This week, the latest innovations in solar power technology including a Cambridge team racing from Darwin to Adelaide in a solar car, community co-operatives empowered by solar panels, and how algae harvest the Sun's energy. In the news, how wobbles in the Earth's core are affecting time, how nerves control prostate cancer growth and the turmeric-thalidomide combo being used to combat cancer. Plus, can you produce power from poo?
In this episode
01:02 - Solar-powered steriliser
A solar-powered medical steriliser for third world countries that uses nanoparticles to produce a scalding jet of bug-killing steam from even icy water has been invented by scientists in the US.
Dubbed "the solar autoclave", the device, which is described in PNAS this week, is the work of Rice University scientist Naomi Halas and her colleagues.
It consists of a flask of water that is placed in sunlight and to which is added a few million tiny gold "nanoshells", each less than 1/5000'th of a millimetre across.
These gold particles, which resemble small dots down a microscope, strongly absorb light, heating up in the process. They pass this heat to the liquid immediately around them, causing it to vapourise and produce a small pocket of steam. This insulates the particle from the liquid, encouraging it, and the steam, to become even hotter.
The bubble of steam expands and carries the now much more buoyant particle to the liquid surface, where the steam escapes at a temperature of 140 degrees centigrade, even if the fluid is kept in an ice bath!
The stream of hot steam can then be tapped off into a sterilising chamber where it condenses, releases even more energy and decontaminates the surfaces of medical instruments or potentially hazardous waste.
Different designs allow for the condensing water either to be recycled, or released. The gold nanoshell particles are stable and remain intact throughout the process.
Tests on samples of a heat-tolerant bacterium called Geobacillus thermophilus, which is routinely used to check the performance of hospital and research autoclaves, showed that the system completely deactivated the bugs within minutes.
The researchers suggest that the instrument, which is very cheap to build and almost free to operate, could enable safe medical sterlisation in resource-poor, remote locations which lack the reliable electrical supplies required to run standard steam-based sterilising devices.
03:57 - Wobbles in the Earth's rotation
Wobbles in the Earth's rotation
Dominic: - I've been looking at a story which has to do with how long days are on our planet, the Earth, and of course, there's a really obvious answer to that, we all know that days are 24 hours long. But at a more deep and fundamental level of course, the sun rises and sets each day because our planet is rotating and the 24-hour period of the day is the period of rotation of our planet. Now, if the Earth were rotating at a steady rate, days would always be at the same length. But this is a spinning ball in space and things can exert rotational pulls on that planet and change the speed at which it rotates. There are quite a lot of different processes that can affect that rotation and a paper in Nature this week written by Richard Holme from the University of Liverpool and his colleagues tries to disentangle what some of these processes are by looking at historical data taken over the last 40 years of how the Earth had been rotating.
Chris - How much of a difference are we talking about in terms of the length of day?
Dominic - We're talking thousandths of a second at most.
Chris - So, a long time then.
Dominic - Well, it actually adds up so that over a couple of years, that can add up to a second and that becomes something you can measure with a clock. If you're looking at where the sun is in the sky, you can start to notice, if you've got a very good telescope that the sun is slightly behind where it ought to be.
Chris - So, what do these guys predict or say is going on?
Dominic - There are all sorts of processes going on on different timescales. On very short timescales, there's weather, there's ocean currents that affects the Earth's rotation on a day to day basis. On longer timescales, the Earth is made up of different radial layers. You have a liquid core and then you have a solid mantle, and those are rotating at different speeds. As they transfer rotation between them, that affects how fast the outer crust of the Earth is rotating. On the very longest timescales, the moon, the Earth's companion in space is gradually draining the Earth's rotational energy, and that means that days are getting longer over periods of tens of millions of years.
But what's really fascinating, three times in the last 40 years, the Earth has suddenly changed its speed of rotation in 1969, '72 and '78. That was at exactly the same time as the Earth's magnetic field shifted. The Earth's magnetic field is produced by the Earth's core and so, they predict that this is presumably also a phenomenon coming from the centre of the Earth. So, what they think is that perhaps there are bits of solid material in amongst this molten material at the centre of the Earth - if that is catching on the solid mantle above it, then when that catches, you have a sort of earthquake very close to the Earth's core. That's affecting both the Earth's rotation and its magnetic field. And so, that might be what caused these blips in the Earth's rotation.
Chris - So, when you say there was a blip, what actually do you mean by that?
Dominic - Well, the Earth has this magnetic field which is very closely aligned to its rotation axis. If you get a compass out, it points to something which is close to the north pole, but it's offset by a couple degrees. And if you have a very sensitive magnetic field measuring device, you can measure how strong that field is. But from time to time, that field is gradually changing and sometimes it shows a very dramatic shift in either its direction or in its magnitude. And that suggests something is going on in the Earth's core where this field is being generated.
Chris - So, by looking at the rotation of the Earth, you are slowly - I suppose - getting a proxy measure for how this field may be generated and what's going on right in the centre of the Earth.
Dominic - Yes. I mean obviously, we can't explore the centre of the Earth and the magnetic field is actually one of the very few things we can measure that's coming out of that centre of the Earth. So, this is telling us something about a part of the planet we don't understand terribly well.
07:36 - A new IVF fertility treatment
A new IVF fertility treatment
This week, Connor Levy became the first IVF baby to be born using a new screening technique called next generation sequencing. This is a new way to check how healthy embryos are before they are implanted. Here's the Quickfire Science on IVF and Next Generation Sequencing with Kate Lamble and Priya Crosby.
- IVF stands for in vitro fertilisation and is used to overcome infertility in couples wishing to become pregnant.
- In IVF an egg is taken and fertilised by a sperm outside the body. The newly formed embryo is then implanted in the uterus of either the biological mother or a surrogate, where the pregnancy continues as normal.
- Louise Brown was the first baby born through IVF in 1978. Since then thousands of families have under gone the procedure.
- Despite being so popular IVF is not always successful. It can also lead to multiple births if more than one embryo is implanted and all survive.
- One cycle of IVF costs around £5000. In the UK the NHS offers up to three cycles of IVF to women under 40.
- Genetic screening can be carried out to check for specific genetic diseases which may affect quality of life, like cystic fibrosis. So that only healthy embryos are implanted.
- Next Generation Sequencing, used on Conor Levy, takes a more general approach, sequencing around 2% of the embryos DNA which can reveal the number of chromosomes in the embryo, as abnormal chromosomes are one of the most common reasons for miscarriage.
- This new screening technique can increase the success rate by of IVF by up to 50%. This should limit the number of cycles needed before success, saving people money and heartache.
- Opponents have suggested that this is another step towards designer babies, where embryos could be chosen based on traits such as hair colour, height or intelligence.
- The inventor of the technique has said that he can't imagine people wanting to go though the strains of IVF for something trivial. But it's been suggested that laws may be altered so that only genes linked to disease could be screened.
09:55 - Thalidomide and turmeric to treat cancer
Thalidomide and turmeric to treat cancer
Researchers in the US and China have combined the turmeric spice pigment curcumin and the drug thalidomide to create hybrid compounds that can kill multiple myeloma cells.
Multiple myeloma is the second most common type of blood cancer, killing 20% of affected patients each year. The drug thalidomide, banned after causing birth defects when given to pregnant mothers to alleviate morning sickness in the 1950s, was recently rediscovered and approved for treating multiple myeloma. Thalidomide works by disturbing the microenvironment of tumour cells in bone marrow. However, it disintegrates in the body. Curcumin, a yellow pigment from the common spice turmeric, is also active against cancers, including myeloma, but is limited by its poor water solubility.
Shijun Zhang at Virginia Commonwealth University, US, and colleagues, have synthesised compounds combining structural features from both thalidomide and curcumin. 'The hybrids have enhanced solubility, and higher toxicity against myeloma cells than curcumin, thalidomide, or a mixture of both,' explains Zhang, 'so our design rational is going in the right direction.' Zhang says the hybrids kill myeloma cells through combined mechanisms of action that include the generation of reactive oxygen species and cell cycle inhibition.
'The advantage of the hybrid compounds is that they are stabilised, and do not degrade in the body as thalidomide does,' says William Douglas Figg from the National Cancer Institute in Bethesda, US, who has conducted numerous studies and clinical trials with thalidomide derivatives. However, from his experience, compounds considered for further trials should be more toxic to myeloma cells.
In the meantime, one of Zhang's hybrid compounds has shown activity against myeloma and prostate cancer in animal models.
12:39 - Nerves control prostate cancer
Nerves control prostate cancer
Nerves connecting up to cancers can trigger them to grow and spread, new research has revealed.
Studying prostate tumours in mice, Claire Magnon and her colleagues at the Albert Einstein College of Medicine in New York found that the cancers responded to chemical signals from nearby nerve cells, leading to enhanced growth, invasion and spread of the tumours.
Blocking these nerve signals, either chemically or by cutting the nerves supplying the prostate gland, dramatically reduced the growth and spread of the tumours in the animals.
The nerves in question are the so-called sympathetic and parasympathetic arms of a network known as the autonomic nervous system, which, in general, has a role in coordinating unconscious processes, including bladder control and prostate secretion.
Tumours seem to provoke these nerves cells to grow into them, although, once connected, the effects on the cancerous tissue of these two nerve supplies are different, the team found.
Sympathetic nerves, which release the nerve transmitter nor-adrenaline, stimulated tumours to grow and establish themselves locally. On the other hand, parasympathetic nerves, which release the chemical acetyl choline, seem to make the tumours more likely to spread.
Consequently, it was almost impossible to establish tumours in mice engineered to lack receptors (called beta-2 and beta-3 receptors) for nor-adrenaline, and animals treated with a drug to block acetyl choline were less likely to show metastatic spread of the tumours to surrounding lymph nodes.
At least some of these effects appear to be down to the surrounding tissue, rather than the cancer cells themselves, because in one series of experiments, the team genetically knocked out the receptors on the cancer cells for acetyl choline. This made no difference to the rate of spread. But knocking out the receptors on the surrounding tissue, leaving the cancer cells able to respond, blocked spread.
To discover whether their findings are clinically relevant, the team also examined 43 samples from human cases of prostate cancer.
High grade tumours and tumours that had spread, they found, were much more likely to have a dense nerve supply compared with lower-grade, less aggressive tumour types.
These findings suggest a new way that cancers might subvert healthy tissue into nurturing them.
Moreover, as the New York team speculate in their paper in Science this week, these findings could also provide the foundation for a new therapeutic approach to the management of prostate cancer...
16:11 - Can we store carbon dioxide underground?
Can we store carbon dioxide underground?
Better sites could now be identified for carbon dioxide storage.
The last few decades have seen more research into renewable and greener energy solutions.
One such solution is Carbon Capture and Storage (CCS).
Rather than tackling how much C02 we are producing, CCS is based on the idea that if we can stop the C02 from reaching the atmosphere, it can't contribute to the climate change.
One approach is to sequester carbon dioxide inside porous rocks, like chalk or sandstone. But some sites hold that gas better than other. This new study has been trying to understand what makes a good CCS site.
To find out, a group at Bristol University has looked at three sites in Norway, Canada, and Algeria. Although similar amounts of C02 was stored (around one mega tonne of gas per year), they have all reacted differently.
Using satellite measurements accurate up to one millimeter to monitor movement and geophones to detect seismic waves, the researcher built up a picture of what was happening deep underground and how each site was reacting to gas injection.
By using an array of geophones around the site, some placed in bore holes; the source of any waves could be pinpointed.
Lots of seismic activity indicates a lot of movement and energy. This energy could cause a crack, and depending on where that crack is, the sequestered CO2 could be released.
Originally a site of natural gas, the Sleipner site, in Norway has shown little sign of faults within the rock, though this may be because it is a very large site so even with a megatonne of CO2 being added every year, it is only 0.003% full. Because it used to house natural gas the site has had little problem coping with the pressure of the gas.
Things haven't gone so well at the other sites with the Canadian site showing large amounts of seismic activity, and rock deformities, where areas of rock are raised or distorted from their original shape at the Algerian site.
To make a marked impact on C02 emissions, 30 billion tonnes a year must be stored in CCS around the world. If we can better understand what makes a good site we can begin to reach this target.
For CCS to really work, the gas needs to remain trapped in the rocks for thousands of years. This requires very stable rocks that will not fracture under the pressure of gas addition.
All the sites showed some seismic activity, ranging from low rumbles that couldn't be felt, to tremors in the local area. While no major incident was recorded, it is of course not idea for the surrounding environment to experience these regular tremors. And with every tremor you run the risk of causing a major fault line, possible releasing the stored gas.
The research will improve how sites for gas injection are chosen and will lead to more reliable containment of the gas.
It should be noted that this is not a final solution to C02 emissions. It's a stop gap measure that has its limits. Once the best sites for CCS are filled up what should we do then?
Claudia Efstathiou spoke to the author of the study, Dr James Verdon from the University of Bristol. James Verdon - Carbon Capture Interview
20:24 - World Solar Challenge: Across Australia
World Solar Challenge: Across Australia
with Stephen Pendrigh, Peter Mildon, Cambridge University Eco Racing
Later this year, the World Solar Challenge will see 47 teams from 26 countries racing across the Australian outback from Darwin to Adelaide in purpose-built solar-powered cars. To complete this 3,000-km long journey, the teams have to design a lightweight vehicle that can use solar panels to travel at 80 kph in one of the world's most harsh conditions and terrains. Chris Smith spoke to two members from the Cambridge team, Cambridge University Eco Racing, Stephen Pendrigh and Peter Mildon about their entry.
Chris - First of all, tell us a bit about the race, Peter. How did it get started and how did Cambridge University got involved?
Peter - So, the World Solar Challenge has been going on since the '80s when it was first setup and teams have been entering cars every 2 years since then. Cambridge first entered back in 2009 for the first time with our car Endeavour. We did okay, we were about 2/3 down the packing order at that point. We then did some work to redevelop Endeavour and sent her back in 2011. There was a small improvement but due to some things like bushfires, the race was slightly disrupted and the finishing position was again, about 2/3rds of the way down. So, for this year, we are building a completely new car. We've got a completely new concept and we're hoping that that's going to mean that we can fight for the top step of the podium this year round.
Chris - Fighting talk. Stephen, what's the new technology you're introducing to win you poll position?
Stephen - So, when you're designing a new car, the two main important aspects of it are to look at the solar and also the aero. So, you're looking into the power into the car and the losses out of it. What most cars before do is they try to focus on the solar and increase it as much as they can and then try to fit the aerodynamics around that. What we've done with ours, is we've completely decoupled the two effects and mainly focused on the aerodynamics, and then afterwards fitted the solar cells inside the body of the car inside a clear chassis. Obviously, the actual solar area for this is much smaller, so we've then decided to actually get the solar cells and to track the sun from east to west throughout the day.
Chris - How ingenious! Because when you normally see people, they've basically turned a car into a mobile solar panel to maximise the collecting area, but there will of course be some bits of panel that are not really in the sun at all, so they're just adding weight and contributing nothing. So, you're saying, "Let's go for just a tight light small compact solar collecting area, but make it directional."
Stephen - Yes, definitely. The key point for this is that the efficiencies have gained by about 20% and we're using a much smaller and therefore, cheaper array than what we would've done if we wanted the same efficiency with the same cells outside.
Chris - So, how are you going to track the sun? Have you got the panel at the front of the car, back of the car, where is it mounted and how will it make sure it's maximum efficiency all the time?
Stephen - We're mainly driving from Darwin in the north, to Adelaide in the south and so, the sun will be directly to the north and behind us. So, we have the driver sitting in the front of the car and the majority of the solar cells are behind the driver, basically down a long central pole, and these rotate around that axis, basically going round from east to west.
Chris - So, if they reverse the finishing line are you going to have to do the race backwards?
Stephen - Yes, we actually will have a much bigger problem if we were going back up further north. We will be at slight disadvantage there.
Chris - What's the energy consumption of the vehicle when it's doing 80 kilometres an hour. That's some speed.
Peter - So, around about our speed which is somewhere between 80 and 90 kilometres an hour, we'll be draining about 1 kilowatt. It depends on the time of the day as to how much power is coming in from your array and how much is going to be charging up or draining the battery that we have. So, we do have the battery there to sort of stabilise the total power consumption. So that means, in terms of driving at our race target speed, we're looking at about a kilowatt whereas in the middle of the day, we'll be getting more power in and obviously in the morning and the evening, it will be slightly less.
Chris - So, you mentioned that there's a battery there. How sensitive is it to - if there is a cloud day because I mean in Australia, you should be pretty okay, it should be pretty sunny all the time. But if it does sort of get cloudy or dark, how much will that incumber you?
Peter - We actually have a few people looking into the race strategy and we get weather data in that we can work out what the optimum solution is going to be in that situation. So, our battery has got about 5 kilowatt hours' worth of energy in it. That will allow us to drive at our race speed for 5 hours or slower for a prolonged period of time. If we know that we're going to be in a cloud for the next entire day, we'll probably drive slower whereas if we know that there's sun coming at the end of the day or there's sun further ahead on the road, we can actually afford to speed up a bit, use up some of our 5 kilowatt hours' worth of energy and then get to the sun quicker.
Chris - Stephen, what is the car made of?
Stephen - The majority of the chassis is a carbon fibre monocoque chassis which basically means that the membrane just on the outside can take all the structural loads, and it also ensures that the car is as lightweight as possible.
Chris - How much does it weigh?
Stephen - It's about 120 kg without the driver and then we say, about 200 kg with the driver.
Chris - Do you have to be really small to drive this car like the Cambridge Cox in the boat race? You select for small people.
Stephen - I mean, I'm 5 foot 10 and I can actually fit in the car, not for the race itself. I wouldn't be legal for the race. However, I have driven the car myself.
Chris - It's going to get pretty hot in there, isn't it?
Stephen - It does get very, very hot, yes.
Chris - No aircon on there, so what do you do about that?
Stephen - The heat is very bad for both the driver and also for the solar cells. We have some active cooling so we have fans going through to try to cool both of them down.
Chris - I wouldn't like to be in that car. What about though Peter, the sort of wider implications of this?
Peter - So, I think the key thing also that our powered cars are looking at is again inefficiency. So, if we look at a typical road car, it'll run at about 40 kilowatts. We're driving at comparable speeds on 1 kilowatt, so we're more than an order of magnitude more efficient than a normal car. To put that into some perspective, our battery is quite small. It's limited by the rules. We could easily have a battery 4 or 5 times the size of that, but if we were to drive at around 30 miles an hour, we could go about 800 km with no solar panels on the car whatsoever. And basically therefore, beat most petrol driven cars in terms of range. So, the key thing here is where we're getting the efficiency savings from. If you could transfer them into a normal car, you would see, even if it was still a petrol car, a significant reduction in emissions.
26:39 - Empowerment through solar power
Empowerment through solar power
with Agamemnon Otero
Dominic Ford was joined by Agamemnon Otero, a co-founder of Repowering London and of Brixton Energy, companies which deliver energy to London communities through renewable energy farms that are owned cooperatively by those communities.
Dominic - Agamemnon, you say that solar power can empower these communities. What does that mean exactly?
Agamemnon - Well, in that way, it's power to, for and by the people. The vision is really resilience to provide training and work apprenticeships around solar, but also to create local leadership and draft proofing education, energy switching information. That's what encourages behaviour change. So, the solar panels are just a mechanism which provides a financial revenue stream for the next 20 to 25 years which enables and empowers the community.
Dominic - So, it's got quite an important educational role in that people are learning how to manage a project like this. Presumably, it's also helping them to save money on their electricity bills.
Agamemnon - Yeah, in that way, I'd say that the most vulnerable communities in London and for that matter throughout the UK, pay some of the highest amount for their energy. About 6 million people use prepay cards and they're paying at £300 to £400 a year, more than most people. We're working directly with low income housing throughout London and these project supply the communal areas and reduce the service charge.
Dominic - So, is the money going to the individuals who own these cells or is it all going to the cooperative?
Agamemnon - The cooperatives are on whole housing associations. For instance, in Lambeth, they're on the roof of Park Estate or Loughborough park Park, Brixton Hill and the communal lighting, the elevators, the community centre, the community office, all are being powered by the energy. And so therefore, the energy bill for the overall estate is reduced, and that is passed on by the estate management board.
Dominic - I guess there is uncertainty there though because if you've got a beautiful sunny week like we've had in the UK in the last week, that presumably going to generate a lot of electricity. But then you have other whole months when it's wet across the UK.
Agamemnon - Yeah, for instance today, there was about 280 kilowatts generated on one solar system and so, of the three systems, there was about 750 to 800 kilowatts generated today which is enough to provide 180 homes worth of energy. On sunny days, it can be quite powerful and generate enough for all the residents that live in the buildings where we have solar panels. But on days like Mordor, it still generates a bit of energy. Only when it's dark does it actually stop generating. So, even on cloudy days which we have so many of, we are generating energy. I mean, we out performed last year by 25% on all of our systems, even though it was quite a rainy and cloudy summer.
Dominic - So, how do you pick the communities you work with and how many cooperatives have you set up so far?
Agamemnon - The cooperatives are based on community engagement and so, when people are enthusiastic about renewables and about having a resilient community and they're looking for more than just a way of generating money, but thinking about CO2 reduction and tackling fuel poverty and creating jobs, we are asked to work with them.
The different communities who have come to us have actually come of their own accord. It started outside my house in Brixton and has moved slowly through that from word of mouth from one community member to another. I think the thing to remember about these projects is that while they don't directly reduce individual energy bills, what they do do is provide financial revenue and 20% of the revenue goes back to the community annually for the next 20 years. In that, there's energy switching and draft proofing. The draft proofing can make 40% reduction in the energy bill and on the energy switching, you can also make savings of 30%. So overall, savings can be up to 70% of the energy bill.
Dominic - So, I guess my instinct would be that enviromental concerns tend to be quite a middle class worry and that perhaps some of these communities who are in fuel poverty, it wouldn't be top of their list of concerns. But you seem to be saying that these communities are actually coming to you for help.
Agamemnon - It's amazing how you can think these things up in glass towers and the uptake is not successful. But the whole process of making it a cooperative which is an iterative process because everybody has to come together and say, "This is something we believe in. This is something we want." And to have something, they have to have a vision and that's pretty much a scoping exercise that happens throughout the process where we have energy surveys to find out, what are the needs of that community. And in that way, they have come to us to say, this is what we want to do and there's been a real big push for young people, especially in Brixton where the first projects were, with the riots there wasa real question around, 'hooded youths' who are perpetrating all these bad things on society. When actually, there are young people who are incredibly intelligent and want to be a part of society and they have been engaged through the internship process.
We have a 15-week internship process and then they do paid work experience on the roofs to work with contractors, putting in the solar panels. So, that has got some of the most amazing community activists - people who've been working for 30, 40 years to say, "Come, please, work with our young people. Let's try to create a system together, co-produce something, which can engage, not only the young people, middle age people who are out of work, maybe working in electrical engineering, but also, vulnerable elderly, about how to be able to use our boiler systems and reduce our energy consumption."
Dominic - It's obviously great you're giving them that opportunity. Very quickly, are you looking to start more of these cooperatives and is there somewhere where people can go to find out more?
Agamemnon - Yeah, we've got a bunch of projects in the pipeline, but right now, we have our third project which is on the Roupell Park Estate and it's open for investment. You get a 50% tax back and there's a 4% return, and you know that it engages and empowers communities with work apprenticeships and paid work experience. So yes, if people want to invest, go to repoweringlondon.org.uk and it's a non-profit, and they can become part of the next cooperative
33:34 - Green Solar: the power of algae
Green Solar: the power of algae
with Bob Lovitt, Swansea University
We've all got an image in our head of solar panels comprising of rows and rows of shining blue sheets, but can algae, which naturally harvest the sun's energy for their own energy needs, offers a more natural alternative to solar power? Dominic Ford was joined by Bob Lovitt from Swansea University who worked on this very problem through a European project called enalgae.
Dominic - Now first of all Bob, why algae in particular?
Bob - Algae offer a very productive way of capturing light and converting CO2 into biomass which can then be used in a number of ways to make energy or chemicals and so on. Compared to normal green of plants, they're very productive, people say of the order of 10 times more productive. So, if you think about a unit area of land, these organisms will produce significantly more amount of biomass compared to say, normal green plants.
Dominic - So, once you've used the sunlight to grow this mass of algae, what do you actually do with them?
Bob - That's a very interesting question because there are lots of things you can do with them. You can basically dry them and burn them to get you energy back as heat or you can refine the materials into protein, as a feed, then use those to generate energy, or you can actually sell the algae as feed for fish, and things like this in farming situations.
Dominic - I guess when I think of algae, I think of blooms in the ocean and if I remember rightly, there was a massive bloom in China just before the Olympics a few years ago. Why are you growing it in farms rather than just fishing it out of the ocean?
Bob - Normally, when you get algal blooms, the first is that they can be very harmful. A lot of algae of the wrong sort contain toxins and these toxins can be - if you've got a water say a desalination plant and you want to make drinking water a sea water, if you have these algal blooms, they can actually contaminate the water and cause really serious problems. Also, if you look up in the natural systems, they're mixed systems. They're basically naturally selected and consequently, are optimal maybe for growth in those certain conditions, but they don't make the products that make potentially more value out of the algae.
Dominic - I guess, any solar-powered generation scheme, what's important is how much sunlight you're collecting. So, I presume - have you got a farm somewhere with a huge collecting area of sunlight?
Bob - We basically are working in what we call photobioreactors. These are contained systems as opposed to raceway systems which is another way of doing it. Basically, large areas of water, looking like canals about 30 cm deep. At this stage, 2 or 3 hectares of these are used to generate the algae. We go for photobioreactors which are different. They're basically pipes. They're slightly more efficient in the way they operate and we can contain the algae themselves in a much better way and control what we're doing with them. Raceways are far more open to contamination. You can get a duck swimming across the top of the algal pond and so on. This means that as like any other farming process, if you get contamination, you have to control that and so, within a raceway, there are a number of problems associated with that which you can avoid if you go to a photobioreactor.
Dominic - You said at the start that algae are much more efficient than other forms of biofuel. What's the difference between covering these 2 or 3 hectares with algae versus planting crops that you might then go and burn?
Bob - The main differences are, that you would need to supply the nutrients that they require far more intensively. This means that we need sources of carbon dioxide like power stations. We need nutrients like phosphate and ammonia, and another nitrogen sources which we get from sewage wastewater treatment systems when we're cleaning up the water, remove the nitrogen phosphorus. What we can do is integrate these processes to effectively combine the waste products if you like of these processes to make algae. The fact is, what we're doing, by integrating with waste processes, at the same time, we can make much better use of nutrients and so on.
Dominic - You're killing two birds with one stone. You're dealing with the CO2 and you're also getting useful energy out of it.
Bob - Yes.
Dominic - How do you harvest energy out of this at the end?
Bob - There's a number of ways in which you do that. Basically, the calorific value of algae is about - I think it's 28 mega joules per kilogram - something like that. If you burn the waste, that's what you get in the calorimeter when you burn algae. If you think about it, that energy is the raw energy, but what you're also doing here is you can make carbon materials which replace other forms of energy if you like. If you're going to make plastics and so on, you start with a fossil carbon. You can substitute that carbon from algae into those manufacturing processes. So, you effectively save a lot of energy that way because you're using the embedded energy that's fixed in the organisms to make substitute for other energy forms really.
Dominic - Am I right in thinking that the facility you got at the moment is actually a test. How are you going to scale that up to industrial production?
Bob - The way we're doing this is that we take what we call a biorefinery approach which is that you cannot expect to make money from the energy that you're capturing using the algae. If you look at the amount of energy you put into the system compared to the amount of energy you get out of it, i.e. the energy put in is things like the ammonia you need, the pumping power you need and so on to move the liquids around, and you compare that with the energy you get out of the system then what you find is you're around 1.3, 1.5 energy return. In other words, you're not making a big energy surplus, but what you are doing is fixing CO2 and you're making chemicals from that, effectively very little energy releasing CO2. So, you've got a low carbon way of doing things.
Dominic - So, you're essentially making the power stations cleaner which are providing the CO2 to the process.
Bob - That's right and then the other approach we're taking is we're taking things like anaerobic digesters and you take the waste products from an anaerobic digester that's maybe setup in a combined heat and power system where you basically take waste materials, you digest them and you make the methane. We can then burn the methane in an engine and then we can take the CO2 from that engine and put it into an algal bioreactor.
At the same time, we can then take the residuals, the nitrogen phosphate residuals from the anaerobic digester, and we can put that into the reactor, and so, you then generate all the nutrients basically from the anaerobic digester. So effectively, what you've done is you've recycled a lot of the waste nutrients back into the algae. We can then refine the algae, basically remove the protein and we can make animal feed or something from that protein while the rest, the remaining waste material can be put back into the digester.
So, what you're doing here is you're using a lot of waste materials that need to be removed from the environment anyway and certainly, anaerobic digestion is now being seen as the way to get rid of food waste, rather than put it in landfill and things like that. So, you need another technology then on the end of the anaerobic digester to absorb the nutrients and then make new materials which then go back into the system to make food. So, you've basically closed the loop on the whole process of nutrient flows in the environment.
41:46 - Magneto-hydrodynamic Solar Energy
Magneto-hydrodynamic Solar Energy
with Douglas Chrisey, Tulane University
How can we make our current solar panel technology more efficient? Chris Smith spoke to Doug Chrisey from Tulane University in New Orleans who is developing something called Magnetohydrodynamic Solar Panels. Sounds like a bit of a mouthful, but let's find out how it works.
Doug - A magnetohydrodynamic generator is quite a bit different from a photovoltaic. In a photovoltaic, you're taking a narrow slice of the spectrum of solar radiation and converting that directly into electrical power in a solid state, and you usually get about 20% efficiency. With magnetohydrodynamic power generation, we want to take that solar radiation and concentrate it to a high temperature and create a plasma. A plasma that will be send through a magnetic field and the magnetic field will separate the positive and negative charges, and we can get about 60% efficiency.
Chris - Wow! That's quite impressive. So, can we just look at how this works then? You've mentioned there are photovoltaic cells and you said when photons of light hit those, they'd cause charges to separate. You're doing it slightly differently. You're heating something to make a plasma where you have charged particles. So first of all, what are you heating to make the plasma?
Doug - We're heating a channel that contains the gas that has material-like caesium that's easy to ionise and then we take that hot gas and send it through an expansion nozzle through a magnetic field and at that point, we can take and produce the plasma, and separate the positive from the negative charges.
Chris - So, as the gas is going through that nozzle, and you've got this positive and negative charges because plus and minus charges are sensitive to a magnetic field. They can be guided in one direction or the other. Meaning, you can presumably push them onto a conductor which becomes negative and another conductor effectively becomes positive and then you've got an accumulation of charge with the potential difference.
Doug - That's correct.
Chris - So, how does this actually then get deployed? How do you get the light into that channel and how much energy can you make this way?
Doug - Well, the amount of energy you can make is just dependent on how much radiation you take and focus on this channel. So, the direct answer to your question is it's very scalable. It can be a small size or it can be large. We envision something as small as what would fit inside perhaps a container, like on a container ship. So, that's so relatively large. But still, that's still easily deployed to different locations like natural disasters or war zones, or developing countries. So, it's a nice way to have power right away. By the way, once the sun goes down and photovoltaic stop working, we can take and heat this channel and we won't have as much efficiency, but we'll still generate power. But it is the 60% efficiency that makes this technology very exciting.
Chris - How easy is it to actually construct an array of these so that you could then produce a big array to provide power for an environment, or a factory or something like that?
Doug - Well, as a scientist working in a lab, just engineering between the lab and actual applications. So, I'd like to say it's easy, but this technology has been around for some time and what we're doing is just a little bit different. We're trying to improve this efficiency, actually reach the maximal efficiency by using superconducting magnets, high temperature superconductors that have trapped magnetic field in them, and as such, reaching very, very high overall magnetic fields on the order of 17 tesla. So, in doing that, we want to put those magnets very close to this very, very hot plasma, essentially, liquid nitrogen temperatures right next to something that's ½ as hot as the sun.
Chris - That's quite an engineering challenge, isn't it? So, how are you doing that and stopping the very, very hot thing, making very, very cold thing become very, very hot?
Doug - First of all, the materials we use have to be special and it is very difficult. It's a real stacking of functionalities here, in terms of needing refractory materials like ceramics as insulators, but also, electrodes made from something like platinum, something that would survive these high temperatures. But to get something very cold next to something very hot, we need to have a lot of special thermal isolation and to do that, we're using some technologies that are currently being used for electronics such as microchannel cooling. If you make the channels of the material extremely small, they have a very high surface and then can take and absorb any of that heat, and take it away so you don't warm up your magnets. Warming up the magnets was something that was found with this approach from long ago. If you warm up a conventional magnet, it will destroy the magnetic field as well.
Chris - If you've got caesium at very high temperature, is that not risky?
Doug - It's a dangerous material, that's correct, so I'm not going to discount that, but it is a closed cycle system. If it were to break and expose it would hopefully react very quickly and become an oxide, and become harmless.
Chris - What would be the cost because one of the things that obviously drives this whole market and determines whether people will use this is what it costs? The present generation of photovoltaics are pretty pricey and they're pretty heavy. How does this device compare?
Doug - I'm just not going to put a number on it. All I want to say is that this approach should last basically forever except for the expandable parts. Photovoltaics are lasting a lot longer than we thought. Let's say, 20 years or upwards of that and that's very good. So, this will last longer than that, but will be advantageous because of the 60% efficiency. So, whatever the final cost is, it will be amortised over that long lifetime and that improved efficiency.
Chris - Is another advantage, not that photovoltaics also increasingly are making use of extremely rare and therefore, extremely costly materials which at the end of the day, we're not going to have as many of them or of them we use whereas if you're using something which is relatively simple like caesium, then actually, you're not going to face that same challenge?
Doug - That's absolutely correct and that's a challenge with many high tech materials these days, be it thermoelectrics, photovoltaics or whatever. We have to start thinking about how we're going to use it, how we're going to recycle it, and how much that adds to the cost. It's a really very good point.
Chris - And dare I ask you, when you think you'll surmount the various difficulties that you're currently trying to overcome?
Doug - With sufficient funding, we're hoping to start hearing more about it. Let's say, hearing more about it in 3 to 5 years, but seeing it deployed as readily, I don't expect it to be before 5 to 10 years.
Could dark matter be failed stars?
Dominic - Yes, he's basically right, and we did have to move very fast in that interview because dark matter is a vast subject.
There are whole books written about the topic, but, Catherine was saying, there was clearly something in our galaxy that has a lot of mass to it, but that we can't see that isn't producing the light.
Now, in the past, people have thought that could be failed stars, that could be black holes, but if it was in the form of compact objects like that you'd expect those objects from time to time to pass in front of stars in the night sky. And that's actually detectable phenomenon. It's called microlensing and there are surveys looking for it. And while we have seen that phenomenon happening, it's quite rare. That tells us the number of those compact bodies is quite small.
So, most of these mass must be in another form which we think is quite diffused and that's these WIMPs that Catherine talked about. We don't know what they are, but that's what Catherine is going after to identify.
Chris - WIMPs?
Dominic - Weakly interacting massive particles!
Can allergies cause coronary artery disease?
Chris - This is an interesting question. You have to be very careful how you phrase the statement because there's a difference between association and causation. Does having an allergy cause heart disease or does one go hand in hand with the other? At the moment, we can't say. One study that was done and it was done by a guy called Jongoh Kim. He's at the Albert Einstein Medical Centre in Philadelphia and what he did was to look at some data that are being collected for a nutritional study and they'd asked people whether they have allergies and rhinitis - that means runny nose, itchy eyes. They'd also looked at whether people had cardiovascular disease, but they haven't actually looked at the correlation between the two and that's what he did. It turned out that people who had reported symptoms of allergy like hay fever or wheezing, had a 2Ã?,½ times greater chance of also having or developing heart disease. Now, that may suggest there is an association between the two; it doesn't tell us that allergies cause heart disease. But it might be linked by inflammation because we know that heart disease is an inflammatory condition of arteries and we also know that diseases or conditions that increase the overall inflammation in the body accelerate cardiovascular disease. Gum disease is strongly linked as a risk factor for heart disease, probably because if you have inflammation going on in your gums, you secrete into the bloodstream various inflammatory stimuli and inflammatory mediators, and this triggers the process of inflammation in the walls of arteries and accelerates arterial disease. It may be that the periodic inflammatory bursts you get with things like wheezing, asthma, hay fever, also increase the general inflammatory tone in your body. And therefore, if there is atherosclerosis - arterial damage - going on, this is going to accelerate a bit in people with those symptoms who also have a risk of heart disease; therefore, you see that association. But, it's one study and no one has yet got quite to the bottom of it. Dominic - I guess it's very difficult to distinguish causation from correlation.
Chris - Well that's exactly right. This is an association. To prove causation, you've got to show there's a dose-dependent effect, for starters. So, you'd have to show that people who had worse allergies had worse heart disease and I don't think that's very easy to do...
Does light bounce off the walls of a room?
Dominic - Well, I think the important thing to remember here is that light travels incredibly quickly at about 300,000 km every second. So, that's far enough that it gets from the sun to the Earth in about 8 minutes. Light certainly does scatter off all sorts of different surfaces, but when you got light on your ceiling, that will be illuminating your walls, but your walls appear bright because the light is scattering off those walls, and they'll for example preferentially scatter some colours more than others. So, the walls in the studio look blue because they're scattering the blue light from the lights above us, but they're not scattering the red light. But they're doing that so incredibly quickly that when you turn the lights out, within about 100 millionth of a second, all of that light has been absorbed into those walls as heat and so, the room is dark. So in fact, when you turn the lights out, you'll see the light gradually fades because the elements in those lights which are gradually cooling down. And that's a much slower process in how it takes for light to travel around the room. Chris - So, if I did have a camera that was sufficiently fast, I would effectively see what's being suggested, but because our eyes aren't sufficiently fast, it appears to us as though it goes dark instantly.
Dominic - Yes and I think about 18 months ago on this programme, Dave Ansell had a news story where somebody had made a camera that could take millions of frames a second and by doing that, you could actually see light ricocheting around the room.
How can we get power from poo?
Hannah - So, should we lay cables courtesy of the colon? First up, we asked Dr. David Waltner-Toews, author of the Origin of Faeces, is it possible to go fracking for faeces?
Waltner - The energy content of dry manure is about 50% that of coal. Right now, the most efficient way to get that energy is to run the manure to something called an anaerobic biodigesture. So, the manure is running to a contraption where certain bacteria in the absence of air will capture methane from the manure which would otherwise be just released into the environment. That methane can then be burned directly. It can be burned for running trucks, for running machinery, or it can be used to generate energy in a secondary process.
Hannah - So, it is possible to get power from poo. Do we currently actually do it though? We delve into the data.
David - My name is David MacKay. I'm the author of Sustainable Energy Without the Hot Air. I'm the Regius Professor of Engineering at the University of Cambridge and I'm the Chief Scientific Adviser at the Department of Energy in Climate Change. Looking back in 2006, one of the biggest forms of renewable energy in the UK was collected from methane gas coming from landfill sites and from sewage. The scale of this in 2006 was about 0.3 kilowatt hours per day per person coming from all forms of waste and that made it the biggest renewable at that time. Since then wind has overtaken incidentally. How does that compare with total energy consumption? Well, total energy consumption in all forms for transport heating and electricity is about 125 kilowatt hours per day per person. So, we do produce power from poo, but it's not as big as our total power consumption at all and there's no way it could be that big either because if you think about how much food you eat, the energy in the food you eat is about 3 kilowatt hours per day per person. Obviously, the energy coming out in your poo has to be a bit smaller than that.
Hannah - So yes, poo does produce power, but we currently consume more energy. So, also look at the wind amongst other places for other sustainable sources of power. Well, making a movement with our next question.