Reviewer Comments - EERE

2011 Algae Platform Review – Reviewer Comments
Reviewer Comments are direct transcripts of commentary and material provided by the Platform’s
Review Panel. They have not been edited or altered by the Biomass Program.
ii. Feedstock Supply R&D (ex. biology, cultivation, resource use, biomass characteristics,
harvesting/dewatering)
iii. Downstream Refining R&D (ex. extraction, conversion, fuel, products, fuel/product infrastructure and
end-use)
iv. Environmental sustainability (example: water use, GMOs, energy consumption)
Reviewer Comments
Reviewer: 1 Criteria Score: 4
Critical success factors were not enumerated. It sounded like investigators were looking for them. I think
they have not evaluated what are the real key deliverables, and what it would take to achieve them.
Reviewer: 2 Criteria Score: 7
Procedures need to be refined to produce "clean" lipids.
Reviewer: 3 Criteria Score: 7
Success factors: Low severity processing has opportunity to provide low cost pathway for extraction of
high value fuels precursors Challenges: separations and gas cleaning
Reviewer: 4 Criteria Score: 6
See Overall Impression text.
Reviewer: 5 Criteria Score: 4
Among the critical success factors is "cost effective methods for production of fuel precursors."
Overcoming this obstacle seems unlikely (even at the outset) using these technologies.
Reviewer: 6 Criteria Score: 4
From a scale up perspective, this approach is extremely challenged from an energy balance or process
control point of view.
Reviewer: 7 Criteria Score: 3
A critical success factor is techno economic screencing of process concepts prior to initiation of lab work.
This was not evident in the presentation.
Presenter Response
A criticism was leveled concerning the economic viability of using microwaves. We agree that if
microwaves are used simply to heat the water in the algae/water slurry that this is an inefficient and
(likely) uneconomical prospect. The reviewers failed to grasp that our hypothesis is that microwaves can
be used selectively to effect cell wall rupture by hydrothermal degradation, thus liberating lipids which
will spontaneously separate from the water phase and spent algal bodies (solids). Further, we have found
that the aqueous phase contains most of the protein material from the cell walls. Thus, the microwaveassisted
process is a way of effecting simultaneous extraction and separation of lipid materials from algae
- this is the hypothesis being tested. This is being accomplished at very low severity conditions compared
to other hydrothermal processes which operate at pressures of about 150 atm and temperatures around
350°C. Our work on pyrolysis is similarly providing evidence that fuels precursors can be effectively
liberated from algae under low severity conditions. Gasification was found to produce a syngas with high
tar loadings, so this pathway has been de-emphasized in the research program.
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