助成番号09－017

松下幸之助記念財団 研究助成

研究報告
【氏名】 李 召羅【所属】 東京大学 アジア生物資源環境研究センター【研究題目】 Monetization analysis of environmental impacts and damages in the production and use ofbiofuels【研究の目的】
Biofuels are widely considered one of the most promising sources of renewable energy by policy
makers and environmentalists alike. However, unless principles and standards for production aredeveloped and implemented, certain biofuels will cause severe environmental impacts and reduce
biodiversity – the very opposite of what is desired. There exist a number of LCA methods and tools. Infact, even if in literature some studies on this specific field can be found, very little research on theintegrated assessment of environmental impacts and damages has been achieved, although it has apotential to evaluate specific systems such as renewable energy efficiently.
From these motivations, the objectives of this study are to develop evaluation methods by introducing
the integrated assessment of environmental impacts and damage focusing on source-oriented
emissions during Well-to-Wheel, and to define the perspectives of sustainable biofuels based on theinterpretations of environmental impacts and damage.
【研究の内容・方法】
Integrated factors based on LIME (Life-cycle Impact assessment Method based on Endpoint Modeling)
was applied to this study. The monetized damage factors (Table 1) were also used with LIME model,
meaning an economic valuation. This was useful for two different scenarios of biofuels to be comparedby integrating different categories. In case the damage indicators for biofuels A and B were conflicting(A was higher on human health and B was higher on biodiversity), the answer was dependent on themonetization factors for four safeguards. Considering the feasibility of biofuels in Japan, alternative
scenarios are considered for two kinds of feedstocks from “Khon Kaen Area in Thailand” and “CountrySide (Satoyama) Forest in Japan” during Well-to-Wheel. This study introduces two kinds of sourceoriented environmental impacts and damage, meaning biofuels emissions and avoided emissions. This
study suggested that there were no or less damages offset by avoided impacts in terms of regional andlocal scales, because safeguards affected by on-site or off-site emissions would be different.
Monetization analysis as an integration way was performed for four safeguards, dividing into global,regional and local scales.
.
Table1 Monetization factors for four safeguards adapted from LIME model
Endpoints

UnitFactor

Human health

USD/DALY

9.70E+04

Social asset

USD/USD

1.00E+00

Biodiversity

USD/EINES

4.80E+10

Primary plant production

USD/kg2.02E-01

The questionnaire for a comparison between midpoint and endpoint decision-making tools wasimproved based on the pilot survey, and it was used to survey 1000 Seoul metropolitan area (SMA)

residents by using the Internet. The respondents were randomly recruited by Korean Survey Company(World survey: www.wsurvey.net/) and included residents in Seoul City and Gyonggi Province (including31 administrative cities). Data management and frequency/nonparametric analyses of the survey
results for all the respondents were conducted using SPSS ver. 18.
【結論・考察】This study suggests major potential sources of biofuels, e.g., grass-type and woody biomass. Theirrelative impacts on the environment in terms of water and fertilizer use and other criteria should becalculated the both approach of each source. As well as comparing potential biofuel feedstocks, thisstudy also recommended a number of major principles for governing the development ofenvironmentally friendly biofuels. Feedstocks should be grown according to sustainable andenvironmentally safe agricultural practices with minimal ecological footprints (the area of land required
to grow and support sufficient amounts of the crop). In particular, emphasis should be placed on
biofuels that can sequester carbon or have a negative or zero carbon balance.
The results of this study illustrate the differences in the LCA outcomes with respect to the midpoint andendpoint approaches (Table 2). By introducing a new impact category for endpoints, the results werechanged dramatically in comparison to the results of midpoints. In addition, it would be possible tointerpret the effect of each indicator on safeguards by integrating separate midpoints. The key
advantage with respect to grouping impact categories in the midpoint and endpoint approaches can bedescribed as “the simplification of midpoints and the segmentation of endpoints.”
Table 2 Framework of LCA interpretation at midpoints and endpoints
Category
Global impact
Global warming
Ozone-layer depletion
Resource consumption
Regional impact
Acidification
Human toxicity
Eco-toxicity
Eutrophication
Local impact
Photochemical oxidant
Waste
Urban air pollution
Land use

Midpoint

Human healthSocial assets

Biodiversity

*
*
*

*

*
*
*

*

*
*
*
*
*
*

*

Primary plant
production

*
*
*

*
*
*
*

*
*

*
*

*

*

*

The respondents were asked to identify the approach that they preferred. Noteworthy is that 68.2%
preferred the midpoint approach for evaluating environmental systems. According to the crosstabulation analysis, individualist group (76.3% of this group) was more likely to prefer the midpoint
approach than the other groups, but none of the differences were statistically significant (Asymp. Sig. 2tailed: 0.091). In terms of the subjective questions, the respondents provided two types of answers
regarding why they preferred the midpoint approach. In the first type, the respondents explained thatthe midpoint approach consisted of familiar words such as “global warming” and “acid rain.” Such words
were familiar (and thus easy to understand) because the respondents encountered them through theInternet, television, radio, newspapers, and other publications, among others. In the second type, therespondents noted that it would be better to evaluate environmental impacts (midpoints) first because
environmental impacts would lead to environmental damage.
Noteworthy is that the respondents’ preference for midpoint and endpoint decision-making tools is notconsistent with that in previous studies. The midpoint approach is limited in its ability to integrateseparated midpoints because of different units, whereas the endpoint approach is limited in its ability tofacilitate a clear understanding of detailed interpretations of LCA results because of unfamiliar
categories.
It would be beneficial to investigate the suitability of midpoints and endpoints for different stakeholders
with a low or high level of environmental expertise by comparing previous studies. In addition, muchwork is needed to compare social preferences of each scenario based on midpoint and endpointinterpretations to generate useful information for decision making purposes.