INDUSTRIAL BIOTECHNOLOGY: Dr. Hunter-Cevera, the National Research Council (NRC) recently released the report “Sustainable Development of Algal Biofuels,” prepared by the committee you chaired. (The report is available at www.nap.edu) How would you summarize the task your committee was assigned, its aim and scope?
DR. HUNTER-CEVERA: The task our committee was assigned by the US Department of Energy (DOE) was first to help anticipate the major sustainability concerns as commercial scale algal biofuel production is widely deployed, second to explore the opportunities for mitigating those concerns, and last but not least, to discuss the tools for assessing what we call the multi-attribute nature of the sustainability of algal biofuels. If you look at page 13 of the report, it lays out the entire statement of task from the DOE. If you notice, the committee was not asked to look at heterotrophs or to make comparisons in terms of various terrestrial processes, for example, but only to look at sustainability concerns for commercial production. No economic assessments were done.
IND BIOTECH:
Why is the timing of this report important with regard to the status of ongoing investment and R&D in, and early-stage scale-up of, algal biofuel technology?
DR. HUNTER-CEVERA: Any developing industry needs to consider sustainability. By addressing sustainability concerns and challenges as the industry develops and grows, it can help ensure success well into the future. If you ignore sustainability at the outset, you might exacerbate sustainability issues for future generations and make it difficult for an industry to scale up successfully. To ensure sustainable development of algal biofuels, we considered it prudent to consider potential sustainability concerns so such factors as management practices, new technologies, engineering design, and perhaps even specific strategies can be developed to avoid and even mitigate these concerns as the algal biofuel arena develops.
If you look at where the algal biofuels industry is right now, what it has achieved is pretty impressive, and where it wants to go has great potential. The DOE asked whether it can be sustainable if it is scaled up even further, looking at a range of factors: water and land resources; environmental impact; nutrient sources such as CO2, nitrogen, and phosphate; human health; safety associated with feedstock cultivation and processing and any toxicity related to the metabolites produced; and the many other factors we considered.
Organisms communicate with each other. When you grow them at small scale, in a laboratory for example, you might have one set of metabolites, but when you grow them at a larger scale we are learning that you might be dealing with a different set of metabolites. So my hat's off to the DOE for asking about sustainability. They see the potential here and the need to ask the questions about whether this technology can be sustainable as scale increases to reach the 2.5% or 5% level of replacing petroleum-based fuels, especially in terms of water and land use and nutrients.
IND BIOTECH:
How would you summarize the main conclusions of the committee as presented in the report?
DR. HUNTER-CEVERA: It always helps to know how we came to the information that we summarized in the report, and I think it is important for the public to know that we looked at a large amount of publicly available information. Not only information in the printed literature, but also information provided through presentations and by request. We invited the major players and the minor players, government agencies and academic researchers, and we even solicited written information from companies, and some companies graciously responded to our request.
In summary, we concluded that if the scale-up of algal biofuel production is going to be sufficient to meet at least 5% of the demand for transportation fuels in the US, this would place unsustainable demands on energy, water, and nutrients with the current technologies and knowledge. The word current is critical, because the committee felt that innovations in biotechnology and engineering have the potential to shift this dynamic towards improving sustainability.
We listed the sustainability concerns in our report, and we decided to categorize them as high, medium, or low. Those identified as being of high concern, if they are not already being addressed, should be addressed. Concerns of medium importance require some assessment or monitoring to ensure that they do not present serious sustainability concerns, and the low concerns are likely avoidable with good management practices and engineering design. A low sustainability concern, for example, would be the risk of mosquitoes, so you would want to make sure there is no standing water. Most companies would likely be aware of the issues we included as low concerns.
IND BIOTECH:
Based on initial reactions and commentaries on the report and the committee's findings, have you been surprised by the response to date and have you noted any particular misperceptions? It is clear from some of the reactions from the algae community that your report rubbed some raw nerves. Why do you think that is so and were those reactions anticipated?
DR. HUNTER-CEVERA: When you consider a subject matter or topic from a 360-degree perspective—and I present it this way because if you look at the diversity of the committee, it represented all perspectives—and you produce a report based on an objective assessment and not just one particular viewpoint, people are going to perceive it differently depending on their preferences. I encourage people to read the report in detail, and if they do, I think they will appreciate that the committee considered all perspectives and mentioned the different areas that need attention to ensure sustainability. We are suggesting areas to look out for to ensure sustainable development. The last thing you want is to pursue something with great potential and then later realize that you should have considered the sustainability factors earlier in its development. The report is saying that you have to look at sustainability from the beginning to the end.
Being chair of the committee was a great experience because there was such diversity, great dynamics, and thought-provoking conversations among the committee members. I hope we didn't rub any raw nerves. Our intention was to say, “Take a deep breath and pause. Ask the sustainability questions now. Look where you are at and where you need to go, and address the sustainability concerns.”
From the majority of the reactions and comments I read after the report was released I think that in general it was perceived correctly. The Academy's role of being an impartial purveyor of information is often a difficult one. The committee does not take sides; it looks at what has been published and presented to us and the information that is in the public domain. I am sure the industry is looking at ways to mitigate sustainability concerns as they are moving forward and scaling up to avoid any barriers they might present. I was not surprised by any of the responses and reactions to the report.
IND BIOTECH:
How challenging was it for the committee to sort through the promises and the hype associated with algae for biodiesel production?
DR. HUNTER-CEVERA: We had a very specific task, spelled out by the DOE, and that was to look at sustainability. All we could do was to use our own expertise and to go through the literature—and if you look at the Appendix to the report you will see that we read a lot of papers—and to review the information and input from companies and federal agencies. We used all of this information to answer the questions defined by the DOE: what are the sustainability concerns; are there potential mitigation strategies for those concerns; and what are the indicators, metrics, and tools that could be used to assess the sustainability. We were not asked to evaluate the promise of algal biofuels, to compare different technologies, or to say what areas needed more funding, for example.
On page 243 of the report, there is a chart showing assessment steps, examples of variables, and an example of a method of assessment. I think this is a good framework for going forward, whether for use by the DOE or an industry working in this area.
IND BIOTECH:
In the late 1990s, the DOE reached similar conclusions as those of the NRC committee about the biological and technical challenges in the development of algal biofuels to meet a substantial amount of domestic fuel demand. These conclusions were published in a US DOE report authored by John Sheehan, Terri Dunahay, John Benemann, and Paul Roessler entitled, “A Look Back at the U.S. Department of Energy's Aquatic Species Program—Biodiesel from Algae.” What elements of the current report are consistent with this earlier report, and what elements are new?
DR. HUNTER-CEVERA: I always say that you have to know where you have been to know where you are going. I think that an increased core understanding of algae and the potential for improvements is definitely fundamental to accelerating the entire algal biofuel enterprise. Factors such as strain development, molecular biology, and genetic engineering all contribute to improving product yield, and I believe these were all part of that earlier report.
We took it one step further and said that any yield improvement would also improve sustainability because it would improve resource-use efficiency. A prominent difference between the two reports is that the Aquatic Species Program focused on biodiesel production. Many processing pathways have been proposed since then. The NRC report provides an overview of some of the proposed pathways, including direct synthesis of ethanol by cyanobacteria and the thermochemical conversion of algal to drop-in fuels. You can imagine that there are probably more than 100 different processes. On page 2 of the report there is a schematic depicting how we narrowed this down to the four scenarios on which we chose to focus.
IND BIOTECH:
What role can biotechnology play in further improving the sustainability of algal biofuels?
DR. HUNTER-CEVERA: We discussed this, and some of the conclusions included improvements in biomass or product yields, such as lipids, alcohols, or hydrocarbon. Others focused on improving culture density and nutrient uptake. Also, how easy is it to harvest and what is the photosynthetic efficiency? These are just some examples of what the committee felt that biotechnology could contribute to improving the sustainability of algal biofuels.
You can imagine that if you improve the product yield you will then increase resource-use efficiency. Improving the ease of harvest could reduce the energy needed for harvesting. As these discussions progressed, the report discussed the possible role that biotechnology could play in improving the sustainability of these processes.
We heard presentations from the Environmental Protection Agency (EPA), groups from the DOE, and from some of the national research laboratories. All of this information helped us connect all the dots in what is a highly integrated process, from strain selection to how the algae are harvested. There is a lot of room for new technology development, and as I said earlier, it is quite impressive how far the industry has already come.
IND BIOTECH:
The report concludes that algal biofuels have the potential to contribute to improving the sustainability of the transportation sector, but that additional R&D is needed to produce the needed innovations. What areas of algal R&D are in need of funding to achieve the desired outcome?
DR. HUNTER-CEVERA: We discussed the R&D needs to achieve the desired outcome, but we did not cover whether these areas are being funded or are in need of funding. On page 72 of the report, you will see a list of bullet points that highlight the types of activities that could help the industry reach a successful outcome. These include everything from a strategy to improve carbon fixation rates and yields of algal crops to commercial production scale, or the development of algal strains or multispecies assemblages that could achieve high productivity and high volumetric concentration over a wide range of environmental conditions, including temperature and light. If you take a regional approach, it is certainly warmer in the South and colder in the North. How do you develop improved crop protection methods? You do not want open algal ponds getting contaminated, for example. Could you design and develop a robust, low-cost, long-lasting production system for algal strains or multispecies assemblages that demands minimal regulation and control of environmental parameters? We are very conscious that technology eventually will have a regulatory policy to go along with it, so why not think ahead about that and work backwards. Could you develop strains that excrete oil or other fuel precursors, especially immiscible products? Could you develop harvesting and processing technologies that require less energy? Could you design and develop integrative biological and engineering production strategies that obviate algal harvesting, drying, and oil extraction processes, or strategies that could reuse the algae, water, and nutrients—in other words, recycle them on a continual basis? Another interesting question that was posed is could you design and develop systems that can process whole biomass into fuels?
IND BIOTECH:
Did the committee consider the impact of other potential product streams that industry is exploring and scaling up for their revenue-generating possibilities, using the oils and other components derived from algae?
DR. HUNTER-CEVERA: That was one of the scenarios we considered. Whereas the focus used to be on optimizing protein production from these single-celled organisms and essentially disregarding all the oil being produced, now we are focusing on the oil production and making fuel, but the revenue potential from the protein produced is also important. We address this in Chapter 4 in the discussion of the scenarios, where we talk about the animal feed industry, the cosmetics industry, and even the fiber industry.
IND BIOTECH:
Life cycle analysis (LCA) methods and tools are more advanced today than they were 12 years ago when US DOE published the report cited above. How would you evaluate the current state of LCA tools for assessing such a complex industrial ecology as carbon to algae to biodiesel?
DR. HUNTER-CEVERA: The committee looked at LCA as a tool for assessing some aspects of environmental sustainability. We even discussed life cycle greenhouse gas emissions and water use consumption that have been reported by others. LCA is an active field, and we felt it best to leave it up to the LCA experts to comment on the current state of the LCA tools. We did not assess which LCA tools are better than the others. We present our conclusions on pages 17–23 and 222–227 of the report, and I would summarize our discussions by saying that there are many tools, including LCA, that can be used for assessing overall sustainability. Rather, you have to have a number of tools, such as cost-benefit analysis, ecosystem service analysis, and a cumulative impact assessment.
IND BIOTECH:
The nexus of water quantity and biomass cultivation and conversion surfaced as a “concern of high importance” in the committee's assessment of the sustainability of algal biofuels. What are the elements of this nexus with algae-based biofuels that are similar and dissimilar to biofuels derived from terrestrial biomass?
DR. HUNTER-CEVERA: Every fuel source has a positive and a negative effect on the resource base, or on aspects of the environment. If you go back in history you can validate that statement. The overall sustainability of different fuels has to be compared to assess whether replacing one fuel with another would contribute to improving sustainability. But the report is not intended to be read as a mere list of sustainability concerns, but perhaps more as a discussion of resource use and environmental effects that need to be compared with those of other fuels to see which fuel option could be more sustainable or better balances the various sustainability objectives. We believe there are comparisons that have to be made, but our committee was not asked to do that.
[Editor's note: A detailed discussion of resource use can be found in Chapter 4 of the report. It includes water, nutrients, land, and energy use and takes into consideration life cycle analysis, scale-up, and the effects of algae production in different geographic regions. Figure 6-1 on page 228 presents a diagram illustrating various tools for assessing sustainability at different scales.]
IND BIOTECH:
The committee targeted an energy return on investment (EROI) of 3 as necessary for the sustainability of algae-based biofuels. How was this target agreed on?
DR. HUNTER-CEVERA: Hall, the author of a paper we reference in the report, suggests an EROI of 3. This was not a suggestion or conclusion of our committee. It is stated in the report that the exact threshold for the EROI to be considered sustainable is “not well defined.” On page 228, it says even an “EROI of 1, the breakeven point, is insufficient to be considered sustainable.” Hall proposes that an EROI of 3 is needed for any fuel to be considered a sustainable source. An EROI can be estimated with an LCA that tracks energy and material flow, which the report discusses in Chapter 4. And the report states that one of the most contentious issues associated with biofuels produced from land crops has been the level of EROI required for the sustainable production of any fuel, and that came directly from the literature.
IND BIOTECH:
The report draws extensively from the scientific literature and public presentations. A great deal of work in this area, however, may not yet be in the public realm. To what extent did the panel interact directly with algal biofuels developers?
DR. HUNTER-CEVERA: We invited representatives from various algal biofuel companies to make presentations to the committee, and they are listed in Appendix C. We wanted even more information, so we solicited information from more companies in writing. Some graciously responded and others declined. When we completed the report, it was reviewed by a panel of 13 reviewers that included representatives from industry. The full list of reviewers can be found in the acknowledgments of the report. The Academy review process requires that the committee respond to every comment made by external reviewers, which we did.
So I believe this process represented an in-depth review of the literature as well as of presentations by members of the EPA, DOE, people involved in the algal biofuels program at NREL in the 1980s, representatives from the Algal Biomass Organization, key academic research institutes, and companies involved in scale-up production of closed and open systems, and freshwater and saline systems. I think we tapped into every resource that is publically available. The report was then subject to review, and we responded to the questions posed by those reviewers. I feel good that this was a thorough process.
IND BIOTECH:
Your report identified several categories of sustainability challenges. Did the committee analyze what work is being done by industry to mitigate each of those concerns? If so, what did it find?
DR. HUNTER-CEVERA: We list a variety of mitigation strategies that have been proposed or studied. We can only review the work being done by industry to the extent that it is in the public domain or that they shared it with the committee. If the industry is pursuing other mitigation strategies that they did not share with us, we think that is fantastic.
IND BIOTECH:
How can the industrial biotechnology community help be an honest broker of the promise of algae-based biofuels?
DR. HUNTER-CEVERA: The DOE asked our committee to write a report about potential sustainability concerns for large-scale deployment of algal biofuels and about potential mitigation strategies. That is exactly what we did. It is up to the DOE and the readers of the report to decide what steps to take next.
