice give or take. Also bear in mind that the 3m^2 panel will set you back somewhere between $4 and $12K.

The motor(s) in this beauty are listed as having a 185kw peak (~250hp) so you'd only get about 30 seconds of driving at full welly on a days solar charging.

However they do also say that the electrical cost per mile can be as low as 1-2c and that presumably factors in normal driving and the benefits of regenerative braking etc. http://www.electroauto.com/info/cost.shtml that I found through their links indicates that an AC powered system could require as little as 0.174-0.288 kwhr per mile. Let's assume that we're getting the 0.174 number here and that our entire system loss is around 25% betwen initial conversion, storage and reconversion back to AC.

Your 2kw hours would then be good for about 9 miles.

And the panel would take somewhere between 8 and 24 years to pay itself back.

Posted by: djellison Jul 20 2006, 07:04 PM

I didn't say it made financial sense

Doug

Posted by: helvick Jul 20 2006, 07:52 PM

It doesn't yet but it's interesting that even now PV is within an order of magnitude or so of being worthwhile.

If 0.174kwhr per mile is realistic (I don't know if it is to be honest) then 50mph cruising would should require about 9kw/hr per hour generating capacity for a system that could charge a car fully on the go.

To get to that you could:
Triple the effective cell area - use the sides of the car and all of the surface area available on a ~3x2x1m car. should be straightforward enough.

Quadruple the cell efficiency - 50% efficient cells would be expensive but should be possible. Not quite impossible but pretty close.

Move far enough South (or North) and get 100% more total solar energy on an average day (say 9 kwhr/day/m^2).

Now instead of generating 2kwhr in a day you would be able to generate 48kwhr per day, with more than 9kwhr/hr for a few hours around midday.

The only real problem is that some bright spark has to come up with a cheap PV technology that gets >=50% conversion efficiency.

Posted by: crabbsaline Jul 25 2006, 01:05 AM

Looks like cost will be around $100,000:

Now I'm curious about what kind of family car they will release in three years. Anybody got a spare 100 grand laying around?