Fuels of the Future

This week, from iPod to iRod as a man's taste for music turns him into a human lightning conductor, why penguins are picky eaters, and better biopsies - why doctors are...
15 July 2007
Presented by Chris Smith, Helen Scales


This week, from iPod to iRod as a man's taste for music turns him into a human lightning conductor, why penguins are picky eaters, and better biopsies - why doctors are attracted to a new magnetic cancer detection system. Also a fuel made from fructose that packs a punch like petrol, we find out how to make hydrogen on demand using aluminium, and grow your own gas - do we have enough land to grow our energy in future? Plus, in Kitchen Science, we turn vegetable oil into biodiesel and ask a white van man to test it...

In this episode


A paper in this week's New England Journal describes a man admitted to hospital with a rather strange pattern of skin injuries including ruptured eardrums, a broken jaw and burns to his chest, neck and the insides both ears!

Doctors discovered that the 37 year old had been out jogging in a thunderstorm, whilst listening to his iPod. Lightning had hit a nearby tree and jumped onto the man as he ran past, a phenomenon known as side flash. This triggered muscle contractions that threw him eight feet. The man's burns ran in two lines up his neck, across the sides of his face and entered his ears. They corresponded to the position of his headphones when the accident happened. Although Eric Heffernan and his colleagues who described the case are at pains to emphasise that iPods aren't a specific risk factor for being hit by lightning, in this instance the combination of sweat, metal wires and headphones channeled the electricity into the patient's head. The sudden heating effect caused by the dischage into the ears caused rapid expansion of the air in the auditory canal, bursting the patient's ear-drums.

It's not known what he was listening to on the iPod at the time the bolt hit, but my money's on Pink Floyd's Delicate Sound of Thunder...

Penguins change their minds on their favourite food

Penguins living in the Antarctic have changed their minds about their favourite food, a change of diet that could have been triggered by the hunting of whales and seals over the last two hundred years.

Now, you might think that an obvious way to find out what a penguin has been eating would be to look inside its stomach but that's only useful for penguins that are still alive.

But luckily, Penguins live up to that old cliché "you are what you eat" because they leave behind traces of what they ate in their eggshells, feathers and bones.

Steven Emslie and William Patterson, from the United States, set about investigating the diets of Adelie Penguins from the ANtartic continent by collecting eggs and feather samples from modern day penguins and also the fossilised remains of penguins that lived 38 thousands years ago.

What they were looking for was the balance of two chemical compounds or isotopes inside the penguin remains known as carbon 13 and nitrogen 15 - both of them are naturally occurring, but they are found in different ratios in different types of animals.

So, for example in fish, the ratio of c13 to n15 tends to be higher than in crustaceans like krill, those shrimp like creatures that live in cold oceans.

By measuring the ratio of C13 to N15 the researchers could predict what the penguins had been eating.

And it turns out all the ancient fossil penguins had isotope ratios that hinted at a diet composed mainly of fish, but that in all the modern penguins the isotope ratios were much lower indicating a shift towards eating Krill.

And that fits neatly with what has been going on the Southern Ocean. Since the 19th century seal hunters and whalers have been doing a very effective job at getting rid of lots of the seals and whales that used to live in the seas around Antarctica and those are the creatures that used to feed on krill.

But now that the numbers of these big krill-eating mammals has gone right down, the number of krill, as we might predict, has gone up.

And it seems that penguins have begun to take advantage of these krill, possibly partly because they are so abundant but also because their other food, the fish, have been declining, with new fisheries opening up in the southern ocean.

And the bad news is that there are plans now being made for people to start fishing the abundant krill around the Antarctic so they can be made into fish meal to feed the fish we grow in farms to eat ourselves. And the chances are that we would do a very good job at getting rid of all those krill as well, which could endanger the penguins.

Researchers confirm the existence of water on an extrasolar planet

For the first time researchers have been able to say with certainty that there is water on a distant planet.

Writing in this week's Nature, UCL's Giovanna Tinetti and her colleagues used NASA's Spitzer Space Telescope to study a "hot-Jupiter" orbiting a star 60 light years away. Like our own Jupiter the planet's a gas giant, but unlike our solar system it sits very close to the parent star, completing an orbit in just 2.2 days. The team were able to watch as the planet eclipsed the star on each orbit and look for the infrared fingerprint of water in the starlight passing through the planet's outer atmosphere. "We can now say with some security that the water signal is definitely there", says Giovanna Tinetti.

But it's unlikely that the planet will become a holiday destination any time soon. It's so close to the parent star that the sunlit side is a sizzling 1200 degrees celsius and even the dark side is a roasting 800 degrees C. As a result it's too inhospitable for life, but, as Tinetti points out, "our discovery shows that water might be more common out there than previously thought. Our method can be used in the future to study more 'life-friendly' environments."

Planet HD189733b also made headlines earlier this year when scientists were able to forecast its weather.

Good news for lovers of muck and magic.

There was good news this week for lovers of muck and magic, because it seems that organic farming could be capable of producing enough food to feed the world.

That's according to a study from team of researchers led by Ivette Perfecto from the University of Michigan in the United States. They've pulled together a huge amount of data on farm productivity from the United Nations Food and Agricultural Organisation and their findings fly in the face of the widely held belief that organic farming won't be a global solution to feeding the world because it produces less food per hectare than conventional intensive farming techniques.

The team showed that in developed countries, organic farms can produce 92% of the food that conventional farms can generate, while in the developing world the picture looks even better - in the poorer parts of the world organic farms can actually do much better than normal farms, producing up to 80% more food. The reason for this is that farmers in developing countries can rarely afford to buy all the fertilisers and pesticides needed for conventional farming, but they can very cheaply produce their own organic fertilisers.

Organic farming and the use of fewer man-made chemicals is thought to have really important benefits to both the environment and human health, and so it's really good news that potentially, if organic farming at a global level is a viable option for future food production.

At the moment, world wide farms produce an average of over two thousand 700 calories per person per day. And this latest study has estimated that a global organic farming system could produce between two thousand 600 and over four thousand calories per person per day - which is more than enough to provide our daily requirements.

But of course one of the big problems we still have to face isn't really how much food the world can generate as a whole, but where the food is being produced. While we in the west have an embarrassment of food, there are still millions of people going hungry every day. But it could be that small organic farms could start producing much needed food in developing countries.

Attractive way to diagnose cancer

Researchers at the University of New Mexico and Albuquerque company Senior Scientific are testing a new breed of iron oxide-based magnetic nanoparticles that are encased in a biocompatible coating. The coating is "conjugated" with antibodies that can recognise specific cancer cells. This causes the nanoparticles to stick to the cancer cells, magnetising them. Then, during a biopsy procedure, a magnetic field can be applied to the needle, pulling the magnetic cancer cells onto the needle. Tests in the dish showed that large numbers of cells could be picked up in this way in just a few minutes. The technique may help to reduce the rate of false negative biopsies where samples fail to pick up rare cancer cells in some patients. The researchers suggest that it may prove helpful in leukaemias, breast, prostate and ovarian tumours. Other doctors commenting on the approach has also suggested that it might help to pick up signs of "silent" cancer spread into an organ previously believed to be free of disease.

Bath University PhD Student Chris Chuck with a fresh batch of bio diesel, made from vegetable oil

00:12 - Kitchen Science - Making Fuel from Vegetable Oil

For kitchen science, we sent Azi to find out how to make biodiesel from vegetable oil, and to prove that it really works in an engine...

Kitchen Science - Making Fuel from Vegetable Oil
with Prof. Matthew Davidson, Prof. Gary Hallway & Chris Chuck, University of Bath

Azi - Hello, welcome to Kitchen Science. This week, I've come to the historic city of Bath and I', actually standing at the university of Bath's Chemistry Department, I'm joined by Professor [Matthew] Davidson and also Christopher Chuck who is a PhD student here. The question I've come to you guys with, and I'm really hoping you can help me out here, is can you run your car on cooking vegetable oil?

Matthew - That's an interesting question as to whether you can run your car on vegetable oil, what's chemically called a triglyceride, a molecule with three long fatty arms on it. What happens is they all just get entangled together, and that means it has a very high melting point. The two most important problems are; firstly the stuff would freeze in your tank, so on a slightly cold morning you would have a solid mess and the second problem is that it simply doesn't burn very well.

Azi - Okay, so what's the solution?

Matthew - Well the solution is actually quite a simple chemical process, and I can show you exactly how we do it. Before we do, I want you to put on some goggles, just to make sure we're safe.

Azi - Okay, I've got my goggles on.

Matthew - Right, well what we're going to do is were just going to take some vegetable oil that we bought at the supermarket, and we're going to take this mixture here, which is methanol and sodium hydroxide. We're just going to mix it with vegetable oil, you can see that the vegetable oil is stirring away with a stirrer in it, it's heated up to about 60 or 70 degrees centigrade.

Azi - Okay, so you've got the vegetable oil in a flask, and you're putting sodium hydroxide which is mixed with methanol, in the measuring cylinder and you're going to tip it in...

Matthew - Yeah, we need to wait about half an hour and what we will see is the separate components; the biodiesel will separate out from the by-product which is called glycerol, which is the other part of the fatty molecule that we started off with.

Azi - So what's the chemical process that is happening inside that flask?Making Bio Diesel at Bath University

Matthew - Well the chemical process is something called transesterification, which is a bit of a complicated term for simply just changing the end of the long fatty molecule. So instead of just having 3 of the fatty molecules attached to one end, a bit like a piano stool with three legs, we're changing the end, just capping off the fatty molecule with methanol. That give us individual fatty molecules, and that's what is actually called biodiesel, that we could use in an engine; and another molecule called glycerol, which is just a waste product of the biodiesel process.

Azi - Well that sounds incredibly straightforward to me, is this something that you could perhaps do to any old oil?

Matthew - Well, yes, it is straightforward, but of course nothing is quite that simple. I'm going to hand you over to Chris now; he's going to show you why it can't work on just any old vegetable oil.

Chris - Yeah, that's right, you have to use absolutely pure, virgin vegetable oil. If you use waste oils, the kind of oils you've cooked your chips in and things, because you've heated it up to high temperatures with food in you might have bits of chips, bits of organic matter and water. But most importantly, you'll have free fatty acids which are the acid versions of those 'arms' [or stool legs]. As soon as the sodium catalyst comes in contact with those free fatty acid arms, it just makes soap, and no biodiesel whatsoever.

Azi - And you can't really run a car on soap, can you?

Chris - No, you can't run your car on soap! There are at least three of four different purification steps that you have to do first to get your waste oil ready to make biodiesel from, which is very expensive to do.

Azi - Alright, well we've got half an hour to wait before our vegetable oil is turned into biodiesel, so we will be back later on in the programme to show you what happens! Back to you guys...

[Half an hour later...]

Azi - Hello welcome back to kitchen science, I'm still at the Chemistry department at the University of Bath, with Chris and Matt and we have biodiesel being made in the fume hood here. The vegetable oil looks really clear, and it's swirling around in the little flask. Chris, what's going on?

Chris - Well, the vegetable oil has completely changed to biodiesel. We're just going to work that out by pouring it into a conical flask and pouring water on top. That water will take away the glycerol, take away an excess methanol, and just leave us with our biodiesel on top, like if you poured oil into water.

Azi - Ok, so you just poured it into the flask, and here goes some water.

Chris - So we can tap off the biodiesel from the top.

Azi - Oh, right, well we've got our biodiesel, we are now going to run over to the engineering department and test it out!


Azi - Okay, so we're now navigating the depths of the engineering department, and we're about to test our biofuel...

Gary - My name is a Gary Hallway, professor of auto-engineering here in the department of mechanical engineering at the University of Bath.

Azi - You've got this huge white van in this lab...

Gary - What we have here is a vehicle research laboratory.

Azi - We've brought some biodiesel with us, so what are we going to do now.

Gary - Well, what we have here is pure biodiesel, 100%, but unfortunately the motor manufacturers in Europe will only guarantee the vehicle if it's got a B5 blend. That means 5% of the fuel will be biodiesel, and 95% will be ordinary forecourt diesel. So we're going to run the biodiesel in a B5 blend through the vehicle and see how it reacts.


Gary - Right, we're going to start the test now. What's happening now is the driver is driving the vehicle on a rolling road, so the wheels are going round, but the vehicle is not going anywhere because it's strapped down.

Azi - That looks like the car is running in the gym.

Gary - That's exactly what it is, it's just like if you were on a running machine in a gym, you run on a conveyor belt. On this particular case, we have a roller going round so the wheels are turning the roller and the roller is absorbing the load. We're measuring emissions, that's oxides of nitrogen, carbon monoxide, CO2and unburned hydrocarbons. All together we're measuring somewhere in the region of about 50 independent signals from the vehicle. What we'll do now is we'll go up into the control room and we'll be able to see real time comparing what's happening with this B5 blend, and what we did previously when it was just 100% forecourt diesel.


Azi - Alright so we're just off to the control room now... Loads of computers in this room. Alright, so what did we get?

Gary - Well the first thing I'm going to do is to look at the vehicle performance. We can see here on the screen that there are no adverse effects on performance from using the actual biodiesel blend. So the next thing we're going to have a look at is the fuel consumption. We can see that the fuel consumption is about the same, there's a little bit of discrepancy in favour of the 100% forecourt diesel, but then again if we now look at the emissions we can see that the engine does appear to be running cleaner. That's because of the clean properties of the biodiesel itself due to the fact that it does contain an amount of oxygen which helps to improve the cleanliness of the burn in the combustion chamber. So all in all, we've got no adverse effects on performance, fuel consumption is about the same and the emissions are fractionally improved.

Azi - But there doesn't seem to be much difference between them, so where is the advantage of using this 5% blend?

Gary - Well the biodiesel it's self has come from a renewable source, so you could actually say that, taking everything into account, the cultivation of the plants, turning the crops into oil and then turning the oil into a fuel, that 5% of it is approaching carbon neutrality.

Azi - Okay folks, so there you go; 5% biodiesel in your normal diesel is a little better for the environment and yes, you can make fuel out of vegetable oil.

00:16 - Science Update - Peppers and Pacemakers

This week, Chelsea finds evidence that Mexican food may not have changed much in hundreds of years, while Bob explores a way to extract energy from vibrations

Science Update - Peppers and Pacemakers
with Chelsea Wald and Bob Hirshon, AAAS

Bob - This week for The Naked Scientists, I'm going to talk about a possible source of energy that has scientists all abuzz. But first, Chelsea's going to talk about the food that fueled one culture of the past.

Chelsea - If you could travel back in time to the Mexico of a thousand years ago, the food would probably have a familiar kick to it. This according to archaeo-botanist Linda Perry of the Smithsonian's Museum of Natural History. She and her colleagues discovered well-preserved scraps of domesticated chili peppers in an ancient Mexican shelter cave. The peppers date back five to fifteen hundred years. Perry was struck by the variety: ten different kinds of peppers in all, including seven in a single location.

Linda Perry (National Museum of Natural History): Because you're not going to be growing seven different kinds of peppers if you're not making some really interesting food.

Chelsea -   What's more, she says the peppers appear to have been used in both fresh and dried forms - providing a broad spectrum of spices that could fuel dishes similar to today's Mexican specialties.

Bob -   Thanks, Chelsea. OK, cue the music!

Forty years ago, good vibrations were giving the Beach Boys excitations. Now, Steve Beeby of the University of Southampton in England is using vibrations to generate real electricity. He's developed devices as small as a sugar cube that you stick on any vibrating surface. The vibrations jiggle a few strategically placed magnets, which surround a copper coil.

Steve Beeby (University of Southampton): So the coil's stationary and the magnets are moving. And that way you build up an electromotive force in the coil, which is basically a voltage.

Bob -   It's a low voltage, but Beeby says it's enough to run small wireless sensors that monitor the structural integrity of machines and bridges. And in theory, it could even power a battery-free pacemaker just from the pulse of a patient's heartbeat.

Chelsea -   Thanks, Bob. We'll be back next time to talk about some surprising things some bugs and plants do to protect their families. Until then, I'm Chelsea Wald...

Bob -   ...and I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists!

girl yawning whilst seated

Why do tears come to my eyes when I yawn?

When people yawn, they tend to tightly shut their eyes, and this does two things. First, it squeezes the lacrimal duct, causing more tears to flow into the eye. Secondly, it squashes closed the tear ducts that drain the tear film from the surface of the eye. As a result, there are more tears in the eye and nowhere for them to go. So, when your yawn ends and you open your eyes again, they are watery...

What throws people when hit by lightning?

Like charges repel and opposite charges attract. So when there's a concentration of negative charge in a cloud, such as just before a lightning strike, negative charges in the ground are repelled and move away, leaving a positively charged ground. When these charges attract each other enough, the lightning overcomes the natural resistance of the air and discharges as a fine thread of lightning, usually only about 1 cm across.

People are thrown around when struck by lightning because of their own muscles, in a process called opisthotonus - sudden catastrophic muscle contraction. When the electricity runs through the body, all of your muscles contract at once. The strongest muscles in the body are the ones which hold you upright, so you are thrown off the ground.

Can you harness the electricity in lightning?

There are 2000 thunderstorms going on at any one time around the earth, this equates to about 100 strikes every second. The average lightning strike unleashes the same energy as about a tonne of TNT. This could be about 1 billion Joules of energy - if you consider a 100W lightbulb in comparison:

A 100 W lightbulb uses 100 J of energy every second, which is 360,000 J per hour, or about 9 million J per day. This means that with the energy from 1 lightning bolt could light just 1 100 W lightbulb for 100 days.

Which is the best way to boil water for a cup of tea?

There are many answers depending on what you mean by better for a cup of tea! But we at the Naked Scientists think that the microwave method might be quite dangerous.

Microwaves ovens emit microwaves, and these form a standing wave inside the oven. This means that certain areas heat up faster than others. This can superheat pockets of water to hundreds of degrees, as the pockets are held in by the surrounding water. When you remove the water form the microwave and stir, these pockets can suddenly expand, and this could result in showering you with boiling water.

Why do I want to cough when cleaning my ears?

There is a cough-ear reflex, but only 2.3% of the population experience it.

There's something called Arnold's nerve, part of the vagus nerve, which supplies the head and neck.

It also supplies the back and lower floor of the external auditory canal, which is the tube towards your inner ear.

If stimulated, this nerve can provoke a coughing reflex.

Although 2.3% of people experience this in one ear, only 0.6% get it in both!

A fuel gauge for a car

00:29 - Making hydrogen on the move

Biodiesel is one option for powering cars of the future, but another fuel we could use is hydrogen. This has the benefit of producing only water when it burns, but can be expensive to...

Making hydrogen on the move
with Jerry Woodall, Purdue University

Biodiesel is one option for powering cars of the future, but another fuel we could use is hydrogen. This has the benefit of producing only water when it burns, but can be expensive to extract and store. We've got Jerry Woodall on the line now to tell us about a simple way he's found to extract hydrogen from water...

Jerry - We use aluminium as our high energy content material. Aluminium, like oil, has a very high energy content; the only difference is aluminium will form an oxide skin so you can't use it for that purpose, whereas oil has all these stable hydrogen-carbon bonds and just sits there in the Earth until you're ready to burn it.

Chris - Now when you say you can't use aluminium in that way, you're talking about using it exactly how?

Jerry - Well, if I want to take the aluminium and use it to split water into hydrogen and oxygen, and have the aluminium grab the oxygen, a piece of aluminium sitting on a shelf won't do it because it has a passive layer of oxide already on it. So we thought that if we have a piece of aluminium with no oxide on it, it will readily split water.

Chris - And so how do you propose to do that? You would have to go through quite a lot of chemical steps normally to strip that protective oxide off.

Jerry - That's correct. This idea of using aluminium has been around for a long time, there are no less than 26 patents in the literature since about 2001; mechanical scrapings, aluminium powder and all these sorts of things. They're ok, but they're not very practical. What I discovered is if I added the element gallium, which is a group 3 element on the periodic table, that gallium in the aluminium prevents the aluminium oxide from passivating it. So if you do that, and make an alloy, in chunks or particles or pellets, this material, when it comes into contact with water, will split the water. Liberating the hydrogen and forming aluminium oxide powder.

Chris - But you don't end up with the skin on the aluminium, the gallium seems to stop it somehow?

Jerry - That's how it does it.

Chris - Do you know how?

Jerry - The gallium prevents the passivating oxide from forming on solid aluminium.

Chris - Do you know how? And how did you discover it?

Jerry - Oh, yes. So the first experiment I did back in 1967 when I was still at IBM. It turns out I discovered this by having a liquid of gallium and aluminium, gallium melts just above room temperature. So I was working on a semiconductor material called, actually, gallium-aluminium-arsenide. What I discovered was that when I had these melts, which I used to grow the crystals from and was mostly gallium and aluminium, if I added water to that I was getting hydrogen coming off, in a big way - Boom Boom! So then, I sat down and figured it out; It turns out, if you're aluminium in a pool of gallium, there is no solid oxide protecting you from further reaction. A water molecule comes along, the aluminium sees it, and splits it into hydrogen and oxygen.

Chris - So how would you see this being used practically, in a car for example, and why would it be better than just having a cylinder of hydrogen sitting in the back of the car?

Jerry - Oh because its hydrogen on demand. Aluminium is safe by itself, the aluminium gallium allow is safe by itself. So I can drive around and if I had a collision, god forbid, nothing would happen.

Chris - So how would the engine get the hydrogen in the right amounts?

Jerry - Very simple, I would have a bunch of aluminium in my 'aluminium tank' if you will, and then I would feed water into it. I would feed it into a pool of gallium, and then add water, the hydrogen comes off and goes into your intake manifold, just like BMW uses.

Chris - How many, I don't suppose you could say miles to the gallon, but how far could you travel on how much aluminium? Is this viable?

Jerry - Okay, to drive a car the size of a US torus 350 miles you would need about 18 gallons of gasoline. I would need 320lb of aluminium to drive the same distance using an internal combustion engine.

Chris - So it's actually quite practical, this could be done.

Jerry - Yes, and it's economically practical right now also.

Chris - What about getting the aluminium back at the end? What are the waste products? How could you complete the loop and make sure it's clean?

Jerry - Right, this is very important that your readers and listeners understand this; you don't get this for free. We had all those dinosaurs, a long time ago, and we take them out of the ground for free as oil, and we can't grow them back again. Aluminium doesn't exist as pure aluminium, it exists as aluminium oxide, so once I've finished using the aluminium up to create my hydrogen, I have to get it back to aluminium again. Now, the major aluminium companies, the factories, take the aluminium oxide that they dig out of the ground, pass electricity through it to get it back to aluminium. You have to do that to get the fuel back again.

Chris - What about the gallium, can that be recycled?

Jerry - Yes, the gallium is totally inert, it's completely reusable. You can use it over and over again, it does not react, it's like a catalyst.

Chris - Brilliant, so to summarise you could envisage making these gallium-aluminium pellets, you put water onto them, react it to get the hydrogen. You get aluminium oxide and gallium back, you then clean that up and pass electricity through it in a power station, say a nuclear power station, or wind or tidal power station to make sure it's carbon neutral, so you've got clean energy, and this is a way in which you could power the planet.

Jerry - That's correct, it's very green. You need to point out to your listeners however, if you're not interested in making hydrogen, what I'm doing should not be of interest. People have asked me, 'if it takes energy to get aluminium back out of aluminium oxide, why not just use the electricity itself?' Well, you've got to get the electricity from someplace, maybe a coal-fired plant or something, that leaves a carbon footprint. So if you are willing to use hydrogen, which is very clean and green as you said earlier in the programme, if you are using a fuel cell or an internal combustion engine the reaction product is just plain old water. You can sniff it, it wont hurt you, you could use this in your house. So the point is this could be a very viable solution, there's enough aluminium and gallium on the planets surface to run a billion cars continuously.

00:36 - Sweet Fuel from Fructose

An alternative to growing crops to make biodiesel is to make use of existing biomass. James Dumesic spoke to Chris smith about a way of making petrol-like fuel from fructose.

Sweet Fuel from Fructose
with Jim Dumesic, Wisconsin-Madison

And now to a story that should appeal to any would-be green with a sweet tooth and that is because scientists have sussed out how to turn fructose into a fuel that can rival the power of petrol. Chris spoke to Jim Dumesic...

Jim - The basic idea that we had was to try to convert carbohydrates into liquid transportation fuel and to compare what we could make by chemical catalysis with what is currently made by fermentation that is ethanol.

Chris - So, what is actually wrong with ethanol then Jim? Why cannot we use that?

Jim - Ethanol has certain disadvantages as a fuel. It has a relatively low energy density. So, the energy per litre of ethanol is about 30% lower than that of standard petroleum, gasoline or diesel. Also, ethanol has a bit of a high volatility and it tends to boil off in hotter weather. So, an ideal fuel will have a little bit lower volatility than ethanol, and finally ethanol loves water and therefore, it tends to be hygroscopic leading to absorption of water into your gasoline, which is undesirable. So, we were looking for routes to make other fuels that would alleviate these potential problems that ethanol has.

Chris - And what did you come up with?

Jim - Well, we came up with this compound called dimethylfuran, DMF. So, if you start with a molecule of a sugar like glucose, well in our case fructose, it has six carbons and six oxygen. It turns out if you remove five out of the six oxygen you end up with this dimethylfuran and it actually has all of the desirable properties you would look for in a fuel that is, it has the energy density that is very similar to petroleum. It has a volatility that is a little bit lower than ethanol, which is good and it also is hydrophobic meaning it does not like water, which is the same as petroleum.

Chris - Now how easy is it to actually do this though? Do you actually get more energy out than you have to put in, in the synthesis?

Jim - Well, we have a two-step process. In the first step, we remove three oxygen by removing three water molecules from the sugar, which leads to a chemical intermediate called hydroxymethyl-furfural, HMF. That process does not theoretically require energy and then in the second step, we pass hydrogen over this HMF and remove two of the oxygen which gives us dimethylfuran, which has one oxygen. Now, we do this all in a solvent and at the end of the process we have to evaporate the solvent to make the fuel; however, the solvent we use is an organic solvent and compared to the production of ethanol by fermentation, where water is the solvent, the energy required to evaporate the organic solvent is about one-third of the energy required to evaporate the water. So, potentially this is an energetically favourable process for making the fuel.

Chris - And I guess that because there is so much in the way of raw materials such as sugars, which are chucked out by plants such as the sugar industry, the chocolate industry, there must be no shortage of raw materials from which you can make this stuff?

Jim - Well, that is the hope. If you look at biomass, over 75% of biomass are sugars. I do point out though that the major sugar in biomass, for example, lignocellulosic, which is the main form, is glucose. Our process works primarily with fructose so that there is a biological step involved in converting the glucose in the fructose. Once we have the fructose, our process works pretty well to make the dimethylfuran.

Chris - Well, let us look at actually how you could use this. So, will it burn and behave in an analogous way to petrol, because that must be a key question?

Jim - Yeah, there was a discussion in the literature on this in the 1980s. People went through and measured the octane number of DMF and it turns out the octane number is something like around 120, which is a very, very good octane. So, dimethylfuran should be a very, very good burning fuel if you can make it efficiently from biomass.

Chris - And what about the cleanness of that burn, will it produce lots of nasty organic residues, which, you know, rather like diesel, it has a very poor press on this, are going to trigger respiratory problems or will it burn clean?

Jim - Combustion people I have talked to here at the engine centre at Wisconsin their suggestion is that it should burn cleanly, but there have not been many studies of this in the past because there has not been a lot of dimethylfuran available. I think now opening the possibility of DMF as a fuel - that would be interesting to study.

Chris - So, say you managed to pull that off and it does perform well as fuel engines will tolerate it; it would not corrode them and things like that, is the process to make it actually scaleable, can we get reasonable amounts of this that you could see then turning out of the petrol pump?

Jim - Yeah, the process should be scaleable because if you look at the steps that we use in our two-step process they are very similar to the kinds of processes that are currently used in the petrochemical industry. Therefore, they potentially should be scaleable.

Chris - And so, presumably you will be doing some tests on this to try and get this running into engines pretty soon and see how it behaves?

Jim - Yeah, that is the next step on our process, actually is to scale it up so that we can make amounts of DMF that are now suitable for engine test i.e., in fact, one of our short-term goals.

00:42 - We Can Drive, but How Would We Eat?

It's all well and good being excited about new fuels, but are the arguments for using them really sound? Can we grow enough crops to make biodiesel? David MacKay brought Chris back...

We Can Drive, but How Would We Eat?
with David MacKay, Cambridge University

Chris -   We've heard a lot of options on today's programme about things that you can do to live a cleaner, greener, meaner life.  Is there a scientific argument for adopting these approaches?

David -   Well it's definitely exciting to have these opportunities for things like hydrogen and other fuels derived from biomass, but an important thing to think about is the actual energy.  Where is the energy coming from? It isn't that we've got a fuel problem, if we want to get off fossil fuels, it's not so much the fuels as where are we going to get the energy from instead of fossil fuels.  I've done a little calculation like your
lightening strike calculation just adding up the numbers for Britain, could we live on our own biofuels for example?  So we start with sunlight, which is a thousand watts per square meter at midday.  It's not midday all the time so we lose out at night time and evening and morning, so it comes down to 250 watts per square meter on average. That's if there's no clouds, but it's cloudy two thirds of the time, so we're down to 80 watts per square meter. That's the figure if you're at the equator, and we're quite far north, so it comes down to about 50 watts per square meter on average is the power of sunlight.  And then the best plants for making carbohydrates out of are 1% efficient, so that gets us down to half a watt per square meter. Now you just need to know, what's the population density of Britain, and it's 4000 square meters per person.  If I get to be dictator of Britain and I say lets have 75% of Britain devoted to growing biofuels, how much energy do we get from that?  Well the raw carbohydrate that you're getting out in the form of plant material is 36 kilo Watt hours per day, and in Britain 36kWh per day is pretty much the amount of energy we're spending on transport at the moment.  You have got to bear in mind that we haven't processed that plant material into fuel.

Chris -   So in other words if we put across all of the space we have available, we could just about be energy self sufficient using plants, but what about food?  Would we have to buy it all in from France?

David -   Exactly.  Earlier on in the show you were saying we could like on organic food, but that organic food needs that land to grow on as well.  So we really have a crunch, and bear in mind that we hadn't actually produced the biofuels from that plant material, and that requires energy too.  Many of these biofuel processes lose a lot of energy along the way, you have to put in extra energy.

Chris -   So when we've got President Bush saying we're going to put across x amount of land to growing all these things to make biofuels, there's not a sound ecological or scientific argument for doing that?

David -   Well, the population density of America is lower than ours, so I'd certainly say that Britain can't live on biofuels for transport in the way that we currently live.  In America, their population density is maybe 5 times lower than ours.

Chris -   They've still got to eat though.

David -   Yes, and I think there's a big worry that in this rush to look green, people will actually end up doing something that's very bad for the poorer people of the world, who would like to use the land for food rather than for our biofuel.

Chris -   Also, is there a risk that if you suddenly switch all this land away from agriculture you may actually make the environment worse?  Because you're establishing even more of a monoculture, you've got lots of one particular type of crop growing for you to make lots of oil which we can turn into biodiesel, and that could have knock on effects for the environment.

David -   Yes, that's right and another environmental effect is the water requirements if we did take over lots more land and start growing lots more crops on it, we'll end up with a world water shortage as well.

Chris -   So what is the answer, do we travel less?  What do we do to get around the problem?

David -   I think we need to be looking at lifestyle changes to be able to live self sufficiently on our own renewables.  Alternatively, we need to be really nice to other countries and say 'Libya, you've got a nice low population density, lots of sunlight, please could we be nice to you and buy a bit of solar power from you'.

Chris -   I did a back of the envelope calculation and found that if you covered the entire Sahara desert in solar cells, assuming they're about 30% efficient and the sun shines for 12 hours in a day, we could generate about 10to the power 15 Watts [1,000,000,000,000,000 Watts].  That's an equivalent of power to the gulf stream, that's a lot of energy, that's a million Gigawatt power stations.  Why aren't we doing this?  This surely should be the answer.

David -   I completely agree, I think solar in the desert is one of the options for humanity.  You could certainly power Europe and North Africa, all at a European standard of living, using just a small fraction of the Sahara desert   Why aren't we doing that?  Well, why are we bombing Iraq?

Chris -   Don't go there...  Well I suppose you could have said that for president Bush.  But to wrap up then, how sound is it to say to people 'everything makes a difference.  Turning off your TV when it's on standby, not leaving your phone charger plugged in when it's not charging anything, this will help to save the planet'.  Will it?

David -   Some of these things definitely do make a difference; but the phone charger thing is crazy.  If you take a typical Nokia charger, it's using less than 1 watt, it's a really tiny trickle.  Probably about 1% of 1% of your energy consumption is going into the phone charger.

Chris -   But the argument is that there are so many people with so many of these things plugged in that en mass, if you add them all up it makes a huge difference.

David -   If you add it all up, you get 1% of 1% of the UK's energy consumption, that's how big a difference phone chargers will make.

Chris -   So we're being penny-wise, pound foolish with that argument.

David -   I think so.  But there are other things on standby which really do make a difference; if you're leaving a computer plugged in all the time, that's using maybe 80W, if it's screen is switched on that's another 100W maybe, a laser printer sitting doing nothing at all is 17W, and all of these things really do add up.  If everyone were careful in switching off those sorts of devices, we could be saving maybe 10-20% of our electricity consumption.

After mowing the lawn why do I still feel like I am vibrating?

This is because of a quirk in the way your body processes incoming sensory information. We have a process called adaptation, where if we experience something all the time, the nervous system shuts off the sensitivity to that thing, to avoid sensory overload. For example, if you visit someone's house, you immediately notice a smell, but after you have been there for a few minutes, you stop noticing. Our bodies are only interested in things that change, so if you are in the jungle, you would need to pay a lot of attention to the smell of smoke if it suddenly arrived. If you were constantly experiencing the smell of all the trees and soil around you, would wouldn't be as able to pick out the smoke.

The same thing happens on your lawnmower - the vibration is there all the time while you're mowing. The body suppresses it's sensitivity to the vibration. When you take the vibration away, they body is suppressing something which isn't there, and so you feel the inverse of what your nerves were trying to cancel; in this case, you feel like your feet are vibrating.

The same thing happens when you've been on a boat for an extended time, you get back on land and still have 'sea legs'!

Are microwave hotspots a problem with a turntable?

That's true to a certain extent, but humans love doing things symetrically. We tend to put our food or drink in the centre of the turntable, which means you can still get hotspots right in the middle.

The best way to microwave something is to put it on one side of the turntable, so that it goes through lots of hotspots and is evenly cooked.


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