Filling Up with Algae

28 June 2009

Interview with 

Anna Stephenson, Cambridge University


Helen -  Now, electric cars are not the only option we have for sustainable personal transport.  Already, there are a number of vehicles on the roads that use biodiesel and that's diesel that doesn't come from fossil fuel but from living creatures, from living plants.  Now, Anna Stephenson is a PhD student at the University of Cambridge and she's looking at alternative ways to meet the demand for biodiesel.  So Anna, hello.  Thanks for coming in to the studio.

moss bioreactorAnna -   How's it going?

Helen -   And first of all, could you tell us what are biofuels and why do we need them?

Anna -   Okay.  Well, the idea of a biofuel is that you might be able to get it to be carbon neutral and this is because when you burn carbon which is a plant, it's carbon which is being stored or fixed during the life of the plant.  Therefore, when you burn it, you're releasing the carbon dioxide which is being fixed during its life and therefore, it's not releasing carbon dioxide which has been stored underground which is what you do when you burn fossil fuels.

Helen -   So that's really old carbon, isn't it?

Anna -   Yes.

Helen -   It's fixed...

Anna -   Yes.

Helen -   ...millions of years ago.  So, we kind of don't count anymore but...

Anna -   Yes, precisely.

Helen -   ...doing it sort of in a neutral way by absorbing it and then releasing it in a sort of short space of time.

Anna -   Yes.  So it then contributes to global warming.  That's the idea but in reality, biofuels do require many inputs which are in the form of fossil diesel or things which have been made, using fossil energy.  For example, fertilizers and also, in fertilizers are added to soil, they release nitrous oxide which is a very potent greenhouse gas.  So, in reality are not carbon neutral but the aim is to be able to make carbon neutral biofuels.

Helen -   So that's what we're kind of working towards.  So I believe there was what's called the first generation of biofuels, wasn't it?

Anna -   Yes.

Helen -   And so, that's really the sort of crops that we could actually eat, things that produce oil like grape seed and soya, is that right?

Anna -   Yes.

Helen -   And there were lots of problems associated with those kinds of crops weren't they?

Anna -   Yes, there were many problems.  For example, palm oil is the main oil which is used in Malaysia and Indonesia and because of that, a lot of rainforests are being chopped down, and killing orangutans but also, releasing loads of carbon dioxide and actually, contributing a lot more to global warming than the actual saving of getting from using the biodiesel.  Also, there are issues to do with competition with food crops for land.  So, power in biofuels really have a long way to go.

Helen -   It is now talk about here we should be using that land for food and you know, that's not really a fair use of it.  So I think, at the moment, it seems quite a lot of bad feeling about biodiesel really, isn't there in the press and so on.

Anna -   Yes.

Helen -   But we've got a second generation we're working towards...

Anna -   Yes.

Helen -    ...a new way of doing it.  What does that involve?

Anna -   Well, at the University of Cambridge, we're doing a lot of research into biodiesel from algae and algae have got a high photosynthetic efficiency which means that we can produce a lot of oil from the sunlight, and this oil, we can then turn into a biofuel.

Helen -   And so this, it's seaweed, is it?

Anna -   Yes.

Helen -   The kelps and things like that or different types?  What sort of species can we use for these sort of things?

Anna -   There are many different types of algae but they're mainly macro algae and micro algae species and in Cambridge, we're mainly focusing on micro algae which is single cells, but in other areas, we're also looking at large macro algal species in a form of kelp, so seaweed.

Helen -   Are they all salt water species or ...

Anna -   No.  They are both fresh water and salt water, but obviously, that's the advantage that if you're using sea water, then you don't have the issues associated with using a lot of fresh water and that benefit...

Helen -    Because that's another problem, isn't there?  With sort of the first generation of biofuels is that they use lots of freshwater and that's another limited product really in the world and...

Anna -   Yes.

Helen -   ...we might need that for other things as well.

Anna -   Yes.

Helen -   And another reasons why using algae is maybe a really likely way of creating good and carbon neutral biofuels in the future.

Anna -   Yes.  Well, the other thing is that you can produce significantly more oil per hectare, using algae, rather than landbased crops.  And this is because you're not producing the leaves and the stalks and all these things which associate with land based crops.

Helen -   How do we actually grow - I'm sorry.  I can't try and imagine.

Anna -   Yes.

Helen -   Can we sort of putting them in ponds or how are we doing it?

Anna -   There are two main ways of growing them.  Either in ponds like large raceway ponds.  That's how it's mainly grown and harvested because at the moment, algae is also used as a food source.  People eat it.

Helen -   Sorry?

Anna -   People eat.

Helen -   Yes.  Do they?  Really?  Goodness.  Okay.

Anna -   Yes.  But you can also use closed systems which are called, 'Photobio reactors.'

Helen -   It's a big kind of just sort of very big containers really.

Anna -   Big fish tanks basically...

Helen -   Right.

Anna -   ...which have got CO2 bubbling through them.

Helen -   Right.

Anna -   And that they have the benefit because you won't have competition from other algal species because if you've got a large pond then other species can get in and overtake.  But the thing is, you needed quite a lot of material and there's energy associated with producing that material for a tank.  So, there are benefits for each.

Helen -   So you really got to look at that whole balance between what you're using and what you're getting out of it.  And how do you actually create biodiesel from the algae?  How do you go?  You can't presume you can't just sort of squash it up and then put it in your car.

Anna -   No, no.  So, it's the same as conventional biodiesel which is an esterification process with methanol.  So what you do is you get your algae and you grow it under specific conditions to be able to produce an algal lipid or an oil and really, what we wanted to try glyceride oil.

Helen -   That's a type of fat, isn't it?

Anna -   Yes, a fat.

Helen -   It's basically a type of fat.  Right.

Anna -   And then you have to remove the fat and there's a lot of research into trying to do this in an energy efficient way because the thing is, there's a lot of water which is with the algae.  And so, we want to have an extraction process which will be able to do this energy efficiently and not have to remove all of the water in, for example, in a step which requires a lot of heat.

Helen -   Right, because it's all about trying to make this as efficient as possible.  So we can actually achieve that goal...

Anna -   Yes.

Helen -   ... of being carbon neutral.

Anna -   Yes.  I mean, what would be ideal is if you could grow algae to have a really high lipid content of maybe 60% and if you were able to light small holes in it and then let the oil just go out into the water and have it set for its layer of water and oil and then if you were able to extract the oil in that way, then you won't need to remove all the water using fossil energy.  And so, then you have your oil and you use esterification standard process to produce the biodiesel.

Helen -   So these are all things we're working towards?

Anna -   Yes.

Helen -   And just very quickly to run that up, in all likelihood, when do you think we might see these actually being used, these algal based biodiesels?

Anna -   Well really, it's in its infancy at the moment.  I'd say in 10 to 15 year's time.

Helen -   And so, not too far off but we still got a bit of a weight at this.

Anna -   Yes.

Ben -   Anna, you've just been talking about how we can use algae to make biodiesel.  But one thing you said was that we need them to be as fatty as possible.

Anna -   Yes.

Ben -   How do you make that happen?

Anna -   Well, there are many different species of algae available to us, just to naturally occurring species and there are many species which are fast growing and many species which produce lipids and there's a lot of research into finding the ideal species which is both quick at growing and also, will produce a lot of fat.  So, that's the research which is going on at the moment.  There is the potential that genetically modifying different species as well, but obviously, that has issues associated with it.

Ben -   But it does seem that if you can find the gene that says, you know, "I make lipid."  And express it as much as possible in whatever species of algae you've chosen.  Then you should be able to make some in this really efficient and really could make an awful lot of biodiesel in a very small space for relatively little cost.

Anna -   Yes, that's the plan.

Ben -   Wonderful.  Well in fact, there were buses in Cambridge that run on biodiesel, I  know that much.

Anna -   Yes, there are.  Yes, indeed.

Ben -   And I know that where I used to live in Aberystwyth when I was a student at the University of Wales Aberystwyth, there was at least one van that was clearly running on homemade biodiesel because as it went past, it smelled very strongly of fish and chips.

Anna -   Fish and chips.  You do hear about sort of people going to the fish and chip shop and asking for old, used oil and putting that into their cars which works on a small scale but obviously, we can't do that everywhere.  Otherwise, all we'd ever eat was fish and chips, I think, wouldn't it?

Ben -   And we did report on the Naked Scientists a little while ago that using oils extracted from coffee to do the same thing.  So, that would actually smell really nice.

Anna -   I'd just be wanting to drink coffee all the time walking past coffee shops and just feeling the need for coffee.  That would be terrible.

Ben -   Anna, would the algal biodiesel smell of pond perhaps?  Smell of nice freshwater in sunny days?

Anna -   No.  I don't think so because once you've extracted the oil then it won't have any of the algal remnants left apart from the oil.


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