Insights into key barriers in the implementation of renewable biofuel technologies

Abstract

Bioenergy can be defined as renewable energy derived from biological sources. As world energy consumption increases and fossil fuel supplies are depleted, national and international energy requirements will become more diverse and more complicated. Clearly, the niche that alternative and renewable energy sources occupy in the energy portfolio will continue to increase over time. Currently, bioenergy in the form of biofuel production including alcohols, lipids, and hydrogen represent working technologies that are in large part only economically limited where large scale production is currently too costly to compete with fossil fuels. As a result, there has been a significant investment in basic science research to make these technologies more robust and more amenable to scale up. This includes large scale cultures of model biofuel producing organisms, consortia of organisms, and even mimetic systems in which components derived from biological sources are incorporated into materials. The success of future biofuel technologies is dependent on advancing these technologies by overcoming some of the key barriers that decrease the practicality of wide scale implementation. A key to the large scale production of biofuels in the form of alcohols, lipids, or hydrogen is to develop mechanisms to limit the costs associated with culturing organisms and harvesting fuels. A technique used to facilitate the production of bio-hydrogen from eukaryotic algae is described and shows promise as a way to reduce costs associated with handling microorganisms used in bioreactors. Immobilization the hydrogen producing alga Chlamydomonas reinhardtii in calcium alginate facilitates manipulation of culture conditions during biofuel production and their subsequent harvest. The design of tailored microbial consortia or co-culturing multiple organisms provides a means of simplifying and reducing costs of media components required for biofuel production by providing key media components metabolically. Finally, genomic and gene expression studies have provided clues into structural determinants responsible for superior hydrogen production by certain enzymes that can be incorporated into model hydrogen producing organisms or merged into biomaterials. Together, these studies have contributed to the progression and knowledge of bioenergy promoting an increasing and long lasting presence of renewable fuels in the global energy portfolio.