Promises and Lies about Biofuels from Microalgae

초록

Biofuels are a potential high energy density liquid fuel for the future, but the way the biofuels are produced will decide how much carbon can be saved and how much bioenergy can be utilized. Converting rainforests, grasslands, and other wetlands to produce food crop–based biofuels creates a "biofuel carbon debt" by releasing much more CO2 than the annual greenhouse gas (GHG) reductions that these biofuels would provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on degraded and abandoned agricultural lands planted with perennials or from biomass grown in ocean incur little or no carbon debt and can offer immediate and sustained GHG advantages. Algal biotechnology is drawing increasing interest again due to its potential of fixing carbon dioxide and producing biofuel at the same time. Consequently, microalgae may conquer the top three environmental problems (global warming, energy crisis, and environmental pollution) in a simultaneous manner is even more exciting. Algae have great potential as a sustainable feedstock for production of diesel-type fuels with a very small CO2 footprint. This demonstration will be an important test of the technology and, critically, of commercial viability. Microalgae contain lipids and fatty acids as membrane components, storage products, metabolites and sources of energy. Microalgae have been found to contain proportionally high levels of lipids (over 30%). Lipid accumulation in algae typically occurs during periods of environmental stress, including growth under nutrient-deficient conditions. Therefore, it may be possible to enhance lipid production rates by increasing the activity of this enzyme via genetic engineering. However, despite all these advantages of microalgal biofuels, there are quite a number of challenges to overcome before economic production of microalgal biofuel can be achieved. All the opportunities and challenges of microalgal biofuels will be discussed.