Podcast: Turning algae into biofuel

Lars Brunner with seaweed

10 December 2013 by Richard Hollingham

This week in the Planet Earth podcast, Phil Kerrison and Lars Brunner from the Scottish Association for Marine Science explain how seaweed could be cultivated to fuel a power station, your car or even aircraft.

To assist those who find text-based content more accessible than audio, a transcript of this recording is available below.

Richard Hollingham: This time in the Planet Earth podcast, could seaweed become a viable economic crop. I'm Richard Hollingham and I'm in Oban, the Scottish Association for Marine Science where they are growing seaweed. I'm surrounded by hills and mountains and woodland just to one side, with a stunning view out across the sea, and I'm in a sort of outdoor laboratory really with a series of, I suppose, oversized bathtubs, fibre glass bathtubs, uninviting bathtubs because they are full of different varieties of seaweed. And I'm with Phil Kerrison and Lars Brunner.

Now, Phil, just explain the sorts of seaweeds you've got in these tanks.

Phil Kerrison: Well we've got a number of different groups of seaweed here. We've got the green species which you commonly find on seashores called sea lettuce. We've also got another one called Palmaria palmata, commonly called dulse and also we've got some large kelps which grow up to two, two and a half metres long.

Richard Hollingham: In fact let's go and look at one of those because they are quite impressive, if we head over to one of the larger tanks here. Wow! That's way bigger than a rhubarb leaf, that's big banana leaf size.

Phil Kerrison: Oh yes, it's incredible how big they can reach. I mean these ones they're allowed to grow for four months and they were reaching up to two metres long, so they've got incredible growth rates.

Richard Hollingham: This kelp here, it's what you would expect, it's slippery and slimy and when you hold it up it's a brown, almost golden, translucent with the light going through it. If you get over the sliminess it's quite attractive isn't it?

Phil Kerrison: Well you could say they're beautiful. They're really common all around the UK and you can find them whenever there is a good low tide, you can see them just at the bottom on the water just peaking up from the surface because they life just in that area, that sub-tidal area.

Richard Hollingham: What's the ultimate purpose of this? Why look at the growth of them and the cultivation of them as crops?

Phil Kerrison: There are various uses that could be made of seaweed. They've been gathered naturally for centuries all around the UK and all around the world for various uses for things like fertilizer, for fuels, for animal feed but now we're looking, as well as those continuing uses, we're thinking of other uses such as bio-fuel.

Richard Hollingham: So that would be turning this stuff, this slimy ribbony material into something you could, I don't know, stick into your car or your aircraft or power a power station with?

Phil Kerrison: Exactly. Just like more traditional bio-fuels like the land crops that are converted into fuel into ethanol and things like that, these have a very high sugar content and that's absolutely perfect because then that can be converted into a fuel which, as you say, you can then pour into your car.

Richard Hollingham: You can't though have a field of kelp or can you have a field of kelp?

Phil Kerrison: Well, yes you can. There's a lot of space just off the coast which is unutilised and all of it, or much of it, could be used for large cultivation fields. It grows naturally in very dense stands with high density in small areas so what we're looking at is creating false seabeds out in the ocean where we can let these crops grow after we seed them.

Richard Hollingham: What about the economics of doing that because it is rather different to planting, I don't know, a field of corn that you can turn into a bio-fuel. It's not really a field is it when it's under water in a relatively isolated place, where in the best will in the world the west coast of Scotland in winter is not the most pleasant place to be.

Phil Kerrison: Well, yes, you will always have problems, or you could have problems accessing these crops because you have to go out on ships to go and harvest them, so to make it an economical crop you would have to grow it at very vast scales and we're talking hundreds of kilometres squared in a large cultivation area.

Richard Hollingham: Let's bring in Lars here, because one of the down sides of doing that, as with traditional agriculture, is you have a mono-culture, you have one thing, but you're looking at ways where actually you can mix perhaps the kelp or a seaweed with everything else in the sea.

Lars Brunner: Well this is some of the work that I'm involved with now revolves around a concept called 'integrated multi-trophic aquaculture - IMTA to be a little bit more snappy. The principle of this and it's an idea that has been applied in several different places around the world all ready, is where you have an existing monoculture of one species. So, for instance, you have salmon growing in cages they will produce waste, they will produce two types of waste. They will produce solid waste that will sink to the seabed as well as defused waste which will move off in the current. If you can find other species that can utilise those wastes, be it seaweeds, for instance, will pick up a lot of the defused nutrients in the water and other species that we cultivate here, urchins, sea cucumbers, can potentially utilise the solid wastes that are produced. You have more species to put to market. You reduce the waste that puts into the local environment and it's a win-win situation all round.

Richard Hollingham: So that's like a mixed crop, all in the same place though?

Lars Brunner: The idea initially would be that it would all be in the same place, the seaweed would be grown adjacent to the salmon cages to utilise the waste and you would also have your other species growing around and about. The advantage of this as well is that you would utilise a lot of the existing infrastructure of the fish farms, so you perhaps don't have as much expense using boats, for instance, time spent with staff and things like that actually putting material out and collecting it. At times when you are not utilising it for other things you can use the staff and the facilities to be harvesting your other crops.

Richard Hollingham: Phil, let's have a quick look at some of these other seaweeds here. These are more seaweeds than kelp in these... well, I mean these are dustbins aren't they, these are plastic dustbins full of different seaweeds and you've some larger round tank, almost like outdoor aquariums here and they're bubbling away, presumably you are bubbling air into those.

Phil Kerrison: What we're doing here is we're cultivating them with constant aeration to keep them moving and these species we're looking at, unlike the kelps which grow from a particular point and grow out, so you just can't split them apart and they will carry on growing, these ones you can rip them in half and then they will regenerate and carry on growing. And in this tank here we've got Ulva lactuca sea lettuce; it's a very thin species-

Richard Hollingham: That does look like lettuce that with a more mossy deep green colour and again hold that up to the light, it's quite beautiful isn't it, it's the sliminess that perhaps puts me off but actually the structure of it and the colour of it... so what could this potentially be used for?

Phil Kerrison: Well you can eat it just straight away. You can have a taste of it now, it's quite nice.

Richard Hollingham: Okay. Really?

Phil Kerrison: Yeah. Or you can put bits of it in soup.

Richard Hollingham: It's all right. It's a bit like salad leaves, it doesn't overly taste of anything. But you would see this, what, as an alternative to lettuce or as something to put into soups and things?

Phil Kerrison: Well, yes, it can be used fresh and used in various dishes. It can also be dried and applied into food as well. It's got a very high protein content, so it's very healthy as well. Just over here in another tank we've got a dulse-

Richard Hollingham: I'm not sure whether to put this down or put it into my mouth, I'll put a bit more into my mouth.

Phil Kerrison: This one here is dulse, a red seaweed; it's got a very different structure.

Richard Hollingham: That is beautiful, really, with these little fronds and almost leaf-like and very red ends to them.

Phil Kerrison: Well, yeah, that's where it's actively growing and you can see where it's growing out and it is constantly regenerating all over the piece and we can just keep on bubbling these and they will carry on growing and growing.

Richard Hollingham: So what would that be used for?

Phil Kerrison: And, again, this has been used traditionally in food for centuries, so we're moving back towards their use as a food supplement now.

Richard Hollingham: And the challenge here is to scale it up a bit and to get the economics right of it?

Phil Kerrison: The method at the moment if anybody wants to go, you can go down to the shore and harvest it yourself but to do that at a scale where it becomes economical is quite expensive because the manpower needed to go and collect the seaweed from the shore, so what we're looking at is culturing it in very large vessels, like 50 metre cubed of water with constant aeration where these seaweed would be constantly growing and you could constantly remove seaweed to keep harvesting throughout the year.

Richard Hollingham: So really, Lars, together this has got considerable potential?

Lars Brunner: It has for somewhere like the west coast of Scotland. These are new novel species that are native to this part of the world that we can use in this part of the world in aquaculture. And again it's new concepts and we're at the stages where these aren't hugely... cultivation isn't taken on a wide scale at the moment but by doing the research at the beginning just now we can push this on and we can provide the answers to commercial partners who what to take this on in the future and grow them, and 10-20 years down the line potentially you have this concept that will provide more products, potentially more employment on the west coast of Scotland.

Richard Hollingham: Lars and Phil, thank you both. We will of course take some pictures of this outdoor laboratory here and its stunning location near Oban on the west coast of Scotland and we will put those on our Facebook page. And that's the Planet Earth podcast from the Natural Environment Research Council. I'm Richard Hollingham, thanks for listening.