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The Pivotal Engine | Dec 31, 1899 12:42

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This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 4th August 2007, 5 pm - 6 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Background:

[Sound of engine starting]

Voiceover:

That's the sound of the pivotal engine: a radical new two-stroke engine design from a sub-division of Mace Engineering -- one of Christchurch's largest companies.

Now when you think about two-stroke engines (if you think about them at all) you'll no doubt think about the type of motors you find on cheap lawnmowers and chainsaws: low cost, but also low efficiency, short lifetime, and very high exhaust emissions.

But two-stroke engines do have an important advantage over their more environmentally-friendly four-stroke big brothers. This is because they have a power stroke once every engine revolution -- rather than once every two engine revolutions as with a four-stroke motor -- and therefore have approximately twice the power-to-weight ratio.

And it is this improved power density that has seen a number of automotive engine manufacturers conducting research into two-stroke motors over the last couple of years.

A two-stroke engine with the environmental features of a four-stroke could significantly improve overall vehicle performance. But the Christchurch engineers working on the Pivotal engine have a big head-start on practically everyone else. They've been developing their engine at full throttle for over a decade.

Interviewer:

I'm now sitting in the office of Paul McLachlan, the inventor of the Pivotal Engine. Can you explain how -- in terms of its basic design -- the Pivotal Engine differs from a conventional two-stroke motor?

Paul McLachlan:

We set out to overcome what are the inherent shortcomings of a conventional two-stroke engine. [In such motors] you have a sliding piston, restrained by a cylinder -- and in that cylinder you're cutting the ports for the engine to breathe, i.e. the transfer ports, and the exhaust port.

[This] causes a number of difficulties. We've overcome these by designing the engine to have a piston which is restrained by a pivot bearing, [but which] still has a connecting rod down to a crankshaft in a conventional way.

[Restraining the piston] allows us to take the load off the surface of the chamber. [This] means that we don't have to lubricate the piston as a sliding piston, and it also means that we have a pivot point on the piston -- which allows us to run water into the piston itself and back out the other side via the pivot.

So it becomes a water-cooled piston. And so we have a water-cooled engine with a water-cooled piston, and that overcomes all of the inherent shortcomings of a two-stroke engine that stops you using it [for example] in your car.

Interviewer:

So I guess a way of explaining it would be to say that in a conventional two-stroke motor you have a cylindrical piston inside a cylindrical cylinder (as it were) sliding up and down.

But in your pivotal engine, the piston is more like a flapper. So seen from the top the 'cylinder' would be square in profile, and seen from the side the piston would be moving up and down -- and tracing out a shape a bit like a Chesdale cheese segment.

[click here to see an animation of the Pivotal Engine].

Paul McLachlan:

Yes, and we're using only the outer part of the cheese segment. So it moves through about a 36 degree radial angle.

Interviewer:

So when you talked about the problems with conventional two-stroke motors -- why they're not used in a normal automotive situation -- I guess you could summarize the problems by saying: low thermal efficiency, short operational life, poor emissions (particularly in terms of oil residue in the exhaust).

How does the Pivotal Engine deal with those issues -- what improvements have you been able to make?

Paul McLachlan:

We'll start with longevity. The problems with a two-stroke engine [in terms of longevity] is that if you're wanting to get the high-performance benefits of a two-stroke engine, then you end up with quite sizable ports. Therefore what you've done is taken away a lot of the physical support for your piston by taking sections out of the cylinder wall.

[But this] also has the effect of reducing the amount of contact which would take heat out of your piston. So we overcome the restraining by the fact that it's held by bearings; and the heat by the fact that we're internally water-cooling the piston.

The emissions are really a matter of two things. There's the lost unburnt fuel with a normal [carburetted] two-stroke -- whereby you lose [fuel] out the exhaust totally unburnt. This decreases the efficiency of the engine, but also results in a very unacceptable level of hydrocarbon emissions.

Now that gets overcome in any two-stroke engine to a very high degree by having a direct injection system -- which means to say you're injecting the fuel from the top of the head, and only after you've closed the exhaust ports, so that you're not losing any of that fuel.

The other [source of] hydrocarbons is the oil you use to lubricate the piston. We overcome that by the fact that the piston is now not actually in contact with the surface of the chamber, and therefore we only need a very small amount of oil [which is directed to] the compression seals.

Interviewer:

So how much oil does the Pivotal Engine use in comparison to a conventional two-stroke?

Paul McLachlan:

At this stage we would say that it's around about a tenth of the amount of oil that you would use in a modern direct-injected type of two-stroke engine.

Interviewer:

... and normally you'd say they use about ten times the amount of oil of a good four-stroke -- so you're using about the same amount of oil?

Paul McLachlan:

We're getting close to being able to having comparable oil usage to a four-stroke engine. But on top of that, of course, you don't have to have an oil change -- so the overall use of oil is actually slightly lower.

Interviewer:

In which areas do you see the Pivotal Engine first making an entry into the market? You've been going for over a decade now with some pretty intensive R & D -- so I imagine that coming to market is something you're pretty keen on?

Paul McLachlan:

Yes, we have in the last two or three years been focussing very much on a first step into the market place. We [initially looked] at light aircraft, and we have a lot of interest from that point of view, but there were various reasons why we decided on a generator product -- we have a good partner in the US for a military generator, and that's our main focus at the moment.

The potential there, of course, is based on its power density -- and so it's a stand-alone portable generator. We have simulated all of the components that make up the stand-alone generator for using our engine, and we end up with a weight which is about 25 per cent of the weight of a [comparable military] generator. So for many applications that will make it an ideal choice.

And there are a lot of other opportunities once we have this first product as a base engine. Certainly we have a lot of interest in the hydrogen potential. We have full control of all of the thermal surfaces on the combustion chamber, and that's due to the fact that we have the piston cooled independently with its own water cooling.

In hydrogen the big advantage is that we actually can run the engine at a reasonable temperature for good thermal efficiency -- but we can avoid any hot-spots on the piston or in the head, [which is] the limiting factor in trying to run hydrogen in a conventional engine.

We see a vehicle such as a plug-in electric vehicle -- which would be a hybrid with hydrogen as the core range-extender in the vehicle -- and we have a lot of interest in that concept.

Interviewer:

In terms of your initial market niche that you're aiming at -- the generators -- do you have anything like a timeline for when you expect the first production to roll off the line?

Paul McLachlan:

We have component supplier already making the key components. We're hoping to have most of those ready at the beginning of next year to assemble engines that are representative of a series-production engine. They will go into test with the generators attached at our partner on the generator project -- and also those engines will then get used in some hydrogen development programmes, which we're working on with some European development companies.

Voiceover:

It's heartening to see that a device as astonishingly simple as the piston-cylinder mechanism in an internal combustion engine can still be improved by a cunning engineer. The ingenious Pivotal engine avoids the efficiency, longevity, and emissions problems that plague conventional two-stoke motors, while still delivering a mind-bending power density at low cost.

Its debut as a military generator will be closely watched, and it will be interesting to see where it ends up being used in the future.


Theme music...

Further information on the Pivotal Engine:

• View the Pivotal Engine photo gallery.
  
  
• Read about two-stroke engines in Wikipedia.
  
  
• Visit the Pivotal Engineering website.
  

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A Brief Look At Forensic Linguistics | Dec 31, 1899 12:41

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This episode of Public Address Science was originally broadcast on Radio Live, 9th June 2007, 2 pm - 3 pm.

You can listen to the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Further information on forensic linguistics:

• Dr Paul Foulkes's website.
  
  
• Read more about Forensic Linguistics at the University of York.
  
  
• Visit the Forensic Linguistics Casebook website.
  

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New Zealand Biofuels, Part 2 | Dec 31, 1899 12:40

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This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 2nd June 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Voiceover:

I fully admit that a few years ago I was something of a biofuels sceptic when it came to the replacement of automotive fuels in New Zealand. Since then, however, things have changed dramatically. The price of fossil fuels has risen enormously (a trend which is expected to continue), and new technology has come onto the scene which promises cheaper and less energy-intensive biofuels processing.

Recently, two New Zealand Crown Research Institutes -- Scion and AgResearch -- have joined forces with US enzyme manufacturer Diversa to work on automotive-type biofuels. Despite the criticisms levelled at some overseas schemes -- in terms of low energy yield ratio (and consequently high cost), as well as concerns over long-term sustainability -- the New Zealand consortium believes it has the answer to sustainable biofuels for this country.

I talked to Dr Trevor Stuthridge at Scion, and began by asking him to describe the feedstock and manufacturing process for their proposed biofuel scheme.

Dr Trevor Stuthridge

Our starting point is to ask: is it possible for New Zealand to convert one of its pulp-and-paper mills over to an ethanol facility?

So we're looking to use wood as our feedstock; and wood is quite a complicated material. It has both the cellulose -- which is what most people are using for next generation biofuels -- but it also has hemicellulose, which is another type of sugar polymer, and it has lignin.

The process that we're developing with Diversa is to look at ways of first physically and chemically breaking the wood down into pulp material -- which is where all the glucose that we use for the ethanol production is -- and also releasing the lignin, which we can recover for energy or chemical production, and also recovering the hemicelluloses, which are another source for making ethanol.

So what we're doing in the first instance is physically and chemically breaking the wood down -- just as they already do in the pulp and paper industry. And then we're using Diversa's unique enzyme cocktails to break polymers [such as] cellulose and hemicellulose into their sugars.

And it's these sugars that we can pass on into another process with another bacteria, or a yeast, that actually ferments it into the ethanol. So in this way we can take a fairly difficult to break down material like wood, and turn it directly into ethanol.

Interviewer

Right, okay. So last week on this programme we also talked about biofuels and looked at the energy yield ratio for corn bioethanol in the US -- which is absolutely terrible -- only just over 1. Do you have a figure for the energy yield ratio for wood bioethanol using the Diversa process on this sort of large scale?

Dr Trevor Stuthridge

We're still working on that, so I don't have numbers at hand yet. In fact, we're going through that exercise at the moment as part of our feasibility study. But certainly our belief is that the energy yield ratio is favourable for lingo-cellulosics -- particularly derived from forestry resources. Management costs for the crop are rather lower (in our opinion), compared to food crops like corn, and the yield per hectare can be rather higher.

Interviewer

Now you've mentioned food crops -- and, of course, one of the criticisms of bioethanol in other countries is that it displaces food crops. Presumably this isn't a criticism that could be levelled at your scheme for biofuel manufacture?

Dr Trevor Stuthridge

We see this as a key advantage of what we're proposing, because much of the lands that the forests are growing on are non-food quality. They're not suitable for food crops.

Certainly this is a key constraint in the United States, where the price of corn has now doubled because of ethanol initiatives. In some states up to half of the corn is being used for ethanol production, and that's starting to impact things like food prices and beef prices.

We think by targeting a non-food crop, and using essentially non-food quality land, we have a significant advantage. And certainly in New Zealand, from an international perspective, that's a key advantage to this country in our opinion.

Interviewer

That's reassuring. But another criticism of biofuels -- certainly in the US and Europe -- is that it takes a huge amount of land to produce just a fraction of the country's fuel requirements. Using your proposed method how much biofuel could feasibly be produced in New Zealand?

Dr Trevor Stuthridge

Our estimate is that a single pulp-and-paper mill facility could produce over 200 million litres per year -- and that would be quite sufficient to take us beyond E15 [i.e. a mix of 15 per cent ethanol, and 85 per cent petrol] in terms of fuel substitution.

In reality, if we took all of the forestry crops and the trees that we're exporting overseas -- it appears even possible that we could completely substitute in the long term. But, of course, there would be a significant capital investment required to process that sort of material.

Interviewer

Okay, right. But wouldn't there also be a massive cost incurred in terms of lost revenue from the wood feedstock that could otherwise have been exported as timber?

Dr Trevor Stuthridge

That's an interesting question and one that we're [considering] at the moment in our feasibility study -- because whilst at times wood and pulp can be very financially positive, there are [also] times when it's non-profitable. So you get lots of ups-and-downs in that market.

With ethanol we believe we'll have a much steadier market -- so on average it's quite possible that ethanol production could even be better economically than current use of the forest resource.

Interviewer

You've pointed out that producing biofuels from New Zealand forests is no less sustainable than producing timber. But actually how sustainable is timber production in reality? Can the land keep on producing indefinitely?

Dr Trevor Stuthridge

[I think that] over the years the forestry industry and the wood-processing industry, have developed very good management strategies for the production of the wood stock, and the harvesting and replanting.

[So] this is still a pretty sustainable option for New Zealand in terms of land use -- we're not substituting for high-value land. I think management practices for forestry are pretty good in this country, from what I can tell.

Interviewer

I guess this is the $64,000 question -- but do you, at this stage, have any feel for the cost comparison to current petrol prices?

Dr Trevor Stuthridge

We don't have a strong feel for that yet. I think the challenge for ethanol at the moment is that in many parts of the world it's still heavily subsidized, and the price is still well above petrol.

The key challenge for ethanol in terms of cost of production is the enzymes -- and that's why our relationship with Diversa is critical to this initiative. I guess overall our aim would be to get the cost of ethanol being equivalent to petrol. We don't believe, as in many other parts of the world, that asking the consumer to pay more for their fuel is likely to be particularly well taken up.

I think New Zealand still has an opportunity to be a leader in this field, whether it's with pulp and paper or forestry or other crops. We're in a position geographically where being self-sufficient is probably the best option for us.

Voiceover:

While it's perhaps a little too early to declare 'mission accomplished' on the transport energy front, the proposed New Zealand bioethanol scheme seems to overcome many of the objections that are made against overseas biofuel manufacture.

Given the scope for improvement in the fuel efficiency of New Zealand's vehicle fleet, sustainable biofuels could -- even in the medium term -- have a dramatic impact on our energy supplies. And, even if not completely perfect, they may well be a much better option than our current dependence on fossil fuels for transportation.

Theme music...

Further information on biofuels:

• Read more about bioenergy at Scion.
  
  
• Visit the Diversa website.
  

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New Zealand Biofuels, Part 1 | Dec 31, 1899 12:39

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This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 26th May 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Voiceover:

There's been a lot of talk about biofuels recently, but what exactly are they? Well, essentially they're the end product of nature's own solar collector. Plants absorb energy from sunlight, and then store this energy by turning water and carbon dioxide into hydrocarbons. By employing an appropriate chemical process, such as burning these hydrocarbons, the original solar energy can be re-released in a concentrated form that we can use.

The neat thing, of course, is that burning these plant-derived hydrocarbons only releases the same amount of carbon dioxide as the plants themselves absorbed from the atmosphere in the first place. So, from this perspective, biofuels can be said to be carbon neutral, because it's theoretically possible to manufacture and use them without adding to the overall amount of carbon dioxide in the atmosphere.

However there is, admittedly, a potential problem. Because the energy in raw biomass isn't necessarily in a form that can be easily used -- then additional energy is required to harvest the biomass and process it into a usable form. Not to mention the energy input that's also required in terms of planting, tending, and fertilizing a biofuel crop.

This leads to something called the energy yield ratio. In simple terms, this is the ratio of the chemical potential energy stored within the fuel, in comparison to all the energy input required to bring the fuel to the point of end use. The higher the energy yield ratio, the more energy you get out of the fuel in comparison to the energy input required during processing.

Some biofuel crops (notably bioethanol from corn in the United States) have an energy yield ratio which is only slightly greater than one -- in other words: absolutely pitiful. But it's important to realize that this is by no means the case for all biofuels. And it's certainly not the case for biofuels in this country.

You might be surprised to discover that (according to the Energy Efficiency Conservation Authority) in New Zealand we already get nearly ten per cent of our total energy input from biofuels -- in the form of the burning of firewood and waste biomass in households and industry. Now, of course, this doesn't translate to ten per cent usable energy output because -- for various reasons -- biofuels are currently consumed in a rather inefficient manner [in 2006, a publication from the National Centre for Climate–Energy Solutions stated that "bioenergy currently provides about 5% of New Zealand's total primary energy supply"].

But if we could economically make use of more biofuels for simple purposes, such as household and industrial heating, then it would have two important results. Firstly, it would displace the consumption of some of the fossil fuels which are currently used for this purpose; and, secondly, it would displace consumption of electricity used for heating -- thus freeing up both electrical energy and our electrical networks for other purposes.

It turns out that an interesting and relatively new manufactured biofuel could help us achieve just that. Wood pellets have been on the market for a few years now, and have the potential to become an important part of New Zealand's energy mix.

I talked to George Estcourt, a scientist at Scion (one of New Zealand's Crown Research Institutes) who studies the production of wood pellets in New Zealand. According to Scion's research, wood pellets are among the most cost-effective form of heating in New Zealand -- far cheaper than coal, electrical resistance heating, or gas. I asked George if wood pellet biofuels have any other advantages to offer.

George Estcourt

Yes, the wood pellet stove is basically designed around the wood pellet. The problem with the normal log fireplaces is that they're tested (to reach their standards of, say, how many grams particulate per kilogram of wood, and that type of thing) [in a] lab using the absolutely correct firewood, moisture content, and so forth.

But as soon as you take it home, and put it in your house, and then you start using a bit of this, a bit of pine, a bit of tea-tree -- and you really don't know what the moisture content is -- your emissions can be ten times [or] a hundred times worse than what they were in the lab. But with your pellet stove, really nothing is going to change, so you're always going to [achieve] high quality results.

The wood pellets themselves are pure wood, which means that there's no other material in there that could cause poor emissions. And [of course] the other thing -- when you get contaminants -- they generally become ash. Anything that can't be burnt ends up in your ashtray. Wood pellets have an ash content of [only] around 0.5 per cent

Interviewer

Right -- and, of course, in the sort of systems you're talking about, the wood pellets are stored in a hopper, and then they're automatically fed through into the combustion space as required. So it's also much more convenient than a conventional log-burner.

Now I think there's a few myths around about the inclusion of dangerous chemicals in wood pellets. Would you mind giving a description of how wood pellets are made, and telling us what they're actually made from?

George Estcourt

The two main feedstocks for wood pellets are either wet sawdust or dry shavings. [The] wet sawdust comes straight off the sawmill bench. Dry shavings [are] produced once you've sawn [and] dried your timber, and then you're basically dressing the timber to put the nice smooth surface on it. The shavings [that] come off are [a] waste product, and one of the best materials to make wood pellets.

The wood waste -- such as the sawdust and the wood shavings -- have to go through a hammer-mill, and that breaks the material down to a very fine particle size. [If] the material [is] not already dry, like the dry shavings, it will have to be dried. Wet sawdust is about 50 percent moisture content -- [so] you need to drive all that water off and get it down to about 10 per cent moisture content.

Once it's all down at that 10 per cent then it goes through a pelletizer, and this is when the hammer-milled product, which is a very fine-looking sawdust, is pushed through a die. So you're pushing the material through the die, it's heating up, the lignin that's within the wood-fibre softens -- and I think the wood pellet gets up to about 90 or 80 degrees Celsius while it's being formed -- and that lignin holds the wood material together as it's cooling down.

It's a natural glue that's within the wood fibre. There's no additives -- it's pure 100 per cent sawdust or dry shavings.

Interviewer

Okay, so just to recap: the wood pellets are made from waste sawdust and waste wood shavings, and they're held together by a natural glue that already exists within the wood itself.

Now because the wood pellets are made from waste products they'll inherently have a very high energy yield ratio. Have you actually calculated or measured it?

George Estcourt

Obviously when you're producing it from a dry shaving, the only energy that you're really using is the electric motor doing the hammer-milling and running the pelletizer itself, so there's very little energy required.

We have people having to dry the sawdust [as well]. One of them was using gas to dry the sawdust. [But] he's [now had] a wood pellet furnace made big enough, so that he's actually burning his own wood pellets to dry the sawdust material. [So he is] using a product that [he has] produced [himself]. [He's] not using fossil fuels any more -- so again it would have quite a high [energy yield] ratio.

Interviewer

At the moment, as you've said, the pellets are made from waste wood. But what happens once your market grows larger than the waste wood supply, and you have to use virgin sources? Does the price go through the roof at that point?

George Estcourt

At the moment there is an abundance of sawdust in the North Island. We think that the industry could [increase] maybe ten-fold before you'd have to think about actually growing crops to make wood-pellets.

What we're hoping [and] trying to encourage [is] more processing of New Zealand logs within New Zealand -- rather than just exporting them. And if you can encourage more processing in New Zealand, and keeping the logs here, then we get more sawdust and wood waste [to turn into pellets]. So there's a double benefit if you try [to] get more processing done in New Zealand.

Interviewer

Right, which all sounds very good.

Now, exotic wood crops are -- so we're told -- produced very sustainably in New Zealand. Do you think it would be important to have legislative controls on any biofuel imports to ensure that they've also been produced in an equally sustainable manner?

George Estcourt

I think it would be helpful to have limitations on what we bring in. [But] on the wood pellet side I can't see that ever happening. We get a lot of emails from companies -- mainly in Europe -- wanting to know if we can export wood pellets to them.

So I think there is [a greater] possibility that we will be exporting our biofuels out of New Zealand.

Voiceover:

So a simple manufactured biofuel like wood pellets -- which makes use of sawdust and shavings that would otherwise be discarded -- will provide clean and efficient heating in domestic or industrial situations, and could make an increasingly important contribution to New Zealand's energy mix.

Next week we look at another big biofuel that could also be manufactured from New Zealand's exotic forests.

Theme music...

Further information on biofuels:

• Read more about bioenergy at Scion.
  
  
• Read more about biofuels on Wikipedia.
  
  
• Visit the EECA website to find out about energy sources and usage in New Zealand.
  
  
• Visit the BRANZ HEEP Project website to find out about household energy end-use in New Zealand.
  
  
• Read the Warm Homes Technical Report to find out about home heating methods and fuels in New Zealand.
  
  
• Read more about biofuels in New Zealand in this 2006 publication from the National Centre for Climate–Energy Solutions.
  

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The Science Behind The Three Most Important Words In The English Language | Dec 31, 1899 12:38

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This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 19th May 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Background:

[FX: People saying the phrase 'I love you' in Dutch, Hebrew, Japanese, Bulgarian, and English.]

Voiceover:

It doesn't matter where you live in the world or what language you speak, that is the message that everyone wants to hear. Love is one of the most powerful emotions in human experience. But, from a scientific perspective, why is love so important -- and can we make any scientific predictions about its eventual outcome?

To answer these questions, I visited Professor Garth Fletcher, a research psychologist at the University of Canterbury. I began the interview by describing his 'intimate relations' laboratory.

Interviewer:

It's basically a room that's wired up so that Prof Fletcher can observe people interacting. I can see a one-way mirror on one side of me, and at least one camera -- am I missing any...?

Prof Garth Fletcher:

Three...

Interviewer:

... there's three cameras here, and presumably microphones hidden all around the place as well?

Prof Garth Fletcher:

Yes...

Interviewer:

When you have people in here interacting, how do you measure or observe the way that they're behaving?

Prof Garth Fletcher:

That's a good question.

We're interested in behaviour, and we're interested in how people think, and we're interested in how people feel. Our aim is to try and understand how those three domains contribute and work together -- specifically in terms of dyadic or couple interactions.

So we do a lot of research where we bring people who are dating, or bring people who are married (in some cases) here , and we might get them to do a variety of tasks. Frequently we'll get them to have discussions with each other, and usually we will have video recording of their behaviour -- we'll have close-ups of their faces, [and so on].

One of the things we've done in the past (in several studies) is develop a procedure where -- once people have had a ten minute discussion -- we take identical video copies of that, and then we separate up the couples.

So we keep one person in this lab; we put the other one in the other lab (and, of course, these labs are soundproof); and then we get them to review the tapes, and get them to report what they were thinking and feeling. Provided you do it straight away it seems like quite a powerful mnemonic, and it's surprising what people can remember.

Interviewer:

One of the things that you have studied -- which I find quite fascinating -- is the role that evolutionary selection plays in partner choice, in terms of attractiveness. I guess we're all familiar with this from the animal kingdom, where the parrot with the brightest feathers... or, I don't know, the lion with the biggest mane attracts a partner. [Presumably] this also happens in human relationships?

Prof Garth Fletcher:

Well, yes, indeed. There is the equivalent of the lion's mane, and the feathers on the bird, and the redness of the band on the woodpecker's leg in humans. And, in terms of humans, we have a pretty good handle actually on what people are looking for.

Basically, I always think they come down to the 'big three'. The first of the big three -- and this is numero uno, and you find this across cultures -- is that people are looking for a partner who's kind and trustworthy and warm and loyal.

Now, that's obvious, but nevertheless you still have to do the research. You still have to find out -- okay -- that might be a stereotype, that may be a first guess, but is it true? Well, the general answer is that it's true, and that it's true for both men and women.

The next one down the list, which is not quite as important, but pretty important, is attractiveness and being healthy. Being attractive, being fit, those kind of factors. And again you see this around the world. But we do find a characteristic gender difference there, and that is very much in accordance with the stereotypes -- which is that for men attractiveness is more important than for women.

The third one is finding someone who has status and resources, or who has the potential -- ambitiousness and so forth -- to get resources and to attain status. And here you find a sex difference, but it's in exactly the opposite way. Here women rate it as more important than men, so it's the mirror image of attractiveness.

Interviewer:

Well, that's an interesting question: which is the more shallow sex, in that case. Is it better to look for physical attractiveness or affluence?

Prof Garth Fletcher:

Well, you know, the question is really: why? Evolutionary psychology has, I think, the most plausible and parsimonious explanation for this pattern.

It's all to do with something called parental investment. Humans are a bonding species, we live together over many long years, and both male and female help raise the children. Only about three per cent of mammals [bond] like this. In every single [case] -- every single one -- the male will help to raise the offspring by guarding the nest, or bringing food, or helping out in some fashion to support the mate and help raise the young.

But even in humans it's still a little asymmetrical -- because the female still invests somewhat more. The male can use that strategy of trying to impregnate as many females as possible, [but] for the female that strategy is closed off, because the woman is only capable of producing so many children. Plus the energy requirements of pregnancy, and so forth, are greater. So the woman normally invests to a greater degree than the man does.

Therefore you would expect women to be perhaps a little choosier, but also to be focussed on slightly different things than the male. The main carrier of good genes is probably attractiveness, [and] the male is particularly interested in that feature.

The woman is a bit more interested in those features of the partner that are going to help her to provide for the children, and help to provide for her, and help to raise the family. So the female will be more interested in status and resources -- things that will contribute to the raising of the family.

Interviewer:

When you talked about the main drivers that people are looking for in terms of partner selection... in some cases looking for a warm, kind person, and a successful person, might not necessarily be compatible -- they might be contradictory. How do people make a trade-off between the three main different aims in this case?

Prof Garth Fletcher:

Well, that's a very good question, and we've actually studied this in part -- as have other people. We published a study one or two years ago, where we looked specifically at the trade-offs that men and women will make.

What we found, interestingly, was that there were gender differences. So that, for example, a woman will be quite likely to trade-off someone who has got high status and resources against not looking that great...

Interviewer:

Thank goodness for that...

Prof Garth Fletcher:

Hmmm, right...

Men are likely to trade-off the other way around. They're more likely to trade-off someone who -- if they haven't got very much in the way of status and resources, that's okay -- as long as they've got something else to bring to the table. And oftentimes that's being pretty attractive.

People will even trade-off to some extent on how intimate and loyal and kind a person is... although in a long term relationship the way people will see that is probably as a necessity rather than a luxury.

Interviewer:

Turning to the application of evolutionary theories -- is there a way to apply it to relationships... to help people solve their relationship problems, or identify where their relationships might be going wrong?

Prof Garth Fletcher:

Many years of research have shown us what the predictors of relationship success are in western cultures. [The] two main predictors are communication and interaction -- and the second biggest predictor is really people's attitudes to each other, and their attitudes to the relationship.

But, basically, if we get couples in here and look at their behaviour we can probably predict what's going to happen down the track about 80 to 90 per cent of the time -- we'll know whether they'll be together in another three years, five years, ten years. It's not perfect, but it's not bad...

Interviewer:

It's extremely good...

Prof Garth Fletcher:

... we know how to do that -- it's not that difficult to do, actually, if you know what you're doing.

Interviewer:

I guess I have to ask -- is that an alarming piece of self-knowledge to have when it comes to your own relationships?

Prof Garth Fletcher:

Well, it's an interesting question... I don't know that I'll answer it directly. But intimate relationships, and sexual relationships, contain some of the most powerful emotions that we know of: grief, love, sexual jealousy. And I've experienced all three -- as many people have.

One of the main things those experiences taught me as a scientist, was that these emotions have very powerful motivating properties. They need to be taken very seriously -- they're worth scientific investigation.

When you understand something pretty well from a scientific angle, it doesn't do anything to prevent the emotions or cognitions or normal behaviours occurring. And you have completely normal relationships, which occur in precisely the same way as everybody else's does. Which is very fortunate...

Voiceover:

Next week on Public Address Science: the equally emotion-provoking subject of biofuels.

Theme music...

Further information on the science of intimate relationships:

• Read more about Professor Garth Fletcher.
  
  
• View a list of Prof Fletcher's books on Amazon.com.
  

(41 responses)
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The Astonishing New Car from Bavaria that Won't Cost the Earth. | Dec 31, 1899 12:37

Play the audio for this post MP3, 7.5 MB

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 12th May 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Background:

[Sound of Ford GT40 engine ignition]

Voiceover:

Many listeners will instantly recognize this sound as the 4.7 litre V8 engine from the Ford GT40. Now I must admit that at some subconscious level, in the primeval reptile part of my brain, I'm tremendously impressed with the stupendous noise and power output of this type of engine.

However, I know in the rational scientific part of my brain -- the bit that's developed over the last million or so years of evolution -- that this car, and others like it, are nothing short of environmental and economic disaster areas.

Luckily for us, the standard passenger vehicle in New Zealand is nowhere near as grossly inefficient and gas-guzzling as the GT-40. Nevertheless, there's still scope to vastly reduce the amount of energy we use, and the import dollars we spend, on travelling from 'A' to 'B' in private passenger vehicles.

The standard car in New Zealand consumes about eight litres of fuel for every hundred kilometres travelled. Compare that with the 1955 Messerschmitt KR200 from Bavaria, which -- fifty years ago -- only required 3.2 litres/100 km, and you can see that there's still considerable room for improvement. Or, for a more modern car, what about the 2005 Audi A2 5-door -- also, coincidentally, from Bavaria, which only requires 3.0 litres/100 km.

It may surprise you to hear this, but a vast amount of energy is consumed by New Zealand's private passenger vehicles. For example, if everyone in this country simply changed their car for the super-efficient Audi A2, then it would not only cut the transport fuel consumption of New Zealand households by more than half -- and would slash New Zealand's total energy consumption by more than ten per cent.

That translates to a total savings at the pump of around 2.8 billion dollars, most of which would otherwise be leaving the country, and adversely affecting our balance of trade. And all this huge savings [is possible] without reducing our total distance travelled by so much as a centimetre -- it's all down to the efficiency of the car we use.

But now the goalposts for automotive fuel consumption have been moved again. Realizing that most driving is merely commuting with one (or perhaps two) adults in the car, Bavarian auto-manufacturer Loremo have recently produced an innovative and sporty-looking two-seater -- which can trundle along the autobahn at 160 kilometres per hour, has ample room for luggage in the back (or, alternatively, a couple of children), and has a truly astonishing fuel efficiency. At only 1.5 litres/100 km it slashes the fuel efficiency record for a production car, and all at a retail price of only €10,990.

Let's try to put all these fuel efficiency figures into perspective. Imagine driving a car down the whole of New Zealand from Cape Reinga to Bluff. In one of those black supercharged Range Rovers that I see parked outside Christ's College every weekday, this would cost around $720 in petrol at the pump. In a standard Toyota Corolla the same trip would cost you a little under $300. In the Audi A2 5-door it would set you back a mere $67 -- only about the same as your diesel road-tax for the trip.

And in the Loremo it would cost you less than the CD you listened to on the way -- only about $33.

The Loremo company have just been exhibiting their new car at the massive Hannover Trade Fair, and I spoke on the phone to Uli Sommer, their head of Concept Development. I asked him how the Loremo had been received...

Uli Sommer:

The response was great. We had a lot of people [at] our booth, and we had many TV teams. And everybody spoke [favourably] about Loremo.

Interviewer:

That's very heartening...

The basic principles involved in the design of fuel efficient cars have been known for many years (going back to cars like the Messerschmitt KR200), but automakers haven't really seen it as being particularly important. Why were you inspired to design a car for fuel efficiency -- rather than, say, speed or power as with other car companies?

Uli Sommer:

From childhood I was a fan of any individual mobility -- especially cars. And [also] from childhood my parents made me [aware of] the problem of [finite energy] resources. So I had a conflict. And [eventually] I tried to solve this conflict by making emotional cars which are really sporty, but really efficient.

Interviewer:

What were the main engineering challenges that you had to overcome in terms of designing the Loremo car?

Uli Sommer:

[From a] certain [perspective] I did [nothing] new. The [most] important [part of the] invention was the idea to make an economic car.

That sounds really simple, but [over] the last [few] years [people] have so often spoken about alternative [fuels] or high-efficiency [motors]. And engineers today know that the efficiency of [motors], or the potential of alternative [fuels]... isn't as large as the potential of an efficient body and chassis.

So we only have two main targets. First target: reduce wind resistance. Second target: reduce weight. And any energy wasted is combined within those two [parameters].

Interviewer:

Okay, so your main design objectives were to minimize weight, aerodynamic drag, and -- I guess -- cost. How did you approach these problems in an engineering sense? Did you rely on wind-tunnel testing, or computer modelling...?

Uli Sommer:

We used [both]. But the most important thing is that we are 'consequent' [(a literal translation of the German word 'konsequent')] in designing.

So we don't use expensive materials [to make] the car lightweight. We are not the best aerodynamic specialists in the world -- we made the car long, narrow, and flat, and gave it a 'consequent' form. So at the first attempt we had a very good drag resistance.

And we reduced [the weight] by using a linear cell structure made of steel plate -- so that the selling price can be [very low].

Interviewer:

So "consequent design" [(a literal translation of the German 'konsequente Konstruktion')] is what we'd refer to in English as 'stringent design' or 'design without compromise' -- where every single design decision must be consistent with the final goals. And, interestingly, this has led you away from the traditional monocoque approach?

Uli Sommer:

It's not a monocoque [design], but it has some similarities.

The structure has three longitudinal girders [at] the height of bumpers, so you cannot open the door at the side. The doors are opening to the top, and because the car is so flat the entrance is [actually] more comfortable than with side doors.

The [resulting] structure is rather simple -- like a nail which doesn't have bending forces and so is rather rigid.

Interviewer:

So you've used a small amount of steel in the linear cell structure -- and then the rest of the body is presumably another material?

Uli Sommer:

That's thermoplastics -- which are cheap, simple, and recyclable. [Our] main construction principle is simplicity.

Interviewer:

Loremo's achievement of 1.5 litres/100 km is truly remarkable (even more so for a car costing under €11,000) -- you're certainly to be congratulated on that! Given the interest that your car has received in Europe, other auto manufacturers have now got a new target to aim at -- do you expect them to try and beat your efficiency in the near future?

Uli Sommer:

The car has some special aspects, which perhaps wouldn't pass any marketing department of a normal car producer!

[However] we are expecting some competition -- there's no question. [The] future will change many things, but we think our concept is very attractive. With or without [competition from] a big OEM [(Original Equipment Manufacturer)] we will survive.

Voiceover:

I certainly hope that Loremo survives. They will be producing a right-hand drive model suitable for New Zealand. And, translating the current price into our currency, you'd expect to pay around $20,000 for a brand new Loremo. While this vehicle might not be suitable for everyone, it must be hoped that other manufacturers will be motivated to lift their game, so that far less energy is wasted in moving us from 'A' to 'B' by car.

Theme music...

Further information on the Loremo car:

• 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).
  

(41 responses)
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Could the Mysterious Agricultural Techniques of an Ancient Amazonian Civilization Make New Zealand Farming More Competitive? | Dec 31, 1899 12:36

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This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 5th May 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Voiceover:

A month or so ago, I wrote an article on Public Address in which I implied that it would be very difficult to reduce greenhouse gas emissions from New Zealand agriculture. Well, it turns out that perhaps I was being unduly pessimistic -- as structural biologist Alfred Harris has subsequently explained to me.

Alfred's good-news story begins -- like all the best stories -- with a mysterious substance hidden deep in the Amazon region of South America. Terra Preta de Indio or 'Amazonian Dark Earths' are areas which contain soil of exceptionally high fertility.

Naturally enough, scientists were very keen to find out what made these soils so special -- but no-one expected the answer that they got. It turns out that these soils were actually man-made.

Pre-European Amazonians had manufactured these soils by working charcoal and manure into ordinary low-fertility earth. Of course, the fertilizing properties of manure are well-known, but it was the addition of charcoal which dramatically improved soil fertility. So much so, in fact, that the soil was still extremely fertile hundreds of years after the collapse of the civilization that produced it.

And here's an interesting co-incidence -- go a third of the way around the world to New Zealand, and archaeologists discover that pre-European Maori also worked charcoal into the soil [although there is no archaeological evidence to suggest that Maori did this with a deliberate intent to increase soil fertility].

It seems like an extraordinary co-incidence. Structural biologist Alfred Harris takes up the story...

Alfred Harris:

In Waimea, for example -- where there's hundreds of acres of what they call 'Maori soils' -- the experimental work was done on that site, and it was very clear that charcoal was mixed far further into the soil than would be expected simply from just the burning of the site.

Interviewer:

It's fascinating that two cultures so far apart should both discover the effects of charcoal in terms of agriculture. At a scientific level, how the does charcoal actually improve soil fertility?

Alfred Harris:

Okay, going back to basics: plant growth is absolutely dependent on a number of key elements -- and the major elements are nitrogen, phosphorus, and potassium. Each of those elements are highly soluble. So given a reasonable sort of rainfall, which you need for good plant growth, they'll move through the soil very quickly.

So the fertility of the soil is really dependent on the ability of that soil to retain those key elements. The soils where charcoal seems to have a particular effect -- and that's in South America, and in Japan, and here in New Zealand -- are derived from weathered volcanic ashes.

Charcoal in the Terra Preta [de Indio] soils in South America increase the fertility and maintain it over very long periods of time. It appears to have more to do with the retention of nitrogen in that situation -- but in Japan, in different types of volcanic soils, it appears the effect is actually to increase the levels of mycorrhizal fungi, which, in turn, makes the phosphate [that is] heavily bound in those soils available to plants.

Interviewer:

Okay, right, so what you're saying is that the charcoal has at least two different effects in volcanic soils. In the case of South America it slows the rate at which nitrogen is leached out of the soil by rainwater. But in New Zealand and Japan, there's a different mechanism, where it effectively unlocks the phosphate already in the soil -- so as to make it available to plants.

Alfred Harris:

Yeah, I don't think there's actually a universal effect. I think what we're seeing is a combination of different effects, which we're only just beginning to understand.

Interviewer:

So the exact mechanics of how charcoal increases fertility isn't necessarily fully understood yet, but it's been conclusively proven that it does actually work?

Alfred Harris:

Beyond a shadow of doubt -- that's absolutely right. And what's been demonstrated (by the Japanese, primarily) is that the addition of charcoal can reduce the amount of fertilizer that you need to put in for the same fertility effect. And they're quite substantial differences... you're talking 20, 30, 40 per cent.

Interviewer:

Right, which begs the question -- why isn't this already standard practice for agriculturalists?

Alfred Harris:

Again, that's a really good question. See what they say all the way through, is that: "Hey, really great that it works -- but the cost of producing the charcoal, and actually incorporating it in the soil means that it's not going to work economically". And they're absolutely right, in [terms] of conventional agriculture, where you've got cheap petrochemical products, and you can fix your nitrogen from the atmosphere using [cheap] energy. But, of course, what's happening now is that the economics of all of that is suddenly changing very fast.

Interviewer:

So the rising world energy prices have now, perhaps, made financially worthwhile the fertilizer savings which are possible from charcoal addition.

But what you're also doing with the charcoal addition, of course, is effectively sequestering atmospheric carbon in the soil -- because carbon charcoal is derived from wood products, and therefore ultimately from the atmosphere. Does the carbon actually stay in the soil long enough to be useful from a sequestration point of view?

Alfred Harris:

Well, these Terra Preta [de Indio] soils in South America were developed about the time that the Spanish conquered... When the Spanish came back there and settled those civilizations had vanished. [So] the suggestion is that [the carbon will stay in the soil] for hundreds, if not thousands, of years.

But the other thing that's really crucial and really interesting is that (back in 1996) some very clever scientists in America discovered that in [the standard practice of soil analysis] for humus content they were throwing out... 27 per cent of the soil carbon. Now what they found was that [this] carbon was produced by mycorrhizal fungi, and it's the glue of soils. And what it does is that it glues the clay particles together in such a way that bacteria can't raid them. [So] that [these carbon] molecule[s] will hang round in the soil... for hundreds of years

Interviewer:

Wow, so you actually get a double effect in terms of carbon sequestration?

Alfred Harris:

That's absolutely right. When you put charcoal in the soil, you're fixing carbon. When you put charcoal in the soil, you're [also] increasing the level of mycorrhizal fungi, which themselves fix carbon. So it's one of those wonderful virtuous circles where you actually get a double whammy. You [end up with] fixed carbon from two different sources.

In a country like New Zealand, which grows biomass, it seems to me to be an absolute must if we're going to change from a fossil carbon economy. You know, it [would] really put New Zealand agriculture back on the world stage, and on the front foot. Because biomass is produced so fast here [that] we have an advantage over virtually every other country in the world.

Interviewer:

Is there actually anyone in New Zealand who's seriously investigating the possibility of using charcoal to make our agriculture more efficient and environmentally-friendly?

Alfred Harris:

I'm involved in a start-up company called 'Aotearoa Biocarbon', and our intention is to produce charcoal in New Zealand. And what we're looking at, [firstly], is... to reduce the amount of fertilizer input.

The other [possibility], of course, is that if charcoal can be used to hold nitrogen in the soil, it can also be used to pull nitrogen out of places where it's not wanted [such as] Lake Taupo. Now, what our company is looking at... is getting paid to take waste from the forestry industry, turn that into charcoal, and then get paid by the powers-that-be to remove nitrogen (particularly from lakes) -- to produce product [that] is a slow release fertilizer, which you can then sell onto farmers.

Voiceover:

So it's possible that the use of charcoal in New Zealand agriculture could reduce fertilizer use, save energy, and sequester carbon all at the same time. With rising petroleum costs it seems like maybe the time has come to re-learn a few lessons about charcoal from the ancient Amazonians.

Theme music...

Further information on the use of charcoal in agriculture:

• Read more about Terra Preta de Indio at Cornell University.
  
  
• Read about the energy-efficient production of charcoal at the University of Hawaii.
  
  
• Read Kelpie Wilson's report on the first meeting of the International Agrichar Initiative in Australia.
  
  
• Read the Terra Preta links page at energybulletin.net.
  

(26 responses)
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New Zealand's Wave Energy Technology programme | Dec 31, 1899 12:35

Play the audio for this post MP3, 8.1 MB

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 28th April 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Voiceover:

What could be more pleasant than a day at the beach?

Well, practically anything as far as I'm concerned. I don't really enjoy sand in my underwear -- and I'm completely bored by lying on hot beach, and giving myself skin cancer.

What I do enjoy, however, is getting out and swimming in the ocean. And, in particular, thinking about ways to extract useful energy from the waves.

As a ball-park figure, New Zealand's total wave energy resource is around 2500 petajoules per annum. That's a lot of energy -- about five times more than all the energy produced or imported into New Zealand every year.

In practice, of course, it's only possible to exploit a small percentage of this energy. Firstly, because we can't surround New Zealand with an impenetrable barrier of wave energy converters. And, secondly, because the efficiency of any practical wave energy conversion system will be far less than 100 per cent.

Nevertheless, wave energy still represents a very significant renewable energy resource for this country -- and one that's actually more reliable and predictable than wind energy. What a shame that the potential of wave energy in New Zealand appears to have been completely ignored.

Well, actually, that's not entirely true.

You may never have heard of them, but Industrial Research Ltd (or IRL) is one of New Zealand's Crown Research Institutes. They've been given some spare change, and told to invent a machine that can extract useful energy from New Zealand's ocean wave resource. And, it turns out, that's exactly what they've done.

I visited energy engineer Alister Gardiner -- who heads the research team for IRL's wave energy programme.

Interviewer:

I'm now standing in IRL's Christchurch laboratories looking at their prototype wave energy device, which has been dubbed the 'Wave Wobbler'. There are two different parts to this device. One part is a large rectangular block about 6 metres long welded together out of steel sheets. It's rather dense and heavy-looking, and it reminds me a little of the monolith from 2001: A Space Odyssey except that it's painted bright yellow. A swing-arm protrudes from the top of this monolith, and is attached to a large rectangular float -- which is slightly smaller and much lighter-looking.

Alister, can you explain how this device generates electricity from ocean waves?

Alister Gardiner:

Well this, of course, is an experimental device -- but basically it's quite simple. The large monolithic hull you mentioned [floats] vertically in the water just below the waterline. The float sits horizontally on top of the water, and the motion of the waves oscillates the float up and down.

Interviewer:

Okay, so the monolith is sitting in the water [and] effectively it hardly moves at all. But the float follows the surface of the waves, and the difference in the motion enables you to generate electricity [via a suitable mechanism].

Alister Gardiner:

Fundamentally, yes. Although, of course, it's not quite as simple as that. There's some quite complex maths around getting the two parts to move together in a synergistic way.

Interviewer:

And you've obviously done quite a lot of modelling to explore that?

Alister Gardiner:

Yes, we spent two years developing some complex [mathematical] engineering models to develop the whole concept and come up with an optimized [design].

Interviewer:

So I know you've had this prototype in Lyttelton harbour, which only has tiny waves. In your further testing -- when you actually get it out into the real ocean -- what sort of power output do you expect from it?

Alister Gardiner:

With the larger scale version which we'll be heading towards commercialization we're expecting round about 100 kilowatts. Which is enough power to keep round about a hundred houses going.

Interviewer:

Okay, right, it wouldn't just be one [machine] by itself -- you might have a hundred or more all moored together in a sort of a 'field' of wave generators?

Alister Gardiner:

Yes, that's right. And we estimate from our modelling that we'd probably get each individual device up to around about a megawatt ultimately. But they will even be larger still.

Interviewer:

So what sort of size are you expecting for that in terms of length and mass?

Alister Gardiner:

Well the 100 kilowatt version, which is really our first commercial focus, may weigh between 30 and 100 tonnes in total. So it's quite a substantial device -- although, of course, you only see a small portion of it above the surface.

Interviewer:

How long [i.e. the length of the device] would that be underneath the water?

Alister Gardiner:

It could be up to ten to 15 metres long.

Interviewer:

And so would you be using water as ballast -- or would it be made out of concrete, or steel, or something [equally] heavy to provide all that mass?

Alister Gardiner:

Yes, that's one of the secrets in fact. Most of the mass is taken up by water. So you don't have to actually tow it out [to the desired location]; you simply flood it when you get it there.

Interviewer:

On land it's actually quite a light-weight device, it's only when you put it into the sea that it [fills up with water and] becomes this very heavy machine?

Alister Gardiner:

Yes, you might argue that it's a submerged yacht with a small float sitting at the top of it.

Voiceover:

Naturally enough, IRL aren't the only company who are looking into wave energy devices. Research teams are working on a variety of different systems in countries all around the world.

The United Kingdom are investing hundred of millions of New Zealand dollars on their marine energy program, and British company Ocean Power Delivery are definitely leading the field in terms of development.

Their 'Pelamis' wave energy device is a truly huge machine. It measures 120 metres long, and floats on the surface of the sea like a gigantic snake.

It couldn't be more different from IRL's 'Wave Wobbler' device, and -- when we'd returned to his office -- I asked Alister Gardiner why the research team at IRL had chosen to take such a different path.

Alister Gardiner:

There's no question that Pelamis is the benchmark at the moment. But we feel that our concept of going for a point-absorber gives us more flexibility -- and, in theory, should provide a more cost-efficient device because of the lower use of materials. It's more flexible because we think we can make smaller devices, [which] could be used off-shore on remote islands at a lower cost.

Interviewer:

What are the comparative efficiencies of the devices -- do you have any sort of feel for that?

Alister Gardiner:

One can look at the Pelamis data sheets, and work out pretty quickly that their efficiency is relatively low -- perhaps just a few per cent. That has it's disadvantages in terms of the size of the device. We feel from our modelling that we can achieve a much higher efficiency than that. And so we've started with an inherent design that we think is cost efficient.

Another point, I guess, is that if a large portion of the device is below the water -- beneath the surface of the waves -- then there's better chance of it remaining viable and surviving storm conditions.

Interviewer:

Which is important when at least some of New Zealand's in the roaring forties, and it's really subject to some pretty horrific waves.

Alister Gardiner:

Exactly, yes. New Zealand is very fortunate in its wave energy resource.

Interviewer:

We're fortunate in wind, too. And we've seen recently a little bit of wind coming on to the market -- there are wind farms generating a very small amount of New Zealand's electricity. How long do you think it's going to be before we see something equivalent to that beginning to happen with wave energy?

Alister Gardiner:

We think it will happen a lot quicker.

I would expect that by 2010 there will be a number of commercial (or pre-commercial) devices in the water from various suppliers. And, by 2015... maybe 2020... we'll certainly see quite substantial uptake of marine energy of various sorts.

Interviewer:

So that's actually really quickly.

Alister Gardiner:

You've only got to look at the energy crisis in the 80s, and so on, to see the massive involvement in wind energy. Now when the fuel prices came down that more or less stopped, which is the only reason it took maybe twenty years for wind energy to get to where it is today. If that research effort had continued we would have seen wind turbines and wind farms much earlier...

Interviewer:

That brings me to something else, which is whether rising energy prices are a threat to New Zealand or also something of an opportunity as well? What I'm thinking here is of Denmark. You talked about the oil crisis in the 70s, and [Denmark] responded by investing heavily in wind energy technology. And they've now become -- as a country -- the world's leading exporter of wind turbines. Is there a similar opportunity for New Zealand here in terms of marine energy?

Alister Gardiner:

There's no reason at all why we can't produce a technology that's competitive globally. And, as I've mentioned, we think that basic concepts that we're putting together are potentially globally competitive.

However New Zealand does need a supportive environment and an enthusiasm to capture this [opportunity]. And this is, of course, what happened in Denmark. There was a strong government support for a particular type of energy technology.

We certainly need that sort of involvement (I think) within New Zealand. Both from the energy companies -- who are obviously very keen on these technologies -- and probably government leadership [as well], and obviously the manufacturing companies that will benefit down the track.

Voiceover:

IRL have clearly come a very long way with their 'Wave Wobbler' device, but only time will tell whether New Zealand has the political and economic will to develop a domestic wave energy industry -- or whether, as with so many of our other innovative technologies, we'll be content to let the opportunity slip through our fingers.

Theme music...

Further information on wave energy devices:

• Read more about the WET-NZ wave energy converter.
  
  
• Read more about the Britain's Pelamis wave energy converter.
  
  
• Read more about wave energy in general in Wikipedia.
  

(41 responses)
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What on earth is a Grätzel solar cell, and why is it so important? | Dec 31, 1899 12:34

Play the audio for this post MP3, 5.1 MB

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 21st April 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Voiceover:

Solar energy... in theory, it should be the answer to all our energy problems. Properly managed, more than enough solar energy falls on the roofs of New Zealand houses to provide all our domestic electricity needs.

So why don't we make use of it?

One problem is that -- fairly obviously -- the sun only shines during the day, which means that storage batteries [or similar] are required to provide energy for use at night. The other problem is that the solar cells used to generate electricity from sunlight are incredibly expensive.

That's because the raw silicon ingots used for solar cell manufacture require production technology that is astonishingly high-tech, enormously energy-intensive, and therefore mind-bogglingly costly. As a result, a 60 watt solar panel (enough to power a single dim incandescent light bulb) will set you back by around $850 dollars.

And why would you pay that sort of money when you get virtually unlimited electricity out of the power lines at a fraction of the cost and effort?

But the price of solar generated electricity is actually coming down. For each doubling of production capacity in the factories that manufacture solar cells, the price has fallen by around 20 per cent. In recent years, that's equated to a price drop of around 5 per cent per annum.

So do we all just have to wait for a few decades until we can afford those shiny solar-electricity panels on our roof?

Well, not necessarily. A new type of solar cell technology has emerged which looks set to change everything. Grätzel solar cells seem likely to slash the cost of solar generated electricity. They've actually been around since the early 1990s, but it's only comparatively recently that scientists have been able to get them work in a reliable manner.

One of the research teams at the forefront of Grätzel solar cell technology is the Nanomaterials Research Centre at Massey University. I talked to Dr Wayne Campbell about what the future might hold for solar energy.

I asked him to start by explaining how conventional silicon solar cells are made.

Dr Wayne Campbell:

The common silicon solar cell [which] you can buy is basically made from pure silicon ingots. It's... sliced up into little slices, and then doped with a n-type or a p-type dopant to make the actual solar cell. It forms what they call a p-n junction. When light shines over that junction you get electron transfer.

Interviewer:

So putting it in very simplistic terms: the energy in the photons of sunlight knocks loose electrons from the doped silicon material, which produces an electric current. In contrast, how do Grätzel cells work -- and how are they made?

Dr Wayne Campbell:

It's a photoelectochemical cell. It works completely differently really. In a simple sense you have a dye, which absorbs light [and] excites an electron up to a higher energy part of the molecule. From there that energy transfers to a semi-conductor -- in this case it's usually Titanium dioxide -- and from there it's collected on a transparent conducting surface. It's basically photoexcitation followed by charge separation... and then you get the loop of the electron back to the dye again.

Interviewer:

So the energy from the sunlight is first absorbed into a dye, and then there's a second step where the energy is transferred from the dye into a semiconductor material. And, in this case, the semi-conductor material is titanium dioxide, which is presumably cheaper to produce than the silicon crystals in conventional solar cells?

Dr Wayne Campbell:

It's a very thin layer, so it's very cheap.

Interviewer:

And is the manufacture of Grätzel cells a simpler production process than for conventional silicon cells?

Dr Wayne Campbell:

Yeah, basically [either] it's screen printing, or simple pyrolysis, or plasma deposition.

Interviewer:

So I know that your research group have been collaborating with Professor Grätzel who invented these Grätzel cells in Switzerland. What aspect of the technology are you actually looking at?

Dr Wayne Campbell:

Our main area [is] not so much developing the cell anymore -- it's just developing a better dye for these cells. The current dyes that are used are quite expensive because they're Ruthenium-based. So they're based on a fairly rare metal which would have limited supplies if it was used in large quantities.

Interviewer:

So you've had quite a bit of success with your research. What are the advantages of the new Grätzel cell dyes that your team has developed.

Dr Wayne Campbell:

It's a lot cheaper to make than the Ruthenium dyes -- basically because it doesn't have any rare metals.

It's based on a chlorophyll molecule, which is the porphyrin haem group in blood (the red molecule in blood). [So] there's no reason for [the Grätzel solar cells] to be toxic -- or anything like that -- [when they are disposed of] afterwards either.

Interviewer:

So basing your dyes on chlorophyll, the chemical that plants use to absorb sunlight, and blood, an energy carrier in animals, that's really a case of science imitating nature. What efficiency are you getting out of the Grätzel solar cells?

Dr Wayne Campbell:

The best for the Grätzel cell was with the Ruthenium dye -- and that's quoted at 10.1 per cent.

Interviewer:

Okay, and with the new dye that you've developed?

Dr Wayne Campbell:

The latest report from Grätzel's lab is for 7.1 per cent, so we're quite happy with that. [And] it seems to be very reproducible, [whereas] some of these other dyes don't always seem to be reproducible.

The dye itself hasn't actually been optimised properly in the cell either. [Grätzel's laboratory tested it with] the electrolytes and stuff that they normally would use with their Ruthenium dyes.

By modifying things like [the electrolytes] you can actually get a lot more performance out of the cell. We expect even better than 7 per cent, definitely.

Interviewer:

So you've got good efficiency -- but not quite as good as normal silicon solar cells, which are around the 9 to 15 per cent range, but of course your Grätzel cells would end up being much cheaper, wouldn't they? Do you have any feel for the cost reduction?

Dr Wayne Campbell:

Probably it's going to be [about] one-tenth the cost -- but we don't have any exact figures really, at the moment.

Interviewer:

Wow, that would be a significant cost reduction compared to the comparatively slow rate that the price of conventional solar cells is dropping. So even if the Grätzel cells stay at their current efficiency you're still cutting something like four-fifths off the price on a per watt basis (in comparison to silicon-based cells).

Dr Wayne Campbell:

Yeah... [the Grätzel cells will only be] a fraction of the [current] cost.

Voiceover:

Despite a somewhat lower efficiency, the much lower cost of Grätzel solar cells is certain to bring about a dramatic sea-change in the amount of solar-derived electricity in our society's energy mix.

Dr Campbell expects to see Grätzel cells based on the more expensive Ruthenium dyes in shops within the next few years. Although it may take a while longer before cells with the cheaper chlorophyll-based dyes make an appearance.

Either way, the Grätzel solar cells are another important part of the jigsaw of technologies that will be needed to ensure a secure energy future.

Theme music...

Further information on Grätzel solar cells:

• Read more about Grätzel solar cells in Wikipedia.
  
  
• Read more about solar cells in general in Wikipedia.
  
  
• Read more about the Nanomaterials Research Centre at Massey University.
  
  
• Read about Dyesol and Konarka, two companies who have already begun to manufacture Grätzel solar cells (using Ruthenium-based dyes) in small quantities.
  

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Will the Pulse Detonation Engine Help to Address New Zealand's 'Air Mile' Issues? | Dec 31, 1899 12:33

Play the audio for this post MP3, 6.0 MB

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 14th April 2007, 2 pm - 3 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Theme music...

Background:

[Sound of a blackbird singing]

Voiceover:

For some people the song of a blackbird is the most beautiful sound in the world. Other people's favourite sound might be Beethoven or Jimi Hendrix. But for me this is one of the most fantastic noises that I've ever heard...

Background:

[Sound of a pulsejet flyby]

Voiceover (cont):

It's the sound of a pulsejet engine. And if you lived in London from 1944 to 1945 you might not be quite so enthusiastic about hearing it. Pulsejets powered the 10,000 Nazi V1 missiles that rained down upon England during World War II.

I've got the engineering drawings of the V1 pulsejet engine sitting in front of me. It's pretty much the simplest machine imaginable. It's literally just an empty tube with one end blocked off by a bank of one-way reed valves.

[A pulsejet] works just like a two-stroke lawnmower motor -- but without the piston. Air is drawn in through the reed valves, fuel is injected, and then the fuel is exploded. But rather than the explosion pushing on a piston, it pushes hot gas out the back of the engine at high speed... thus producing thrust.

It couldn't be simpler, or cheaper to make. And it's long been the dream of aircraft engine manufacturers to use low cost pulse-jets on commercial aeroplanes.

So why don't they? Well, the answer is efficiency. Basically a pulsejet engine doesn't have any [efficiency]. The Nazi V1 missile used nearly 600 litres of fuel just to travel a few dozen kilometres across the English channel.

A pulsejet engine is inefficient because the fuel is combusted in a subsonic explosion. This means that the pulsejet operates with a very low compression ratio. An efficient diesel car engine might operate with a compression ratio of 20:1, whereas the pistonless pulsejet engine can only achieve compression ratios of around 2:1.

But what if the explosion were like this...?

Background:

[Sound of a detonation explosion]

Voiceover (cont):

My ears are slightly ringing. That's the sort of supersonic detonation combustion that you can achieve if you get just the right conditions.

In this type of detonation explosion the compression ratio can reach 100:1, [which is] much higher than a normal jet engine. A pulsejet with this sort of compression ratio is called a pulse detonation engine. If such an engine could be successfully developed then it would be a breakthrough in aircraft efficiency and cost.

And that [could have] important implications for New Zealand. It would allow the air-transportation of goods and tourists (to and from) New Zealand at much lower cost, and using much less carbon dioxide-producing fuel. [In other words, reducing the energy consumption and greenhouse gas emissions for each 'air mile'.]

Dr John Hoke works for the United States Air Force Research Laboratory in Dayton, Ohio. He's the head researcher on their pulse detonation engine development programme. His research team have been testing their newly designed pulse detonation engine on a Rutan Long-EZ aircraft. I asked Dr Hoke how things have been going...

Dr John Hoke:

Well, we're doing basic and applied research here. We're able to detonate most practical fuels, [and] we've done high speed taxi tests with [the Rutan Long-EZ] aircraft with a pulse detonation engine attached. We've not flown that aircraft yet with a pulse detonation engine. We have every intent to do that, but at this point we're still doing research.

Interviewer:

So you've successfully managed to achieve detonation combustion in your engine -- and therefore a much higher compression ratio than in a pulsejet. What sort of improvement in efficiency has this translated into?

Dr John Hoke:

When you detonate a fuel-air mixture, you're going to get about three to four times improvement in efficiency over what the pulsejets are getting. You also have much higher exhaust gas velocities. So where the pulsejet typically operated at about Mach 0.6 or [Mach] 0.8, the pulse detonation engine is thought to be able to run very efficiently at Mach 2 to [Mach] 4.

Interviewer:

Okay... Mach 2 to [Mach] 4 -- in other words between two and four times the speed of sound -- that's a much faster speed than passenger aircraft operate at today. So would the pulse detonation engine actually be a suitable replacement for the ordinary turbofan jet engines on commercial aircraft?

Dr John Hoke:

The turbofan [engine] is made for lower speed. You wouldn't put a pulse detonation engine on a commercial aircraft because typically they don't go Mach 2 to [Mach] 4. However, when you look at these things, the pulse detonation engine is a constant volume process, and the efficiency of that is inherently higher than a constant pressure process...

Interviewer (interruption):

... which is the combustion process you'd have in a normal jet aircraft engine...

Dr John Hoke (cont):

... yes. And what's thought for commercial application would be to take this constant volume combustor, and stick it in the middle of one of your turbofans. And then you're talking about potentially a 5 to 27 per cent increase in efficiency of fuel economy.

Interviewer:

So by sticking a pulse detonation engine inside a normal jet engine -- to replace the combustor -- you can get up to a 27 per cent increase in fuel efficiency. In aircraft terms, that's huge!

But what about the case where you actually want to operate a commercial airliner at, say, two or three times the speed of sound, maybe as a replacement for Concorde? Would a straight pulse detonation engine -- the sort you're working on now -- have an application in this context?

Dr John Hoke:

Potentially, yes. The one thing people point out is the noise. High noise-levels can have an impact on structures and what-not, but to our experience the noise [of our pulse detonation engine] is not a whole lot different than an aircraft on afterburner. I've stood right next to the thing when it's running, and it's loud, but it's acceptable.

Interviewer:

Okay, that's quite surprising. I've heard a pulsejet engine, and they are really loud. But you're saying a pulse detonation engine isn't actually that bad?

Dr John Hoke:

Well, you're definitely wearing hearing protection. The sound levels coming out the back of the pulse detonation engine are very directional -- so if you're standing down behind the engine you're gonna see some pretty loud noise levels, I think. At the exit of the pulse detonation engine you're talking about 190 to 210 decibels, and I believe your ears start to bleed around 160 [decibels]. But when you're travelling Mach 2 [or] Mach 3 the sound is behind you. I think you have more serious [no