Constructed wetlands as biofuel production systems

Abstract

A study advocates the efficient production of cellulosic biofuel using waste nitrogen through wastewater treatment with constructed wetlands in China. The analysis suggests that the net life-cycle energy output of constructed wetlands is higher than many other biofuel production systems. Clean biofuel production is an effective way to mitigate global climate change and energy crisis1. Progress has been made in reducing greenhouse-gas (GHG) emissions and nitrogen fertilizer consumption through biofuel production2,3,4. Here we advocate an alternative approach that efficiently produces cellulosic biofuel and greatly reduces GHG emissions using waste nitrogen through wastewater treatment with constructed wetlands in China. Our combined experimental and literature data demonstrate that the net life-cycle energy output of constructed wetlands is higher than that of corn, soybean, switchgrass, low-input high-diversity grassland and algae systems. Energy output from existing constructed wetlands is ∼237% of the input for biofuel production and can be enhanced through optimizing the nitrogen supply, hydrologic flow patterns and plant species selection. Assuming that all waste nitrogen in China5 could be used by constructed wetlands, biofuel production can account for 6.7% of national gasoline consumption. We also find that constructed wetlands have a greater GHG reduction than the existing biofuel production systems in a full life-cycle analysis. This alternative approach is worth pursuing because of its great potential for straightforward operation, its economic competitiveness and many ecological benefits.

Cite this article

Liu, D., Wu, X., Chang, J. et al. Constructed wetlands as biofuel production systems. Nature Clim Change 2, 190–194 (2012). https://doi.org/10.1038/nclimate1370

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