* Posts by Robin Trow

2 posts • joined 23 Jun 2008

World's fastest production car to gain electric twin

Robin Trow

World's fastest production car goes leccy

Before anyone gets carried away over the specification for the Shelby Supercar, let's put some numbers to the claims. My car (Honda Civic IMA Hybrid) achieves about 50 mpg (UK gallons) and therefore, consumes energy at the rate of 65 kW.h/100 km, assuming the engine and transmission are 25% efficient, that's about 16 kW.h/100 km at the drive wheels. To travel 200 miles (320 km) it will consume 52 kW.h at the drive wheels.

If the supercar can match this mileage, the batteries will need to take on 58 kW.h (assuming the electric motors and batteries are about 90% efficient) in 10 minutes, which is charging rate of 350 kW. With a UK domestice supply at 230V single phase, the current required is just over 1,500 A. Quite a bit higher than any domestic supply I know of.

If a 3-phase supply is used, the current reduces to 500 A. Which is a medium sized industrial supply. For the technically minded I have assumed the power factor is unity, it will probably be less than 0.9 and the current (but not the power) will increse proportionately.

On this basis Shelby Super Cars are talk through their tailpipes and any charging system would require a major industrial installation.

As with most claims about alternative energy sources, the claimants are more interested in attracting publicity than putting down the facts.

It's an unfortunate fact that petrol is a very compact energy source and replacing it with something else is going to be very very difficult.

Heavyweight physics prof weighs into climate/energy scrap

Robin Trow

At a Book on Global warming with Some Numbers

I started to read the article and had to download the draft of the book.

Absolutely brilliant. I've only got about 3/4 through part1 , but so far all the numbers seems to add up. They're all rough estimats, but that's explained in the Preface and it's important to find the order of magnitude of the problem rather the details.

I'm considering sending the link to the to my MP. I expect he believes that turning off al the phone chargers and pc's on standby are all that's required!

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