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Topic with many replies

Efficiency of the Tesla Roadster...or where is clean energy coming from?

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Author Message
Written on: 02 January 2008 [00:14]
Topic creator
registered since: 20.07.2007
Posts: 586
There is no doubt, the Tesla Roadster is a very efficient vehicle compared to other sportscars. I tried to find out what its energy consumption is and how the consumption compares with other cars.

Tesla states that the car has an efficiency of 135mpg (US). Thats 1.74lt/100km or 162 UK mpg. Pretty good I thought! This however relates only to the station-to-wheel efficiency.

When looking at the full-cycle energy-equivalency of gasoline with electricity from the USA grid, that figure increases to 49 mpg (U.S.) (4.77 l/100 km).

So if the electrical energy is mainly produced burning fossil fuel (and thats the case in the US), then the car is not as green as one might think. But to be fair, 49mpg is still a quite impressive figure for a sportscar like the Tesla Roadster and the Tesla engineers deserve our respect...

NB: The average American car has a full-cycle energy-equivalent of 23.2 mpg (U.S.) (10.1 l/100 km).

Twike 890 http://images.spritmonitor.de/461746.png
Written on: 07 January 2008 [18:10]
registered since: 08.09.2007
Posts: 88
ecoadmin wrote:

When looking at the full-cycle energy-equivalency of gasoline with electricity from the USA grid, that figure increases to 49 mpg (U.S.) (4.77 l/100 km).

Hi ecoadmin,

how did you calculate that? And what's the assumption on the percentages of gas, oil, coal etc. used in the production of electricity in the US?



Mitsubishi i-MiEV + Citysax 002, davor/formerly Twike 808 and 891
Written on: 08 January 2008 [12:56]
Topic creator
registered since: 20.07.2007
Posts: 586
Hello Frank,

The figure of 49 mpg - 4.77lt/100km is from the wikipedia Tesla Roadster page.

I know, one has to be careful when using wikipedia as a info source, buts thats all I could find.

Wikipedia goes on to say that when using a newer power plant station to produce the elecricity the value drops:

To compare the full-cycle energy-equivalency of gasoline with electricity generated by newer, 58% efficiency CCGT power plants,[26] the factor of 21,763 Wh/gal[25] in the above equation yields a fuel efficiency of 87 mpg (U.S.) (2.70 l/100 km).

How moch oil, gas or coal is used in the US can be seen on this link:

What it does not say is, how much is of the various fossil fuels is used to produce the electricity.

Another source is here the CIA - Worldfactbook:
Electricity - production by source:
fossil fuel: 71.4%
hydro: 5.6%
nuclear: 20.7%
other: 2.3% (2001)


Twike 890 http://images.spritmonitor.de/461746.png
Written on: 31 May 2008 [16:50]
registered since: 31.05.2008
Posts: 75
Throwing out a figure of "49 MPG" isn't very meaningful unless it's compared to other cars. Tesla Motors' website claims a well-to-wheel efficiency twice as good as the Honda Civic VX.


Now admittedly they've chosen the numbers most favorable to themselves, but still it seems fairly certain the Tesla Roadster, which is optimized for extreme efficiency, is appreciably more efficient in energy usage than, say, the Honda Insight (parallel hybrid) driven by a friend of mine. He averages, I think, nearly 50 MPG, and the Tesla Roadster is undoubtedly much more efficient than that.

Ultimately, from the standpoint of powering an electric car, it doesn't really matter how efficient or inefficient is the process of producing electric power, unless the electric car is actually *less* efficient than gassers (gas-powered cars) are. And I don't think anyone is claiming that.

This thread seems to be along the lines of the same old tired argument that "An electric car is only half the solution, and therefore worthless." No, that is wrong. Half the solution isn't worthless-- it is, in fact, half the solution. The other half would be producing electric power with non-polluting, renewable resources, such as nuclear, solar, nuclear, wind, nuclear, tidal, nuclear, geothermal, and of course nuclear power-- which is, at the moment, the only *practical* form of non-polluting power generation for areas where hydroelecric power isn't available.
Written on: 07 January 2010 [17:38]
registered since: 14.08.2007
Posts: 140
The second half of the equation is near and dear to me, as one of the motivating factors to get off oil was the fact that it costs way more than the price per gallon seen at the pump to drive an ICE (internal combustion engine) -- oil wars, environmental damage, etc.

Lensman wrote:

The other half would be producing electric power with non-polluting, renewable resources, such as nuclear, solar, nuclear, wind, nuclear, tidal, nuclear, geothermal, and of course nuclear power-- which is, at the moment, the only *practical* form of non-polluting power generation for areas where hydroelecric power isn't available.

Your otherwise excellent argument derailed by claiming that nuclear is

1. non-polluting (see Chernobyl & Three Mile Island and NIBY storage of spent fuel rod issues)
2. renewable (Uranium is fininte, and the economics of extracting it change with the price of uranium per kg)
3. and practical -- there is enough political back pressure that it is not a practical solution to implement (see Sierra Club - http://www.sierraclub.org/policy/conservation/nuc-power.aspx). IF the public opinion/legislation battle is won (big IF), then there's the construction/build time to plan and bring these plants online (10-20 years), build the requesite breeder reactors (to enrich Uranium to be useful in the power plants) and re-establishing Uranium extraction in the US so we're not dependant on the good will of other nations for our fuel...

The major problem with electricity production from sustainable sources is that with the exception of hydro they are for the most part variable production -- sometimes there's wind/sun, sometimes there's not. People don't like unrelieable electricity (brown/black-outs). Electricity is a make-it-when-you-need-it/use-it-or-lose it power format -- it is not currently stored at a national grid level. Solar peak occurs about an hour off of usage peak, so meeting peak demand becomes difficult without some form of stored energy source (potential energy) to burn to turn the generators (water/oil/coal/uranium/etc). Of course traditional hydro has its own damming environmental problems, namely declining populations in the northwest fisheries and flooding canyons but tidal hydro is just getting started (think of putting "windmills" in the river or ocean tidal currents).

Getting back to the practicality of implementation question, how do we rapidly cut our CO2 emissions and what do we do with all the existing coal plants in the US? An interim option (and a potential solution to the production variablity of other solar/wind) is co-firing coal with a biomass fuel source such as Miscanthus (this was proof-of-concepted in Denmark on a commercial scale, and can be mixed with coal up to 50% in existing plants with some adaptations). Cutting coal use by 50% would make a huge impact in the US CO2 emissions. As a Perennial plant (grows back on it's own year-after-year) Miscanthus requires very little input (tilling, fertilizer, herbicide) and can be grown on land unsuitable for food crops so would not compete with food production. More on Miscanthus here: http://miscanthus.illinois.edu/ This could be fairly rapidly ramped up once the decision was made (less-than 5 years) and has significant POSTIVE political pressure and virtually no negative pressure (competition with land for food production and water usage by the growing plants being the major concerns).

One would hope that 100% biomass buring plants would supplant coal plants as biomass harvesting is much less environmentally damaging than 'harvesting' either coal or uranium. And a CO2 sequestering biomass buring power plant could result in a CO2-negative terraforming process, extracting CO2 out of the air while the plant grows, and then putting deep in the ground once it's burned.

Commute suck? Twike it; You'll like it!
Written on: 09 January 2010 [21:38]
registered since: 09.01.2010
Posts: 16
Have you looked at the Fisker Karma? It is a lot like the
Tesla, it has twin 200 horse power electric motors that make this a very fast, energy cheap car. It is even great to look at.

Written on: 09 January 2010 [21:45]
registered since: 09.01.2010
Posts: 16
I would like to talk on the energy production issue. I have spent 35 years in the field, and for the most you are very correct, Hydro is the best, Pump storage is the next best, then I feel Nuke's are the next best. Then you get into all of the fossel fuel type of plants, but there is Geo-thermal it offers a never ending power and no carbon output. Nuke's would be by far the best if we could find a better way to deal with the spent fuel rods. The fossel fuel plants could be made to be ok if they find a way to do Co2 Sequestering. That can work for Gas fired plants too. There are the fluid bed plants that have a super low Co2 output.

Written on: 09 January 2010 [22:00]
registered since: 09.01.2010
Posts: 16
One last thing, the company that makes the batteries for the Phoenix Motor Co. is working on a one Meg-a-watt battery. It is the size of a rail box car, but if it works can be used to help with peak hours on the grid and to charge cars at fuel stations. For a fast recharge.

Written on: 14 January 2010 [02:08]
registered since: 09.01.2010
Posts: 16
There is a lot being said about the Nuke Power plant. They are very good "except" for the spent fuel rods. I agree with that, now everyone gives Three Mile Island, where no Radiation was discharged into the air, Yes, it was a close call.. but close only counts in horse shoes,and....and so on. the only Nuke plant that Discharged into the air was the Russian Plant. But they caused their own mess. they "locked" out the Back-ups, all the safety's everything that would have saved it. Second American Nuke plants are build much better than theirs, we have Huge amounts of cement to protect it, and much tighter rules to keep us safe. Our Operators have training that they must go through every two years, unlike any other place in the world. I attended these classes you have to be the best or you will not work in one of these plants or operate them. So to say they are bad is not really looking at the big picture. There is a huge amount of the world that depends on Nuke power, France almost 80%, and all over Europe, over half of the countries have more than half of their power supplied from Nukes. If they are so bad why have there not been more accidents. Also if those Countries replaced Nuke power with Coal, Or Natural gas, think of the mess that would cause in the air we need to breath. Next you never talked about pump storage, It is a way to add the flex of hydro to your system with out building huge dams, or changing the river flows or even affecting the fish. Why would you not want to use these and they can be used when you need them only on peak hours for as long as there is a need. then at night when prices are down and there is extra power you reverse the flow of the Generator to pumps they are now sucking the extra Power up so you do not have to sell it cheap, and are filling the pond back up for the next day to us again. Pump storage would help fix a lot of problems. It needs to be looked at real hard. Then the people that build Batteries are working on a One-Megg-A-Watt battery, which will store power until the system needs it and can be used to discharge back into the system to support it and send back the power that was used to charge it. There are ways to store power It is just that we are not building them, The plants that burn Coal, Or Natural gas are easier to get permits to build, The Government does that because the people who write the laws are backed by coal Companies, or gas Companies. If permits were easy to get for pump storage you would see lots of them .

Written on: 14 January 2010 [12:17]
registered since: 23.02.2009
Posts: 110
The first major problem I see for Nuclear power ... is that at best it is an intermediate patch of a fix ... ultimately renewable power is the destination... so to me, investing in nuclear is short sighted and the same resources would be better spent on more renewable power... especially considering the amount of time it takes from start to finish to get a plant up and running compared to the same start to finish with Renewable power facilities.

As far as I am concerned Nuclear power is good for deep space probes and travel ... but here on the earth ... there is no other source of power that can compete with what the earth gets from solar ... 99% of all the other renewable energy options are second hand solar power like wind and hydro.

That having been said... Nukes have lots of real problems... they are not the daemon some make them out to be ... and they are not the saints others make them out to be.

RE & Efficiency enthusiast
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