Posts by David Haywood
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Tim Kong wrote:
am on the lookout for a second car and would prefer to buy something that is sustainable and economical...
... on the list is the Prius
Your other option is to go for a small diesel like the Citroën C3 1.4SX 5DR, which is actually slightly more efficient than the Prius. This would work around any (potential) battery disposal problems, and have decent room for any (potential) kids.
And if any of the Citroën bits fall off you can just lick-and-stick them back on again. Brilliant!
In case you haven't found it yet, this is a good NZ site for comparing fuel efficiency of different models:
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What's the science behind the three most important words in the English language? Find out in this week's episode of Public Address Science...
NOTE: A complete transcript of this episode is available here.
Further information:
-- Read more about Professor Garth Fletcher.
-- View a list of Prof Fletcher's books on Amazon.com.
This episode of Public Address Science was originally broadcast on Radio Live, 19th May 2007, 2 pm - 3 pm.
Public Address Science dedicated RSS feed
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Michael Stevens wrote:
Can't you get some new writers on who will post regularly?
I've posted once a week (on average) ever since I started on Public Address.
You may not read it (or like it), but I certainly post it!
The last few weeks have been science articles (which even come with an 'audio track' option, by the way):
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Keith Ng wrote:
Is the two-stroke engine used because of size? i.e. Is there a minimum viable size for a four-stroke engine that limits how small vehicles can get?
Two-stroke engines are used mainly for their power-to-weight ratio and cheapness. They have good power-to-weight ratio because they produce one 'power stroke' in every two, rather than one in every four (as per the four-stroke engine). They also use simple reed valves & ports (hence no valve-train requirements) and are usually air-cooled -- all of which makes them very cheap.
But there are also drawbacks. The fact that they generally use crankcase compression (i.e. a dry sump) means you have to mix oil with the petrol, which is substantially unburnt and comes straight out the exhaust pipe. The fluid-dynamic and thermodynamic compromises involved in getting the exhaust gas out, and the air/fuel in (over a wide range of engine speeds), means that you are often operating with non-optimal combustion -- which produces all the nasties like CO, UHCs, and NOX, etc. Plus there's usually no catalytic converter, of course.
They can, however, be optimized to perform much better than the standard-issue model, by using fuel injection, seal lubrication metering, and cunning exhaust design, etc. But this all makes them more expensive -- although I seem to (vaguely) remember than someone had a plan to improve 3rd-world two-stroke engine design by doing just this.
Incidentally, the big constant-speed two-stroke diesel ship motors are very efficient, and are among the highest-efficiency heat engines ever built. Generally speaking, small engines are usually less mechanically efficient because friction becomes a large proportion of their output power.
Keith Ng wrote:
I totally get some geek cred deducted for not knowing this.
Not at all. I did my honours' dissertation on an improved two-stroke engine design. Otherwise I would never know this crap. God knows, I often wish that I didn't.
Oh, and probably the Japanese scooters have better emissions...
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I see the petrol heads are coming out of the woodwork...
Keith Ng wrote:
I was gutted to discovered that my last (first and only) vehicle, a very humble 1984 Honda City, only rates at around 4-5L/100km. I use to be so impressed by its fuel efficiency...
... ultimately, isn't it a marketing/design/purchase problem?
Don't be gutted, dude -- 4-5 litres/100 km is stunningly good! My headache-in-a-can Citroën -- which I suffer to own on account of its fuel efficiency -- only does 6.5 litres/100 km.
You're probably right about fuel efficient cars basically being a marketing/design problem now. But it seems to me that if fuel prices continue their expected rise, and if straight men are driving them elsewhere, then it can only be a matter of time before they become more acceptable in New Zealand. Look how far soccer has come in this country.
Stephen Judd wrote:
The problem with scooters and tuktuks is that they generally have two-stroke engines with a very dirty exhaust as far as particulates go...
Exactly... not to mention all the unburnt oil/hydrocarbons, carbon monoxide, and nitric oxide you could wish for (and before anyone gets excited: nitric oxide is the uncool one, which makes you dead rather than high).
Bart Janssen wrote:
Which raises a question I have about the loremo. Just how much of the modern safety engineering is retained in a superlight car like the loremo?
As I understand it, the linear cell structure is safer in terms of crashes than the monocoque approach (for a given weight). The Loremo certainly meets all the European automotive safety standards.
The US State Department's electronic journal 'Economic Perspectives' reports that:
Lighter weight formerly meant costly metals such as aluminum and magnesium. Now, ultralight steels can double a car’s efficiency without extra cost or decreased safety. With clever design, even conventional steels can yield surprising results. A German startup (Loremo) diesel roadster combines 160- to 220-kilometer-per-hour top speeds with a fuel economy from 1.5 to 2.7 liters per 100 kilometers...
Bart Janssen wrote:
... you do realise that changing languages mid conversation is very very geeky
Alas, I am guilty of being both a geek and an idiot. It turns out that I actually got Stephen confused with a certain Stefan J-----, who really is German, and who sends me helpful emails whenever I make a mistake RE: Germany. I can only explain this by saying that my brain cells are dying due to lack of differential equations over the past few months. On the plus side, the other Stephen and I have now resolved to use the intimate form in our conversations -- which, by the way, sounds dodgier than it actually is.
Philip Wilkie wrote:
... a govt intent on improving our CO2 balance could do a lot worse than removing this very specific disincentive.
You're dead right about this. And I wish you could convince our politicians of it...
Of course, as Stephen McKernon from the Cycling Advocates' Network has pointed out to me:
... sustainability is not just about fuels. It's also about social and economic consequences. First, cars are implicated directly in congestion, accidents and urban sprawl (for example), each with its economic costs outside the transport system. Second, cars are implicated less directly in problems such as obesity/ low levels of physical activity, over-spending/ household debt, social isolation and so on. In other words, energy-sustainable cars merely continue to contribute to other sustainability issues. Driving down car use is an important part of sustainable transport. To put this another way, the real issue in transport is sustainable TRANSPORT, not sustainable energy.
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Plum wrote:
[The Loremo is comparable to] cities on the sea floor... a jet pack for everybody... an elevator to the moon...
Sorry, but this story just was a bit detached from political reality for me.
Wow, is a more fuel efficient car really in the same category as the examples you cite?
At any rate, the article was more about the fact that such efficiency could be achieved on a production vehicle, which -- as I said in the conclusion -- might hopefully encourage other automakers to lift their game. And, of course, the fact that there is considerable scope for energy savings in New Zealand even with slightly more fuel efficient cars.
I'm sorry that you didn't like it, dude. But as you might appreciate, a science news programme is necessarily reporting on topics that may or may not eventually pan out. It would be a little difficult for me to cover only the technology that will definitely become a huge success.
That said, I have been amazed at the number of micro-cars I've seen in European cities over the last eighteen months -- and so, in my (admittedly, fairly worthless) opinion, the Loremo has a decent chance of success.
But you may well have greater insight into such things than me... in which case, perhaps you can give me some good sci-tech investment tips!
Steven Judd schrieb:
"Konsequent" is usually translated as "consistent" or "rigorous".
Ich bin mir nicht sicher, ob ich Ihren Einwand richtig verstehe. Das englische 'consequent' ist eine wörtliche Übersetzung des deutschen 'konsequent' im ursprünglichen Sinn des Wortes (und heute etwas archaisch), was in meinem Oxford English Dictonary als "logically consistent" definiert ist.
Aber um es vollständig klarzustellen übersetzte ich es auch als "consistent" und "stringent", was, so glaube ich, genau das ist, was Sie gemeint haben.
Ich bin nun ein wenig verwirrt, was ich verkehrt gemacht haben soll!
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What's so astonishing about a new car from Bavaria called the Loremo? Find out in this week's episode of Public Address Science...
NOTE: A complete transcript of this episode is available here.
Further information:
-- Read more about the Loremo.
-- Read about the Audi A2 a super-efficient (but very expensive) 5-door car which ceased production in 2005.
-- Read about the Messerschmitt KR200 a 1950s production car with a fuel consumption of only 3.2 litres/100 km.
-- Read about the Volkswagen '1-litre' car a concept car with a fuel consumption of only 1.0 litres/100 km. Volkswagen have no plans to produce or sell this vehicle (unfortunately).
This episode of Public Address Science was originally broadcast on Radio Live, 12th May 2007, 2 pm - 3 pm.
Public Address Science dedicated RSS feed
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Chaos Buddha wrote:
With respect to the whole climate change thing, I'm as un-learned as everyone else . . . I *want* to form my own opinion, but having seen how the mainstream media origami'd the GE thing, I'm loath to take anything I see/read there from that general direction as being solid. I want facts, I need solid data from both sides of the fence before I can decide which sit to sit on. But there just doesn't seem to be a reliable source of good, honest, unbiased information.
I know just how you feel. Another good (albeit slightly older) article that tries to look impartially at this debate is from New Scientist:
Climate change: Menace or myth?
We are also trying to put something factual together on this topic for PA Science -- but I am having a hell of a job pinning down one of my interviewees...
Addendum:
I've just noticed that the online version misses out some important information from the print version. I'll see if I can find this elsewhere. -
Foss Leach wrote:
There is no direct evidence that any Polynesians (including Maori) deliberately set out to improve the fertility of dryland soils by adding things such as charcoal...
Thanks for posting Prof Leach's comments, Owen. From the papers I'd read there seemed to be very good evidence that the Amazonians deliberately used charcoal -- but, unfortunately, I must have got my wires crossed when it came to evidence of deliberate use of charcoal by Maori.
My apologies for that. I have emended the transcript and audio to change the words from:
...pre-European Maori also worked charcoal into the soil to improve fertility.
to:
...pre-European Maori also worked charcoal into the soil.
Please pass on my thanks to Prof Leach for pointing out my mistake. I do go to a lot of effort to prevent any error of fact in my journalism -- but (obviously) this one got past me.
I shall attempt to be more vigilant in future!
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Judi,
Curiously, I am thinking of experimenting with charcoal in my raised-bed vege garden. I plan to dig charcoal into two of the beds, and leave the other two charcoal-free.
I shall report on the results (with photographs) as they come to hand...
Cheers,
David