While fusion power remains one of the most promising long-term power goals, another optimal future energy source may be algae.  Syracuse University’s Radhakrishna Sureshkumar, professor and chair of biomedical and chemical engineering describes, "Algae produce triglycerides, which consist of fatty acids and glycerin. The fatty acids can be turned into biodiesel while the glycerin is a valuable byproduct."

In the future, farms of algae tanks may provide affordable fuel capable of sustaining the auto industry without switching to scarce rare earth metals or radical redesigns.  However, a key challenge is to maximize algae growth and minimize the growth of parasitic organisms.

Green algae uses electro-active pigments Chlorophyll a and b, along with carotenoids, to capture sunlight.  That capture covers a very specific range of the visible light, namely the blue-violet spectrum.  By targeting them with that specific light, their growth can be sped up, while other types of undesirable photosynthetic microbes can be eliminated.

Professor Sureshkumar and SU chemical engineering Ph.D. student Satvik Wani have made an advance towards that objective.  By creating a suspension of silver nanoparticles, the researchers were able to backscatter blue light into an algae growing chamber, preventing more photons from escaping.  The increased exposure to the visible light's blue range led to a 30 percent increase in algal growth.

The pair found that growth could be maximized by optimizing the concentration of suspended nanoparticles and their size.  Professor Sureshkumar comments, "Implementation of easily tunable wavelength specific backscattering on larger scales still remains a challenge, but its realization will have a substantial impact on the efficient harvesting of phototrophic microorganisms and reducing parasitic growth.  Devices that can convert light not utilized by the algae into the useful blue spectral regime can also be envisioned."

The breakthrough could lead to advanced algae growing tanks that first filter light through a suspension of silver nanoparticles.  Silver nanoparticles are today commonly used in electronics, optics, wound dressings, and more for their unique properties.  They're also being evaluated as a possible treatment for HIV-1 [PDF].

The researchers published their work in the August 2010 edition of the prestigious journal Nature.