This Small Business Innovation Research (SBIR) Phase I project aims to develop an innovative Raman-based real-time microalgal biofuel analyzer. Although microalgae are popular feedstock with great potential for biofuel production, there is currently no suitable, fast and field-deployable analytical tool available. Current Raman systems cannot be deployed for microalgal applications due to deleterious broad interferences from microalgae?s abundant pigments, which emit fluorescence thousands times more intense than Raman signals from the components of interest. The proposed analyzer enables the characterization of microalgal productions of oil (bio-diesel) and other valuable components both qualitatively and quantitatively, in a non-destructive and real-time manner. This project is based on recent technology advances at BaySpec, Inc. in ultra-compact and narrow-line 1064-nm fiber lasers, volume-phase gratings, fiber optic probes and infrared detector arrays, coupled with Raman analyzing algorithms developed at Sandia National Labs. The broader/commercial impacts of this research will provide the biofuel industry and research institutions an unprecedented means of rapid and comprehensive algal and oil characterization in a compact, low-cost, rugged, field-deployable, universal analyzer. It will help to solve the problems due to the enormously large biodiversity and unexplored territories in microalgae. In addition to its commercial potential, the efficiency of R&D efforts being undertaken around the world towards a sustainable and economic algal biofuel production will be greatly facilitated. Furthermore, this algal analyzer will have much wider applications, including environmental monitoring, homeland security, life science, and chemistry.
The sharply rising demand for biofuels, including high-energy density, low-pollution, carbon-neutral and ready-to-use algal biodiesel, has generated explosive interest in microalgae-related research and development. Currently, almost all major research institutes and universities have research groups investigating microalgae. There are over a hundred start-up companies in the U.S. striving to understand microalgae and make algal biodiesel economical. Government polices already provide the roadmap for sustainable biofuel productions [1]. However, at the same time a gap is rapidly broadening between the enthusiasm on microalgae and the general availability of analytical tools used today – most are still from 1980s, in a grow-harvest-dry-weigh-extract-analyze routine. These low efficiency, low-throughout and non-universal assays, together with the complex biodiversity and limited knowledge on microalgae have made the R&D efforts on microalgae difficult, and impossible to reach the demand. Raman spectroscopy provides specific measurement of the condition of living microalgae samples in situ. The Raman technique simultaneously measures features indicative of the state of the sample including carotenoids, proteins, and lipids (biofuel) in aqueous solution. However, common Raman laser wavelengths such as 532 and 785 nm excite fluorescence in the highly complex microalgae samples. In the Phase I effort we utilized a dispersive 1064nm Raman spectrometer developed at BaySpec, Inc. to overcome the fluorescence issue. Note that high laser power is required to measure the spectra of real world samples where the total biomass is 0.1% in solution. It has been shown that the living samples can survive extreme irradiance on the order of gigawatts/cm2 because the aqueous bath quenches local heating effects that will destroy living cells under normal conditions. An example of real-time measurement of the microalgae is shown in Figure 1. Raman spectra using 1064nm excitation provides real-time snapshots of the state of the microalgae growth over time, and therefore conditions can now be monitored and adjusted to maximize the production of biofuels as well as indicate the optimal harvest date. The future state of this application involves deployment of the 1064nm Raman spectrometer in the field. The system includes a highly sensitive 1064 nm Raman spectrometer coupled with a fiber optic immersion probe for real-time in situ measurements. 2009 Algal Biomass Organization Annual Report, www.algalbiomass.org/documents/ABO2009AnnualReport-FINALFORWEBSITE.pdf. 2009.
