Growing duckweed for biofuel production: a review

Abstract

Duckweed can be utilised to produce ethanol, butanol and biogas, which are promising alternative energy sources to minimise dependence on limited crude oil and natural gas. The advantages of this aquatic plant include high rate of nutrient (nitrogen and phosphorus) uptake, high biomass yield and great potential as an alternative feedstock for the production of fuel ethanol, butanol and biogas. The objective of this article is to review the published research on growing duckweed for the production of the biofuels, especially starch enrichment in duckweed plants. There are mainly two processes affecting the accumulation of starch in duckweed biomass: photosynthesis for starch generation and metabolism-related starch consumption. The cost of stimulating photosynthesis is relatively high based on current technologies. Considerable research efforts have been made to inhibit starch degradation. Future research need in this area includes duckweed selection, optimisation of duckweed biomass production, enhancement of starch accumulation in duckweeds and use of duckweeds for production of various biofuels.

Succinic acid production from duckweed (Landoltia punctata) hydrolysate by batch fermentation of Actinobacillus succinogenes GXAS137

“…) and wheat (3.15 t ha À1 year À1 ) (Cui and Cheng, 2015). Fourthly, duckweed biomass contains abundant protein and free amino acids, which are useful as nitrogen source in a fermentable feedstock.…”

Taxonomy of duckweeds (Lemnaceae), potential new crop plants

“…Apart from their use as food and feed, duckweed biomass with high starch content produced under suitable cultivation conditions (Sree and Appenroth, 2014;Sree et al, 2015a, b) can be used as a raw material for biofuel and biogas plants (Jain et al, 1992;Su et al, 2014;Cui and Cheng, 2015). This would substantially replace the use of food crops that are grown in arable lands as raw materials for biofuel production.…”

The influence of light intensity and photoperiod on duckweed biomass and starch accumulation for bioethanol production

“…Duckweed grows faster than most other plants, and under ideal condition, some species can double their biomass every 16 h to 24 h (Peng et al, 2007). The duckweed starch content varies by species and growth conditions ranging from 3% to 75% of dry weight (Reid and Bieleski, 1970;Xu et al, 2012;Cui and Cheng, 2015). Duckweed starch can be readily converted to ethanol using the same protocol that used for corn starch (Ge et al, 2012).…”

“…As to the influence factors for starch accumulation, nutrient starvation especially nitrogen and phosphorus, sodium, abscisic acid and other chemical growth inhibitors had been widely investigated (McLaren and Smith, 1976;Thorsteinsson and Tillberg, 1987;Janas and Osiecka, 1995;Janas et al, 1998;Cheng and Stomp, 2009;Xu et al, , 2012Cui and Cheng, 2015). On the other hand, starch is the product from the photosynthesis, light is the only source of energy for photosynthesis, and also the direct source of energy for starch accumulation (Stitt and Zeeman, 2012).…”

“…Therefore, there is great interest in exploring novel starch sources that do not necessarily compete for cropland and can be digested much easier than lignocellulosic biomass to make bioethanol production more sustainable. Recently, duckweed has drawn increasing attention for bioethanol production due to its high biomass and starch production Cui and Cheng, 2015 Duckweed, a small floating aquatic plant, belongs to the monocotyledonous family of Lemnaceae. The geographic ranges of duckweed span the entire globe and 37 species belonging to five genera (Lemna, Landoltia, Spirodela, Wolffia, and Wolffiella) have been identified so far (Appenroth et al, 2013).…”