Sustainability Criteria for Bioenergy Systems: Results from
an Expert Survey
Thomas Buchholz*, Valerie A. Luzadis, Timothy A. Volk
State University of New York, College of Environmental Sciences and Forestry (SUNY-ESF),
Department of Forest and Natural Resource Management,
346 Illick Hall, One Forestry Drive, Syracuse NY 13210, USA
Draft version 2008/07/25
Manuscript submitted on July 25th 2008 upon pending invitation for a special issue on
International Trade in Biofuels (ITIB) of the Journal of Cleaner Production
Abstract:
Environmental impacts associated with the use of fossil fuels, rising prices, potential limitations
in supply and concerns about regional and national security are driving the development and
use of biomass for bioenergy, biofuels and bioproducts. However, the use of biomass does not
automatically imply that its production, conversion and use is sustainable. In order to
operationalize sustainability assessments of biomass systems, it is crucial to identify critical
criteria, but keep them at a manageable level. The selection of these criteria can vary
depending on individual’s expertise, geographical region, and attribute on spatial scale. No clear
consensus has yet emerged as to what experts consider critical indicators of sustainability.
Objectives of this paper were to analyze how experts score sustainability criteria and to identify
levels of agreement and uncertainty.
Input on sustainability criteria for bioenergy systems was based on ratings and rankings from 46
international experts from academia, business and NGOs. The experts completed a survey
ranking a suite of 35 criteria found in emerging sustainability assessment frameworks for the
attributes of relevance, practicality, reliability, and importance.
Energy balance and greenhouse gas balance were perceived as especially critical. Social
criteria and locally applied ones ranked generally low in all four attributes. Ten of the 12 most
important criteria based on average scores also lead the list of the most critical criteria for
inclusion. The majority of these 12 criteria were focused on environmental issues, four were
social and only one was economic. Although being perceived as important, food security ranked
very low in both practicality and reliability. Scale of operation and profession of experts
explained most of the ranking differences between experts rather than regions. Low ranking
criteria, especially in the attribute importance, were characterized by a low consensus
suggesting the need for further debate regarding their inclusion in sustainability assessments.
Outcomes of the survey provide a foundation for sustainability assessments such as certification
of international biomass trade and are also applicable to assessing individual bioenergy projects
within their specific geographic, ecological, societal, and technological context and scale.
Keywords: Bioenergy; sustainability criteria; expert survey; international biomass trade;
certification
*
Corresponding author. Email: tsbuchho@syr.edu, phone: +1 315 470 4850, fax: +1 315 470 6934
Submitted to the Journal of Cleaner Production
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1 INTRODUCTION
Environmental impacts associated with the use of fossil fuels, rising prices, potential limitations
in supply and concerns about regional and national security are driving the development and
use of biomass for bioenergy, biofuels and bioproducts. At the same time, cheaper biomass
production capacities in developing countries are increasingly being linked with the energy
demand in industrialized nations, forming a rapidly expanding international biofuels trade.
The use of bioenergy does not automatically imply that its production, conversion and
distribution are sustainable. The network of interconnected supply chains associated with
international biofuels makes ensuring sustainability more challenging than biomass that is
produced and used locally, but the assessment framework could be similar at either scale. A
sustainability assessment of bioenergy systems needs to include the whole production cycle
including biomass production and transportation, conversion technology, and energy allocation.
In order to operationalize sustainability assessments of bioenergy systems, it is crucial to
identify critical criteria, keep their numbers at a manageable level, and remain responsive to the
local context. Certification is one mechanism for conducting criteria based assessments and is
currently driven by international and national efforts related to global biomass trade such as
Roundtable on Sustainable Biofuels (RSB) Lausanne, or the Cramer Commission (2006). While
there has been a great deal of discussion about sustainability through these efforts and other
forums (van Dam et al. 2008), no clear consensus has yet emerged on which indicators are
critical and which framework should be become standard practice.
Goals and Objectives
Like any standard, sustainability standards are based on human values and it takes time and
debate to reach consensus. To contribute to this effort, we surveyed and analyzed experts’
opinions on bioenergy sustainability criteria and frameworks currently under discussion around
the world to identify the criteria that are viewed as most important, relevant, practical, and
reliable. The goal was to identify areas of agreements and uncertainty among international
experts on what to include and how to organize the assessment of sustainability of bioenergy.
Similar survey efforts are being pursued on national levels (e.g. Wellisch (2008) performed an
expert survey focusing on Canada) but to date, none measure and analyze consensus at an
international level.
Specifically, the study objectives were to:
¾
Analyze how currently discussed sustainability criteria are perceived in their application
value and importance by bioenergy experts around the world;
¾
Identify levels of agreement and uncertainty amongst experts on criteria;
¾
Explore which frameworks are preferred for sustainability assessments of bioenergy
systems;
2 METHODS
2.1 Study population
We identified a population of 137 bioenergy experts as key participants in the current bioenergy
debate with specific attention to range of experience in regions, types of bioenergy systems,
scale of operations, and professions. Experts were identified through the bioenergy literature,
conference participation lists, and members of international bioenergy organizations such as the
International Energy Agency (IEA) Bioenergy. Each expert was identified as having a
considerable influence in the discussion of sustainability assessment of bioenergy systems.
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2.2 Survey Design
Criteria identification and scoring
Through a literature review, we identified 35 sustainability criteria which are regularly discussed
in the context of bioenergy (see Appendix 1). Sources for criteria identification included Cramer
et al. (2006), van Dam et al. (2006), Fritsche et al. (2006), Jürgens and Best (2005),
Lewandowski and Faaji (2006), Modi et al. (2006), Reijnders (2006), Five Winds International
(2006), Smeets et al. (2005), the Sustainable Bioenergy Wiki (2006) of the Roundtable on
Sustainable Biofuels (RSB) Lausanne, Upreti (2004), and the World Energy Council (1999).
Criteria were grouped into the broad categories of social (15 criteria), economic (4 criteria) and
environmental (16 criteria). Participants were asked to score each of these 35 sustainability
criteria on four attributes including relevance, practicality, reliability, and importance using the
following definitions:
¾
Relevance: How relevant is the criterion to the concept of sustainable bioenergy systems?
Does its assessment contribute to a better understanding of the sustainability of the
bioenergy system?
¾
Practicality: Are there existing scales and/or measurement units? Are there measurable
threshold values? How easily can data be obtained? Is measuring the indicator cost, time
and/or resource effective?
¾
Reliability: How reliable is the result of assessing the criterion? Is there a high degree of
uncertainty attached to the criterion? Are results reproducible? How easily can consensus
be achieved?
¾
Importance: How important is the criterion for assessing the sustainability of the bioenergy
system? Is it critical, i.e. is it according to your opinion mandatory to include it in a
sustainability assessment of bioenergy systems?
The attributes relevance, practicality, and reliability were scored using the same scale (Low,
Medium, High, No Opinion). The importance attribute was measured using a slightly different
scale (Low, Medium, High, Critical, No Opinion) where ‘critical’ was meant to be chosen by
participants for a criterion which needs to be included in any bioenergy sustainability
assessment. The goal here was to identify criteria that should be included in any sustainability
assessment of bioenergy or those that would be specific to a certain project and could be added
on a case by case basis.
Respondents were also given the opportunity to comment or add missing criteria and score
them in a special section of the survey.
Evaluation of assessment frameworks
In the third portion of the survey, respondents evaluated five different frameworks for organizing
criteria in sustainability assessments. The frameworks were rated using the following scale (No
Opinion, Poor, Fair, Good, Very Good, Excellent) and respondents were asked to reveal their
preferred framework. Respondents also were given the opportunity to comment or add missing
frameworks and score them. The following sustainability assessment frameworks were included
in the survey:
¾
Social, Economic, Environmental; abbreviated in the following as SEE;
¾
Benefits, Opportunities, Costs, Risks; abbreviated in the following as BOCR;
¾
Strengths, Weaknesses, Opportunities, Threats; abbreviated in the following as SWOT;
Submitted to the Journal of Cleaner Production
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¾
(Driving force), Pressure, State, (Impact), Response; abbreviated in the following as
(D)PS(I)R;
¾
Greenhouse Gas Balance, Competition for Land, Biodiversity, Economic prosperity, Social
Well-Being, Environment based on Cramer et al. (2006); abbreviated in the following as
Cramer.
Respondent demographics
Respondents were asked to provide information about their professional background,
geographical expertise, and the scale of bioenergy projects they are familiar with. This
information was used to assess if there were large differences of opinion between groups of
respondents based on these characteristics.
2.3 Survey implementation
In May 2007, 137 experts were asked by email to participate in the study. Participants received
a survey and explanatory cover letter and a maximum of two follow up emails spaced two weeks
apart to encourage participation. 46 individuals agreed to participate within the study time frame.
A telephone follow up with 10% of those who did not participate revealed no significant
differences from respondents and no one specifically refused for reasons other than workload
and timing. As such, the results of this study represent the opinions of 46 key bioenergy experts
from all over the world.
2.4 Survey analysis
Overall approach
Results were analyzed using SPSS 16.0 and Microsoft Excel software. Scores from
respondents who consistently scored criteria with ‘no opinion’ within one attribute (relevance,
practicality, reliability, importance) were not considered. As a means to compare scoring
between criteria but within attributes, an average score was calculated for each criterion and
attribute. While ‘no opinion’ received no ranking, scores were counted as Low = 1, Medium = 2,
High = 3, Critical2 = 4 and the resulting mean was taken as the average score. The magnitude
for each attribute was calculated by the using the mean of all average scores within one
attribute. The magnitude therefore allowed comparing the weight of attributes.
In order to make statements on the homogeneity of scores given by respondents for each
criterion, a ‘consensus score’ was calculated using the standard deviation of counts within the
response categories (low, medium, high). Criteria with a strong tendency towards one extreme
or the middle in scorings received a high consensus score compared to those criteria with
greater variation and scorings evenly distributed across the three response categories (and
therefore having a low standard variation) over the complete scale.
For further analysis, respondents were divided in groups according to their demographic
characteristics. Groups were aggregated when necessary for analysis (results in those cases
are so noted). Fisher’s Exact Test (Fisher 1967) was used for small group responses to detect
significant scoring differences between groups of respondents based on contingency tables.
2
‘Critical’ only applicable for attribute ‘Importance’.
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3 RESULTS AND DISCUSSION
3.1 Demographic characteristics of respondents
Over half of the respondents had a professional focus on biomass production (Figure 1). The
representation of primary scales of operation was more evenly distributed, but the focus was a
national scale (Figure 2). Respondents had experience in all continents except Antarctica but
most of the respondents had experience in Europe and North America (Figure 3). Most
respondents worked for government agencies or in academia (Figure 4). For demographic
analysis the following groups were aggregated to increase group size:
¾
Professional expertise: ‘Liquid transport fuels’ and ‘Other’; ‘Electricity generation’ and ‘Heat
generation’;
¾
Regional expertise ‘Africa’, ‘Asia’, ‘Australia’, ‘South America’;
¾
Professional occupation: ‘Industry’ and ‘Consulting’; ‘Nonprofit Organization’ and ‘Other’.
35
35
31
30
30
30
Biomass production
20
Liquid transport fuels
N
Electricity generation
15
10
7
3
5
25
Local
20
Heat generation
15
Other
10
Global
7
0
Figure 1: Primary expertise of respondents, N=45.
‘Other’ included expertise in air emissions and
overall project designs.
Figure 2: Primary scale of operation of
respondents, N=46.
30
20
20
15
10
6
3
4
Africa
16
Asia
14
Australia
12
Europe
10
N
22
5
18
18
18
24
25
N
10
5
0
5
Supranational
10
3
1
National
N
25
North America
8
South America
6
Anywhere
4
2
0
Government/policy
Industry
Academia
6
Consulting
7
Nonprofit Organisation
4
4
Other
2
0
Figure 3: Primary regions of expertise of
respondents, multiple answers accepted, N=46.
Figure 4: Primary segments of profession of
respondents, multiple answers accepted, N=44.
‘Other’ included independent research and UN.
3.2 Criteria scoring
Table 1 shows the average score for each criterion on each of the four attributes (relevance,
practicality, reliability, and importance) as rated by all 46 experts. Further analysis was based
on these average scores and in particular for the top third highest ranked criteria in importance.
Differences in importance between social, economic, and environmental criteria
The 35 criteria included in the survey were in a ratio of about 4:1:4 (social, economic,
environmental) however the experts rated more environmental criteria as important than social
Submitted to the Journal of Cleaner Production
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or environmental criteria. The majority of the 12 criteria with the highest importance values were
focused on environmental (7) issues followed by social (4) and economic (1). One interpretation
of this result might be that it reflects a normative weight on these criteria. Alternatively, it could
simply reflect a weight in terms of effort already spent to design and evaluate those criteria. It
could also reflect the biophysical science disciplines often associated with bioenergy
professionals. The outcome of even a few social criteria could be weighted more than many
environmental or economic criteria in a sustainability assessment. However, developing more
elaborate assessment systems (measured in the numbers of criteria considered important) for
environmental considerations suggests otherwise.
Based on the average score of each criterion for the four attributes, taken all together
environmental criteria were highest in both importance and relevance, followed by economics,
then social criteria. Social criteria as a group were rated higher in practicality than environment
and economic criteria groups and economic criteria as a group were rated as most reliable
followed by environmental then social criteria groups. In summary, environmental criteria were
rated as more important and relevant, social criteria as more practical, and economic criteria as
more reliable.
The suggestion of social criteria as being perceived as less important is further supported by the
fact that 8 out of the 12 criteria with the lowest average score in importance are of a social
nature (see Table 1) as for instance Respect for human rights (no. 7) or Cultural acceptability
(no. 5). Furthermore, Employment generation (no. 16), a criterion often discussed in
sustainability forums like the RSB or the IEA Bioenergy Tasks 29 and 40, did consistently rank
in the middle third for all four attributes relevance, practicality, reliability, and importance. One
reason for this ordering may be due to experts giving higher ratings to those areas they know
best. It is highly likely that most experts in bioenergy have biophysical science as their primary
disciplinary strength. Sustainability assessments may be improved by ensuring the breadth of
disciplinary foundations of participants across appropriate biophysical and social sciences.
Another surprising observation was that the criterion Macroeconomic sustainability (no.18),
which could indicate if a bioenergy system can be run profitably in absence of subsidies, was
ranked in the low third for relevance, practicality, and importance. This notion could be
interpreted as a general agreement that government support is going to be required, especially
in the near term, to develop bioenergy systems to the point that they can be profitable.
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Table 1: Average scores of criteria for all attributes, sorted by the importance score. For criteria names
see Appendix 1. A high average score indicates a more relevant, practical, reliable, or important criterion.
CRIT.
NO.
CRITRION NAME
RELIABILITY IMPORTANCE
NATURE OF
RELEVANCE
PRACTI-
CRITERION
SCORE
CALITY SCORE
SCORE
SCORE
34
Greenhouse gas
balance
Environmental
2.84
2.33
2.17
21
Energy balance
Environmental
2.87
2.51
2.39
3.44
30
Soil protection
Environmental
2.85
2.23
2.07
3.27
4
Participation
Social
2.80
1.98
1.95
3.16
32
Water management
Environmental
2.74
2.12
2.00
3.14
22
Natural resource
efficiency
Environmental
2.78
2.02
1.86
17
Microeconomic
sustainability
Economic
2.74
2.46
2.30
1
Compliance with laws
Social
2.46
2.13
1.95
3.09
24
Ecosystems protection
Environmental
2.87
1.98
1.95
3.07
13
Monitoring of criteria
performance
Social
2.73
2.12
2.02
2
Food security
Social
2.53
1.91
1.79
2.95
33
Waste management
Environmental
2.70
2.39
2.23
2.93
20
Adaptation capacity to
environmental hazards
and climate change
Environmental
2.63
2.05
1.80
26
Crop diversity
Environmental
2.48
2.10
1.95
8
Working conditions of
workers
Social
2.65
2.27
1.98
12
Planning
Social
2.47
2.22
2.03
2.79
19
Economic stability
Economic
2.51
1.98
1.79
2.79
3.55
3.11
3.10
3.02
2.90
2.86
2.83
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Table 1, continued.
CRIT.
NO.
CRITRION NAME
RELIABILITY IMPORTANCE
NATURE OF
RELEVANCE
PRACTI-
CRITERION
SCORE
CALITY SCORE
SCORE
SCORE
23
Species protection
Environmental
2.51
1.74
1.68
2.76
29
Use of chemicals, pest
control, and fertilizer
Environmental
2.53
2.23
2.07
2.72
35
Potentially hazardous
atmospheric emissions
other than greenhouse
gases
Environmental
2.57
2.26
2.17
2.72
16
Employment generation
Economic
2.51
2.33
2.15
2.69
11
Property rights and
rights of use
Social
2.55
2.00
1.76
2.68
31
Land use change
Environmental
2.40
1.79
1.64
2.68
28
Use of genetically
modified organisms
Environmental
2.44
2.07
1.85
2.64
25
Ecosystems connectivity
Environmental
2.44
1.91
1.71
2.57
7
Respect for human
rights
Social
2.28
1.55
1.50
2.48
18
Macroeconomic
sustainability
Economic
2.30
1.83
1.89
2.39
5
Cultural acceptability
Social
2.23
1.58
1.45
2.37
9
Respecting minorities
Social
2.20
1.62
1.45
2.35
27
Exotic species
applications
Environmental
2.18
1.88
1.69
2.33
6
Social cohesion
Social
2.16
1.62
1.46
2.26
3
Land availability for other
human activities than
food production
Social
2.18
1.70
1.63
2.25
10
Standard of living
Social
2.14
1.77
1.67
2.14
15
Noise impacts
Social
2.00
2.05
2.02
2.10
14
Visual impacts
Social
2.02
1.81
1.55
1.98
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3.2.1 Relations between attributes
High average scores for relevance and practicality correlated strongly with high average scores
in importance and reliability, respectively (Figure 5). Therefore, firstly, highly relevant criteria
were in general also perceived as highly important, and secondly, very practical criteria were
also perceived as very reliable. However, no connection could be found between the two pairs
of attributes relevance-importance and practicality-reliability.
Figure 5: Correlation of scores from all respondents for different attributes for the 35 critiera. The x-axis
represents the mean average scores of the first mentioned attribute, while the y-axis represents the mean
average score of the second attribute. Each dot represents one of the 35 criteria. A high average score
indicates a high score in the respective attribute.
3.2.2 Critical criteria
The importance attribute of each criterion was scored as critical (i.e. participants thought the
criterion would need to be mandatory in any bioenergy sustainability assessment) by at least by
one respondent (Figure 6). There is limited agreement between respondents which criteria
should be critical ones. Only the criteria Energy balance (no. 21) and Greenhouse gas balance
(no. 34) were scored as critical by more than half of the respondents. This is an interesting
outcome in the light of the dispute on how ‘net energy’ balance should be considered in
bioenergy systems (Dale 2007, Hall et al. in press).
10 out of the 12 most important criteria (~top third) based on average importance scores (Table
1) also lead the list of the most critical criteria, i.e. those criteria that had the top critical scores
among all respondents (Figure 6).
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Figure 6: Proportion of survey respondents scoring the attribute of importance as critical (N=36-45). For
criteria names and descriptions Table 1 and Appendix 1.
3.2.3 Criteria Importance Ratings
A number of criteria were scored as having high importance. The top 12 (~top third) criteria in
the importance attribute had an average score > 2.9 (Table 2) (marked with an X in the column
‘All respondents’, namely Compliance with laws (no. 1), Food security (no. 2), Participation (no.
4), Monitoring of criteria performance (no. 13), Microeconomic sustainability (no. 17), Energy
balance (no. 21), Natural resource efficiency (no. 22), Ecosystems protection (no. 24), Soil
protection (no. 30), Water management (no. 32), Waste management (no. 33), and Greenhouse
gas balance (no. 34). When the importance attribute is examined by subgroups, twenty three of
the 35 criterion were rated in the top third by at least one subgroup and 12 criteria were not
included in the top third criteria list for any of the subgroups. All groups have at least 8 criteria in
common among the top third of the scores3 suggesting that there is a fairly stable consensus on
many of the most important criteria. The groups ‘National’, ‘Supranational’, ‘Europe’, and
‘Academia’, shared 11 of the 12 top ranked criteria with the scores for all respondents. The
groups ‘North America’, ‘Government/Policy’, and ‘Industry + Consulting’ had 10 top of the 12
top third criteria in common with all respondents.
3
The groups sharing only 8 of their top third criteria with the complete sample were the group comprised
of all other regions than Europe and North America, the groups ‘Local, ‘Global’, the group lumping
nonprofit organizations and others than government/policy, academia, and industry + consulting.
Submitted to the Journal of Cleaner Production
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Survey on Sustainability Criteria for Bioenergy Systems
Table 2: Top third criteria according to average score for importance for all respondents and subgroups.
Only criteria occurring in one of the groups in the top third are listed. Groups are listed in a descending
order from left to right in how many criteria they shared in their top third’ scoring with the complete sample
population, i.e. NGO/Others diverged the most in their top third scoring compared to the complete group.
Numbers of respondents vary within each group as respondents scoring with ‘No opinion’ were not
included.
1
Compliance with laws
X
2
Food security
X
3
Land availability for
other human activities
than food production
4
Participation
7
Rspct for human rights
X
8
Workng cond. for lab.
X
11
Property rights and
rights of use
N
36-45 6-10 23-30 8-9
X
X
X
X
X
X
X
X
X
X
X
X
13 Monitorg. of crit. perf.
X
17 Microecon. sustainblty
X
X
X
X
X
19 Economic stability
X
Adaption capacity to
20 environ. hazards &
climate change
X
X
X
X
X
X
X
X
X
X
X
X
22 Nat. res. efficiency
X
X
X
23 Species protection
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Ecosystems
connectivity
X
X
26 Crop diversity
30 Soil protection
X
X
21 Energy balance
25
X
7-8
X
12 Planning
24 Ecosystems protection
5-6 19-23 15-21 14-17 14-18 15-18 10-12
OTHERS*
CRIT. NAME
NGO /
IND./
CONSLTG.*
ACADEMIA
MENT
GOVERN-
OTHER
BY PROFESSION
REGIONS.*
NORTH
AMERICA
EUROPE
GLOBAL
SUPRA-
NATIONAL
NATIONAL
LOCAL
PONDENTS
BY REGION
CRIT.NO.
ALL RES-
GROUPING BY SCALE
X
X
X
X
X
X
31 Land use change
X
X
X
X
32 Water management
X
33 Waste management
X
34 GHG balance
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Submitted to the Journal of Cleaner Production
X
X
X
X
X
Survey on Sustainability Criteria for Bioenergy Systems
11
Scoring of the top third important criteria in other attributes
Table 3 lists all criteria ranked in the top third in the importance category and compares the
ranking for respondent scores for the categories of relevance, practicality and reliability. Seven
of the top 12 criteria (Participation (no. 4), Water management (no. 32), Natural resource
efficiency (no. 22), Compliance with laws (no. 1), Ecosystem protection (no. 24), Monitoring of
criteria performance (no. 13), and Food security (no. 2)) were not ranked in the top third for
either practicality or reliability. While these criteria are seen as important, respondents were not
confident that they could be measured with the current suite of tools that are available. This
suggests that methods to assess these criteria need to be developed and/or refined so they can
be included in sustainability assessments based on information that can be collected and
summarized using commonly accepted methods and techniques and agreed on by diverse
groups of stakeholders. This seems to be especially true for the criterion Food security (no. 2),
which was the only criterion scored in the top third in terms of importance and ranked in the
bottom third in practicality (see Table 3). At this point in time the impact of bioenergy on food
security is seen as an important issue, but since there are a number of complex factors
influencing food security, the connections between the two issues are not clear (e.g. The
Guardian 2008, Mathews 2008). These criteria will be a challenge moving forward because
even if there is agreement on the issue of what criteria should be included, there may still be
disagreement on how to measure them or the accuracy of the outcomes from the
measurements. Assessment techniques that are agreed upon and seen as reliable need to be
developed (see also van Dam et al. 2008) along with some agreement on the criteria.
Stakeholder consultations such as in the FSC process for standard development to certify
sustainable forest management (Forest Stewardship Council 2008) can greatly help in attaining
such goals.
The criteria Compliance with laws (no 1) and Food security (no. 2) were also ranked in the top
third in importance but were not in the top third in terms of relevance. This may be an indication
that these are issues that are seen as important but are difficult to link directly to bioenergy
systems. Another interpretation for this observation is the dominance of respondents from
developed countries where both, compliance with laws and food security are commonly
perceived as problems of less developed countries.
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Table 3: The position and rank of criteria ranked in the top third for importance in other attributes.
Numbers indicate position of the respective criterion in the top third (1), second third (2), and low third (3)
based on the average score for each attribute. Numbers in brackets indicate the exact position of the
respective criterion.
CRIT.
NO.
NATURE OF
CRITERION
NAME
RELEVANCE
RANK
PRACTICALITY
RANK
RELIABILITY
RANK
1
Social
Compliance with laws
2 (22)
1 (11)
2 (14)
2
Social
Food security
2 (15)
3 (23)
2 (22)
4
Social
Participation
1 (5)
2 (21)
2 (16)
13
Social
Monitoring of criteria performance
1 (9)
2 (12)
2 (15)
17
Economic
Microeconomic sustainability
1 (8)
1 (2)
1 (2)
21
Environmental Energy balance
1 (1)
1 (1)
1 (1)
22
Environmental Natural resource efficiency
1 (6)
2 (18)
2 (19)
24
Environmental Ecosystems protection
1 (2)
2 (20)
2 (11)
30
Environmental Soil protection
1 (3)
1 (9)
1 (7)
32
Environmental Water management
1 (7)
2 (13)
2 (12)
33
Environmental Waste management
1 (10)
1 (3)
1 (3)
34
Environmental GHG balance
1 (4)
1 (5)
1 (5)
3.2.4 Magnitude and consensus within attributes
Looking at the magnitude4 of an attribute revealed, that the attributes relevance and importance5
had the highest magnitude (2.5) across all the criteria followed by the attributes practicality (2.0)
and reliability (1.9). Therefore, most criteria were more likely to be perceived as relevant and
important than necessarily practical or reliable.
Figure 7 shows all criteria sorted according to their consensus score for the attribute
importance: criteria are sorted from a high to low consensus score from left to right, i.e. from a
high standard deviation to a low consensus score. Using the standard deviation as consensus
score was possible as there was no occurrence where criteria were scored on both extremes
but little in the medium scale. Therefore, a high consensus score indicated a high consensus in
scoring among respondents.
4
Or the mean average score for all criteria within an attribute.
5
To make numbers comparable, criteria scores as ‘critical’ were counted as ‘high’ as ‘critical’ does not
exist for other attributes than ‘importance.
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Figure 7: Respondents’ consensus on criteria for the attribute importance. Criteria are sorted along a
gradient from high Consensus scores and therefore from a high consensus (left) towards low Consensus
scores and a low consensus amongst respondents (right).
Consensus may also be interpreted by the proportion of respondents who rated a criterion as
critical or high importance. Energy balance (no. 21), Greenhouse gas balance (no. 34),
Participation (no. 4), Soil protection (no. 30), Ecosystems protection (no 24), Water
management (no. 32), Natural resource efficiency (no. 22), and Microeconomic sustainability
(no. 17) were rated as critical or high importance by over 75 % of respondents. Ten criteria had
fewer than 50% of the respondents rate them as critical or of high importance. Of them, eight
were social criteria (no. 5, no. 7,no. 9, no. 14, no. 6, no. 15, no. 10, no. 3), one environmental
(Exotic species applications, no. 27) and one economic (Macroeconomic sustainability, no. 18).
Looking at consensus scores for all four attributes, the highest consensus was reached on
importance (overall average standard deviation: 0.28) followed by relevance (0.27). The
weakest consensus was observed in the attributes practicality and reliability. Criteria with low
scores in importance also had the highest amount of disagreement. All criteria scored in the top
third for importance ranked also in the top third in consensus on importance except for Waste
management (no. 33). Vice versa, the criteria ranked in the low third in the attribute importance
except for Ecosystem connectivity (no. 25) also ranked low third in consensus on importance.
This observation carries an important implication: low ranking criteria might be scored low
because they are heavily disputed.
Figure 8 shows the relationship between average criteria scores in the four attributes and the
level of consensus for each criterion. While criteria scoring high in relevance also showed a high
consensus rating (R2=0.95) this tendency was less observable for importance (R2=0.65) and
reliability (R2=0.47), and absent for practicality.
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Figure 8: Correlations between consensus data (using the standard deviation of the average scores) and
criteria scores for different attributes. High average scores indicate a high score in the respective
attribute.
3.2.5 Group differences in importance ratings
Only 8 criteria (criteria no. 4, 14, 25, 28, 29, 30, 32, 35) showed significant scoring differences
among groups which indicates that there is fairly broad consensus on scoring despite the
respondents varying professional backgrounds, region, and scale of operations (see Table 4).
However, within these 8 criteria, there was broader disagreement on how to score them. Except
for the criterion Use of genetically modified organisms (no. 28), each criterion listed in Table 4
was ranked significantly different by more than two groups. One general finding was that the
experts with a Government/Policy background (in the category ‘Segment of profession’) scored
criteria more often in a significantly different pattern and higher in importance than the other
groups.
On a broader scale, it was noted that most criteria affected by significant scoring differences
amongst groups were of an environmental nature. There seemed to be wider agreement for
social criteria and especially economic criteria. Social criteria showed only significant scoring
differences between regions which might suggest that cultural differences are influencing these
patterns. However, no such pattern could be detected in the consensus analysis (Figure 7).
While the category ‘Scale of operation’ revealed four pairs of groups differing significantly in
scoring, ‘Region of expertise’ and ‘Segment of profession’ had five and eight such pairs,
respectively. The ‘Segment of profession’ might therefore divide bioenergy experts the most in
as how important they perceive a given criterion rather than ‘Scale of operation’ or ‘Region of
expertise’.
Comparing the top third most important criteria with results on significant differences in scoring
amongst groups, it becomes apparent that the criteria Participation (no. 4), Energy balance (no.
21), and Soil protection (no. 30) are ranked high in importance but also show significant scoring
differences between various groups. To advance overall acceptance of a sustainability
assessment scheme for bioenergy systems, it might be advisable to streamline research efforts
into these three criteria which are commonly perceived as important but are controversially
discussed, dividing experts, and might hamper overall progress in developing assessment
frameworks.
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These significant differences also indicate that sustainability assessments might need to be
fine-tuned for each project, i.e. criteria used might need to vary how they are scored or even
which ones need to be included in assessments from case to case in order to achieve a wide
ranging support basis and therefore sustainability rather than scoring against specified
thresholds. Such a structure or process rather than goal oriented systems approach for
certification is already used by the ISO 14001 standard (e.g. Hayward & Vertinski 1999), the
ISO BS7750, or the European Union's EcoManagement and Audit Scheme (EMAS) (Germain et
al. 2002) which are offering frameworks for certification of environmental management systems
but do not specify standards or goals. In such an approach, the process itself gets certified
rather than the outcome. However, although such approaches can embrace different scales,
number of stakeholders involved, project boundaries, and conditions to a better extent, there is
a risk of low-aiming and unmotivated outcomes.
Table 4: Significant differences in scoring criteria by respondents’ professional background. Groups with
significant differences printed in black, indifferent groups printed in gray. Those groups scoring a given
criterion as more important are listed above other groups. The symbols and symbolize a significant
scoring difference between groups on an alpha level of 0.1 and 0.05, respectively, using the Fisher’s
Exact Test (chapter 2.4). For content of aggregated groups (‘All other regions’, ‘NGO/Others’) see chapter
3.1.
CRIT.
NO.
4
CRITERION NAME
SCALE OF OPERATION
REGION OF EXPERTISE
Participation
25
Ecosystems
connectivity
28
Use of genetically
modified organisms
North America
>>
Use of chemicals,
29 pest control, and
fertilizer
Europe?
14 Visual impacts
All other
regions
30 Soil protection
32 Water management
Potentially hazardous atmospheric
35
emissions other than
greenhouse gases
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Survey on Sustainability Criteria for Bioenergy Systems
3.3 Preference of frameworks
The classic Social-Economic-Environmental (SEE) framework for sustainability was the most
frequently selected assessment framework (Figure 9) followed by the one developed by Cramer
et al. (2006) which is an effort to formulate a set of sustainability criteria for the production and
conversion of biomass for energy, fuels and chemistry commissioned by the Dutch government.
This effort is the most holistic framework to date developed specifically for biomass trade. For
the purpose of this study we used the most widely familiar framework – SEE – to organize the
criteria for presentation in the questionnaire. This pre-determined structure might have
influenced the framework preference choice of respondents. Over a quarter of the respondents
had no preference for a particular framework
Preferred framework
20
18
18
16
14
N
12
13
SEE
10
BOCR
10
SOWT
8
6
4
no preference
(D)PS(I)R
3
2
Cramer
2
0
0
Figure 9: Number of survey respondents preferring a given sustainability assessment framework for
bioenergy systems, population N=36.
Group analysis revealed significant differences between professions. While respondents from
the government/policy group were mainly in favor of the SEE framework and significantly
differed on an alpha level of 0.05 from all other groups with this ranking, there was a support for
the Cramer (2006) framework by respondents with a background in nonprofit organizations.
Academia, industry, and consulting showed a split support for the Cramer framework as well as
the SEE framework. Support for the other frameworks suggested was negligible.
3.4 Respondent comments
Many comments from respondents focused on the applied side of bioenergy sustainability
assessments – several respondents suggested criteria with focus on government policies on a
national and global level (taxes, subsidies, market mechanisms, incentives, regulations), long
term planning, (scientific) capacities of institutions, public awareness/education, but also the
impact and use of technology for poorer countries. Several comments also specifically
mentioned the problem that all criteria are relevant and important but hamper in practicality and
reliability, a comment supported by the findings of the study. Few comments mentioned that it
would be unnecessary to include criteria that would prevent project implementation anyway
such as (micro)economic sustainability, as the project wouldn’t go ahead anyway in case of
non-compliance.
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Respondents frequently mentioned the need for flexibility of frameworks and use of criteria for
specific projects, regions, scales, or for specific focus groups (business, practitioners, etc.), e.g.
suggesting that the SEE as the as most widely recognized (SEE) and the Cramer framework as
a well developed (Cramer) framework should be used as an overarching framework while the
other frameworks could serve as sub-frameworks for individual projects or parts of a
sustainability assessment (e.g. just the economic perspectives).
But there was also a notion amongst respondents that the whole bioenergy sustainability
discussion misses an overarching systems approach and that focusing on bioenergy itself might
miss the final goal of sustaining human life and standard of living.
4 CONCLUSIONS
This study provided an overview on how bioenergy experts rated criteria currently under
discussion for sustainability assessments of bioenergy systems and measured the level of
consensus among them. To our knowledge this is the first attempt to look into differences in
scoring criteria amongst experts according to their backgrounds at an international scale.
We conclude that the majority of criteria currently under discussion are valid for serious
consideration due to the high level of respondent importance scores. Similarly, we find that the
ten criteria that rated lowest in importance had much less consensus on their value indicating a
need for further deliberation.
The top third of criteria ranked as critical or highly important focused more on environmental and
economic criteria than social. Greenhouse gas balance, energy balance, soil protection,
participation, and water management are seen as the five most important criteria. Energy
balance (no. 21) and Greenhouse gas balance (no. 34) and received the highest scores on all
four attributes. Social criteria and especially locally applied criteria such as visual impact,
standard of living, or social cohesion – though perceived as relevant – ranked low in reliability,
practicality, and importance.
Criteria which where belonging to the top third in terms of importance did often not score high in
reliability and practicality. This was especially true for Food security (no. 2) which ranked very
low in both practicality and reliability.
The greatest differences on which criteria are critical was based on the scale (namely experts
working on a ‘Supranational’ or ‘Global’ scale) and profession (namely experts with a
‘Government/Policy’ and ‘NGO/Others’ background) indicating the need to retain local context
flexibility with any bioenergy sustainability criteria and indicators approach. Sustainability
assessments need to be fine-tuned for each project, i.e. criteria used might need to vary how
they are scored or even which ones need to be included in assessments from case to case in
order to achieve a wide ranging support basis. There are indications that experts working at the
implementation level for bioenergy systems, namely on the local level and in biomass exporting
countries, tend to score criteria differently. These voices need to be considered in future
research and sustainability assessments. Looking into significant differences between groups
also indicated that lowest consensus exists between different professions rather than regions,
scales of operation, or primary area of expertise. This might be interpreted as a need to
strengthen interdisciplinary exchange as disciplines divide scorings rather than continents.
Furthermore, there was a relation between consensus on criteria scoring and how criteria were
ranked within the attributes except for the attribute practicality. Low ranking criteria, especially in
the attribute importance, were characterized by a low consensus and their rank can therefore be
expected to be highly disputed. At the same time, all criteria were perceived as relevant and
important and therefore all criteria deserve further attention to make them more practical and
reliable, this is especially true for the criterion Food security (no. 2). To move forward,
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discussion on how to measure criteria is equally important (see also van Dam et al. 2008). In
order to get expert consensus on key criteria (top third, critical ones, etc.) more exchange is
needed between disciplines and scales, even when expert input can only be received from a
few regions.
Outcomes of this survey provide a foundation for further deliberation of sustainability
assessment such as certification of international biomass trade and are also applicable to
criteria selection to assess individual bioenergy projects within their specific geographic,
environmental, societal, and technological contexts and scales.
4.1 Framework discussion
There was a strong support for the SEE framework from experts working in government differing
from the support for the Cramer framework from nonprofit organizations, while industry,
academia, and consulting experts were split between the two frameworks.
4.2 Future research focus
Results suggest further research on the following points:
¾
Research focus should be on criteria ranking high in importance but low in reliability and
practicality, namely Food security (no. 2) but also to some extent Participation (no. 4),
Water management (no. 32), Natural resource efficiency (no. 22), Compliance with laws
(no. 1), Ecosystem protection (no. 24), Monitoring of criteria performance (no. 13).
¾
The general survey approach proved to be valuable to measure the current level of
consensus and uncertainty in the debate on bioenergy sustainabilty approaches. Periodic
efforts to gather input of and exchange among experts with a wide range in professional
backgrounds would be extremely valuable. Special effort should be made to include
experts with a local focus and working outside of Europe and North America.
¾
For further refinement of sustainability criteria especially at the project level, multi-criteria
analysis is a promising implementation tool, integrating various stakeholders’ voices and
values while acknowledging each project’s unique characteristics (Buchholz et al. 2007,
Buchholz et al 2008).
ACKNOWLEDGEMENTS
We gratefully acknowledge the time and efforts that the responding bioenergy experts invested
in returning the surveys. Without their selfless support this research would not have been
possible. We also thankfully recognize support by Stephen Stehman, and the Physics
Department of the College of Saint Benedict / Saint John's University for making their statistical
tools freely available online.
LITERATURE
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Cramer, J., Wissema, E., Lammers, E., Dijk, D., Jager, H., Bennekom van, S., Breunesse, E., Horster, R.,
Leenders van, C., Wolters, W., Kip, H., Stam, H., Faaij, A., Kwant, K., Hamelinck, C., Heuvel van
den, E., Bergsma, G., Junginger, M., Smeets, E. 2006. Project group Sustainable production of
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biomass - Criteria for sustainable biomass production. Final report of the Project group
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Dale, B.E. 2007. Thinking clearly about biofuels: ending the irrelevant “net energy” debate and developing
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Fisher, R.A. 1967. Statistical Methods and Scientific Inference, 2nd Edition. Hafner Publishing Company,
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Five Winds International 2006. Sustainability Assessment Framework and Tool (SAFT) for Biobased
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Hayward, J., Vertinsky, I. (1999). High expectations, unexpected benefits, what managers and owners
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APPENDIX
Appendix 1: Sustainability criteria used in the survey with explanations and categories.
CRIT.
NO.
NATURE OF
CRITRION NAME
CRITERION
CRITERION EXPLANATION
Compliance with laws
Social
criterion
Complying with
regulations like
bribery
2
Food security
Social
criterion
Enough land locally available for food production
including agricultural set aside land, preference of
marginal sites for energy crops
3
Land availability for
other human activities
than food production
Social
criterion
Enough land locally available for housing, energy (e.g.
firewood), recreation, and other resource supply
4
Participation
Social
criterion
Inclusion of stakeholders in decision making; facilitation
of self determination of stakeholders
5
Cultural acceptability
Social
criterion
Consideration of spiritual values, handling of local
knowledge
6
Social cohesion
Social
criterion
Migration and resettlement, wealth distribution, fair
wages, intergenerational equity, charity
7
Respect for human
rights
Social
criterion
Health services, liberty rights, security, education
8
Working conditions of
workers
Social
criterion
Worker health, work hours, safety, liability regulations,
exclusion of child labor
9
Respecting minorities
Social
criterion
Recognition of indigenous peoples’ rights, gender issues
10
Standard of living
Social
criterion
Public service support, access to energy services (e.g.
electricity lifeline tariffs)
11
Property rights and
rights of use
Social
criterion
Land and resource tenure, dependencies on foreign
sources (e.g. financial investments, knowledge) fair and
equal division of proceeds, customary rights
12
Planning
Social
criterion
Stating clear objectives, a management plan is written,
implemented, and updated as necessary
13
Monitoring of criteria
performance
Social
criterion
Monitoring systems in place for all criteria (e.g. leakage
or additionality in GHG accounting)
14
Visual impacts
Social
criterion
Visual effects of construction and feedstocks on
landscape
15
Noise impacts
Social
criterion
Noise from production, transportation and conversion
processes
16
Employment
generation
Economic
criterion
Number jobs created, quality of jobs created
17
Microeconomic
sustainability
Economic
criterion
Cost-efficiency incl. startup costs, internal rate of return,
net present value, payback period
1
all applicable laws and internal
certification principles, countering
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Appendix 1, continued.
CRIT.
NO.
NATURE OF
CRITRION NAME
CRITERION
CRITERION EXPLANATION
Macroeconomic
sustainability
Economic
criterion
Trade balances, foreign investments, financial flows
across project boundary, changes in overall productivity,
‘economic development’
19
Economic stability
Economic
criterion
Project lifetime, degree to which applied technology and
operational aspects are proven, flexibility to changes in
demand and supply, product diversification
20
Adaptation capacity to
environmental hazards
and climate change
Environment
al criterion
Diversification of feedstocks, available knowledge on
site demand of feedstocks
21
Energy balance
Environment
al criterion
Conversion efficiencies, energy return on investment,
energy return per hectare
22
Natural resource
efficiency
Environment
al criterion
Efficient use of resources at all stages of the system
23
Species protection
Environment
al criterion
Protection of rare, threatened, or endangered species
24
Ecosystems protection
Environment
al criterion
Safeguarding protected, threatened, representative, or
other valuable ecosystems (e.g. forests), protecting
internal energy fluxes / metabolism
25
Ecosystems
connectivity
Environment
al criterion
Preventing land fragmentation, e.g. presence of wildlife
corridors etc.
26
Crop diversity
Environment
al criterion
E.g. impacts and risks associated with monocultures like
its impacts on landscape and wildlife, and its
susceptability to catastrophic failure
27
Exotic species
applications
Environment
al criterion
Invasiveness, risks to other species and land uses
28
Use of genetically
modified organisms
Environment
al criterion
Appliance with law, risk to other land uses
29
Use of chemicals, pest
control, and fertilizer
Environment
al criterion
Insecticides, herbicides, chemicals in the conversion
process, impacts on surrounding environment
30
Soil protection
Environment
al criterion
Impacts on soil fertility like. changes in nutrient cycling,
rooting depth, organic matter, water holding capacity,
erosion
31
Land use change
Environment
al criterion
Impacts of land conversion on energy fluxes, radiation
balance, roughness of land cover, biochemical fluxes,
hydrological cycles which eventually affect ecological
balances
32
Water management
Environment
al criterion
Surface and groundwater impacts, riparian buffers,
irrigation and cooling cycles and waste water
management
33
Waste management
Environment
al criterion
Disposal of ashes, sewage, hazardous/contaminated
solid and liquid material
18
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Appendix 1, continued.
CRIT.
NO.
NATURE OF
CRITRION NAME
CRITERION
CRITERION EXPLANATION
34
Greenhouse gas
balance
Environment
al criterion
GHG balance of system covering CO2, CH4, O3, NO2,
H2O
35
Potentially hazardous
atmospheric
emissions other than
greenhouse gases
Environment
al criterion
Emissions of SOx, CO, NOx, and particulates
Submitted to the Journal of Cleaner Production