4
Hill et al. compared these results with five existing papers. Although it is difficult to
compare directly because inputs and products are different among studies, producing excess input energy was shown in four of six studies, Wang et al., Shapouri et al.
(2004), Graboski (2002) and Hill et al. (2006). On the other hand, two of the six
studies, Parikka (2004) and Pimentel (2003), have opposite results. Based on those
studies, a clear result has not been obtained in terms of carbon-neutral biofuel production from the viewpoint of the life cycle. Hill et al. noted that those results are
not derived from a common consensus of included inputs for biofuel production.
For instance, it is difficult to define the ratio of agricultural capital use for biofuel
crops from total inputs of agricultural capital for agricultural production. The
UN-GBEP (Global Bioenergy Partnership) and many other institutions, however,
have discussed a unified evaluation method of biofuel production that may be established. It is expected to establish international standards to evaluate biofuel production (Technical Innovation Council on Biofuels 2008).
Not only the energy balance of biofuel production but also the greenhouse gas
emissions from soil are important in producing energy crops in the field. With
greenhouse gas emissions from the cultivation of energy crops, the affirmation of
carbon-neutral bioenergy may not be held.
Expanding the demand for bioenergy provides an incentive for farmers to shift
current crop production systems to new crop production systems with energy crops.
In fact, the number of farmers who do not sign up for the CRP (Conservation
Reserve Program) in the United States is currently increasing. The CRP was started
in 1986 to shift agricultural land located in disadvantaged areas to grass fields or
forests. Some of the benefits from the CRP are increasing stored carbon in the soil,
maintaining the productivity of land, mitigating land degradation caused by water
and wind and protecting biodiversity. Extensional expansion of energy crops may
drain benefits from the CRP. As a result, reducing greenhouse emissions through
using biofuels, which is the most important projected contribution, is not only
expected but also adversely affected by agricultural production through decreasing
productivity of the land and the loss of biodiversity. In addition, it is noted that
increasing agricultural production based on economic incentives leads to excess
inputs of chemical fertilizer and pesticides (Fike et al. 2006; Parrish and Fike 2005).
The increasing pricing pressure caused by the increasing demand for biofuels likely
brings the same consequences. Increasing energy crop production with excess
inputs could lead to harmful effects for ecological systems, including water
systems.
It is expected that the so-called second-generation biofuels may alleviate the
tight food supply because of biofuel expansion. Second-generation biofuels are produced from lignocellulosic biomass. Lignocellulosic biomass is hemicellulose, lignin and lignifying tissue, which are cells in the blade and stem (McKendry 2002).
Although it takes time to put them into practical use, second-generation biofuels are
expected to avert acute competition between crops for food and crops for biofuels
since any part of crops except the edible part and agricultural residue may be used
H. Matsuda and K. Takeuchi
Hill et al. compared these results with five existing papers. Although it is difficult to
compare directly because inputs and products are different among studies, producing excess input energy was shown in four of six studies, Wang et al., Shapouri et al.
(2004), Graboski (2002) and Hill et al. (2006). On the other hand, two of the six
studies, Parikka (2004) and Pimentel (2003), have opposite results. Based on those
studies, a clear result has not been obtained in terms of carbon-neutral biofuel production from the viewpoint of the life cycle. Hill et al. noted that those results are
not derived from a common consensus of included inputs for biofuel production.
For instance, it is difficult to define the ratio of agricultural capital use for biofuel
crops from total inputs of agricultural capital for agricultural production. The
UN-GBEP (Global Bioenergy Partnership) and many other institutions, however,
have discussed a unified evaluation method of biofuel production that may be established. It is expected to establish international standards to evaluate biofuel production (Technical Innovation Council on Biofuels 2008).
Not only the energy balance of biofuel production but also the greenhouse gas
emissions from soil are important in producing energy crops in the field. With
greenhouse gas emissions from the cultivation of energy crops, the affirmation of
carbon-neutral bioenergy may not be held.
Expanding the demand for bioenergy provides an incentive for farmers to shift
current crop production systems to new crop production systems with energy crops.
In fact, the number of farmers who do not sign up for the CRP (Conservation
Reserve Program) in the United States is currently increasing. The CRP was started
in 1986 to shift agricultural land located in disadvantaged areas to grass fields or
forests. Some of the benefits from the CRP are increasing stored carbon in the soil,
maintaining the productivity of land, mitigating land degradation caused by water
and wind and protecting biodiversity. Extensional expansion of energy crops may
drain benefits from the CRP. As a result, reducing greenhouse emissions through
using biofuels, which is the most important projected contribution, is not only
expected but also adversely affected by agricultural production through decreasing
productivity of the land and the loss of biodiversity. In addition, it is noted that
increasing agricultural production based on economic incentives leads to excess
inputs of chemical fertilizer and pesticides (Fike et al. 2006; Parrish and Fike 2005).
The increasing pricing pressure caused by the increasing demand for biofuels likely
brings the same consequences. Increasing energy crop production with excess
inputs could lead to harmful effects for ecological systems, including water
systems.
It is expected that the so-called second-generation biofuels may alleviate the
tight food supply because of biofuel expansion. Second-generation biofuels are produced from lignocellulosic biomass. Lignocellulosic biomass is hemicellulose, lignin and lignifying tissue, which are cells in the blade and stem (McKendry 2002).
Although it takes time to put them into practical use, second-generation biofuels are
expected to avert acute competition between crops for food and crops for biofuels
since any part of crops except the edible part and agricultural residue may be used
H. Matsuda and K. Takeuchi