Optofluidics assists solar energy collection and fuel production

Lausanne, Switzerland--Optofluidics, which can enable the simultaneous delivery of light and fluids with microscopic precision, is applied to the field of energy in a recent Nature Photonics (doi:10.1038/nphoton.2011.209) review from professor Demetri Psaltis in the Optics Laboratory at École polytechnique fédérale de Lausanne in collaboration with researchers from Cornell University (Ithaca, NY) and Toronto University (Toronto, ON, Canada). The group focuses on optofluidic opportunities in sunlight-based fuel production in photobioreactors and photocatalytic systems, as well as optofluidically enabled solar energy collection (http://www.laserfocusworld.com/articles/2010/06/photonics-applied.html) and control, providing physical and scaling arguments that demonstrate the potential benefits of incorporating optofluidic elements into energy systems.

The authors say that one of the main strengths of optofluidics is the simultaneous and precise control it offers over fluids and light at small scales. The tools used by the optofluidics community to enable this control include micro- and nanofluidic channels and photonic elements such as waveguides, optical resonators, optical fibers, lasers, and metallic nanostructures. Recently, a number of demonstrations have shown how collocated and simultaneous control over both fluids and light can be used to manipulate single strands of DNA and other nanoscale objects, or even induce optically driven reactions.

The review focuses on two emerging opportunities for optofluidics: photobioreactors and photocatalytic reactors for solar-energy-based fuel production, and liquid-based systems for the collection and control of solar radiation. In the area of light-powered fuel production they discuss how the simultaneous control of light and fluids at small scales can offer several advantages. The use of small confined spaces can increase energy production rates because the reactants have only a short distance to diffuse before reaching the photocatalytic surface or photosynthetic microorganism. This allows for smaller systems, thereby increasing the associated power density and potentially reducing operational costs (for example, to maintain proper thermal control over the system). In the area of solar collection and control, optofluidics offers adaptability and flexibility. Fluid-based optical interfaces can be readily modified using microfluidic handling techniques without the complications associated with moving solid components.

The paper then concludes with a quantitative description of how optofluidic elements can be incorporated into these systems and some of the technical barriers that must be overcome before such integration can be achieved.

SOURCE: EPFL; http://actu.epfl.ch/news/optofluidics-for-energy-applications-2/