If that headline doesn't grab you, not sure what will. A recent lifecycle analysis of algae biofuels has been making the news recently (well a highly select subset of news media at least), due to its fairly controversial conclusion that algae biofuels production has a more negative environmental impact than corn ethanol and other biofuel technologies, based on certain key metrics.
As expected, the algae biofuels community has reacted with strong condemnations of the study, raising questions about the study and even the lead study author's motives, although others are using the outcry as a business development opportunity. (Official algae trade association response here)
What does the study say exactly? The study (unfortunately behind a pay wall, so I'm not posting graphs or tables) determined that algae biofuels production was more energy and water intensive than corn, canola or switchgrass ethanol, and didn’t actually result in a net greenhouse gas emissions reduction. It did however recognize its positive land use impacts relative to other technologies.
Per the study, algae cultivation was the primary contributor to this negative energy balance, mostly from the nitrogen input needed (via fertilizer) and CO2 production/use. A large fraction of this burden came from “upstream” use, i.e., the amounts of land, water, and energy required to produce the CO2, fertilizers, and electricity for algae production. The study also downplays the benefits of siting algae for flue gas CO2 usage, arguing that, because very large quantities of biomass will be required to effectively use flue gas, this will in turn ramp up the nitrogen input needed. When the algae cultivation LCA model was "modified to incorporate use of flue gas rather than industrial-grade CO2", the total energy consumption and GHG emissions were still larger than corn, canola, and switchgrass.
Additionally, while the study didn’t measure downstream processing, it determined that including this would be unlikely to change the life cycle assessment for the entire fuel cycle given the large impact of cultivation impact.
Importantly, the study’s data demonstrate that algae’s LCA burdens can be substantially reduced via use of partially treated wastewater that would supplant chemical fertilizers. We covered wastewater treatment as one of our pathways in our own algae study a few months back.
(Interestingly, an older study from June 2009 arrived at a fairly similar result, but passed much more quietly. With less robust data collection (relying mostly on older data, lab work and non-field-based calculations of inputs), the study calculated energy and carbon balances for two production pathways and calculated negative energy and carbon balances (with secondary impacts from cultivation and harvesting). That said, this was not an LCA study per se, but rather designed to point out areas of concern for future research.)
Given the beatings that earlier generations of biofuels have taken in the media, the algae industry reaction is understandable, as this study has been picked up by US News and World Report, NY Times, Discover and a variety of widely read blogs.
In reviewing the ABO pushback, I think many of their points have merit, especially concerning the use of out-of-date data. But none of ABO’s “assumptions” are actually in operation on a commercial scale, with publicly available data. A co-located algae facility that recycles water, nutrients and incorporates energy reuse of waste biomass would undoubtedly have a better GHG/Energy/Water profile, but one of those doesn’t yet exist. That's not to cast aspersions on the industry, as I know many millions of dollars and dozens of companies are focused on doing just that. Wastewater treatment algae facilities are another option, but some of the challenges with this process include the difficulty of scaling algae systems dependent on wastewater and finding cheap CO2 sources close to wastewater inputs.
It is apparent, and also referenced directly by both studies, that finding standardized data is extremely challenging, as is determining which production pathway to focus on (which we also covered in our report). There is a real paucity of current, publicly available, commercially-proven, peer-reviewed data. The author of the most recent study has stated he used 10 year old data and invited companies to share more recent data with him.
I hope, optimistically, that both the algae industry and algae scientists (especially at DOE and National Labs) use this as an opportunity to kick-start their own LCA analysis with accompanying data collection and sharing efforts. Until that data is released in a scientific, peer-reviewed manner, or we start seeing these advanced new facilities go commercial, algae will have a tough time pushing back against studies arguing against its beneficial environmental impacts.