Winds, Wings, Whale Fins and Wind Power
How can we make the most of the wind? In this week's Naked Scientists, we find out how Humpback whales have inspired a new, more efficient design for turbine blades and stall-resistant aeroplane wings and how an inflatable wind generator flies like a kite to extract energy from high altitude winds anywhere in the world. We also hear how a specially-designed wind generator has helped Antarctic-based scientists save 30 thousand litres of diesel. Plus, a simple programme to cut child deaths in the developing world by 30 percent, a new technique for keeping tabs on tumours and a sugar-based solution for keeping virus vaccines fresh without fridges...
In this episode
01:49 - Saving newborn lives
Saving newborn lives
Sometimes lifesaving research doesn't have to involve complicated or expensive technology - it just needs a little thought, according to new research in this week's New England Journal of Medicine.
Researchers funded by the US National Institutes of Health and the Bill and Melinda Gates Foundation have discovered that a short training course can help to cut the rate of stillbirths by more than 30 per cent in developing countries - given that estimates suggest that there are 3 million stillbirths worldwide each year, and nearly 4 million infants die within a month of birth, that's a staggering difference for such a simple solution.
The researchers were testing the effectiveness of a three-day training course for birth attendants or untrained midwives, which highlighted simple techniques for caring for newborns, breastfeeding, keeping babies warm and dry, and the signs of serious health problems.
One healthcare worker from Argentina, the Democratic Republic of Congo, Guatemala, India, Pakistan and Zambia went to the US to learn newborn care techniques, and went home to train others - reaching around 3,600 untrained healthcare workers in rural communities.
Researchers also taught the health care workers how to check infant health, diagnose whether a baby was stillborn, and check for other conditions. And they provided local health care workers with scales for weighing newborns, hand-held pumps and masks to fill babies' lungs with air, and clean-delivery kits to prevent infection. Then the scientists compared data on babies born before and after the training had been given.
Overall, they studied 120,000 births, and found that the rate of stillbirths dropped sharply--from 23 per 1,000 deliveries to 15.9 per 1,000. The scientists think this is because some of these babies would not have taken a breath on their own, and would have been considered to be stillborn. But with their new knowledge, a birth attendant could help the baby to start breathing and - in many cases - save its life. Supporting this idea, the researchers didn't find a difference in the number of babies who appeared to have died in the womb, suggesting they couldn't have been saved at birth.
It's a simple intervention, but it shows that giving the right training to the right people, in the right place, can help to save lives.
04:53 - New technique for cancer monitoring
New technique for cancer monitoring
Scientists have discovered a new trick for keeping tabs on cancers.
One of the most malignant aspects of cancer is the ability of the disease to spread to other parts of the body, a process termed metastasis. And although surgery or localised treatments like radiotherapy can target the initial disease very effectively, it is usually metastatic spread and disease recurrence from a remote site that ultimately leads to the demise of the affected individual.
But tracking down these remote tumour deposits and detecting their activity can be very difficult, especially when they are small, so it's often impossible to give precise prognostic information to the patient.
Now, however, scientists at Johns Hopkins in the US have developed a new, highly sensitive, genetic test that looks for signature DNA changes that are peculiar to an individual patient's cancer.
The new technique, which is published in the journal Science Translational Medicine and has been dubbed PARE - short for Personalised Analysis of Rearranged Ends - works by looking for DNA rearrangements; that is chunks of entire chromosomes that have swapped places with each other.
This process occurs quite commonly in cancers, but the pattern of rearrangements will be unique to any individual patient's tumour. What study author Victor Velculescu and his colleagues have found is that the levels of these rearranged DNA sequences in the bloodstream can be used to quantify the tumour burden in a patient's body, follow the response of the cancer to treatment and then monitor for evidence of recurrence; in fact the technique is so sensitive that it can potentially pick up evidence of disease activity long before anything is visible on ascan.
This means that, in instances of relapse, doctors could intervene with chemotherapy much sooner, potentially improving the prospects for the patient. The downside of the approach is that it is currently very expensive. It involves sequencing their entire genome, meaning that the price tag is over 5 times higher than a CT scan, the current gold standard for detection of disease recurrence.
But with sequencing costs dropping all the time, in all likelihood this won't remain an obstacle for long. "If current trends in genome sequencing continue, PARE will be more cost effective than CT scans and could prove to be more effective," says Kenneth Kinzler, Professor of Oncology at Johns Hopkins.
08:38 - Scientists stitch up "lab-on-a-chip"
Scientists stitch up "lab-on-a-chip"
Our more crafty listeners may be fond of whipping up a skirt or shirt with needle and thread, but now researchers in Australia have managed to use cotton thread and sewing needles to stitch together a "lab-on-a-chip" - technology that could one day be used for cheap diagnostic tests for medicine or other applications, according to research published in the journal Applied Materials and Interfaces...
Chips like this are called micro-fluidic devices - they pull tiny amounts of liquid around their surface in a tightly controlled way. And they're normally made by etching channels into silicon, glass, metal or other hard surfaces to make chips the size of a postage stamp. But Wei Shen and his team figured that they could make a chip using cotton threads to wick liquid around surfaces instead.
The first challenge was to prepare the cotton thread. Natural cotton fibres are coated with wax, so the researchers had to use a special treatment, called plasma treatment, to remove it. Then they stitched cotton thread into paper to make little microfluidic sensors that could detect and measure different chemicals often found in the urine of patients with certain illnesses.
The team were testing for nitrite ions and uric acid, both of which can be detected by other chemicals that change colour. So, by treating the base paper with the detection chemicals before sewing them, they could make paper and thread-based detection chips.
This research is a fairly crude demonstration of the technique, but with a bit more research, it could be possible to develop cheap and effective sensors fop many different chemicals. And because the sensors are simple and cheap to make, they would be ideal for applications in the developing world, such as sensing contaminants in drinking water or soil, or for healthcare applications.
11:35 - Protein dimmer switch to control cell metabolism
Protein dimmer switch to control cell metabolism
Scientists have discovered the biochemical equivalent of a cellular dimmer switch to control metabolism.
It's well known that genes can be turned on and off to allow cells to respond to different metabolic demands. And, in recent years, scientists have also discovered that the levels at which genes are expressed (turned on) can also be controlled to further tweak the sensitivity of the system.
But now scientists have discovered that the proteins, including enzymes, that drive the metabolic pathways inside cells can also be manipulated to make them more or less active. Writing in Science, Fudan University, Shanghai, scientist Shimin Zhao and colleagues show, using liver cells, that a chemical moiety called an acetyl group (a chain of two carbon atoms) can be added to lysine, one of the amino acid building blocks that makes up proteins.
This modification occurs in response to certain chemicals and also to changes in a cell's immediate environment, which can have the effect of altering - and in some cases doubling - the activity of the protein.
This means that there is a whole new layer of complexity to the way cells respond to local conditions and signals such as hormones or even glucose levels. Understanding how this works in detail will inevitably lead to new drugs for old diseases, and a better understanding of many pathological and physiological processes.
14:13 - Resurrection Plant tropical vaccine key
Resurrection Plant tropical vaccine key
with Matt Cottingham, University of Oxford
Chris - Scientists have announced that they've discovered a way to use a secret, known previously only to nature, to solve a big problem in the third world; how do you keep viruses, and particularly live viruses that you're going to use as vaccines, alive despite a lack of refrigeration? The secret has come from a plant called the Resurrection Plant, which is an incredible organism. It can withstand near total desiccation. You can dry it out for months on end, in some cases years, and then it springs back to life as soon as it touches water. Scientists have discovered how the plant does that and they've now been able to borrow the same trick and apply it to viruses. Matt Cottingham joins us from the University of Oxford, lets start with the plant first. How does it do this?
Matt - Well the key is that it has lots of trehalose inside its cells. Trehalose is a common sugar, similar to sucrose which is ordinary table sugar. When the sugar dries out, it forms a glass; a glass is a particular type of chemical entity which is essentially a liquid but so viscous that it's effectively a solid. Actually, the glass in your window is called glass because it's that type of chemical, and although it seems completely solid, it's actually chemically a liquid because the molecules are disordered.
Chris - So it presumably stabilizes the cells and the components of those cells in the plant, so that when the plant dries out, the chemicals and their structures don't fall apart. So when you do add water, the sugar then breaks down again, and everything comes back to life?
Matt - That's right. If you take all the water out of something, what would normally happen is you get crystals, and crystals have a very tight structure and they will actually disrupt the structure of the plant, or in this case the vaccine, which you want to preserve. So by having lots of sugar which doesn't crystallize under those conditions, but instead forms a glass, that actually allows protection against desiccation.
Chris - So how have you stolen what the plant is doing and applyed this to the vaccine technology world?
Matt - Well, it's very simple. We simply take a mixture of sucrose and trehalose, and formulate the vaccine into that and then dry it. And what we've hit upon is a particular method of drying that actually enables the vaccine to retain its structure and its activity.
Chris - Which viruses are you thinking of because obviously, there are certain viruses that are pretty stable and you don't need to do special tricks to make sure that people can get infected with them. I'm thinking of common things like norovirus which people catch on cruise liners. Not all viruses are as stable as that though.
Matt - That's right. So most viruses are quite stable but they really need to remain wet, so they're normally transmitted in droplets, say from a sneeze or via the faecal/oral route where you've probably got a tiny bit of moisture on your fingers. But in this case, if we want to be able to stabilize this, it's really crucial to have them dry because if they're dry, then the chemistry which should normally degrade them can't actually happen.
Chris - So which viruses are you looking to use and how?
Matt - So, we focused in this work on two viruses, adenovirus and a pox virus called 'modified vaccinia virus'. These are exciting because they're two viruses which may be used to form the platform for a new generation of vaccines against diseases like malaria and HIV, and TB where there aren't any vaccines or where the current vaccines are no good.
Chris - And what is the impediment or problem with using these agents in the third world at the moment?
Matt - Well, the problem is that they're live viruses. So, they're living organisms and they're very sensitive to heat, so all the live viral vaccines at the moment have to be kept in the fridge. They're usually manufactured in Europe and they're shipped all over the world in refrigerated containers, and they even have to be kept in the fridge at their destination. If they do warm up, then they essentially have to be thrown away.
Chris - I would presume then that the actual spend on keeping vaccines cold probably makes up a significant proportion of the total cost of the vaccine then?
Matt - Yes. It's about 20 percent and that doesn't include wastage.
Chris - Which is a huge amount and obviously, totally beyond the realms of many countries to spend money or even to have the infrastructure to keep a vaccine cold. So presumably your platform would enable you put viruses into these sugar glasses. They would therefore be stable at what sorts of temperatures, for how long?
Matt - We've managed 45 degrees for six months.
Chris - Which is pretty impressive.
Matt - Yes. It's amazing.
Chris - You presumably then would just take the vaccines out to the bush in the middle of nowhere and they would remain stable until someone had them administered?
Matt - That's right, yes.
Chris - Do you think that these sugars would be safe in the body?
Matt - Yes. They're completely safe.
Chris - How do we know that?
Matt - They are actually already used in the current vaccines . Some of the current vaccines. So it's a combination of these sugars together with the new method of actually performing the drying that has enabled us to do what we've done.
Chris - Any idea when you'll be able to wheel this out and when people will begin to see the benefit of this?
Matt - Yes. We're thinking possibly as early as 5 years, maybe more like 10 because we've done this very much on a laboratory scale. So now, we have to actually do it according to good clinical manufacturing practice which is a set of legislations which we need to adhere to in order to make a product that could actually be used in humans. That's being done by our commercial partners, Nova Laboratories in Leicester.
Chris - All right. Well, we wish you luck with it and thank you very much for joining us, Matt, and telling us about your work. That was Matt Cottingham. He's at the University of Oxford and he and his colleagues have published a paper - it's in Science Translational Medicine this week - in which they outline how these new sugar-based glasses can be used to make viruses survive intact in very otherwise hostile conditions.
20:11 - Wind turbines inspired by Whales
Wind turbines inspired by Whales
with Professor Frank Fish, West Chester University
Kat - When you see a whale, it probably doesn't make you think of wind turbines, but our next guest, the very aptly named Professor Frank Fish from West Chester University in the states was inspired by the fins of a humpback whale to design a better wind turbine. So we're joined by Frank. Hello...
Frank - Hi. How are you doing?
Kat - Hi. Good. Now, tell us about the story behind this because I understand that you saw a picture of a whale and it set off your train of thought.
Frank - Actually, it wasn't a picture. It was a little bit more three-dimensional than that. It was a sculpture of a humpback whale and I saw that it had, aside from very long flippers, these very curious bumps along the leading edge, the front edge of the flipper. And I was quite embarrassed because I actually started saying that "this is impossible" until I did see a picture, and then tried to figure out why it have these curious bumps that you just don't see on anything else.
Kat - It does seem counter intuitive. You'd think that bumps would interfere with the action of the fin. So, what are the bumps doing?
Frank - Well, what it appears is that they modify the flow. So, if you have a wing-like structure - like taking your hand and putting it out of a car window and playing aeroplane - what will happen is a wing will modify the flow of air. It'll push it down and as a result, you get a lift force as you raise the angle of the wing. And that occurs up to a particular point, in which case the hand or the wing will go through what's called 'stall' if the angle is too big because the air flow or water flow can't move around it in a nice controlled fashion. Stall is something you don't want to happen. It's awful when it happens in aeroplane, but for every humpback whale, what the bumps do is that they can increase the angle at which you can have that flipper directed into the flow, without stalling.
Kat - So you can have a sharper angle and get more drive from the wind?
Frank - Exactly. So, the whole idea is that, because you can raise it at a higher angle, what's called an angle of attack, you can then place it into a wind or water flow and you can get more lift out of it, and thus, more energy if you're putting it into a windmill. You can also have a safety factor; a big problem with windmills is that you get gusts of wind from any direction and that sometimes exceeds the stall angle, and the result is that the windmill becomes unstable. It starts to vibrate and can even blow apart. With this, you can actually have a higher angle, get more energy out of the wind and in the same way, also protect the windmill because it's less likely to form these vibrations.
Kat - So how have you been applying these kind of bumpy fins to wind turbines? Have you got large scale ones or is this kind of just small scale work at the moment?
Frank - Well, I work with a company and we've had a test windmill up in Canada and it was about a 30-kilowatt windmill, test windmill, and what we found is that under moderate air speeds, you could actually get a 20 percent increase in the amount of energy that we could produce with the windmill.
Kat - That sounds absolutely phenomenal. Why have people not thought of making bumpy wind turbines before?
Frank - Well again, it's sort of counterintuitive. I mean, whenever you see wing-like structures, we always think that they need a nice sharp, clean leading edge, so aeroplanes or car spoilers or windmills, or fans, anything like that. So this is a bit counterintuitive that you wouldn't think of putting these bumps along the leading edge. Part of the argument has been that, if you do that, you're going to disrupt the flow in another way and that is, you're going to increase the amount of resistance that wing will go through the air or through the water with. What we have found with the bumps is actually - there is no penalty for having these bumps along the leading edge. They don't increase the resistance. And additionally, as you go up to higher and higher angles, there's actually a reduction in the amount of resistance compared to a wing that doesn't have the bumps, simply because the wing isn't stalling. When it stalls, the amount of resistance goes up quite a bit. So we can operate at higher angles with less resistance than if we didn't have the bumps.
Kat - That sounds brilliant. We've had a question in from Silverwing Benoir in Second Life; he says, is this similar to the dimples on golf balls? Is it a similar function that's going on?
Frank - It has similarities, but there are distinct differences. What a golf ball does by having the dimples on it is to turbulise the air over the surface of the golf ball. So normally air will move in nice, even layers over a surface, and that's what we call laminar flow. The trouble with laminar flow is it's not very stable. You can't maintain it at very high speeds or with very large entities. And so, by having the dimples that turbulise the flow over the golf ball, which means that the flow will continue over more of the surface, and as a result, there's less resistance, and the ball travels further when it's hit. With the tubercles, or these bumps along the leading edge, what they do is they do create a different flow regime, but not necessarily turbulising the flow. What they do is they produce large swirling masses of flow, what are called vortices. These vortices interact over parts of the wing to actually help to speed up the flow over say, the bump itself and keep that flow attached over the entire surface of the wing, so that again, you don't stall out.
Kat - So, at the moment, you are testing this wind turbine up in Canada. How long might it be until this starts to be adapted more widely as turbine technology?
Frank - Well, I think it's ready to go. The big problem is that there's always a large capital investment in redesigning structures such as windmill turbine blades, especially when you're talking about very large wind turbines. We have had success in actually putting these on ventilation fans and there again, we're seeing that there's an improvement for the manufacturer because they can push as much or more air with fewer blades, by having these bumps on the fan blades. And so, what that means for the producer is that there's less material cost. Then the actual fan operates with greater efficiency, which means for the end-user, they're going to pay less in their electric bills to ventilate some area using the fans with the bumps.
Kat - Fantastic! That sounds like a great example of stealing from nature to make something that's greatly improved. So, thank you very much, Frank. That's Professor Frank Fish from West Chester University, explaining how the bumps on the edge of a whale's fins have inspired him to make new, better wind turbines.
25:14 - Is the use of bumps on turbine blades similar to putting dimples on golfballs?
Is the use of bumps on turbine blades similar to putting dimples on golfballs?
We posed this question to Professor Frank Fish from Westchester University...
It has similarities, but there are distinct differences. What a golf ball does by having the dimples on it is to turbulise the air over the surface of the golf ball. So normally air will move in nice, even layers over a surface, and that's what we call laminar flow. The trouble with laminar flow is it's not very stable. You can't maintain it at very high speeds or with very large entities. And so, by having the dimples that turbulises the flow over the golf ball, which means that the flow will continue over more of the surface, and as a result, there's less resistance, and the ball travels further when it's hit. With the tubercles, or these bumps along the leading edge, what they do is they do create a different flow regime, but not necessarily turbulising the flow. What they do is they produce large swirling masses of flow, what are called vortices. And these vortices interact over parts of the wing to actually help to speed up the flow over say, the bump itself and keep that flow attached over the entire surface of the wing, so that you don't stall out.
Why is it colder at higher altitudes?
Well, the reason, Dennis, is if you think about it, the distance between the Earth and Sun is a very long way. It's a hundred million miles or so. And therefore, the distance between the Earth's surface and the top of Everest at 29,000 feet is a tiny fraction of the total distance to the Sun: in the grand scheme of things, it's a trivial change in the actual distance. So that isn't why the temperature changes and therefore also why it isn't hotter.
The reason it's actually colder is because, as you go up in the atmosphere, the Earth's atmosphere feels less pressure the higher up you go. So as the gas in the atmosphere rises it feels less pressure, which makes it expand. When the gas expands it does some work. And and if it's doing work, it must be losing some energy; and if it loses energy, its temperature must drop because we define temperature as the average energy of the particles. Therefore, if the energy of the particles is lower, the temperature must be lower.
That's why, at altitude, the temperature appears to fall. In space, outside the earth's atmosphere, if you're facing the Sun, you can actually fry. That's why space suits are specially designed in order to keep people from getting too hot in the sunny bits but also prevent them from becoming too cold in the non-sunny bits.
30:32 - Wind Power in the Antarctic
Wind Power in the Antarctic
with Johan Stander, University of Stellenbosch
Chris- How do you power a research station in Antarctica? The answer is, usually, with very large diesel generators. That means you also need to get the diesel down there, and that costs a lot both financially and also from an environmental perspective because you've got to burn more fuel to ship it there. But now, scientists from the South African National Antarctic Program, or SANAP for short, have come up with a much more environmentally friendly solution. They're making use of the notoriously powerful Antarctic winds. Meera Senthilingam caught up with the Antarctic's temporary resident, Johan Stander, who's a mechanical engineer at the University of Stellenbosch...
Johan - Most Antarctic stations are quite dependent on fossil fuels and it's becoming more expensive to fuel stations - not only the fuel itself, but transporting the fuel to Antarctica. Secondly, governed by the Madrid protocol we're actually obliged to minimize the environmental footprints of stations in Antarctica. That's why we actually investigated the possibility and feasibility of sustainable energy sources of solar and especially wind, since Antarctica is one of the windiest places on Earth. We designed turbines specifically to harness the Antarctic wind which is quite extreme compared to other wind sites in the world.
Meera - How did you set about designing this turbine for this particular environment?
Johan - First of all, the most important obstacle is the low temperatures in which turbines should function. In that case, we spent some time selecting specific materials that can cope in the low temperatures varying from +10 °C to -40 °C in the winter. So the steel we select has a high carbon content, we select the epoxy for blades that is also used in aircraft design and we kept the turbine itself as simple as possible, as robust as possible a design. Meaning, less parts, more reliability.
Meera - And what about things like oil for, say, movements of the turbine blade?
Johan - So the only thing we're actually using as a lubricant is a grease. This grease is food lubrication grease meaning it's also a biodegradable to some extent. It can cope with temperatures up to -50 °C.
Meera - And how many of these turbines have you made so far?
Johan - So far, we're testing a prototype. That is a 15-kilowatt machine. It has hub height of 12 meters, a rotor diameter of 7.2 meters. The blade itself is a black blade. It's a glass fibre epoxy blade and then the nacelle which is actually the interface between the rotor, the tower, and the tail vane is a steel structure. We didn't go for an active yaw system, the yaw system being the system that keeps the rotor in the wind. We went for a passive system just to eliminate the amount of parts needed and obviously, to make maintenance easier. The tower itself is a lattice structure, which obviously induces less snow accumulation than a tubular tower and the foundation is rock anchor foundation. Since we're limited in construction materials and a construction time that was the easier option.
Meera - Just how windy is Antarctica? So what kind of wind speeds do you get there and are they quite predictable wind speeds? Are they constant or are they variable?
Johan - Compared to other wind regimes in the world, Antarctica is known for its katabatic wind regime which is actually driven by cold air, like opening a fridge and when you feel the cold air rushing over your feet, that's the same principle, the same mechanism that's actually governing Antarctic winds. The wind is quite extreme. The highest wind speed that we've measured here at SANAP in the last 7 years was 52 metres/second at a height of 10 meters. Temperature-wise, the colder it gets, the more extreme the wind. At the moment today, the wind speed is around about 7 meters/second and the maximum temperature is -2°C. What is quite interesting when comparing Antarctic wind regimes to a normal wind regime is that it's quite constant throughout the year. At SANAP, it's around about 11 and 9 meters/second for at least 60% to 70% of the year.
Meera - So what's the expected figures for the amount of power it's hoped to produce then?
Johan - So far, we have converted about 100 kilowatt hours during the test and the capacity factor of the machine or the site is 80%, meaning it will operate at rated power for 80 percent of the time per year. The wind energy converted is estimated at being equivalent to 30,000 litres of diesel fuel.
Meera - So how would the turbine work? Will it be running constantly and therefore, will it be actually creating power that can then be stored?
Johan - There's no storage at the moment. Since this is such a small system compared to the diesel generator system we have, all power will be fed to the station. In days of excess wind where the power is not required it will be dumped in the snow smelter which actually provides the station with water. So there's no storage. All power will be fed to the grid.
Meera - So in terms of the prototype, it seems to be working very successfully. So, if this continues, will you be scaling this up in the future for the site?
Johan - After the end of this year, we will increase the amount of turbines. So we'll erect two more turbines then increase their total capacity to 45 kilowatts. Maybe in the future, if the foundation does allow it, we can change the generator or increase the capacity of the generator.
Meera - And I guess that makes sense because a lot of the work actually taking place out in Antarctica is looking at the environment and the effects of things like climate change. So it make sense to make the site itself as efficient as possible, and therefore, not contribute to this in itself.
Johan - Yes, saving diesel fuel and reducing emissions, increasing the autonomy of the base... That's the main aims. I mean, what's the point of doing research here while polluting?
Kat - Absolutely. That was Johan Stander from the University of Stellenbosch who has now returned to a slightly warmer Cape Town from Antarctica, and he was talking to Meera Senthilingam. Just in case you're wondering how fast an average wind speed of around 9 to 11 meters/second is, that's about 25 miles an hour. That's a Gale force 6 or a strong wind on the Beaufort scale. Definitely what you'd call a wind chill factor!
37:22 - Lets Go Fly a Turbine...
Lets Go Fly a Turbine...
with Pierre Rivard, Magenn Power
Chris - Capturing the wind at ground level is pretty effective, but not everyone is as lucky as those souls down in Antarctica with those horrendously strong and very cold winds. Winds are much faster though higher up in the atmosphere. But how do you get a wind turbine up there to make use of them? Well, Pierre Rivard is a researcher who works for Magenn Power, they're a company who've developed an inflatable answer to the problem. Hello, Pierre.
Pierre - Hello. Good to be here.
Chris - Welcome to The Naked Scientists. Please tell us first of all, how much more powerful are the winds that you can get access to if you can get a bit further up there?
Pierre - Well Chris, the wind power is a cubic function of speed. Meaning by that, that if you double the wind speed, you have eight times the wind power available to you, and in most locations around the world, going as high as a thousand feet above ground would double the wind speed accessible to wind power.
Chris - So in other words, you could turn your average wind turbine from pumping out, say for a big one, 1500-kilowatt probably into at least a megawatt?
Pierre - Yes, but more importantly, the percentage of nameplate capacity that would be gainfully employed could as much as double. In other words, a typical wind turbine would be productive only at 20 percent of its nameplate capacity, but up there, it could be employed to as much as 50 percent of its nameplate capacity which reduces the stranded asset element of wind power.
Chris - And this is what you're saying with respect to the fact that the wind up there, higher up, blows regularly, reliably, and most of the time whereas down on earth, unfortunately it doesn't.
Pierre - Yes, absolutely. Professor Ken Caldera from Stanford University with his colleague, Dr. Christina Archer characterised this energy as the most concentrated source of global renewable energy on Earth. They believe that there's enough energy up there to power the needs of civilization a hundred times over, and it's only a matter of time before we learn ways to harness this energy.
Chris - Speaking of which, you've got one possible solution. Talk us through it.
Pierre - Okay. Well, we've demonstrated what we believe to be the world's first airborne wind turbine. We were followed for a year by the Discovery Channel in 2007 and demonstrated 1 kilowatt of airborne production of electricity, and we brought it down through a tether to ground level. We're now engaged in scaling up this 1 kilowatt prototype to 30 kilowatts which we hope to achieve by mid-year of this year and rapidly scale up to the 100-kilowatt mark shortly thereafter.
Chris - Okay, so the basic premise is that you have a system that gets a generator way up there high in the atmosphere to a thousand feet or something?
Pierre - Yes. We're starting at a thousand feet because the length of the tether is less daunting in terms of lifting its own weight. Our design is very unique. We use kind of a paddle wheel, kind of a wind turbine which we elevate to a thousand feet and again, because we have eight times the power accessible to us than what we would have at ground level, the actual energy conversion efficiency is not quite as important as the fact that we have eight times the power available to us as what we would have at the ground level.
Chris - So this looks like a giant suspended water wheel, I guess is one way of thinking about, isn't it? So you float that up using something buoyant, helium presumably, to get it up there.
Pierre - That's correct. We could use other buoyant gases such as hydrogen or natural gas, or some of the welding gases, but we use helium right now because it's an inert gas, and it's the best way to start. Ultimately, we could use hydrogen which could be renewably produced using water and electrolysis in the developing world.
Chris - So this takes the generating system up to a thousand feet or so, where it sees the wind, and this causes it to rotate. So presumably, you have a core spindle which is stationary and the body of the generator rotates around that spindle, and that's how you get the power out.
Pierre - Yes, that' correct. We have some proprietary ways of doing this. Some of the aerodynamic challenges which were documented in the Discovery Channel program, identify that there's a challenge in flying a paddle wheel broad-wise to the wind, but we managed to solve this issue, and we've also moved away from a central generator on the axle to a more innovative approach which we find is to be lighter and would also leverage on automotive parts from the electric car industry to reduce cost, but also to enhance the commercialisation of the product.
Chris - And you recover the electricity down the line that's supporting, or tethering, the machine up in the air.
Pierre - Yes. The tethering is very important. We use a plastic by the name of Vectron. For some of the listeners, they may know Vectron as a plastic that has more strength than steel on a per weight basis. And within the Vectron tether, we had some embedded copper wires that would bring down the electricity to the ground level and we also had some data links within the tether. So it's a highly engineered tether at the present time and this is no longer a technological issue for us.
Chris - Presumably, you could use this where you wanted sustainable, reliable power. But in say, remote places, so if you were running a station in the middle of a desert or something, rather than have to ship and lug of diesel out there or to have a generator, you could put one of your systems up in the air, above where you're working, and just bring the power down to the plant.
Pierre - Yes, indeed Chris. This is one of the typical, crucial applications. Our tagline is wind power anywhere and really, when you think about the 1.6 billion people without electricity on Earth, when you use, let's say solar, you have a renewable source that is intermittent and without storage it's difficult to harness around the clock. However, our device, because the winds are more constant and stronger at altitude, multiplies the number of sites where wind becomes economical and makes sense, and certainly to bring renewable energy to the rural electrification of China and India, we believe we have a great solution here.
Chris - And just to finish off, the one thing that's going to recur to many people is, I hope there's no airports nearby.
Pierre - Yes. We have to abide by some regulations if we are within a certain radius of an airport. We obviously would not get a permit to fly. We need to provide some light markers every 50 feet along the tether, and our device also has a transponder onboard the device, which means, in the unlikely events that it becomes unattached, then a local radar could track it as it travels because of the transponder on board. So everything is done according to regulations and it hasn't been an issue in the demonstrations we've done to-date.
Chris - Brilliant. Well we must leave it there Pierre, but thank you for joining us. That was Pierre Rivard who worksfor Magenn Power, based over in a Canadian company, but also right across America. As long as you live in an area where there are no aeroplanes, then they could have the solution for you in the form of a way of generating power using an inflatable turbine!
Can whale fin dimples be used on aeroplanes?
We posed this question to Professor Frank Fish from Westchester University...
The quick answer is yes. What it allows us to do is to make the wing and the aeroplane safer because you can operate at higher angles and really go beyond where a plane wing would normally stall. As a result, you don't need all the mechanics and extra control surfaces that you find on aeroplane wings. You can eliminate those and all the heavy components that go with it. That makes it more economical for a plane to fly because now, you've lightened the plane, this makes it easier to get off the ground, and to fly along. And this way, you can either make it cheaper to fly or you could actually take your wing and add more fuel in there, the result being that you can extend the range of the plane. You won't have to make as many stops. So, this is potentially beneficial to airplanes as much as windmills or any other lifting surface.
52:35 - 10th Naked Anniversary!
10th Naked Anniversary!
with Chris Smith, Kat Arney
Chris - It's a very special day today because it was this very day, 10 years ago, that the first ever edition of the show that ultimately became The Naked Scientists actually got broadcast. It all started in the first place because a group of us at Cambridge University ended up on a local radio station during what was called National Science Week. This was back in 1999. This gave us a relationship with that radio station, so we then ended up, eventually, with a radio program that we launched there 10 years ago today in the year 2000. You can imagine quite how horrified I was when I replaced my car earlier this year and when I was clearing it out, I discovered in the glove compartment a cassette that said on it "1999". When I played it, it was that first program from 1999's National Science Week. I have a little bit of it for you and for bonus mark, perhaps you can tell us who this interviewer you're going to hear on here is, or where else you've heard him..
The First Naked Scientist Appearance!
Chris - The radio debut for Dr. Chris and Dr. Kat. The mystery voice, incidentally, was Pete Cousins and he still appears on The Naked Scientists every single week because he's the guy who makes all our wonderful jingles!
57:08 - Does snow cool the world by reflecting light?
Does snow cool the world by reflecting light?
We put this question to John King, from the British Antarctic Survey in Cambridge:
John - Well, the thing about snow is that it's quite reflective compared to bare ground. A good thick snow cover will reflect back up to 80 percent or even more of the sunlight that's falling on it. Whereas bare ground or grasslands might only reflect 10 or 20 percent of the sunlight falling on it and so, the sunlight warms it up considerably. So, if you replace that bare ground by snow cover, then a lot of the sunlight that would've heated the ground just gets reflected back into space.
So, if you remove a snow cover by ploughing it up or sweeping it away or whatever, revealing the bare ground underneath, then the ground is going to absorb a lot more sunlight, and will warm up a lot more quickly than if the snow were there. We are having an effect on the reflectivity, the albedo of the planet by changing land use for instance; cutting down forests and replacing them with grasslands. But that generally has the opposite effect, forests absorb quite a lot of sunlight, grassland is less reflective.
People have suggested that we could partially offset global warming by painting the roofs of all of our buildings white. I think some calculations have been done that have showed that this will be a good thing, but it wouldn't have a very large effect because you're only talking about a rather small area of the planet that you'll be changing the reflectivity of.