by Jonathan Williams
r. Babetta Marrone and Dr. Jim Coons are in charge of developing the Ultrasonic Algae Biofuel Harvester, as their part of Los Alamos National Laboratory (LANL)’s part of the 3-year NAABB project. Their work in making algae come together around acoustic energy is a bright spot in the future of algae harvesting, traditionally a costly link in the algae production chain.
Team Leader for the NAABB Harvesting and Extraction research unit, Dr. Marrone earned her Ph. D. from Rutgers University in biological sciences on a National Science Foundation Pre-doctoral Fellowship. She was also a National Institutes of Health Postdoctoral Fellow in physiological chemistry at the University of Wisconsin. Dr. Marrone worked at the St. Louis University School of Medicine as a research assistant professor before ending up at LANL in 1985.
Dr. Jim Coons has a Ph.D. in chemical engineering from the University of Queensland and has worked on a variety of energy projects around the world, from natural gas to nuclear fusion technologies. He joined the Harvesting and Extracting team last year to help out with the development and scale up of the acoustic harvesting technology that Dr. Marrone is heading up.
Together, they are working to develop a system that uses ultrasonic waves to concentrate algae in a solution, rupture the algae to release the lipids, and then collect the lipids and biomass. A little over a year into this three-year project, they have made some strong headway in developing a system that could be scaled to a commercial level.
They were able to take the time to discuss with me the progress of their research at a recent algal biofuels conference in St. Louis.
Can you briefly describe some of your research with algae at Los Alamos National Laboratory?
Marrone: The project that we are working on now is sponsored by NAABB and it’s somewhat broad in the sense that we are really looking at a new approach to try to manipulate algae for biofuels. Our approach uses acoustic fields, or ultrasound, to do those manipulations.
There are really three distinct processes that we are looking at in our research. One process is the harvesting or concentration of the algae. For that we use one particular routine with acoustic fields to gently push the algae away from the water in order to concentrate the algae. The second routine, which is now a completely separate process, changes the acoustic fields and uses the ultrasound at a higher pressure. It creates bubbles within the algae cells and forceful streams around the algae to try to break up the algae cells to release the lipids. Then the third process uses the gentler acoustic regime in the first step to try to separate out the lipids from the water and the remaining biomass.
Right now, its three separate steps, or three different routines, but eventually we want to integrate them.
What is the ultimate goal of the Ultrasonic Algae Biofuel Harvester, and what all will it be able to do when you have a finished product?
Marrone: To collect or harvest the algae and remove the lipids will be the main point.
Coons: Part of the problem in dealing with algae is the water issue. If you have to dry the algae before extracting the lipids, it’s extremely costly. What we are talking about is developing and using ultrasound to basically extract the lipid in a wet process so that it doesn’t require drying. The creation of sound waves, whether it is for concentration, disruption or the separation of the lipid from the biomass, is a very efficient way to deliver energy into the system.
One of the main issues for a healthy, sustainable algal biofuels industry is how do you actually remove the lipid in a cost effective way.
And how far along is the development of a commercial device?
Coons: Well, the NAABB program is a three-year program and the goals are very demanding. We are really challenged to deliver an industrial scale unit that can be field tested within a three-year period. We’ve just started the second year and we are hoping that the larger scale ultrasonic harvester will work as efficiently as it does at the laboratory scale. The industrial scale device that we will be putting forward in just a few months will have to make it through a down-select process before field tests can be conducted.
Marrone: So depending on the demonstration – and if we meet the targets in terms of how much algae we can process with the prototype – hopefully commercialization will follow.
Coons: It would be overly optimistic to suggest that our version after three years would be final. I am sure that this would need more refinement and more development, but we are seeing reasons to be very optimistic about a short-term deliverable product.
Obviously, it will be very important to keep energy input levels low. What have you found the energy uses of this device to be?
Marrone: They are very, very promising and very low. There are a lot of reasons for that. Essentially, you are not adding anything to the process materials so you don’t have to remove it later or worry about it in your waste stream or recycle stream. So it’s a very simple process with no moving parts, and it happens instantaneously on the algae being subjected to the fields.
Many people like to express their energy balance in the form of a net energy ratio, or the ratio of the energy coming in to the energy that is coming out. In NAABB, we have been tending to focus on the costs with making certain assumptions about the types of algae we will be working with and the cost of electricity. But our costs are pretty competitive, and actually, very competitive.
Coons: We have an objective within the NAABB program for harvesting or just a concentration field. Basically, the line that was drawn in the sand for us was something like 1.2 cents per gallon of lipid. That’s pretty cheap and initially we thought that they must have miscalculated or something. But based on our extrapolated results, we believe that we will be able to actually beat that.
In terms of energy ratios, I can’t remember what the calculation was. However, we believe that the harvesting concentration of the lipid will be well below the 1.2 cents per gallon. Basically, our estimates indicate that we are going to somewhere around 10 to 15 cents per gallon for all three of these harvesting, extraction, and separation.
You know, biocrude, if you want to call it that, at 15 cents per gallon is very, very attractive. There are things in there that we didn’t consider such as the cost of moving around water. But we think that in the terms of our technology its really, pretty much, at the rock bottom end in the terms of costs.
The article that I read concerning the Ultrasonic Algae Biofuel Harvester said that this device could be very scalable. Do you have any comments on the potential scalability of this device?
Marrone: Right now we are at a very small lab scale and our immediate goals will be to get to an intermediate scale where we can process a liter of algae within a reasonable amount of time. I think everything is saying that we should be able to scale up. We don’t really know a lot of the details yet, but we are in the process of gathering data right now.
Coons: We do have a strategy for scale up and there are a number of elements. Probably the most important is that we have a physics based model that we are using to make sure we can design an efficient acoustic resonator. That’s a really important aspect of this.
Because of this three-year program, one thing that we have done that is also probably an asset to the whole scale up approach is to select an intermediate scale. It’s much larger than what we have been testing at in terms of its capacity for flow, but to get from that intermediate scale to what we would say would be the low end of industrial scale would be fairly trivial. It won’t necessarily require any more scaling, but what we have to do to really build confidence is to show improvements experimentally in how much flow and under what conditions we get the best performance for this intermediate scale.
This will be the first time we have had the opportunity to design a highly efficient resonator and design experiments at larger than laboratory scale. Our past efforts were based on a proof of principal approach where we grab materials and pieces that were readily available and accept considerable inefficiency in the resulting devices. But if we succeed through the down select, we will have an opportunity to test a more precisely designed and highly efficient resonator at an intermediate scale that can be easily built up to an industrial scale.
We, again, have reason to be optimistic, but we also know that we have to prove that the intermediate scale device will operate as we expect.
One thing that people have talked about at this conference is the efficiency of extracting or separating the lipids from the biomass. In your early results, how efficient has your technology been at extracting the lipids from the rest of the biomass?
Marrone: I think we’ve gotten numbers up to 100% in some cases. Typically we are at 75%. I want to point out that at extracting the lipids, what we have specifically measured is actually the disruption of the cells. So if 100% of the cells are disrupted we are assuming that all the lipids are released. We haven’t gotten to a point where we can separate it out and capture it yet, so I just wanted to qualify that statement. But the ultrasound is very effective, up to 100% without that much tweaking at disrupting cells.
A DOE article said that you were looking to create a fairly portable device. How big do you envision a portable version of the Ultrasonic Algae Biofuel Harvester?
Coons: Well, the industrial scale unit that we are talking about, which is something that we will have to deliver for field tests, is something that we envision will be a device that would fit on the back of a pickup truck. It is something that would fit even on the laboratory bench. It’s going to be that size, that portability. We see advantages for a device like this, moving from pond to pond, with very low capital cost. There are a number of advantages for this size device and the ability to process around a thousand liters of algae per hour.
As of right now, are there any limitations you’ve seen to this device? Does it not work on certain strains of algae?
Marrone: There definitely are some considerations; I wouldn’t say limitations per se, but some considerations that make it the most cost effective. It’s things like how much lipid is contained in the algae. The higher the percentage, the more bang for your buck. Additionally, how much algae is in your initial concentration is a huge factor as well. The more concentrated, the more you can beef up your cultivation, the better. So the amount of lipids per cell, the number of cells in your cultivation, the size of your cell, the density of your cell will all be important factors.
Coons: Bigger is better than smaller, more concentrated is better than dilute. The physics are there for the technology to work even at very dilute concentrations, but it does impact the costs. Basically, the more you have to do to gather your lipid in large quantities, the more costly any technology is going to be.
You’re partnered with Solix Biosystems in the development of this device. In that regard, who is going to own the intellectual property once the device is finished being developed? And who do you see as the main commercial users of this device?
Marrone: We are working on an agreement concerning the intellectual property of this technology that will benefit all the parties involved. Solix is definitely still interested and we are working closely with them to get something hammered out.
What are your feelings about developing this technology in a national lab, as opposed to the lab of a private company?
Marrone: This is a very innovative approach and it is risky in that sense. But I will say that I think being at Los Alamos, where we can rapidly pull together interdisciplinary teams, really has helped the innovation along and reduced the risk. I think that the considered approach that we are taking is best. It would be so easy just to do trial and error and build something this big and see if it works. But that’s not the way we do things.
We like to carefully consider the problem so that we can understand what is going on in “the box” and then incorporate that into how we develop the final product. We just wouldn’t do it any other way. You can say that maybe it slows things down, but I think in the end we’re going to be able to deliver a better product with higher efficiency – something that works. To develop something in a new area like this, it is a project that I think you can only really do at a national lab.