Progress in Industrial Ecology – An International Journal, Vol. 10, No. 1, 2016
3
Environmental and technical evaluation of the use of
alternative fuels through multi-criteria analysis model
Antonis A. Zorpas*
Faculty of Pure and Applied Sciences,
Environmental Conservation and Management,
Cyprus Open University,
P.O. Box 12794, 2252, Latsia, Nicosia, Cyprus
Fax: +357-22411601
Email: [email protected]
Email: [email protected]
*Corresponding author
Diana Mihaela Pociovălişteanu
Faculty of Economics and Business Administration,
“Constantin Brancusi” University of Targu-Jiu,
Eroilor Street, No. 30, Targu-Jiu,
Gorj 210135, Romania
Fax: +40-726187718
Email: [email protected]
Lydia Georgiadou
Faculty of Pure and Applied Sciences,
Environmental Conservation and Management,
Cyprus Open University,
P.O. Box 12794, 2252, Latsia, Nicosia, Cyprus
Email: [email protected]
Irene Voukkali
Institute of Environmental Technology
and Sustainable Development, IETS,
P.O. Box 34073, 5309, Paralimni, Cyprus
Email: [email protected]
Email: [email protected]
Abstract: The current way in which the fossil natural resources are consumed
as energy resources does not reflect the concept of sustainability and therefore
raises new priorities for the existing energy system and sets the challenge to
find alternative energy sources that enhance the quality of life without
jeopardising the environmental and human health. This study investigated the
consequences of the use of alternative fuels (hydrogen, natural gas, bio-ethanol
and bio-gas) by focusing on several factors that can be expected to influence
the environmental, economic and social sector, in order to verify the feasibility
Copyright © 2016 Inderscience Enterprises Ltd.
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A.A. Zorpas et al.
of increasing their share compared to conventional fuels. The results indicated
that economy criteria of alternative fuels is consider to be significant advantage
over traditional fuels, while the comparative evaluation that resulted from the
combination of properties with the optimal values, highlights and drives the
exploration of hydrogen as the ‘best’ alternative fuel source.
Keywords: alternative fuels; hydrogen; natural gas; bio-ethanol and bio-gas;
sustainable development; analytic hierarchy process; AHP; multi-criteria
analysis.
Reference to this paper should be made as follows: Zorpas, A.A.,
Pociovălişteanu, D.M., Georgiadou, L. and Voukkali, I. (2016) ‘Environmental
and technical evaluation of the use of alternative fuels through multi-criteria
analysis model’, Progress in Industrial Ecology – An International Journal,
Vol. 10, No. 1, pp.3–15.
Biographical notes: Antonis A. Zorpas is a Professor (Lecture) in Cyprus
Open University. He is a Chemical Engineer and he holds a PhD in the
Section of Environmental Engineer. He is the Editor in three scientific
books: “Sludge Management; From the Past to Our Century”, “Natural
Zeolites”, “Sustainability Behind Sustainability”. He has published more than
70 scientific papers and more than 200 papers in international conferences.
He is research back-round includes: solid and liquid waste treatment and
management, composting and bio solids, waste minimisation monitoring,
evaluation, sustainable development and strategic planning, EIA, LCA, risk
assessment analysis and multi criteria analysis models.
Diana Mihaela Pociovălişteanu is an Associate Professor at the “Constantin
Brancusi” University of Targu-Jiu, Faculty of Economics and Business
Administration, Tg-Jiu, Romania. Her PhD and Postdoctoral studies are in
Economics. Her research focuses on macroeconomics, sustainability, migration
and energy. She has been Visiting Researcher in the University of A Coruna,
Department of Economic Analysis and Business Administration. She is a
member of the scientific committee of several international conferences:
Scientific 2nd World Symposium on Sustainable Development at Universities
(WSSD-U-2014), Manchester, UK, 3–5 September, 2014; EDaSS 2014; EdaSS
2013; EdaSS 2012; A Coruna, Spania; Euro-Agroland 2015, Nitra, Slovakia.
Lydia Georgiadou holds a Master degree in Environmental Conservation and
Management and she is acting as a Consultant.
Irene Voukkali holds a Master degree in Environmental Engineering and she is
the Quality Control Manager of the Institute of Environmental Technology and
Sustainable Development. Until now, she has published five chapters in
scientific books; more than 15 research papers in scientific journals and more
than 30 papers in international conferences. Her research mainly focuses
on sustainable development, EMAS, environmental management systems,
strategic development, and liquid waste treatment.
This paper is a revised and expanded version of a paper entitled ‘Environmental
and technical evaluation of the use of alternative fuels’ presented at
The International Conference “Sustainable Energy Use and Management”
(SEUM), Targu-Jiu, Romania, 20 May, 2014.
Environmental and technical evaluation of the use of alternative fuels
1
5
Introduction
For decades, fossil energy sources (expect the energy produced from nuclear) played a
dominating role in energy production all around the planet. The usage of fossil source
like carbon and oil is considered to be very problematic mainly owing to their negative
effects on climate change (Gaigalis et al., 2015). It can be said that from ecological and
economic point of view, it is not reasonable in now a days to base energy supply on fossil
energy sources.
Sustainable energy development requires alternative fuels, which are viewed as a
cleaner means of chemical energy storage with respect to fossil fuels. Alternative fuels
are derived from resources other than petroleum, and according to Iliev (2015) when
those fuels are used they produce less air pollution compared to gasoline as well as
economically beneficial than oil.
Generally fuels derived from biomass (Cervero et al., 2008) have several advantages
in which the most important one includes:
•
no emission of sulphur during their combustion because biomass lacks sulphur
compounds in its composition
•
no production of particulate matter or PAH’s (polycyclic aromatic hydrocarbons)
during their combustion
•
biomass-derived CO2 in fuel emissions is recycled in the feedstock production.
Also the purity of ethanol is essential, with respect to its water content, since water
occurrence in the reaction medium decreases selectivity. Biofuels are generally
considered as offering many priorities, including sustainability, reduction of greenhouse
gas emissions, regional development, social structure and agriculture, security of supply
(Ilkilic and Yucesu, 2008; Unal and Alibas, 2007).
Sustainable fuels may offer a promising alternative (Demirbas, 2008a, 2009b).
Owing to the high price of petroleum especially after petrol crisis in 1973 and then
gulf war in 1991, geographically reduced availability of petroleum and more stringent
governmental and European regulations on exhaust emissions, researchers around the
World have studied on alternative fuels and alternative solution methods (Demirbas,
2009a; Durgum and Sahin, 2007). Alternative fuels like biofuels are considered to be
very important because they replace petroleum fuels contributing the way for the
conservation of natural resources. It is expected that the demand for biofuels will rise in
the nearest future. Biofuels are substitute fuel source for petroleum; however, some still
include a small amount of petroleum in the mixture (Demirbas, 2008b).
The main benefit between alternative fuels (like bio) and conventional fuels
(like petroleum) is the content of oxygen (Demirbas, 2007a). Alternative fuels are
non-polluting, locally available, accessible, sustainable and reliable fuel obtained from
renewable sources (Demirbas, 2007b). Sustainability of renewable energy systems must
support both human and ecosystem health over the long term, goals on tolerable
emissions should look well in the future (Ludwig, 1997; UNDP, 2004). Electricity
generation from biofuels has been found to be a promising method in the nearest
future (Karki et al., 2008). The future of biomass electricity generation lies in biomass
integrated gasification/gas turbine technology, which offers high-energy conversion
efficiencies (Demirbas and Urkmez, 2006).
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A.A. Zorpas et al.
Alternative fuels (Dincer and Zamfirescu, 2014) are non-conventional fuels that can
be obtained from biomass (in which case they are called biofuels) or from fossil fuels
(in which case they are called synthetic fossil-based fuels). Blends of fossil-derived fuels
and biofuels are also considered alternative fuels (e.g., gasoline + bio-ethanol blends).
The classification of fuels is presented in Figure 1.
Figure 1
Fuels classification
The necessity for alternative fuels is clarified by the two main reasons:
•
fossil-based fuels deplete, thus new fuel sources must be discovered
•
high carbon dioxide emissions are associated with fossil fuel combustion, and it is
desired to limit these in order to have a better environment and avoid the danger of
global warming.
1.1 Hydrogen – natural gas – bio-ethanol – bio-gas
The use of hydrogen as an energy carrier is one of the options put forward in most
governmental strategic plans for a sustainable energy system. The attractiveness of
hydrogen lies in the variety of methods to produce hydrogen as well as the long-term
viability of some of them (from fossil fuels, from renewable energy: biomass, wind,
solar, from nuclear power, etc.), the variety of methods to produce energy from hydrogen
(internal combustion engines, gas turbines, fuel cells), virtually zero harmful emissions
and potentially high efficiency at the point of its use. Nevertheless, the advantages
offered by hydrogen are significant enough to warrant the exploration of its possibilities
(Verhelst and Wallner, 2009). The large-scale introduction of hydrogen as a fuel
would reduce the consumption of fossil fuels and keep the air clean free from pollution
(Ramesh Bapu et al., 2011). The world is heading toward hydrogen economy with
the general perception that hydrogen as a fuel is environmentally clean because its
combustion results in the generation of harmless water.
On the other hand as at the beginning of the 21st century, fuel cells poised to meet the
power needs of variety of applications. Fuel cells are electrochemical devices that convert
chemical energy to electricity and thermal energy (Ramesh Bapu et al., 2011). Electricity
made by the conversion of primary energy sources is easily transported and delivered to
end-users. Hydrogen is a clean fuel and efficient energy medium for fuel cells and other
devices. Building an infrastructure that allows for easy and cost-effective transportation
and delivery of hydrogen energy is a critical step toward a future hydrogen economy.
Environmental and technical evaluation of the use of alternative fuels
7
Hydrogen can be produced from water, renewable energy sources and from other fuels.
Hydrogen (hydrogen life cycle in Figure 2) could be used for a broad range of
applications to supplement or substitute the consumption of hydrocarbon fuels and fossil
fuels in an environment friendly manner.
Figure 2
Hydrogen life cycle
The large-scale introduction of hydrogen as a fuel would reduce the consumption of
fossil fuels and keep the air clean free from pollution. Hydrogen can be produced from
renewable energy sources by various methods. Electrolytic, prototypic/photo-biological,
photo-electrolysis and thermo-chemical hydrogen production technologies are currently
under development and use. The combination of hydrogen with fossil fuels such as
gasoline, natural gas, ethanol, methanol for fuelling IC engines provides less emission
and increase performance (Ramesh Bapu et al., 2011). The aim of the hydrogen energy is
to expand the role of hydrogen as a fuel for surface transportation. The use of hydrogen
initially will be as an additive to conventional fuels. The combination of hydrogen with
fossil fuels such as gasoline, natural gas, ethanol and methanol for fuelling IC engines
provides less emission and increase performance.
Natural gas (NG) is recognised as the fossil fuel causing least damage to the environment
(Gaudernack and Lynum, 1997), since it is the cleanest of all fossil fuels and the main
products of combustion of natural gas are carbon dioxide and water vapour. The
combustion of natural gas releases very small amounts of nitrogen oxides (NOx),
sulphur dioxide (SO2), carbon dioxide (CO2), carbon monoxide (CO), other reactive
hydrocarbons and virtually no particulate matter. Coal and oil are composed of much
more complex molecules and when combusted, they release higher levels of harmful
emissions such as nitrogen oxides and sulphur dioxide. They also release ash particles
into the environment. The main component of natural gas, methane, is itself a potent
greenhouse gas.
Bio-ethanol (CH3CH2OH) is an alcohol-based alternative renewable green fuel produced
by fermenting and distilling starch crops that have been converted into simple sugars.
8
A.A. Zorpas et al.
Feedstocks for this fuel include corn, barley, wheat, rice straw, sugar cane bagasse,
pulpwood, switchgrass and municipal solid waste. The use of bio-ethanol is promoted for
its positive environmental impacts on the climate change. Like other biofuels, bio-ethanol
is not only expected to reduce CO2 emissions but also considered to be CO2-neutral
(Balat, 2008).
Bio-gas is a gaseous matter that is similar to natural gas and can be defined as a biofuel
produced by a large number of anaerobic microbial species that inherently possess the
capability to ferment organic matter under controlled temperature, moisture and pH to
yield a high energy value fuel. So the bio-gas is the end product of the microbiological
fermentation (metabolic product of the methane bacteria) (Valeria and Emese, 2011).
Anaerobic digestion embraces the concept of sustainability and proximity (Asam et al.,
2011).
2
Materials and methods
For the determination of optimal alternative fuel, the multi-criteria model of analytic
hierarchy process (AHP) was applied (Zorpas and Saranti, 2015), for the pair-wise
comparison of the candidate technologies. The objectives served by the application of
AHP model include the determination of most viable fuels in terms of technical,
environment, economic and social criteria.
The application of the methodology of AHP is performed by using the software
MakeiItRational Professional (www.makeitrational.com).
The AHP analysis (Zorpas and Saranti, 2015) is based on three fundamental
principles:
•
breakdown of the problem into sub-problems
•
pair-wise comparison of criteria and various alternative scenarios
•
composition of preferences.
The analysis is completed through four steps as follows:
•
degradation of the problem into sub-problems and formation of an hierarchical
structure
•
pair-wise comparison of decision elements used to derive normalised absolute scales
of numbers whose elements are then used as priorities
•
calculation of priorities for the problematic data
•
composition of preferences for alternative scenarios to solve the problem.
The key element, of the method, is the pair-wise comparison of the components at each
level of the hierarchical structure, namely the criteria and sub-criteria of the alternative
scenarios, which affect the problem. For this purpose, comparison matrices are structured
for the comparison of elements of a level of hierarchy with the elements of the next
higher level and so. The input data in comparison matrices, which represent the
expression of preferences of the decision makers, resulting from the fundamental scale of
Saaty, is a qualitative scale that includes values from 1 to 9.
Environmental and technical evaluation of the use of alternative fuels
9
These values are used by the decision makers for the purpose of benchmarking
as equal (1), moderately strong (3), strong (5), very strong (7) and very strong (9)
importance. On the basis of the scale preferences of Saaty, all possible gradations of
preference are P = {1, 2, 3, 4, 5, 6, 7, 8, 9, 1/2.1/3.1/4.1/5.1/6.1/7.1/8.1/9}. Therefore, the
scale proposed by Saaty is a mathematical approximation of preferences and the
importance of the criteria and alternative scenarios is attributed to the decision makers.
Nevertheless, in case that there is a precise measurement with respect to the preference of
a criterion or alternative scenario over another, it is possible to use the accurate
measurement (Bottero et al., 2011; Karimi et al., 2011; Saaty, 1987, 1990).
To ensure consistency in the pair-wise comparisons, during AHP analysis, the
calculation of the consistency ratio (CR) is necessary to take place in order to assess any
discrepancies in matrices of pair-wise comparisons that should lead the decision makers
to revise their initial estimates. According to the literature, any pair-wise comparison
matrix is considered to be consistent and hence acceptable when CR is less than 10%
(Ozdemir, 2005). In addition to that, a sensitivity analysis on the AHP weights is
unfolded to show the impact of varying weights to the final outcome (Georgiou et al.,
2012).
The increased use of alternative fuels should be accompanied by a detailed analysis of
the environmental, economic and social impact in order to determine the feasibility
of increasing their share compared to conventional fuels. As part of this study we attempt
a comparative assessment of alternative fuels: hydrogen, natural gas, bio-ethanol and
bio-gas, through conducting a multi-criteria evaluation so as to justify the impetus to
explore the ‘best’ alternative fuel resulting from this approach. To carry out the
comparative evaluation of alternative fuel sources, data were gathered in terms of
technical, environmental, economic, social and political aspects:
•
technical criteria: calorific value, octane number, density
•
environmental criteria: sustainability of production methods, emissions of carbon
dioxide (complete combustion), main by-products (complete combustion), impacts
on ecosystems
•
economic criteria: production costs, labour force, resource availability
•
social criteria: job creation, public acceptance, safety.
3
Results and discussion
Global warming causing a serious environmental problem owing to the release of
high amounts of greenhouse gases during fossil fuel combustion. The increase in
per capita energy use and improved living standard in both developed and developing
countries has led to increase in fossil fuel consumption, much of that increase is
from the transportation sector (Lanjewar et al., 2015; Speth et al., 2015). Several factors
like the rising fuel prices, continual increasing of oil demand and alarming GHG
emissions have turn the research worldwide to develop alternative fuels that are
renewable, which produce less harmful emissions (COx, NOx, SOx) and can help nations
to become more energy independent. Promotion of alternative automotive fuels as a
clean and safe energy resource can be expected to play a major role in improving
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A.A. Zorpas et al.
the urban air quality and dependency on conventional fuels (Lanjewar et al., 2015;
Rahman et al., 2015).
The evaluation of the parameters (Table 1) of the technical, environmental, economic
and social criteria resulting from the approach of the Malty criteria analysis shows that
the economy of alternative fuels has significant advantages over traditional fuels.
Given that the use of non-renewable energy sources (fossil fuels) increases emissions of
carbon dioxide in the atmosphere, with consequent environmental, economic and social
costs, enhancing the use of alternative fuels may be an ideal solution to tackle these
impacts.
It is the main energy property of a substance and is the energy obtained by burning a
unit weight of fuel. Specifically calorific value defines the amount of heat which is
released by the complete combustion of a unit quantity of the substance. Hydrogen has
the highest calorific value: bio-ethanol < benzene < bio-gas < gas < hydrogen. Octane
number is a measure of the quality of fuels for internal combustion engines. It shows the
anti-knock rating of the fuel, i.e., how to withstand a compressed fuel without exploding.
All alternative fuels have much higher octane rating than gasoline, with little difference
between them: gasoline < bio-ethanol < ~hydrogen gas < bio-gas.
Regarding the environmental impacts (Table 1), the use of hydrogen as a fuel does
not have negative ecological effects. Unlike natural gas which brings degradation of
ecosystems by the processes of mining/extracting, bio-ethanol and bio-gas change land
use for the cultivation of raw materials.
According to the economic criteria, natural gas has a much lower price than the
conventional gasoline fuel as well as the lower production cost. On the other hand
(on social criteria), all alternative fuels enhance employment. However, the attitude of the
public for the hydrogen fuel contains positive and negative perceptions, natural gas
constitutes a popular fuel and bio-gas is highly accepted by farmers. The dangers
of hydrogen managed more easily than those of hydrocarbon fuels. The flammability
limit of natural gas and bio-gas is narrow making them safer than gasoline as opposed
to bio-ethanol which is slightly wider flammability limit of the fuel, as it is highly
flammable.
Figure 3 shows the weights of the core evaluation criteria. 43.12% is the weight of the
environmental criteria, followed by the social criteria (32.54%), technical criteria
(20.51%) and economic criteria (3.83%).
The final ranking of the usage of the alternatives fuels is given in the form of
bar chart, which lists the technologies under evaluation (y-axis) in conjunction with the
overall alternative utility of each technology (x-axis). Total utility represents the total
score that occupies each scenario with respect to the satisfaction of the criteria and
sub-criteria (as presented in Table 1). The scenario with the highest total utility is
considered to be the optimal one. From the application of AHP model it is determined
that the use of hydrogen as an alternative fuel seems to be better than the usage of natural
and bio-gas (which seems to be equal), which are better than bio-ethanol. However,
as all the proposed alternative fuels were evaluated and compared with gasoline
(Table 1 characteristics), it is determined that the proposed alternative fuels seem to be
more accepted than gasoline. According to Figure 4, the best alternative fuel which
accomplishes the criteria and sub-criteria is hydrogen. According to these results
(Figure 4), hydrogen satisfies all the criteria in addition to the rate of 25%, when
compared with the bio-gas and natural gas which rate between 20% and 22%, bio-ethanol
range is close to 17% and gasoline up to 15%.
Environmental and technical evaluation of the use of alternative fuels
Table 1
Technical, environment, economic and social criteria of the alternative fuels
11
12
Figure 3
A.A. Zorpas et al.
Basic categories of criteria weights (see online version for colours)
Similar behaviour with the final ranking is presented in the sensitive analysis
(Figure 5). The adjacent chart gives the results of the sensitivity analysis (Figure 5 which
is gradient sensitivity analysis diagram). X-axis shows the values attributed to the
weighting factor being studied (e.g., no environmental effects – 40%) and y-axis shows
the values corresponding to the score of each alternative technology. Ratings by each
scenario are shown as lines in ascending or descending slope by varying the weighting
factor. The line x = y represents the equation weighting attributed to the criterion being
studied. It is obvious that hydrogen, natural gas and bio-gas have high satisfaction rate of
environmental and social criteria and sub-criteria, while bio-gas has high satisfaction rate
in economic criteria and sub-criteria. Gasoline has the worst satisfaction rate with respect
to economic and environmental criteria and sub-criteria.
Energy is considered to be a key element in the interactions between nature
and society and is considered a key input for the environment and sustainable
development. Increased energy use is the universal driver for raising the quality of life
in all societies, from developing to developed countries, thus is essential to human
welfare and quality of life (Yilmaz and Ilbas, 2008). Energy resources are needed to
satisfy human needs, improve quality of life and allow industrial, social and economic
development. The environmental impact by the use of fossil fuels cannot be ignored.
Carbon dioxide generated by burning hydrocarbons is a major component of greenhouse
gases (by its weight). According to some estimates, the continued use of fossil fuels
at the present levels will lead to an inevitable increase in the concentration of carbon
dioxide in the atmosphere. If the existing policy on the use of energy resources is pursued
further, the average temperature of the surface layer of the atmosphere may rise
by 6°C by the end of this century. As a result, large-scale climate changes on the
planet should be expected, which will be accompanied by irreversible damage
to the biosphere and mankind, as the combustion of fossil fuels is accompanied
by large amounts of harmful emissions hazardous for human health (Sinyak and
Kolpakov, 2012).
Environmental and technical evaluation of the use of alternative fuels
Figure 4
Final ranking of the alternative fuels (see online version for colours)
Figure 5
Sensitive analysis of the alternative fuels (see online version for colours)
4
13
Conclusions
Alternative fuels contribute to domestic and international sustainability targets as the
latter is non-polluting, accessible, sustainable, reliable and displace oil imports thus
increasing energy security. From the application of AHP model it is determined that the
use of hydrogen as an alternative fuel seems to be better than the usage of natural and
bio-gas (which seems to be equal), which are better than bio-ethanol. However, as all the
proposed alternative fuels were evaluated and compared with gasoline, it is determined
that the proposed alternative fuels seem to be more accepted than gasoline.
Identifying the potential benefits of the alternative fuels justifies the feasibility of
increasing their share compared to conventional fuels. The introduction of alternative
14
A.A. Zorpas et al.
fuel economy may lead to improvements in the environment by reducing emissions of air
pollutants and contribute to a cleaner and healthier air, following the replacement of
fossil fuels, thus embracing the concept of sustainability.
Moreover further research must be done regarding the implementation of alternative
fuels in industrial or local level and measure the impact on sustainability as well as how
citizens accept or not those fuels.
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