Oil, Fuel Cells and Alternative Energy

04 June 2006
Presented by Chris Smith, Phil Rosenberg


Powering the generators for the show this week is Nicky White who describes how oil is formed, how we find and extract oil and how long oil supplies will last, Lynne Macaskie discusses how fuel cells can be run on hydrogen gas created by bacteria and sugary waste, and Peter Hughes explains how his Electro-Kinetic Road Ramp could soon be powering your street lamps. In Science Update, Bob and Chelsea reveal how llama spit can be used to spot the ultimate power-up, caffeine, and in Kitchen Science Derek Thorne and Chris Muirhead reveal a cool way to chop your vegetables...

In this episode

Hiv Spikes a Thorn in Scientists' Side

2006 marks the 25th anniversary of the diagnosis of the first cases of HIV. Yet despite millions of dollars of global scientific toil, HIV has grown to become one of the worst pandemics ever known with at least 25 million deaths, 40 million people currently infected, over 4 million new cases occurring each year, and a predicated 100 million people affected by 2010. These figures make gloomy reading, but new research published in this week's edition of the journal Nature has given scientists their most intimate look at the AIDS virus yet, potentially opening up new avenues for vaccine research. Florida State University's Professor Ken Roux and his colleagues used the viral equivalent of a CAT scan, known as cryoelectron microscopy tomography, to produce detailed 3D images of the AIDS virus, which resembles a spiky meatball. The surface spikes behave like grappling hooks, enabling the virus to cling onto and hijack human cells. But our traditional understanding of what they look like - a lollypop - turns out to be wrong, which might partly explain why no successful vaccines have yet been produced. In fact, the spikes comprise a head supported by a tripod-shaped stalk. "Until now the design details of the spikes, and their distribution pattern on the surface of the virus, have been poorly understood limiting our understanding of how virus infection occurs and frustrating efforts to create a vaccine. So we're hoping, within a relatively short period of time, there'll be a new set of synthetic envelope spikes that could be used as vaccine candidates based on this new model", Roux said. To produce the images the research team suspended viral particles in a drop of water on a tiny copper grid. The floating particles were then flash frozen, encasing them in a flawless microscopic ice-cube, which the researchers were then able to examine under an electron microscope.

Right-click To Quit

Researchers in the Netherlands are developing an online computer-generated 'virtual counsellor', dubbed a 'chat-bot' to help smokers to kick the habit. Betsy van Dijk and her colleagues at the University of Twente, together with a Dutch anti-smoking organisation called Stivoro, hope that the anonymity of the web, together with twenty-four hour access to their virtual life coach, will help more smokers to quit. The team are planning a female chat-bot who will respond, with the same answers and facial expressions as those used by real-life counsellors at Stivoro, to questions and confessions tapped into a chat-box by nicotine-craving would-be quitters. But the idea isn't just a pipe-dream; indeed virtual life-coaches are developing something of a track record including pursuading elderly people to take more exercise, which was the achievement of "Laura", a chat-bot created by Boston-based researcher Timothy Bickmore. Meanwhile, if the quit-smoking programme is a success, the team are planning to wheel out a raft of counsellors tailored to help with other problems including phobias and alcoholism.

Belt Up, But Not Too Tightly

Seat belts should be more sympathetic to the elderly according to a recent study. Ruth Welsh and her colleagues at Loughborough University in the UK and Australia's Monash University, found that people 65 and over, and especially women, were significantly more prone to serious chest injuries compared with younger indivduals. Most of the injuries were caused by seat belts tightening too much, suggesting that car manufacturers should install 'smarter' seat belts which tailor their behaviour to the user. This could well be about to happen because late last year a team at the UK's Cranfield University, working in collaboration with car manufacturers Nissan, produced an ultrasound finger scanner which can estimate bone strength. It can then use the data it collects to reprogramme a car's safety features including the firing of the air bag and how rapidly the seat-belt 'grabs' the wearer. According to Cranfield's Roger Hardy, "The system could be built into dashboard consoles, the driver's door or even, when miniaturised sufficiently, into the gear lever. It would need to be used each time the car's ignition was switched on, before the driver was able to move off."


- Going Nuclear

How should we solve the coming energy crisis?

Going Nuclear

Our world is living under the threat of climate change and we're running out of fossil fuels fast. So how should we solve the coming energy crisis? 

At the moment, the UK government is deciding whether we should build new nuclear power stations to cope with our rising energy demands.

But there are many complex issues involved - including the environmental, political, economic and scientific aspects.

To help make sense of it all, the Institute of Physics has asked three writers - including our own Dr Kat - to look into the issues surrounding nuclear power and new power stations.

Over the next ten weeks, the team will be detailing their investigations on a blog entitled Potential Energy.

You can check out their thoughts, and add to the debate yourself at www.potentialenergy.iop.org

Liquid nitrogen boiling at room temperature

Freezing Objects in Liquid Nitrogen

Derek - Hello there and welcome this time to Hills Road Sixth Form College. We've come here with some new Naked Scientists colleagues of ours who are new recruits to the show and are going to do some live experiments for us. I wonder if you could tell us who you are and what you do please?

Chris - I'm Chris Muirhead and I'm a lecturer at Birmingham University in the School of Physics and Astronomy.

Derek - Ok and we have got some seriously amazing experiments that Chris has set up for us and we're ready to do. We've also got some fantastic participants here from Hills Road Sixth Form College. Guys can you just tell us your names and what year you're in please?

Jemma - I'm Jemma Raven and I'm in year 12.

Will - William Brook, year 12.

Derek - So what we have here is a big pot of some stuff. It's in a cylindrical canister which is about two feet tall and ten inches across and Chris has actually got some pretty amazing experiments to do with this stuff. So Chris, what are you about to do?

Chris - Well I'm just about to take a piece of ordinary garden hose, which you can see is a really soft and flexible piece of material, and I'm going to lower it into this liquid and going to see what happens to it.

Derek - Ok then. Will, tell us what you see.

Will - Well it's all spurting out everywhere and frothing over. And it's coming out of the end of the tube, which is above the level of the liquid.

Derek - Ok, so we've dropped it in there. Now what Chris?

Chris - I'm going to take it out and now you're going to see what's happened to the properties of this material. What you can see here is that the material has gone completely hard and solid. Instead of being flexible, it's absolutely rigid. And just to show you how rigid it is, I'm going to take it and I'm going to smack it on the floor.

Derek - Ok, Jemma, tell me what happened.

Jemma - It's in lots of little pieces on the floor.

Derek - So Chris basically smashed that thing on the floor and we are now pretty much treading on tiny pieces of shattered garden hose. So that went from being bendy to being very very solid. We're going to find out what was going on there. So Chris, please give us a bit of an explanation.

Chris - Before I tell you exactly what happened to the garden hose, perhaps we ought to spend a few minutes thinking about what we as scientists think about as a low temperature. What you probably mean by low temperatures is what happens when you open the door of your fridge and it's cold in there. That would have a temperature of perhaps a few degrees above freezing point. From our point of view, that is really warm and far too warm to enable us to do some of the experiments that we're going to show you today.

Derek - So from your point of view you mean as a scientist working with this sort of stuff.

Chris - Yes, that's very warm stuff as far as we're concerned. If you go out into a really cold day in the Antarctic, perhaps I could ask our friends here from the college what you think would be a really cold day in the Antarctic.

Derek - So what do you think is the coldest the Antarctic ever gets? Will, what do you say?

Will - About minus 100 degrees?

Chris - Not quite so low as that. About minus 89 degrees, and that's the coldest temperature that was ever recorded to have occurred naturally on Earth. If you go down now to 196 Celsius, the air around you will turn into a liquid. Now we can't quite show youl iquid air, but what we've got in this bucket is liquid nitrogen.

Derek - You've mentioned liquid nitrogen there Chris. I wonder if these guys have heard of liquid nitrogen at all. Jemma, have you ever heard of that stuff?

Jemma - Yes, we had a few demonstrations at school.

Derek - Ah so they've already seen it. But the question is then, why does it work? Why is it a liquid?

Chris - It's a liquid because when things are hot, the thermal energy causes them to move around very fast and that prevents them living close to each other which they have to do in a liquid. As you cool a gas down, the atoms move less and less rapidly, and eventually the attractive forces between the atoms hold them together in the form of a liquid. If you go even colder, they turn into a solid.

Derek - So I suppose the usual example for this would be water. When we have it at room temperature it's a liquid; if we take it very cold it becomes a solid which is ice; and then if we heat it up to 100 degrees it becomes steam which is the gas.

Chris - That's absolutely correct. And what happens with the liquid nitrogen is it turns from a gas into a liquid at this temperature of minus 196 Celsius.

Derek - Ok then. We took a piece of rubber tubing and put that into the very cold liquid and then we were able to smash it. It became brittle didn't it. Why did that happen?

Chris - Well for a rather similar reason that a gas turns into a liquid. Temperature is a physicist's rather fancy way of saying jiggling around. When you cool things down, they jiggle around less and less. When you take a piece of rubber and you bend it, it's important that the atoms can move past each other, because when you bend it you're changing its shape and the atoms have to move. If you cool it down, the atoms become locked into position so they can't move past each other and the material becomes very brittle.

Derek - Ok so you've put a piece of rubber hosing into liquid nitrogen and the tubing clearly didn't enjoy it. What would happen if we put living things into this kind of temperature?

Chris - Over here we've got some parsley, and what I'm going to do is take this parsley and I'm going to lower it into the liquid nitrogen.

Derek - Ok well before we do that, Will and Jemma, we've seen what the liquid nitrogen will do to the rubber tubing. What do you think will happen to the parsley?

Will - I think the parsley will snap because it will freeze and the water won't be able to slip past each other and so it won't be able to bend at all and the force will just break it apart.

Derek - Jemma? Any thoughts?

Jemma - Just frozen parsley.

Derek - Indeed. So let's stick it in.

Chris - Ok here we go. As far as the liquid nitrogen is concerned I've just stuck something red hot in there. It's like putting a red hot poker into some water and it causes it to boil. The parsley is now very cold, and we take it out and there you are. Parsley all ready to put into your favourite dish.

Derek - So what Chris has done there is to immediately rub it around in his hands and it's immediately just gone into chopped bits, which I must say that if I'm cooking with parsley would take quite a while. So that's quite a good culinary application of liquid nitrogen there.

Chris - Absolutely correct. What you have to be a little bit careful about is not to stick your fingers in there. If you stick your fingers into liquid nitrogen then your fingers will go solid like the garden hose did and when you warm them up again they'll go soft again just like the garden hose did. Unfortunately they'll be permanently damaged because what you will have is severe frostbite. A few days later they'll start to go black and you'll lose your fingers.

Derek - Ok then, thank you very much for that experiment. I'd just like ot quickly ask Will and Jemma what they thought about it.

Jemma - Very interesting and very good to see.

Derek - And Will, what about you? Do you think that liquid nitrogen might have a good application in the kitchen maybe?

Will - Well I was shocked at how smashable things were when they are at very low temperatures. And so you could chop up lots of different vegetables like that.

Derek - Yeah I think it could make life very easy in the kitchen. So there you go, a bit of kitchen science there in the end from us. Thank you very much to Chris who's come over from Birmingham University and to Will and Jemma from Hills Road Sixth Form College. That's all from us. We'll be back next week, as always, with some more kitchen science. So please do join us then. Until then, goodbye.

- Science Update - Theft amongst birds and Caffine in Camels

The Naked Scientists spoke to Chelsea Wald and Bob Hirshon

Science Update - Theft amongst birds and Caffine in Camels
with Chelsea Wald and Bob Hirshon

Phil - Now it's time to hop over the ocean for this week's science update, where Bob Hirshon and Chelsea Wald will be looking at an anti-theft mechanism in scrub jays and how camel can help calculate the amount of caffeine in your coffee.

Bob - This week for the Naked Scientists since the topic is energy, we'll discuss a newly developed test for that chemical that many of us use as our personal fuel: caffeine. But first, Chelsea has some news of some research from your neck of the woods. It involves some very energetic birds that will go to great lengths to protect what's theirs.

Chelsea - Burglary is rampant among western scrub jays. That's why these small woodland birds hide their food. Now researchers at Cambridge University have found that they also keep close tabs on each other. Psychologist Nicola Clayton says that if a scrub jay hides his food when another bird is watching, he'll go back to check on it later. If the coast is clear, he'll move the move the food once. And if the same observer is still there, he'll move it several times to confuse the would-be thief. If a new bird is there, he won't move it at all.

Nicola - To do so they must not only recognise different individuals but they must remember who was watching at a particular time. So the idea is that they're keeping an eye on the competition.

Chelsea - Which for a bird is a surprisingly sophisticated sort of paranoia.

Bob - Thanks Chelsea. And now to caffeine. If you sometimes worry that that cup of decaff you got is really decaff, you'll be happy to learn that a handy caffeine detector for beverages may soon be on the way courtesy of a llama. Why a llama? Well along with camels, llamas are among the few species that make antibodies to caffeine that can withstand high temperatures. Protein chemist Daniel Crimmins and his colleagues at Washington University in St. Louis Missouri were able to use those antibodies to detect the caffeine in a hot cup of coffee.

Daniel - And then you no longer have to schlup around your camel or your llama to your favourite coffee house to do the measurement. We cloned the antibody sequence by standard molecular biology techniques so we can make as much as we needed to.

Bob - A llama named Very Senorita had the toughest antibodies, so they're using hers to develop a commercial product for home use.

Chelsea - Next week we'll be talking about one of our favourite topics: bacteria. We never tire of the amazing things they can do like make the world's strongest super glue or survive Mars-like conditions. Until then, I'm Chelsea Wald.

Bob - And I'm Bob Hirshon, for AAAS the Science Society.

- Lobsters With The Lurgy

The Naked Scientists spoke to Dr Donald Behringer, Old Dominion University in Norfolk, Virginia

Lobsters With The Lurgy
with Dr Donald Behringer, Old Dominion University in Norfolk, Virginia

Chris - If you're a Caribbean Spiny Lobster and you're ill, don't expect any sympathy. But, don't worry, it's all for the greater good of the population. A team working in the Florida Keys has been looking at a particular virus that infects the Spiny Lobster and has found that fellow lobsters, or conspecifics, that are not infected, try to avoid those that are. Here's Donald Behringer from Old Dominion University in Norfolk, Virginia.

Donald - In the first study we discovered a virus that infects lobsters, specifically Spiny Lobsters down in the Florida Keys, and it turns out to be the first virus discovered to infect any lobster in the world. And what we discovered beyond that is that it has some really interesting impacts in that the healthy lobsters are actually able to detect and avoid infected conspecifics before those infected conspecifics actually become infectious to other lobsters.

Chris - Do you know what the giveaway signs are of an infected lobster then?

Donald - It's not a rapidly progressing virus. In the beginning they really show no outward signs. It takes them anywhere between about 30 to 80 days to show outward signs and that's largely dependent on their size. It progresses much more rapidly in the smaller individuals. But once they do begin to show signs, the signs are that their blood turns a milky white colour; normally it's clear with a grey or an amber tint. And then, along with that, they start to become lethargic; they cease grooming, their movement rates slow down and eventually they don't move at all and then they pass away.

Chris - So it turns into a scruffy lobster, first of all, but what is it that their conspecifics are able to spot about them that you think gives away the fact that they've got something wrong with them?

Donald - Lobsters are very chemically sensitive so we theorise that it's some type of a chemical clue that they're either receiving or not receiving from the infected individuals. But it might be a culmination of visual and chemical clues and that's one of the things that we hope to investigate here in the next year or so.

Chris - So do you know roughly how many lobsters, if you just randomly sample the population, are actually carrying the agent?

Donald - From our field sampling - and we do this yearly. There is a certain suite of sites that we establish as permanent sites that we go back to, to get an idea on whether it's changing in these areas. We also do a larger sampling throughout the Florida Keys each year and the prevalence seems to stay in the range of about 5% to 8%. But those results are from actually looking at them visually and looking for the latter stages of infections. And then, when we actually have gone out and sub-sampled populations in various areas and analysed them using microscopic techniques, histology, it's slightly above that. But we were surprised. We thought when we did the histology that we'd find it much harder than that. But the histology might not be sensitive enough to pick up those really early stage infections.

Chris - Is it a threat to these lobsters or is it not actually making a major dent in the population?

Donald - That's troubling too. We often get the question of is this going to be the death knell for the lobster population. But one of the things we're not clear on is how long it's been in the population. What we do know is that the time that we've been aware of it conclusively and actually had an idea that it was a virus, the prevalence again hasn't changed dramatically. So that's one of the things we want to try and figure out. Hopefully if we can figure out regarding whether it's a chemical detection and if that chemical detection is something very specific to the virus, that might give us an indication of knowing whether these two things actually evolved together or not, the behaviour and this virus.

- Sugar-powered Fuel Cells

The Naked Scientists spoke to Professor Lynne Macaskie, University of Birmingham

Sugar-powered Fuel Cells
with Professor Lynne Macaskie, University of Birmingham

Chris - We've heard about the science and we all know where it ends up; that's in our cars. And it ultimately translates into a lot of carbon dioxide that we think is promoting a greenhouse effect which is warming our planet up and promoting climate change. Now one way we might be able to bypass this problem is to develop cleaner sources of energy. Someone who's here to talk to us about that is Lynne Macaskie from Birmingham University. Tell us about your work.

Lynne - We were looking at alternative ways of making energy using bacteria which are very small organisms found in the soil and found in water and found in loads of places. On eof the clever things that bacteria can do is that they can make hydrogen. You can make hydrogen from the petrochemicals industry but as we've just heard, the lifetime of that industry may be finite. So it's high time we started looking at other ways of making hydrogen as a potential fuel because when it's burned, it just leaves water.

Chris - So it's a lot cleaner.

Lynne - It's a lot cleaner and the water is clean. So if we also look to a potential water crisis through global warming, we have a way of making clean water as well.

Chris - Presumably, if we take water out of the ground and turn that into carbon dioxide, Nicky, that's not carbon neutral because you're taking away a stable source of carbon that's been locked away and releasing it into the air. Whereas what Lynne is suggesting is using energy that is already available from various sources and it's not liberating new carbon dioxide. Would you say that that was a fair comment?

Nicky - That's correct, but the oil industry is looking at ways of sequestering or burying the carbon dioxide that's produced during the burning of hydrocarbons as well.

Chris - So then how does your technique actually work?

Lynne - Well bacteria can eat sugars and for this we were looking at sugars that would otherwise go to waste and may be buried and end up back in the environment. This is an awful waste of sugar and a waste of energy. Since bacteria love to eat sugars, what we decided to do was to see if we could make them make hydrogen. Now when we eat, we breathe out and the bacteria do the same thing: they eat bacteria, breathe out and they breathe out hydrogen. In Birmingham we've actually got the Cadbury plant not very far away, so we had a little project with Cadbury's to see if we could take some of the waste from confectionery and feed it to bacteria and see if we could make the bacteria make hydrogen.

Chris - How much do they chuck away that you could potentially be using? What's the energy value going down the drain each day just because there's no way to use it at the moment?

Lynne - It's very high in sugar and if it was reusable then I'm sure they'd reuse it. I don't have the figures to hand as to how much is actually thrown away. It might actually be recycled into animal feed; I don't know that information. But to be able to reuse the waste on site may have the potential to generate energy and offset some of their own fuel demands, while at the same time reduce the pressure on the National Grid.

Chris - How much energy can you generate and how do you actually do it? Talk us through the nuts and bolts of how bacteria ultimately culminate in the production of energy.

Lynne - It's a bit too premature to say how much could actually be done in the future. We can calculate that to run a house at a base level without cookers or heating, you could make a drum of perhaps one or two cubic metres of bacteria, so that's the sort of level one would be looking at. The way they do this is they make the hydrogen, and you pass the hydrogen into a machine called a fuel cell. What the fuel cell does is it splits the hydrogen and the electrons go off into the circuit and run a load, for example, an electric fan. Then at the other end, the electrons recombine with the protons from the hydrogen and the oxygen from the air to make water. So actually it's possible to couple the bacterial vats into a fuel cell and couple that into an electrical device.

Chris - How much space would this take up? Is it feasible at the moment? The beauty of what Nicky is talking about, oil, is the energy locked away in a tiny amount of oil is huge. In order to produce a viable amount of hydrogen how many barrels of bacteria would you need?

Lynne - It's a bit too soon to say that. We did a basic calculation where we calculated that you could probably run the background energy demands of a house on something that was about the size of a fridge-freezer.

Phil - How much fuel do you need to put into something like that? How much chocolate or sugar would you need to run a household or something domestic?

Lynne - You're looking at quite a lot really. You're looking at bagfuls. So it's quite unlikely that the average house would generate that much sugar. I think at the moment that we'd be looking at factories that produce very concentrated wastes and lost of it. But the next stage of the work would be to look at domestic waste and to see if in an ideal world if one could recycle one's composting material into making hydrogen, which you could then use for the fuel supply of the house.

Chris - Do you have to genetically modify the bacteria to make them more efficient at doing this, or can you find these bugs living naturally in the environment?

Lynne - You can usually find these bugs living in the environment if you go looking for them. Obviously genetic engineering will help you to make better ones but it's probably best to go with what nature has provided. Sometimes you can make bacteria breed if you put them together and you end up with better strains by selective breeding rather than genetic modification.

Chris - And very briefly Lynne, what's the time scale on the roll out on this kind of thing. At the moment this is sitting in your laboratory. When could we expect, reasonably, to see the first commercial and viable uses of this technology?

Lynne - Well the technology is likely to be installed in individual companies within five or ten years. For the hydrogen economy to take off in a real way, I think we're realistically looking at 15 years, if not 20 years.

- Electro-kinetic Road Ramps

The Naked Scientists spoke to Peter Hughes, Director of Hughes Research Ltd.

Electro-kinetic Road Ramps
with Peter Hughes, Director of Hughes Research Ltd.

Chris - Someone who's got a very interesting development up his sleeve is Peter Hughes. Thank you for joining us on the programme. Can you tell us about your invention?

Peter - Yes, it's very straight-forward and simple invention. It consists of a number of articulating plates that fit in the road, and when a vehicle passes over them, it causes a mechanism to rotate that in turn rotates a generator that produces electricity.

Chris - How much electricity?

Peter - It depends upon the weight of traffic, the number of vehicles and their comparative weight, but we're talking in the order of between 5 kilowatt hours and anything up to 50 kilowatt hours.

Chris - Well that's more than enough to run a set of street lights isn't it?

Peter - Almost certainly yes. It would run several small houses or alternatively it would run a lengthy section of the highway.

Chris - Now the obvious thing here is that traffic isn't going to be running over this continuously, so how do you soak up the extra energy the cars produce in order to release it in a gentle fashion for street lighting and housing?

Peter - We charge storage batteries during the periods when we have very heavy traffic flow. When the traffic is light, we then use the storage battery facility to continue to power the lights.

Chris - What's the payback period on this? Obviously it's very easy to lump down a bit of concrete to create a speed control measure that everyone hates, and in fact we know that pollution goes up in the areas where these things are as people bounce over them and then accelerate. Your thing is obviously very complicated to plumb in and build, I presume. So how long does it have run for before it's paid for itself?

Peter - It's between three and three and a half years and thereafter your energy is absolutely free.

Chris - That sounds fantastic. So when is it going to be run out?

Peter - We're rolling them out at the moment. We have enquiries from all over the world, including a very large number from the United States and Canada, but many other countries too. We're starting to manufacture them as of now.

Chris - Have you got a contract from Cambridge yet as I think we need one!

Peter - Well hopefully that will come in due course.

Chris - So how much does each one cost to build?

Peter - We have a modularised system, so for example if you wan to power a set of traffic lights, then you need a quite small unit. Or you can power up to four traffic lights at a junction and there we're talking in the order of about £15 000. If you want to do far greater energy generation, then you can add modules on as you require them.

Chris - And what about maintenance and the service lifetime? Do they clap out after ten cars? Presumably not.

Peter - No, I think it's reasonable to say that we reckon that the life span of this device will be about ten years. It depends of course on the level of traffic and weather conditions and many other things. But we reckon about ten years because most of the components used in this device have been tested in other applications over many many years. They've shown themselves to have very long lives indeed.

Chris - Thanks Peter. That was Peter Hughes who's invented an electro-kinetic road ramp that we should see rolling out in the UK in the near future.

- OIL : From formation to Extraction

The Naked Scientists spoke to Dr Nicky White, Bullard Laboratories, University of Cambridge

OIL : From formation to Extraction
with Dr Nicky White, Bullard Laboratories, University of Cambridge

Chris - Now tell us a bit about the science of oil because it's something we all take for granted. We just go to the filling station and just fill up. How much oil is being burnt off every second around the world? Do you know?

Nicky - That's not a question that's easy to answer. What I can say is how much oil we use annually. We use 30 billion barrels of oil world wide.

Chris - And how much is that in a barrel?

Nicky - There are six barrels of oil in a cubic metre, so a cubic metre is a large box; a metre by a metre by a metre.

Chris - So how much space underground is this that was oil and is now empty?

Nicky - Well that's a complicated question. The best way to answer it is to look att he North Sea. Most people probably know that the North Sea is an important oil province. If you go out into the middle of the North Sea there's about 200 metres of water and underneath that water there are about ten or fifteen kilometres of layered sediment; so dirt basically. If you go down about four kilometres into that dirt, what you find is oil. But it doesn't occur in caverns, it occurs within the pore spaces of sandy rock. A sandy rock would have a porosity of about 30% or so, which isn't very much. Those pore spaces would be filled with oil.

Chris - So how do we know where to go looking?

Nicky - Yes that's the hard bit for the oil industry. The easy picking were all on shore. The main way in which they were found was through oil seeps which occur at the surface. So that makes it very easy indeed. So the classic oil fields in places like Texas, Louisiana and indeed the Middle East were all found in that sort of easy way. And you can drill relatively cheap holes down to the oil.

Chris - And they must have some sort of cap over the top of where the oil is, to stop the oil floating up the surface, in other words trapping it.

Nicky - Yes. There are several ingredients to all this. You need something to make the oil in the first place but you certainly need something to trap it at depth. These sandy horizons which have the oil trapped in their pores usually have an impermeable layer, like an area of limestone or salt for example on top, which stops the oil coming out.

Chris - So what's the difference between oil and coal? They contain many of the same types of chemicals don't they?

Nicky - They do indeed. They're both basically decayed organic matter. So if you decay organic matter in the absence of oxygen, you'll get things like coal and oil. So why are they different? The main difference is that oil is formed from decaying algal matter primarily. This is rather surprising I suppose. Whereas coal is mostly due to the decay of things like trees and organic matter.

Chris - Why should there be that distinction? Is it obvious?

Nicky - The main reason is that when you decay organic matter, depending on whether it's trees, algae or indeed sheep, it'll have a different composition in an organic chemical sense. So when you cook it, which is the primary thing you need to do to release oil or gas, what you produce in the cooking depends on the ingredient you start with to some degree.

Chris - So we've got to the stage where we've produced the oil. I assume that most oil in this world is millions of millions of years old.

Nicky - Yes, so if we take the North Sea, the oil there was made between 60 and 30 million years ago.

Chris - So the end of the dinosaurs to fairly recently really.

Nicky - Yes.

Chris - And why is that the cut off? Was there not enough biomass, plants and living things on Earth to make things like that?

Nicky - It's a little bit of both, but it's primarily because of the cooking time. The layer in the North Sea which is the best source rock, which is the layer of organic matter, is a layer that occurred in Jurassic times. That's about 150 million years ago. That layer got progressively buried by later sediment pouring in on top of it, which made in sink down. As it did so it cooked up. It took all that time to cook and was basically ready between 60 and 30 million years ago.

Chris - So we have a porous sponge of rock which has this stuff stuck in it. How do you get it out? Most of us have this idea that someone sticks a drill bit down and then you see the old Wild West picture where loads of stuff comes gushing out the top of your derrick. How is it achieved?

Nicky - In places like Texas in the old days that was all you had to do, and people drilled more or less at random until they found something, which can be expensive even on shore. The trouble these days is that most oil is found off shore and it's rather hard to find. Drilling holes off shore is extremely expensive. So if you drill a hole in three kilometres of water off West Africa you could pay up to 60 million dollars per hole, so you kind of need to know it's there before you drill the hole. So what do you do? To find out what's down there you have to drill a hole. Well the major technique that is used by the oil industry to locate favourable structures and indeed favourable rocks is called echo-sounding. Ina way we think of it as a downward-looking Hubble, so it's a way in which we can produce spectacular 3D images of the sub-surface from the sea bed or the land surface down to about twenty kilometres depth. We can see that hidden world in fully three dimensions and identify structures. So it's still a risky business, but you can basically reduce the risk quite a bit by collecting all this echo-sounding data first.

Chris - So say you have ticks in all the right boxes and you drill a hole, how do you actually get the stuff out?

Nicky - The oil that occurs in the pore spaces of the buried sandy rocks is under quite a lot of pressure, so in fact it pretty much comes out of its own accord, at least to start with. In the lifetime of producing an oil field, that pressure starts to drop. One of the things you then need to do is encourage the pressure back up. The main way in which you can do that is put explosives down the bore hoels and break up the rocks, which encourages better flow. Or you can drill holes which are called water injectors. You drill extra holes around the side of the oil field and you pump down seawater. It's like pushing oil on a pan-full of water. You can push the oil towards the producing gaps.

Chris - So how much oil in the reserve can we actually get at? When you say that this field is spent, roughly how mush oil is actually left in there?

Nicky - Unfortunately most of the oil is left behind. We can produce between 30 and 40% economically.

Chris - That's terrible.

Nicky - It's appalling. We're getting a bit better at inching those numbers up but it's a great technological feat.

Chris - So how much oil is left in the world? Because when I was at school just over ten years ago, people were saying that by the millennium we'll be really worried about how much oil there is. Now people are saying figures like 300 years of coal, 50 years at least of oil. How much is actually out there still?

Nicky - There's a lot of doom and gloom. The pessimistic line is that if you take liquid hydrocarbons, so oil only and not coal or tar sands or gas, liquid hydrocarbon production will peak at about 30 billion barrels a year in something like 10 to 15 years time and then decrease rapidly over the next 100 years. However there are optimists who believe that even that scenario is too pessimistic.

- How do some animals incorporate the stinging cells of other species into their own defences?

This morning I listened to the May 14th broadcast. One of the discussions was about the stinging cells (nematocysts) of jelly fish. Someo...

How do some animals incorporate the stinging cells of other species into their own defences?

Sea anemones, which also possess nematocysts, are the primary food of Nudibranchs (sea slugs) in my geographic area. The nudibranchs will feed on the anemone and some of the nematocysts survive unfired to be transported to Cerata. The cerata are similar to the tentacles of the anemone and lie on the dorsal surface of the slug. I used to examine these cerata and the incorporated nematocysts using an electron microscope many years ago. It's really quite fascinating to follow the progression from the digestive tract into the cerata. I don't have a clue how they accomplish this. Anyway, if anyone is interested in more information, the two species I know of are called Aeolidia papillosa and Coryphella rufibranchialis. You should be able to find some info about these creatures on the web.

- When a rocket takes off, what's it pushing against?

I understand the basic idea that for every action there is a reaction, which is why I can walk across the ground. But when a rocket is in...

When a rocket takes off, what's it pushing against?

A rocket works by throwing something out of the back so the rocket goes forward. So the action and reaction are actually inside the spacecraft. The fuel pushes outwards and pushes the spacecraft forwards. So in space what we actually use is a fuel called hydrazine and we burn this out of the back of the spacecraft through little thrusters. This is how we manoeuvre the spacecraft and push it around. There are some other ways we do it as well. We're looking at things such as ion drives. That takes individual atoms, ionises them so that they've got an electric charge, and then uses electric fields to throw these gas molecules out f the back of the spacecraft. We've used that sort of application to send a spacecraft to the moon. It took a long time to get there but was moving very fast by the time it got there. So that could be a possibility for long range spacecraft. The bottom line is that if you want to slow something down you have to apply force in the opposite direction to which you're travelling. So you have these retro-rockets which fire against the direction in which you're travelling. So the rocket has a certain momentum moving in one direction and you want to give it momentum in the other direction so they cancel each other out. So the rocket is pushing against itself.

- How much extra fuel do you use by flying a Football World Cup Union Jack flag on your car?

Please can you calculate how much extra fuel will be burned by a motorist during the current World Cup campaign as a result of flying fla...

How much extra fuel do you use by flying a Football World Cup Union Jack flag on your car?

No comment! They scare horses as well apparently!

- What happens to the cavities left after oil and gas extraction?

What happens to the great hollows that we're leaving below the sea beds when you extract all this oil and gas?

What happens to the cavities left after oil and gas extraction?

First of all, when the oil is extracted, it's coming out of the pores in the sandy rocks and in most places the framework of that rock remains reasonably intact. You do in the long term get some subsidence. Perhaps the most notorious example is in the Netherlands where they don't really want anymore sinking but there's a very large gas field in the middle of the Netherlands called the Groningen gas field. There's a lot of subsidence associated with that. There's also a lot of subsidence associated with coal fields but that's a little bit different because you're excavating underground. When the oil comes out it's seeping out of the pores, so you're not actually making a big hole down there.

- Why are solar panels only 16% efficient?

I've been following the progress of solar panels and hear that they're only about 16% efficient. What's the score with this?

Why are solar panels only 16% efficient?

They are only about 15% efficient. The best ones yet are in the order of about 30%. There's new research going into this now where people are working out a way of making them spit out far more electrons, or current, for one photon or particle of light. But it's certainly experimental at the moment and the thing is that they're so expensive to build and environmentally costly to build that it's not like Peter's ramp. It's actually costing you far more to build them and run them at the moment than they actually ever pay back, so it's just not energy efficient.


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