What is Dr. Pfromm Missing When He Says Algal Fuels are Doomed?
[Peter]Pfromm and K-State researchers Vincent Amanor-Boadu, associate professor of agricultural economics, and Richard Nelson with the Center for Sustainable Energy conducted an in-depth analysis on algae biodiesel production. Their first algae-related nonprofit study, "Sustainability of algae derived biodiesel: A mass balance approach," supplied the cover picture in a recent edition of Bioresource Technology, a peer-reviewed journal. _Eurekalert
Pfromm and his colleagues came to the conclusion that it is impractical to make biodiesel from algal oils, due to the physics of limited available sunlight, and the chemistry of limited available carbon and CO2 feedstock. These limitations -- and other shortcomings pointed out by Pfromm et al -- make the production of algal biodiesel a difficult uphill battle. The authors criticise economists who promote algal fuels, for focusing entirely on the financials, and not looking hard enough at the physics, chemistry, and microbiology of the process.
And yet, it seems as if Dr. Pfromm and his colleagues may have missed a few things regarding the algal fuels picture themselves. There is no doubt that the energy equations must balance, as must the chemical input and output equations. And there are certainly huge problems involved with both the open pond (or raceway) approach to algal farming, as well as the closed bioreactor approach. It is likely that it will take at least 5 years, and possibly 10, to solve these problems well enough to make algal fuels competitive and ready to scale up.
Dr. Pfromm is not alone in his pessimism toward algae. Many photosynthetic fuels researchers have turned away from algae toward cyanobacteria, and other engineered bacteria. That is because bacterial DNA is easier to access and manipulate than algal DNA. Other microbial fuels researchers have turned away from sunlight and CO2 altogether -- in favour of a feedstock and energy supply from biomass sugars.
Any photosynthetic fuels maker trying to feed his microbes with atmospheric CO2 and sunlight alone is doomed to fail. Photosynthetic microbes need a lot more carbon than they can get from the atmosphere (a mere 0.04% CO2). But cement plants and fossil fuel burning power plants provide copious amounts of CO2 which can be pumped into growing environments for microbes. And sunlight can be augmented by artificial light to enhance growth.
But the biggest thing that Dr. Pfromm and other algal skeptics seem to overlook time and time again, is that the early profits from algal fuels will not likely come from algal oil biodiesels. The early profits will come from the prolific biomass potential of algae.
Sure, eventually it will be economical to separate the lipids, proteins, and carbohydrates in order to best utilise the individual components of algal mass. But in the early stages, the algal biomass itself is the high-value crop. Micro-algae and seaweed (macro-algae) are most prolific, compared to land crops.
Growing algae for biomass, rather than for lipids, allows for much more economical and less fastidious growing methods and harvesting techniques. Locating algal biomass farms near sources of wastewater and waste CO2 allows for low-cost feedstock which can be converted quickly and economically into algal biomass. Omitting the lipid separation step streamlines the process in many ways.
Once you have the biomass, you can choose from a wide variety of methods for converting the biomass to either energy, fuels, or high value chemicals. Gasification to syngas allows for direct power generation using gas turbines, conversion to hydrocarbons via catalytic synthesis, or fermentation to alcohols and other chemicals. Pyrolysis can be even more economical, allowing the elimination of the potentially expensive drying step -- using simple straining and filtering instead.
Thermochemical (and fermentation) conversions of algal biomass to energy and fuels can take advantage of the more advanced state of development of those approaches, compared to more direct microbial fuels. Eventually, algae and other microbes will become more economical for production of fuels than the thermochemical and fermentation approaches to biomass treatment. When that happens, the industry will shift in that direction -- as the economics dictates.
Dr. Pfromm and his colleagues make some excellent points which microbial and algal fuels researchers must necessarily deal with. But they will do so successfully, in time. In the meantime, it is best to follow a logical progression in these things, as nature, science, and technology allow.
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