Cassava - Bioenergy Crop Plants - page 308

In Thailand, cassava became an important industrial crop after World War II. Cassava produc-
tion in Thailand has since progressed from basic starch production to the world's largest producer
of bioethanol. Such progress was made possible by the announcement in 2003 by the Thai cabinet
to include bioethanol as a renewable energy (Suksri et al. 2007). Although molasses is the major
source of ethanol in Thailand, the country already has a cassava-derived ethanol pilot plant and the
government was aiming to build 12 full-scale plants by the end of 2008. Thailand's leading petro-
leum company also announced a feasibility study that would use cassava to produce 1 million L of
bioethanol per day (Spotlight 2006).
In southern China, cassava was initially used as a food crop but has now become an important
crop for on-farm feeding of animals and for processing into various industrial products such as
native starch, modified starch, sweeteners, and alcohol (Hershey et al. 2001). Cassava production
in China remained unattractive to farmers for a long time and it was only until the late 1980s
when many new cassava-based products were developed successfully that farmers started to
increase their production. The government of China supports cassava breeding and production
and this has encouraged a lot of farmers to venture into cassava farming. In India, cassava was
initially introduced as a food crop but has now changed its status to a commercial crop in the
states of Tamil Nadu and Andhra Pradesh (Srinivas 2009) as a result of intensive research and
development efforts of different research institutes. In Vietnam, cassava has been reported to
have great potential as food and feed crop in the north and as a cash crop in the south (Van Bien
et al. 2009).
13.6 ProBlems and concerns oF current
BIoFuel ProductIon
Record oil prices have boosted demand for biofuels as consumers and companies look for cheaper
and cleaner energy sources. Biofuels like ethanol and biodiesel have been widely viewed as the
answer to reducing greenhouse gas emissions (up to 40%), but critics warn that a reliance on them
could lead to higher food prices, deforestation, and ultimately do more damage to the environment
than the fossil fuels they are supposed to replace (Lumpar 2007).
A major hurdle for widespread adoption of biofuels is the challenge of growing enough crops
to meet demand. “Replacing only five percent of the nation's diesel consumption with biodiesel
would require diverting approximately 60% percent of today's soy crops to biodiesel production,”
says Matthew Brown, an energy consultant and former energy program director at the National
Conference of State Legislatures (Dand 2010).
Another dark cloud looming over biofuels is whether producing them actually requires more
energy than they can generate. After factoring in the energy needed to grow crops and then convert
them into biofuels, turning plants such as cassava, corn, soybeans, and sunflowers into fuel uses
much more energy than the resulting ethanol or biodiesel generates (Lang 2005).
Resilience and sustainability of cassava in marginal lands, drought-prone locations, or acid soils
explains its importance as a stable crop in areas with poor resources for soil fertility and crop man-
agement. However, weeds compete for the nutrient resources in these areas and can significantly
affect the crop yields. Although the larger leaf canopy of cassava plants in later stages of growth
helps in suppressing the weeds, the slow initial growth rate of cassava renders the crop particularly
vulnerable to weed interference soon after planting. Weed control during tuberization stage is par-
ticularly very critical for higher crop yields (Melinfonwu 1994). These weeds not only increase crop
management costs but also serve as reservoirs for new and invasive pests. The cassava root scale
( Protortonia navesi ) is a recent pest in the Brazilian “Cerrado” that causes qualitative and quantita-
tive damage by sucking plant sap and is hosted by 13 weed species during the growing season and
five weed species after harvest (Oliviera and Fontes 2008).
New migratory plant pests increase risks over global food security, and cassava mealy bug
( Phenacoccus manihoti ) in Africa is one such example. Cassava mealybug (CMB) was introduced