The A.I.M. Interview: Sandia and DOE’s Ron Pate Page 3

by David Schwartz

What is your reality check on the industry—especially any areas you think are misunderstood, or misrepresented?

I’ll give two examples. The first deals with the current technical readiness level of algae biofuels, which I think has been misrepresented by some. The other deals with the resource requirements for algae biofuels, the implications of which I think are misunderstood by many.

In terms of technical readiness, I think that commercially viable biofuels production based on autotrophic (photosynthetic) microalgae system approaches are still some years away rather than being a very near-term proposition as some have suggested. A few even claim that enough research has been done and it is now just a matter of building large scale systems so that commercial production can begin and we can rapidly wean ourselves off of imported petroleum!

I’ve already noted that algae biofuels remains an emerging field that needs further technical maturity, and I think there is a lot of evidence out in the open literature and RD&D community to strongly back that up. My opinion is that another decade or more may be required, depending on levels of investment made, to advance the science, engineering, practical experience, and objective testing and assessment associated with autotrophic microalgae systems at progressively larger scales. This is needed to clearly demonstrate and validate reliable and repeatable long-term production at the technical and economic performance levels required to be commercially viable and cost-competitive. DOE’s current project portfolio is helping support this technical progression.

Heterotrophic algae, which uses more mature bioreactor technology, could have a shorter time scale, but that will depend on the availability of low-cost sugars and the ability to scale-up sustainable production to the high volumes and low cost levels needed to compete in the fuels markets rather than in the lower-volume high-value products markets.

The second case deals with the question of how far algae biofuel production might be able to sustainably scale up in the U.S. on the basis of resource requirements and availability. Many are familiar with the potential of algae for much higher productivity than more conventional feedstocks, and this often gets translated into enthusiastic optimism that algae can be a silver bullet—capable of displacing much, if not all, of our petroleum use.  For example, in A.I.M’s “The Buzz” from several weeks ago there was some discussion on the future market potential for algae biofuels that included the following comment:

“… Algae have the potential to replace a much larger percentage of fossil transportation fuel than can traditional feedstock. This implies that fuel from algae represents a market that can grow to hundreds of billions of dollars annually.”

Despite the optimism reflected in this statement based on algae’s productivity potential, there are additional resource demand requirements for large scale-up of algae production that will offset some of the potential benefits. These issues have not gotten much attention, but will likely impose real-world constraints to how far the industry can be sustainably built-up unless some really significant breakthroughs emerge.

Now, I want to stress that I’m hopeful that algae can successfully contribute to a national portfolio of options for biomass-based transportation fuels. I also come at this from the perspective that biofuels need to be able to scale-up to aggregated production volumes that can really make a significant contribution to national fuel supplies and the domestic economy, without adversely impacting the environment and other agricultural markets.

A good starting point for this is the mandated target for advanced biofuels under RFS2, which calls for the production of 21 billion gallons per year (BGY) of biofuels beyond corn ethanol by 2022. Five BGY of that falls into the categories of “renewable diesel” (1 BGY by 2022)) and “other advanced biofuels” (4 BGY by 2022) where algae can be expected to most directly contribute. If we look more broadly at U.S. fuel demand, we currently consume about 139 BGY of gasoline blend fuels, 60 BGY of distillate fuels, and 24 BGY of aviation fuel[1]. The point is that making a real impact on fuel supplies with biofuels demands thinking in terms of sustainably producing many BGY, and I’d like to see algae among the “silver buckshot” that contributes to this.

To get a better handle on the issues for autotrophic algae biofuels scale-up, several Sandia colleagues and I began a high-level analysis in late-2008 in support of DOE’s algae biofuels roadmap effort. Some of this analysis was summarized in a recently published peer reviewed paper in a special issue of the journal Applied Energy focused on Energy from Algae[2]. The results of this analysis have also been put into presentation form Algae Scale Up Assessment_RCPate_Sept2011_v3.

The paper develops and applies some simple scaling laws for autotrophic microalgae biomass and oil production under a reasonable range of productivity assumptions in order to assess the requirements for land, water (under evaporative loss conditions with open cultivation systems), CO2, and the major macronutrients of nitrogen (N) and phosphorus (P) under various scale-up scenario conditions.

Simplifying assumptions are used to bound the problem and provide for ballpark estimates. More precise projections really can’t be done at the present time with any validated fidelity anyway due to limited understanding and data for a lot of the processes involved under the necessary range of conditions. However, by tracking the fundamental mass balances involved, this paper tells an overall story that I expect will be reasonably close, within a factor of a few, rather than being an order of magnitude or more off.

The analysis focused on the pathway of producing oil as biofuel feedstock from autotrophic algae and assessed likely resource constraints based on reasonable expectations for levels of algae productivity and degree to which key resources might be expected to be available to apply toward algae biofuels production.

The main conclusion of the paper is that sustainable autotrophic microalgae biofuels production in the U.S. beyond about 10-15 BGY, if not less, could be a significant challenge due to resource constraints. Land is not the problem, but the affordable and sustainable availability of nutrients (nitrogen and phosphorus), CO2 (which comes as a surprise to many, but is based on the informed assumption that concentrated sources will be required), and water will likely be.

This analysis provides what I would call a preliminary baseline assessment that ignores the possible savings one could achieve by capturing and recycling nutrients, water, and some downstream produced CO2, which can be done up to a point. However, there will be cost, performance, and system complexity tradeoffs associated with doing that successfully in practice, so those measures will help, but can’t be expected to overcome the fundamental scale-up limit problem. The Sandia paper also ignores detailed algae production system issues, including the technical and economic performance of processes and systems. It assumes that affordable systems will become available that can provide good technical and economic performance at commercial scales. The analysis assumes the use of open systems when considering the upper bound of potential evaporative water loss from cultivation, and also ignores heterotrophic algae production.

Heterotrophic algae does not produce primary feedstock, but instead represents a biochemical conversion pathway that still depends on the supply of some form of primary upstream photosynthetic biomass feedstock to provide the sugars needed for heterotrophic algae growth.

This approach can certainly scale up (as Solazyme has been in the process of demonstrating for some time now) and can add to what is possible with autotrophic algae production, but the extent to which this can be successfully done will be heavily dependent on the availability of affordable sugars in sufficient quantities. If those sugars come from commodity crops, like cane, beet, corn syrup, sweet sorghum, or other such crops, the degree of affordable and sustainable scale-up will also run into limits driven by competition with other agricultural markets for the use of those crops and sugars and/or for the farm production capacity (land, water, fertilizers, etc.) used to grow them. Depending on the crop, the food/feed/fiber vs. fuel controversy could also be a factor in the discussion.

The longer-term goal for heterotrophic production is to use sugars from lignocellulosic biomass from energy crops or waste materials that would hopefully allow for more sustainable scale-up to higher production levels with fewer adverse impacts on other markets and the environment. This is the same hope that drives many of the other advanced lignocellulosic biofuels being pursued, so success and degree of scale-up possible will depend on progress in bringing the cost for non-food/feed cellulosic biomass and sugars down.

Assuming that 10-15 BGY (within, say, a factor of two in either direction) could be a practical upper limit for autotrophic microalgae biofuels production in the U.S., that still amounts to a significant volume of fuel with multiple tens of billions of dollars worth of market value that can contribute to the domestic economy and the displacement of imported petroleum. Adding heterotrophic (and mixotrophic combination of heterotrophic with autotrophic) algae production to this could certainly extend the levels of production volume that could potentially be achieved, depending on the source and cost of sugar feedstock and the price of petroleum.

My point, offered in the spirit of “managing expectations,” is that getting sustainable algae biofuels production in the U.S. up to the level of many tens of billions of gallons per year is a worthy goal, but could well be a difficult challenge to meet due to resource requirements and constraints.  Achieving much higher autotrophic microalgae oil content and biomass productivities could be among future hoped for breakthroughs. This would help relax resource constraints, but it won’t entirely eliminate them. The degree to which sustainable heterotrophic algae production fed by sugars could add to this will depend again on the availability of affordable and sustainable sugar feedstocks. How far algae biofuels production could go on a global scale is another story, and needs more analysis to objectively evaluate.

What advice do you have for the industry?

Take advantage of the resources available from DOE and other federal agencies, including the leveraging of information and expertise within the R&D communities associated with those agencies, and including the possible funding opportunities that make sense to go after. Keep in mind that the funding opportunities will usually require some significant level of cost-share and will be competitive.

Put your promising new technology, or process, or unit operation, or system into perspective within the overall value chain for algae biofuels and co-products. Keep in mind that it has to make good sense and be capable of appropriately scaling up in a way that can be both affordable and sustainable at sufficiently large production levels for biofuel markets. That means that resource use intensity, especially for energy, water, and other key input resources, needs to be kept as low as possible. For those who are contributing only a piece of the value chain, rather than being vertically integrated, look for opportunities to strategically partner in a complementary way so that your technology or process can be appropriately adapted and integrated into a viable system that can be deployed at scale.

Finally, be realistic and don’t “oversell.” Algae has a lot of potential for biofuels, but also faces economic and technical challenges that will take time, dedicated effort, and patience to overcome. Careful and credible due-diligence is needed in terms of quantitative technical, economic and life cycle analyses, and will be expected when being seriously considered for public or private funding. Making unsubstantiated assertions and overly-optimistic claims will not hold up to careful scrutiny, and can end up causing problems for the industry as a whole by those who over-promise and under-deliver.