sr241 said:
you think massive vehicles are safer in crash, how? do you know conservation of momentum (mass * velocity). In heavy vehicle impact of crash will be higher due to high momentum. And you think extra weight in Tesla and Prius are for safety only battery and hybrid system doesn't add mass hugely? think again.
of course crumble zones and air bag add safety but protects passenger cabin only
"well to charging station efficiency electricity from natural gas 52.5% (80% of it is 40.3%)
well to gas station efficiency diesel from crude oil gas 90.1% (50% of it is 45%)
well to gas station efficiency natural gas from natural gas 86%
well to gas station efficiency Hydrogen from natural gas 61%
well to gas station efficiency gasoline from crude oil gas 81.7% " these data are from Tesla official site (http://www.teslamotors.com/performance/well_to_wheel.php) you think that site is crackpot ? whose side are you on?
Go away. We are having a nice conversation about safety in this hijacked thread.
Also the way you've tried to represent that data is skewing it to the point where it's out of context. Also I really don't know where you are getting figures of 50% from for a 4 stroke diesel engine in ANY production car. But that's just total ********. Most efficient diesel out there atm is closer to 40%. Even taking 45% (which is a stretch)
Running your results with real figures.
You get a well to wheel efficiency of 40% with electricity.
You get a well to wheel efficiency of 40% with a 45% efficient diesel.
The above is overly simplistic and giving the worst possible scenario for an electric potential and best possible for diesel. This puts them on a roughtly equal footing efficiency wise.
However in reality we don't care about the efficiency figure itsself. All we care about is fuel (energy) consumption.
A blue motion diesel polo gets 70MPG and a power output of 70BHP. Which is 0.03 l per km. A litre of diesel has an energy of about 38MJ. A small blue motion polo uses 1.14 MJ/km travelled. An electric car such as the tesla with 250 BHP gets 1.14 km/MJ. So that's 0.88 MJ/km.
Now let's take a likkle look at emissions shall we. CO2 is the biggest concern right now. Blue motion polo = 99gCO2/km A gas fired power station generates 143kg/GJ. Thats 143g/MJ used. Thats 125gCO2/km.
Car weights: Polo about 1 ton ,Tesla about 1.25 tons.
So as a summary with more real figures:
The efficiency is about the same well to wheel.
The tesla uses about the same energy to travel a km despite being heavier and having much more power. This is at a slight cost of more CO2 per km.
The only reason this isn't being used widespread is that you can only get about 200miles on a charge with the Tesla and it's costs about £70000. The blue mostion costs 14 grand and gets about 600 miles to a tank of fuel.
The tesla is also cheaper to refuel given night electricity rates. I pay about 12p per kWh (I can't find a real figure, this seems semi sensible). As you say it takes 58 kWh. Coming to a grand total of £6.96 to charge something that will get you 200 miles. £6.96 will now get you about 5.5 lites of diesel (1.2 gallons imp) giving you a total range of 84 miles in the polo.
Basically what you are saying by just looking at efficiency figures is that it'd be better to pop to the shops in the car using a 6 litre engine that gets 40% efficiency rather than a 1 litre engine that gets 30% efficiency. You are totally ignoring the fact that the 6 litre engine burns far more fuel.