Comments on: Electric cars – an opportunity for SI, or a threat?

By: Jeremiah

Jeremiah — Sun, 13 Dec 2009 17:30:34 +0000

A few years back I was sent an email of a video of one of Al Gore’s seminars on Global warming. Even though all of his visual displays used metric units, Al spoke mostly in USC. It was very confusing to compare what Al was saying to what was on the displays. I wonder if the people in the audience felt the same way, especially those who may have attended and didn’t have a clue to what the units Al spoke meant.

In addition when I hear someone giving a speech on a scientific subject and does not use metric units, I don’t take their point seriously and view it as pseudo-science. If they can’t use proper units of measure then to me their doctrine can’t be sound.

By: John

John — Sat, 12 Dec 2009 20:28:24 +0000

As a side issue to the use of electric or hybrid cars, at the recent climate conference in Copenhagen, there were over 1200 vehicles provided to move delegates around, including to and from the airport. Precisely five of these – the fingers on one hand – were ‘alternative’ propulsion’ – i.e. not petrol or diesel, but either pure electric or hybrid.

We measure vehicle CO2 emissions, even in the backwards UK, as g/km. The USA measures its vehicle emissions in g/mile. As we are all being asked to become aware of our carbon footprint, it would be nice to see some universal (metric) standards as to how this should be measured. And then get the media, including the BBC and the popular press, to use it, instead of simply saying ‘reduce your carbon footprint’ but giving no criteria as to how we measure any reductions.

By: Richard Birkby

Richard Birkby — Thu, 10 Dec 2009 00:06:01 +0000

Martin Vlietstra is quite right – education (and public awareness) is a key issue. He echoes and reinforces philh’s comments by his example.

By: philh

philh — Wed, 09 Dec 2009 16:42:06 +0000

The term ‘mpg’ is often referred to as consumption when in fact it is a measure of economy.
L/100 km measures this directly and is on the whole a better way of doing so. It makes both types of calculation relatively easy i.e. how much fuel will be used on a given journey, or how far will a vehicle travel on a given amount of fuel.
That’s probably the reason for the convention of L/100 km rather than L/km. It accomodates the second type of calculation more easily without losing the simplicity of the first.

By: Martin Vlietstra

Martin Vlietstra — Wed, 09 Dec 2009 08:40:38 +0000

Richard Birkby wrote “As for petrol, the “mpg” figure seems bigger, therefore better.” This is purely a result of cultural compartmentalising. People need to be educated that costs can be expressed not just in money, but also in commodities such as petrol.

Thus, bananas at 88p/kg cost less than bananas at £1/kg. It should be the same with petrol – If I “pay” 8 litres of petrol to travel 100 km, then I am “paying” more than if I “pay” 6 litres to travel the same distance. Given the current Copenhaegn conference, this manner of thinking is particularly topical.

By: philh

philh — Tue, 08 Dec 2009 16:31:41 +0000

Whilst the above remarks about marketing are true it isn’t the only reason.

People think the watt is an exclusively electrical unit like the volt. It’s poor understanding of basic science.

By: Richard Birkby

Richard Birkby — Mon, 07 Dec 2009 14:48:03 +0000

Jeremiah is spot on with his comments on marketing. Whatever ways can be found of getting around fair comparisons will be employed. To digress slightly, when I lived in the UK I noted that coffee was a good example of this. It would be sold in UK-packaged 227g packs and imported (usually Italian) 250g packs. The headline price would be lower for the UK-packaged product. Needless to say, the unit price (in a very small font) would show a different story.

As for petrol, the “mpg” figure seems bigger, therefore better. It is interesting to note, however, than in everyday parlance, many countries prefer using km/l rather than the official l/100 km. My point still holds though.

By: Ezra Steinberg

Ezra Steinberg — Sun, 06 Dec 2009 23:07:07 +0000

How sad and baffling that the PM refers to persons who deny climate change science as “flat earthers” and “anti-science”, yet he does not apparently see that clinging to an outmode hodge podge of measurement units (Imperial “system”) is very much the same.

If he did and pushed hard for it, the UK could go nearly 100% metric by the time of the London Olympics. Maybe he’s just waiting for the results of the next election??

By: Jeremiah

Jeremiah — Sun, 06 Dec 2009 05:51:14 +0000

The reason for choosing the horsepower over the kilowatt is quite simple. It is all a part of deceptive advertising. The horsepower provides the illusion that one is getting more power, because the numbers are bigger. 50 kW of power is about 67 horsepower. 67 is a bigger number then 50 and gives the impression one is getting more power by stating the value in horse power.

The horsepower is also a unit that can’t be related easily to something else. Thus the average person has no real reference points for understanding how much power a horsepower really is. A kilowatt however has a number of common reference points. It is easy to image the kilowatt as the power to light 10 x 100 W light bulbs. The kilowatt is also used to measure the output of electric heaters as well as countless other home products. Thus the kilowatt is easy to reference.

By not having a suitable reference for the horsepower, the use of it makes a very handy means to deceive and deception is what it is all about.

By: John Frewen-Lord

John Frewen-Lord — Sat, 05 Dec 2009 18:13:16 +0000

I was reading only the other day about a hybrid car, in which both the petrol engine AND the electric motor ratings were given in hp. I can, to a small extent, undertand the petrol engine being rated in hp, but the electric motor? Bizarre. I can only assume that it was to provide a comparison between the two forms of propulsion – in which case, it surely makes more sense to convert the petrol engine to kW rather than the other way round. As this Metric Views article states, the mess looks likely to continue – but why?