Feature: Beyond the hype of algal biofuels

The promise of biofuels from algae is undoubtedly compelling: replacing carbon dioxide-belching fossil fuels with a clean and (literally) green alternative that will even eat some extra carbon as it grows. The picture is enticing, the hype is almost unbelievable, but so far that is all we have: hype.

At the BioProcessing Network Conference in Adelaide in October, David Lewis, a no-nonsense chemical engineer and relative newcomer on the algal biofuels scene, cut through the hype and clarified the reality of the promises, and left the audience with more than a little hope about the future.

Also read about Associate Professor Ben Hankamer's research on biofuel production from microalgae at the University of Queensland.

David Lewis was introduced to algae during his PhD, which he spent working out ways to control the unwanted blue-green algae in drinking-supply reservoirs. He subsequently took up an academic position in the School of Chemical Engineering at the University of Adelaide and stayed with algae as the basis for his research program.

However, being a good chemical engineer, his thinking shifted to converting this raw material into real products and culminated in Lewis setting up the Microalgal Engineering Research Group within the School in 2003.

The group’s first project involved turning algae into feedstock for aquaculture, which is an important and growing industry in Australia, particularly so in South Australia, with the established oyster and burgeoning tuna farming industry.

“One of the bottlenecks in aquaculture is the production of live feed,” says Lewis. “So we were looking for different ways to optimise the growth of algae for this purpose.” In undertaking that project, Lewis learnt lots about the composition of algae, including one interesting thing he didn’t previously realise: these tiny plants are chock-a block full of oil.

By 2007 Lewis had built up quite an expertise in algal chemistry and was invited to attend a workshop in the U.S. on the future of algal biofuels, which was just taking off at that time as a tangible idea.

“At the workshop, we were put in working teams with other scientists from all over the world, and the one I was in decided that yes, we would all go ahead with this because despite being high risk, it was topical, and it was the right time.”

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At the same time a funding opportunity came up from the Australian Government – namely the Asia-Pacific Partnership (APP) – whereby several countries including Australia joined together to invest funding for research into CO2 mitigation.

Together with colleagues Peter Ashman in Adelaide and Michael Borowitzka from Murdoch University in Perth, they pitched a proposal for some of this APP funding for their biofuels from algae research, and were successful. The $1.89 million grant allowed them to go ahead with building a pilot plant at Karratha in the northwest of Western Australia, which was completed and running by mid-2011.

“We had decided even before applying for the funding that a pilot plant had to be part of any such program,” Lewis explains. “So much work has been done on growing and harvesting algae for biofuels in the lab, that there was no point doing any more. We knew that unless we could scale up, there would be no significant progress.”

Hitting the pond running

So when the funding came through in 2008, Lewis and the team wasted no time in ramping up the project, quickly amassing a sizable team of researchers across the two sites. “Michael looked after the biology and we did the engineering,” says Lewis.

“We were also very fortunate that Michael already had an awesome strain of algae from previous work that has a very high oil content and can survive in an open pond environment in high salt.”

Having this strain first up meant the team could really hit the ground running. “To grow algae for fuel you need a lot of it, which also means you need lots and lots of water, and you can’t use freshwater because we just don’t have enough of it.

“We therefore need to use seawater, which is of course plentiful and cheap, but you need an algal strain that can handle it and thrive. Indeed, one reason that a lot of groups around the world have struggled in this field is their lack of an appropriate strain – so we had a big advantage first up.”

Based on Borowitzka’s work with his selected strain and the collective experience of Lewis and Ashman, the group already had a lot of the algal chemistry, biology and engineering nailed at the lab and tiny-pond level. But, what happens when you go big?

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According to Lewis, when you start to scale up ponds full of algae, the biology changes, and the challenges magnify. So from 2008 until now the team has been working on all the involved processing steps simultaneously: how to grow enough algae, harvest the algae, get enough oil out, etc, and to be able to do it at scale. Plus, it all has to be energy and cost sustainable.

The first of these challenges is growing a product of sufficiently high purity, explains Lewis. “These ponds are like very shallow lakes full of algae, so basically anything can and does get in them, and thus the climate and conditions – temperature, wind, dust, contamination, etc – will dictate how the algae grows, and these changes are very difficult to predict accurately. So really we learnt how best to do this as we went along with the scale up.”

The team quickly realised that understanding the biology of their algal system and their requirements in terms of product was a big key to future success. “For example, one reason that our pilot plant produces one of the purest algal products anywhere is that our algae strain will survive in salt concentrations of 3.5 per cent (seawater) up to 11 per cent.

“And once you get up to 4-5 per cent most other contaminating algae and microorganisms die. So we still get invasion of our ponds all the time, but nothing else can take hold in the hyper-saline conditions, and the algae outcompetes everything.” So that has taken care of one of the biggest challenges of growing algae in open ponds on the sort of scale needed for commercial production.

The next challenge was harvesting such a huge amount of algae and doing it without expending huge amounts of energy or money in the process. Lewis explains that algae will only grow at fairly dilute concentrations – he says it looks a lot like green cordial – so that it still gets enough light for photosynthesis.

And this is why the ponds have to be so big and shallow. The problem from a technology standpoint is then collecting the amount of pure biomass you need from so much water.

“We looked at a few technologies around the world and then decided to develop our own to overcome this challenge. I can’t talk about this a whole lot about it due to our commercial interests, but I can say that it is based on electrokinetics and that we currently use about 0.1 kilowatt hour (kWh) of energy to harvest 1 tonne of pond matter, which produces 20-25 g useful organic weight of algae per m2 per day. This is as good as anyone is getting anywhere at the moment,” says Lewis.

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“The technology is now established at the Karratha plant and we are working towards producing the same amount but using only 0.01 kWh. That is where we want, and need, to be.

“We also have to think of the end point cost of our product – our ultimate aim is $1 per litre. Currently we are down to about $5 per litre, but of course who is going to buy the equivalent of petrol at that cost? No-one. So obviously we have to get that down to a mark where you can compete with fossil fuels and still make some money on top of that.”

Once harvested, the next challenge is breaking the algae cells open to extract the oil, and that is another area of technology that Lewis’s team had to develop in-house. “It sounds simple, but it’s actually very complex technologically.

“How to get enough energy onto the cell wall that we break the cells open without smashing them apart completely. It is especially hard with these guys growing in up to 11 per cent salt. They are pretty tough.” But again, without being able to reveal how, the team is confident it has cracked that nut too.

One of the final challenges is getting the end product out of the harvested and damaged algae, in this case, the oil. There are well established ways to do this that involve solvents such as hexane, and the program at Karratha uses a fairly standard stepwise extraction process at the moment.

Come together

In the midst of all this process development, the biofuels pilot plant at Karratha became operational on schedule in mid-2011. Along the way, the university teams were joined by an industry partner SQC, an algal technology company based in Adelaide. According to Lewis, SQC saw the joint venture as a good opportunity to expand its business, and Lewis’s team certainly welcomed the accompanying injection of cash.

Then, late last year, the three entities involved, Murdoch, University of Adelaide and SQC, spun out a joint venture company called Muradel. “This company will take over the pilot plant and all the intellectual property at the end of October this year, which is when the APP project funding finishes,” says Lewis.

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“Muradel aims to take all this technology we have developed over the last few years and scale it up to the next level, into a commercial reality. The pilot plant currently covers one acre, but at least 1000 times that area is needed to make a commercially viable amount of fuel. This will involve securing the millions of dollars needed to build the next step: a demonstration plant.”

According to Lewis, the field of algal biofuels needs a couple of breakthrough technologies to take things to that next level. “We really need to reduce the number of processes, something like a black box in which we can run several processes all at once: harvest, damage and extract, for example.” One option for that which is currently on trial in the U.S. is microwave technology, and everyone is watching with interest.

“The field also really needs a breakthrough process for oil extraction from the algae,” he says. “Producing biocrude negates the need to cavitate and extract, but then extra steps may be required for refining. Can we develop a technology that allows us to extract clean oil straight from the algae?”

To this end, Lewis has recently been talking to Geoff Fincer in Adelaide, a plant geneticist, to find a biological solution to this hurdle. Together, they are working out how to modify the algae for easier processing into fuel, by literally going to the source. “We are currently looking for an industry partner for this project,” says Lewis.

“We have money from BioInnovation SA, and are now seeking support from the ARC with the necessary industry partners. This will be a long-term investment.”

Now that the pilot plant is up and running, the team can go back to the lab and look more broadly at the processes, and one direction is the direct conversion of biomass to biocrude oil without even breaking the algae open. “So we are now looking at processes for taking this big mass of horrible ugly crude oil and pulling out just those components needed to make biodiesel or even jet fuel.

The jet fuel angle is particularly exciting because all of the big airlines are currently very interested in securing a fuel feedstock for their industry, even funding their own biofuel research projects including into algae.

Indeed, Airbus and Boeing have plans for their own global biofuel ‘service stations’ across the world and Airbus estimates that by 2030, up to 30 per cent of jet fuel could be plant-derived.

On top of that, in July of this year, the relevant regulatory authority body in the U.S., the Air Transport Association, ratified the requirements for using biofuels in passenger jets.

“This is great for us,” says Lewis, “because we now have a target set of criteria to meet. And so we now also have a team who are looking specifically at how to convert our crude product into something that meets these requirements.”