(741b) Simultaneous Supercritical Transesterification and Hydrothermal Liquefaction of Algae Paste

Simultaneous supercritical transesterification and hydrothermal liquefaction of algae paste.

Bhavish Patel and Klaus Hellgardt

Imperial College London, Department of Chemical Engineering, South Kensington, SW7 2AZ, London, UK.

Rising population and increasing energy demand has increased the consumption of fossil fuels and accelerated the onset of climate change [1] . Recent unprecedented rise in atmospheric CO₂level [2] re-iterates the urgent necessity for utilisation of a renewable energy source. The use of biomass, particularly algae offers great potential as an alternative for liquid fuel production due to its environmental, social and economic sustainability. An integrated algal biorefinery concept for production of biofuels, biochemicals and by-products has been suggested as a promising way forward [3]. In order to eliminate the high energy requirement for drying wet algae paste [4], hydrothermal liquefaction and supercritical trasesterification of wet algae paste can be employed.

The chemistry of these processes can be complicated. Thus, to understand the chemical behaviour during hydrothermal conversion, in our previous work we presented a new methodology for observing functional group transformation using ³¹P-NMR [5] . Our investigation found that under hydrothermal conditions, the majority of molecular degredation occurs within contact time of less than 10 minutes. [6].

In order to maximise the product distribution, direct transesterification of wet algae paste provides an amenable alternative for production of biodiesel from lipids as well as biocrude from the other fractions by liquefaction. We have employed Stainless Steel batch reactors in our study for in-situ transesterification and liquefaction of wet algae paste with ethanol and methanol. In our quantitative study we will present the kinetics for biodiesel production and characterisation of light and heavy biocrude to shed light on the chemistry of this new integrated process. The Box-Behnken experimental design and response surface methodology is applied to decipher optimum reaction parameters for economic processing conditions.

[1] Gruenspecht, H. (2010). International Energy Outlook 2011. Center for Strategic and International Studies

[2] http://www.esrl.noaa.gov/gmd/news/7074.html[12th May 2013, 03:00 AM GMT]

[3]  Patel, B., Tamburic, B., Zemichael, F. W., Dechatiwongse, P., Hellgardt, K. (2012). Algal Biofuels: A Credible Prospective?. ISRN Renewable Energy, Vol. 2012, Article ID 631574.

[4] Lardon, L., Hélias, A., Sialve, B., Steyer, J. P., & Bernard, O. (2009). Life-cycle assessment of biodiesel production from microalgae. Environmental science  and technology, 43(17), 6475-6481.

[5] Patel B., Richard C., Hellgardt K., Supercritical Upgrading of Algae Paste[abstract]. In: AIChE 2012 Annual Meetings; 2012  Oct 28 – Nov 2; Pittsburgh. Pennsylvania.

[6] Patel, B., Hellgardt., K. (Forthcoming 2013). Hydrothermal Upgrading of Algae Paste: Application of 31P-NMR. Environmental Progress and Sustainable Energy.