The face of renewable energy is about to get microscopic

 

If we can do it, bacteria can do it too: sometimes better! Recent discoveries have shown that bacteria have diverse capabilities that could lead to novel applications, including wastewater treatment and energy generation.

Shewanella, for example, is a bacterium that lusts for raw electricity in the form of electrons from nature. Shewanella is a staple bacterium used in microbial fuel cells — a bio-electrochemical system — to transform energy from organic compounds into electricity. In theory, these microbial fuel cells can convert up to 90 per cent of oxidation energy into electricity and have the potential of considerably reducing careless expenditure in wastewater treatment.

Why aren’t these gems replacing standard electrical power sources you ask? The reality is that limitations in bacterial loading and complicated electron transfer methods have impeded progress towards the application of this technique in commercial or industrial settings. That is, until now.

A recent study published by Shenlong Zhao and his colleagues at the Harbin Institute of Technology has introduced a 3D graphene aerogel coupled with platinum nanoparticles as an anode. This anode, a conductor through which the electrical current generated flows, has a porous structure that immobilizes bacterial cells and facilitates transport of electrolytes. Zhao and colleagues tested conductivity, diffusion, bacteria loading capacity, and long-term stability of the proposed anode. They reported that in all categories the 3D grapheme aerogel couple with platinum nanoparticles was more effective than common carbon cloth anodes. What’s more impressive is the efficacy with which, in a preliminary experiment, the microbial fuel cell generated power by using wastewater from a treatment plant in Beijing, China. This is the very first time that a microbial fuel cell is used to run an actual electrical device.

As energy needs rise uncontrollably on a global scale, this new anode could be the answer to better, cleaner energy as well as a definite alternative to oil and carbon-based energy sources. It would also significantly reduce the costs in multiple industries, namely wastewater. In the US alone, 4 per cent of  the electricity produced is consumed by wastewater facilities. On the other side of the spectrum, poor waste management in lower income countries directly impacts on biological diversity, food production and various life support systems on which we all depend. Given that only 20 per cent of wastewater is adequately treated, the addition of 3D graphene aerogel could have an incredible impact on efficacious wastewater management worldwide as well as significantly reducing the burden on aquatic ecosystems.

Harnessing the power of microbes to produce renewable energy has gone from wishful thinking to imminent reality. Though much more work needs to be done, carbon-based energy sources may soon be a thing of the of past, replaced by the use of microbial fuel cells.

 

Sources:

Logan, B. E. and Regan, J. M. (2006) ‘Microbial Fuel Cells: Challenges and Applications’, Environmental Science & Technology (September), pp. 5172–5180.

UN- Water (no date) Wastewater Management: A UN-Water Analytical Brief. Available at: http://www.unwater.org/fileadmin/user_upload/unwater_new/docs/UN-Water_Analytical_Brief_Wastewater_Management.pdf (Accessed: 23 November 2015).

Yin, H., Zhao, S., Li, Y., Zhao, F., Liu, Z., Luan, E., Yin, H. and Tang, Z. (2015) ‘Three-dimensional graphene/Pt nanoparticle composites as freestanding anode for enhancing performance of microbial fuel cells’, Science Advances, 1(10), p. 1500372. doi: http//dx..org/10.1126/sciadv.1500372.