tc14 elaee analysis of electricity generation alternatives

8/2/2019 TC14 Elaee Analysis of Electricity Generation Alternatives

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Abstract

Comparing power generation alternatives is not an easy task due to their different characteristics,

and social and environmental impacts. Any comparative analysis requires a systematic procedure and

adequate data considering the whole life cycle of the complete chain of electricity generation. In this work, wedefine intensity coefficients of electricity generation due to impact causing factors like emission of greenhouse

gases, water consumption, population morbidity, risk of accidents, etc. The power generation alternatives

considered are wind, hydro, coal, natural gas, oil, nuclear and biomass, and the set of criteria included

emission of greenhouse gases, water consumption, occupied area, use and processing of natural resources,

population morbidity, fatalities in severe accidents, cost of electricity and operational efficiency.

The impact coefficient results present large variation due to different data from the literature, but

some general observations can be outlined. For global warming, coal and oil present the highest impacts and

biomass and wind, the lowest impacts. For immobilized area over time, hydropower present the highest

impact, nuclear, biomass with co-generation and wind present intermediate impacts, and fossil fuels present

the lowest impacts. For use and processing of natural resources, biomass presents the highest impact; wind,

hydro and nuclear power present the lowest impacts. For water consumption, coal and nuclear present the

highest impacts, wind and biomass present the lowest impacts, and natural gas, intermediate impact. Forpopulation morbidity, coal and oil present the highest impacts; nuclear, hydro and wind present the lowest

impacts. For the number of fatalities in accidents it is important to analyse the situation of hydropower. If the

accident of Shimantan is considered, this option is by far the one with the largest impact coefficient. Nuclear

power presents number of fatalities in accidents similar to the coal and oil alternatives, and wind and

biomass, the lowest figures. For cost of electricity generation all alternatives present close figures, natural

gas seems to be the most competitive one but the cost data present large variation for all options. For energy

operational inefficiency, biomass, oil, nuclear, coal and wind present the highest inefficiency, and hydropower

present the lowest inefficiency.

Keywords: life cycle, electricity generation, sustainability

1. Introduction

There are today several alternatives for the expansion and diversification of electricity supply, but

making a decision about them is not an easy task. The points of view of the different stakeholders

(government, investors, local citizens, environmental groups, etc.) are important and must be included in the

evaluations, which must take into consideration environmental, social and economic dimensions (Magalhes,

2009; La Rovere et al., 2010, Cesaretti, 2010, Goldemberg & Lucon, 2008). Such comparative analyses

require adequate data considering the whole life cycle of the complete chains of electricity generation. Manyauthors complain about data scarcity, their large variation or spread, and inadequate format to carry out

3rd

ELAEE 2011 Latin American Meeting on Energy Economics

April 18-19, 2011 Buenos Aires, Argentina

ANALISYS OF ELECTRICITY GENERATION ALTERNATIVESACCORDING TO ENVIRONMENTAL, SOCIAL AND ECONOMIC CRITERIA

Joo M. L. Moreira, Professor (PhD)Center of Engineering, Modeling and Applied Social Sciences, Universidade Federal do ABC

Rua Santa Adlia, 166, 09210-170 Santo Andr, SP, BrazilPhone: +551149960115, Email: [email protected]

Marcos de Araujo Cesaretti, Technical Engineer (MSc)Center of Engineering, Modeling and Applied Social Sciences, Universidade Federal do ABC

[email protected]


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comparison evaluations (Rosa, 2007; La Rovere et al., 2010; Brazil, 2007; Fthenakis & Kim, 2009; Gagnon et

al., 2002; Goldemberg & Lucon, 2008; Lenzen, 2008; Markandya & Wilkinson, 2007; Sovacool 2008).

Recently, several studies were published about comparisons of different power generation

alternatives. Lenzen (2008) and Weisser (2007) discussed the emission of greenhouse gases for several power

generation alternatives considering the whole life cycle. Rosa (2007) compared several power generationoptions using a qualitative evaluation, and La Rovere et al. (2010) and Rio and Burguilo (2009) performed

similar analysis using a quantitative approach. Evans et al. (2009) utilized literature data to compare

photovoltaic, wind, hydro, geothermal, natural gas and coal power generation options considering as criteria

the emission of CO2, use of natural resources, technical limitations, occupied area, use of water and social

impacts. Fthenakis and Kim (2009) compared occupied areas for different power generation options, and

Admantiades and Kessides (2009) compared their cost of generation and emission of greenhouse gases.

Curran et al. (2005), taking into consideration different groups of stakeholders, suggested as important criteria

for such evaluations water consumption, emission of greenhouse gases, emission of pollutants, use of natural

resources, occupied area, and emission of residues.

In this work, we consider the problem of evaluating several power generation alternatives according to

environmental, social and economic criteria. We collect in the literature data considering the whole life cycle

of complete chains of electricity generation, and present them in a useful form to perform such analysis for

different conditions and aims. To do that we define intensity coefficients of electricity generation due to

impact causing factors such as emission of greenhouse gases, water consumption, population morbidity, risk

of accidents, etc. In most cases, the impact coefficient is defined per unit of electricity generation, following aprocedure adopted by many authors (La Rovere et al., 2010; Brazil, 2007; Fthenakis & Kim, 2009;

Goldemberg & Lucon, 2008). Eight different criteria and seven different power generation option are

considered.

We start in Section 2 defining the impact coefficient, which accounts for the impact electricity

generation causes on the environment and society. We choose a set of criteria that may be acceptable to a

broad group of stakeholders, and for each criterion, we associate an impact coefficient. In Section 3 we

present average values and estimated uncertainties or variations for the impact coefficients. In Section 4 wepresent the conclusions.

2. Methods

In this section, we present how the impacts caused by electricity generation are estimated through

impact coefficients. They are defined by ratios involving the generated impact and the product of an economy,

or specifically, the electricity generated. Then we select a set of criteria useful for such evaluations taking intoconsideration the possible interests of different groups of stakeholders. Finally, we present the source of the


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data used for estimating the impact coefficients, most of them based on complete production chain and life

cycle analysis.

2.1. Estimation of impacts

Electricity is a basic input to any productive activity, has strong interaction with the environment and

society, and causes different types of impacts. Let S i be the generation rate of the ith type of impact while an

economy produces a product Y. We can define an impact coefficient, i, relating the ith type of impact and the

production activity as

(1)

where represents a change in the variables Si and Y. The index i identifies each type of impact that the

production activities may cause to the environment or society. If the product in question is electricity

generation, the several impacts may include CO2 emissions, radioactive waste generation, loss of biodiversity,

noise, air pollution, diseases, etc.

We can estimate the impact due to the electricity generation, E, in the economy through

. (2)

The first ratio in the right side of Eq. 2 represents a coefficient that yields the amount of i th impact per unit of

electricity generated. Let it be called as the ith type impact coefficient for electricity generation, iE,

(3)

The second ratio in Eq. 2 represents the electricity intensity of the economy, IE. Therefore, the impact

coefficient due to electricity generation in the economy is

. (4)

Eq. 4 says that the impact coefficient i due to electricity generation by an economy depends on two factors:how the economy generates and uses electricity, the technology and natural resource utilized, etc, which is

given by i; and how much electricity the society uses, which is given by IE (Curran et al. 2005; Weisser,

2007; Lenzen, 2008). For instance, we can reduce the emission of greenhouse gases to the atmosphere by

reducing the amount of electricity used in the society (reducing I E), or reducing iE through moving from

alternatives that emit very much greenhouse gases to others that do not. Wind, biomass and nuclear power

emit less CO2 than fossil fuels, and thus they present smaller iE. Moving from one alternative to another may

reduce environmental impacts without decreasing the amount energy that is generated.


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Some impacts can be represented directly by numerical values and others cannot. For example,

damage to human health due to pollution can be estimated as society morbidity. Other impacts such as loss of

biodiversity or climate changes are more difficult to assess. In these cases, a way to circumvent this difficulty

is to relate the consequence to some causing factor that can be evaluated through available data. For example,

the CO2 concentration in the atmosphere can be taken as an indicator to the global warming intensity; the

occupied area can be an indicator of stress on the region biodiversity.

2.2. Selected criteria and impact coefficients

The set of criteria to evaluate impacts due to electricity generation by different alternatives have to

consider the environmental, social and economic dimensions. Table 1 presents the selected criteria, which are

not exhaustive, but try to cover the main issues related to electricity generation. We can say that the public

consider global warming, immobilized area and water consumption important environmental issues that

deserve to be included in the set of criteria. The dematerialization was considered a criterion because it isdesirable to reduce the mass of material utilized and processed by society, in order to reduce the stress on the

environment (Goldemberg e Lucon, 2008; Reis & Cunha, 2006; Veiga, 2006; Weisser, 2007; Curran et al.,

2005). In general, the greater is the amount of material input in the production processes, the greater will be

the corresponding environmental impacts.

Table 1Criteria and impact coefficients for evaluating electricity generation alternatives

Dimension Criterion Variable associated with the impact coefficient (iE)

Environment

1.Global warming

2.Imobilized area (rea x time)

3.Use and processing of naturalresources (dematerialization)

4.Water consumption

1.Emisso de CO2 (kg CO2/MWh)

2.Imobilized area (m2 year/MWh)

3.Mass of input materials that strongly perturbs theenvironment (kg/MWh)

4.Water consumption (m3/MWh)

Social

5.Radiation, pollution and humanhealth

6.Safety and risk of very damagingaccidents

5.human morbidity (morbidity/MWh)

6.fatalities in accidents (numer of deaths)

Economics7.Direct cost of electricity generation

8.Energy and operational efficiency

7.Direct cost of electricity ($/MWh)

8.Product of energy efficiency and capacity factor(dimensionless)

Regarding the social dimension, we consider human morbidity and consequences of potential

accidents. The society considers good health as an important indicator for welfare (Markandya & Wilkinson

(2007) and thus population morbidity was included as a criterion. In addition, the society considers the

possibility of occurring potential accidents and the risk to the public safety important issues as well. We


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consider the number of deaths in accidents reported in the literature as the indicator for this criterion

(Sovacool, 2008). The greater the number of deaths in accidents the history of a power generation option

presents, the more concerned the society is about this option.

Regarding the economic dimension, we consider as criteria the cost for electricity generation and the

overall operational efficiency of the generation plant. There is no doubt that cost is an important criterion. Theoverall operational efficiency can be considered a means to account for potential externality costs. We can

consider that systems with higher operational efficiency tend to require fewer natural resources, produce less

waste and cause less environmental impacts. These facts tend to reduce possible undesirable external costs.

We take as operational efficiency the product of energy efficiency and the capacity factor, aiming at taking

into consideration low thermal efficiencies, intermittency, seasonal variations, etc,

2.3. Data utilized to estimate the impact coefficients

Table 1 presents also the variable associated with each criterion and that will allow estimating its

corresponding impact coefficient. The necessary data, obtained in the technical literature, must consider the

life cycle of the complete production chain for electricity generation. Recently, many studies have been

published about energy generation, principally related to emission of greenhouse gases, immobilized area and

use of water (Kenny et al., 2010; Fthenakis & Kim, 2009; Evans et al., 2009; IPCC, 2007; Weisser, 2007; Lee

at al., 2004; Gagnon et al., 2002). An interesting publication about accidents in the energy sector has been

published with the number of fatalities in accidents that has been reported in the technical literature and press

(Sovacool (2008, p.1810-1819). Data about cost of electricity generation, thermal and energy efficiencies, and

capacity factors are more easily found in the literature.

Table 2 presents the sources of data for each criterion, which take into consideration the life cycle of

complete production chains of electricity generation. For some specific cases, the chosen data are from Brazil.

3. Calculated impact coefficients for different alternatives of power generation

This section presents the calculated impact coefficients, iE

, i=1,..,8, as specified in Table 1, for the

different alternatives of power generation, namely, coal, oil, natural gas, nuclear, biomass, hydropower, and

wind power. The impact coefficient for each criterion is based on the corresponding variable presented in

Table 1. In general, the data take into account the whole production chain and life cycle for electricity

generation. When that does not occur, it is mentioned in the text.

The results present important variation due to different data found in the literature. The uncertainty or

variation bars shown in the figures below are due to these data variations, sometimes as large as an order of

magnitude. The vertical bar encompasses the maximum and minimum values found in the literature and

accompanies all results presented in this section. The horizontal dash indicates the average value of all


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reported data. When only one source of data is available, there is no vertical bar in the figure, and one may not

interpret it as certainty. The cost of electricity is an exception since the horizontal dash indicates the cost of

electricity generation for each alternative in Brazil.

Table 2Source of data used for estimating the impact coefficients of different alternatives of electricitygeneration. All data are based on complete production chain and life cycle analysis.

Criterion and variables used to

estimate its impact coefficient

Source of data*

Global warming - emission ofgreenhouse gases

Baldasano et al. (1999, p.3766,3767,3769,3770); Lee at al. (2004,p.91,96); Weisser (2007, p.1550); Gagnon et al. (2002, p.1271);IPCC (2007, p.269,283); Goldemberg & Lucon (2008, p.191);IAEA (1997); Markandya & Wilkinson (2007, p.982); Rashad &

Hammad (2000, p.218); Holdren & Smith (2000, p.103).Imobilized area (rea x time)areaand time of occupation

Fthenakis & Kim (2009, p.1471), Gagnon et al. (2002,p.1274,1275), Kenny et al (2010, p.1973), Eletrobras (2000, p.114-120), Evans et al. (2009, p.1085)

Use and processing of naturalresources (dematerialization)amount of natural resources used forgenerating electricity

Brasil (2007f, p.190); Cochran & Tsoulfanidis (1999, p. 4, 370);EPE (2009, p.209,213,216); Goldemberg & Lucon (2008, p.192);IAEA (1997); Rashad & Hammad (2000, p.213).

Water consumptiondirect andindirect use of water for generatingelectricity

Evans et al. (2009, p.1085); Fthenakis & Kim (2010); La Rovere etal. (2010, p.427).

Radiation, pollution and humanhealthpopulation morbidity due tooperation of facilities involved in theelectricity generation

Markandya & Wilkinson (2007, p.981,983).

Safety and risk of very damagingaccidentsnumber of deaths due toaccidents reported in the literature orpress

Sovacool (2008, p.1810-1819).

Direct cost of electricity generation -$/MWh

Alvim et al., (2007); Benson & Orr (2008); BRASIL (2007b;2007c; 2007d; 2007e; 2007f); Carvalho & Sauer (2009); Cochran &

Tsoulfanidis (1999); Fthenakis & Kim (2009); IAEA (2006a); IPCC(2007); Kenny et al. (2010); Kok (2009); La Rovere et al (2010);Lee et al. (2004); Rafaj & Kypreos (2007), ANEEL (2008, p.30).

Energy and operational efficiencythermal efficiency, energy efficiencyand capacity factor

Alvim et al., (2007); BRASIL (2007b; 2007c; 2007d; 2007e;2007f); Carvalho & Sauer (2009); Cochran & Tsoulfanidis (1999);Fthenakis & Kim (2009); IAEA (2006a); IPCC (2007); Kenny et al.(2010); Kok (2009); La Rovere et al (2010); Lee et al. (2004); Rafaj& Kypreos (2007).

* Always take into consideration the life cycle of the complete chain of electricity generation. Situations in which thisdoes not occur are mentioned in the text.


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3.1. Emission of greenhouse gases

Figure 1 presents the impact coefficient for emission of CO2 to the atmosphere per unit of electricity

for several generation alternatives. The results present large variation according to different authors data or

specific technology. Coal and natural gas emission data consider different types of CO2 sequestration systems.

Hydro, wind and nuclear power emit CO2 indirectly. Hydropower plants emit CO2 equivalent due to methanegas generated in the reservoir, and during their construction. Methane gas has a global warming potential 23

times greater than CO2. According to ELETROBRAS (2000, p.113), in average, the Brazilian hydroelectric

plants emit 356.88 kg/daykm2 of CO2 and 18.29 kg/daykm2 of methane. Biomass emits some CH4 and its

overall emission depends on the type of culture used to generate electricity. Nuclear power emits CO 2 during

construction and decommissioning (deactivation after its end of life) (ELETROBRAS, 2000; Gagnon et al.,

2002; Goldenberg & Lucon, 2008; IPCC 2001). Wind and biomass power are the alternatives that emit less

greenhouse gases.

Figure 1Impact coefficient of equivalent CO2 emissions (global warming)for electricity generation alternatives (

1E).

3.2. Immobilized area

The immobilized area for energy generation precludes its use for other economic aim and, if it is very

large, may affect the regional biodiversity. The latter is an issue for enterprises such hydroelectric dams, wind

farms and coal mining. Fthenakis & Kim (2009) introduced the concepts of transformed area (m) and

immobilized area over time (myear) for computing direct and indirect use of area for generating energy. The

area downtime takes into account both the operating time and the time required to recover the location to its

original condition. We assume that larger areas would cause greater environmental, social and economic


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impacts, without questioning the activity itself that is developed, or that area immobilization is in itself an

important impact.

The recovery time to the sites original condition varies greatly according to the type of ecosystem

that had initially existed and to the type of occupation and technology utilized. It is difficulty to establish a

procedure to obtain the average recovery time after decommissioning a power plant and the other structures ofits production chain (Fthenakis & Kim, 2009, p.1471). Table 3 presents the recovery time utilized to

determine the immobilization time (Fthenakis & Kim, 2009; Gagnon et al., 2002; Kenny et al., 2010;

Eletrobras, 2000; Evans et al., 2009). The numbers quoted represent simple average values from several

figures found in the literature. Nuclear power presents a very large figure compared to other alternatives. It

requires a small area for the plant operation and for storing its nuclear waste, however, the time required to

store it is very long which increases substantially the immobilization time.

Table 3Occupation and recovery time for different electricity generation alternatives takinginto consideration the life cycle of the complete production chains

Power generation

option

Occupation and

recovery time

(years)

Biomass 40

Coal 35

Wind 30

Natural gas 35

Hydro (reservoir) 100

Nuclear 10.000

Oil 40

Figure 2 presents the impact coefficient of immobilized area for several power generation alternatives.

The occupation area for the different alternatives was obtained in the literature (Fthenakis & Kim, 2009;

Gagnon et al., 2002; Kenny et al., 2010; ELETROBRAS, 2000, p.114-120; Evans et al., 2009); thehydropower data, obtained from the Brazilian dams, present the greatest spread. Biomass usually immobilizes

a large area but in Brazil, its electricity is co-generated with ethanol and sugar. Only 5 % of the total

immobilized area is assigned to the electricity co-generation. Fossil fuel plants require small areas for

generating electricity. Nuclear power presents large immobilized area due to its very long occupation time.

The impact coefficient result with largest variation is from hydropower.


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Figure 2Impact coefficient of immobilized area for electricitygeneration alternatives (2E).

3.3. Use and process of natural resources

Some environmentalists consider that the use and processing of large amounts of natural resources

tend to perturb significantly the environment, and that the impact of any economic activity tends to increase

with the amount of used natural resources. They consider that an important measure of sustainability is the

amount of natural resources involved in the economic activities, and that it is important to dematerialize the

economic activities (Veiga, 2006). The impact of use and processing of energy resources depend, among

many factors, on the energy density of the resource. The various fuels have different energy densities and

require different processes in each link of its production chain. The sugar cane bagasse (biomass) has a low

energy density (0.215 kWh/kg of dry material (BRAZIL, 2007, p.190), then follows the fossil fuels (1.53

kWh/kg for coal, 2.82 kWh/kg for oil, 3.48 kWh/kg for natural gas (EPE, 2009), and 50,000 kWh/kg for

nuclear power (Goldemberg & Lucon, 2008). Hydro and wind power do not alter the nature of the natural

resource while producing energy and return them to the environment in very similar conditions. The

processing and use of biomass, fossil fuels and uranium tend to cause important environmental impacts while

the processing of wind and hydro natural resources usually do not.

Figure 3 shows the impact coefficient of use and processing of natural resources expressed in terms of

kg of material utilized per electricity generated, 3E (kg/MWh). The wind and hydro power are considered to

have negligible impact coefficient since they return air and water to the environment almost unchanged.

Nuclear power presents very low impact coefficient due to its very high energy density. Fossil fuel power

plants present intermediate impact coefficient and biomass present the highest impact with a large variation


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depending on the crop utilized as the natural resource. The horizontal dash for biomass represents the value

yielded by sugar cane bagasse, the crop utilized in Brazil for generating electricity through co-generation.

Figure 3Impact coefficient of use and process of natural resourcesfor different electricity generation alternatives (3E).

3.4. Water consumption

The water consumption is a good criterion of environmental and social impact due to its overall

importance for human and natural life. Generating electricity requires considerable amounts of water

throughout its production chain and life cycle. Water can be used (consumed) or used and returned to the

environment (circulated). The results presented here include consumed and circulated waters. Fossil fuels,

biomass, and nuclear power require water as coolant in their thermal cycles during electricity generation. In

hydropower, there is water loss by evaporation, which depends on the size of the dam and local temperature

(Evans et al. 2009).

Figure 4 summarizes the results of consumption of water. Natural gas present large variation for the

impact coefficient, but the highest thermal efficiency of combined-cycle power plants may allow also very

low impact coefficients. Biomass presents high water consumption, about 72.9 m3/MWh for the complete life

cycle of the production chain. However, in Brazil the biomass electricity is co-generated with sugar and

ethanol. We consider that its water consumption is only 5 % of the total consumption, i.e., 3.6 m3/MWh. Coal

and nuclear power are the greatest water consumers, oil and hydro power are intermediate consumers, and the

biomass co-generation and modern natural gas plants can be considered low water consumers. Wind power


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requires virtually no water for electricity generation when compared to other alternatives (Fthenakis & Kim,

2010).

Figure 4Impact coefficient of water consumption for differentelectricity generation alternatives (4E).

3.5. Social impacts

Among the several concerns of modern society, we can point out diseases caused by the normal

operation of the industrial facilities, which emit pollutants to the environment. Emission of gases to the

environment by fossil fuels and biomass plants may cause respiratory diseases to individuals living in their

vicinity; radiation and radioactive contaminants coming out from nuclear power plants are too concerns of the

public. To take into consideration this type of concerns, we consider as impact coefficient in the social

dimension the morbidity of population per unit of energy generated.

The public is also concerned with the safety of industrial facilities and the risk of accidents of severe

consequences. We consider as another impact coefficient in the social dimension the number of fatalities that

has occurred in accidents. Sovacool (2008) has published an interesting article reporting all accidents that

occurred in the last hundred years in the energy industry, in which there are brief description of the accident,

location and number of deaths among other data.

Figure 5 presents the impact coefficient of morbidity for different alternatives of electricity

generation. The data present large dispersion for those alternatives based on fuel combustion due to use of

more or less sophisticated systems to control the emissions. Respiratory diseases are the primary source of

morbidity. Nuclear, hydro and wind power alternatives present very low morbidity coefficients. It seems


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natural to the public that hydro and wind power do not cause morbidity to individuals in its vicinity. On the

other hand, nuclear has low impact coefficient but the public perception is that possible potential radiation

disease may affect their state of health in the future.

Figure 5Impact coefficient of morbidity for differentelectricity generation alternatives (5E).

Figure 6 shows the number of fatalities due to important accidents that occurred in the history of the

electricity generation. By important accidents, we mean those that caused fatalities or financial damages

greater than a million of dollars (Sovacool, 2008). Some few accidents caused a large number of fatalities and

the majority caused a small number. Hydropower caused in three accidents over 171,216 fatalities until today

and the other alternatives, coal, nuclear and oil, with 60 to 70 accidents each, caused 5099, 4100 and 3330

fatalities, respectively (Sovacool, 2008). Natural gas has caused less than 537 fatalities in about 80 important

accidents until today, and biomass and wind power do not present important figures (Sovacool, 2008).

Regarding hydropower and nuclear power generation, an important note should be made regarding

fatalities in accidents. With respect to hydropower, one accident, the Shimantan accident that occurred in

China in 1975, caused 171,000 direct and indirect deaths. Similarly, with respect to nuclear power, the

Chernobyl accident that occurred in the former Soviet Union in 1986 caused 4056 direct and indirect deaths

(Sovacool, 2008). No other accidents of such magnitudes occurred in the history of these two generation

alternatives, and based on the current safety standards, they can be considered unlikely to occur again today.

If we exclude these accidents, we obtain Figure 7. In this case, hydro and nuclear power present lower impact

coefficients of fatalities in accidents than fossil fuel power plants.


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Figure 6Impact coefficient of fatalities in accidents for differentelectricity generation alternatives (6E).

Figure 7Impact coefficient of fatalities in accidents for differentelectricity generation alternatives without the Chernobyl and Shimantan accidents (6E).

3.6. Economic impacts

The first impact coefficient considered in the economic dimension is the cost to generate electricity

($/MWh). Figure 8 shows the electricity cost of different power generation alternatives. The data spread forgeneration cost is large and the horizontal dash for each alternative shows the Brazilian cost as reported by


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countrys national operator of the electric system. The data spread indicates that, in principle, all alternatives

may be competitive if operation is carried out efficiently and with low cost. Another impact coefficient in the

economic dimension is the overall operational efficiency of the electricity generation system as an indication

of externality costs and shown in Figure 9.

Figure 8Impact coefficient of cost for differentelectricity generation alternatives (7E).

Figure 9Impact coefficient of operational inefficiency for differentelectricity generation alternatives (8E).


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In order to facilitate the analysis and comparison with the other impact coefficients, we consider the

overall operational inefficiency rather than the efficiency. In this way, the larger the impact coefficient, the

greater is the consequence to the environment, society and economy. Figure 9 shows the coefficient of

operational inefficiency for the different generation alternatives. Since the efficiency is the product of energy

efficiency and capacity factor, the fossil fuels and nuclear alternatives present similar results because they are

all based on steam cycles with similar thermal efficiencies. The exception is natural gas because of its larger

thermal efficiency. Wind power presents a high inefficiency due to its low capacity factor and hydropower

presents the lowest operational inefficiency.

4. Conclusions

In this work, we obtained impact coefficients for different power generation alternatives due to

different criteria involving environmental, social and economic dimensions. The electricity generation

alternatives considered were biomass, coal, natural gas, oil, hydro, nuclear, and wind power, and the set of

criteria considered included emission of greenhouse gases, immobilized area over time, water consumption,

use and processing of natural resources, population morbidity, fatalities in accidents, cost of electricity and

operational inefficiency. The data were obtained in the literature and take into account the complete

production chain and life cycle of all alternatives.

Since the data presented important variation, we included in the results the average, maximum and

minimum values of each impact coefficients for the different power generation alternatives. The impact

coefficient results are presented in figures, and can easily be used by analysts for different types of evaluation.

For global warming, coal and oil present the highest impacts and biomass and wind, the lowest

impacts. Coal, oil and natural gas present the largest data variation. For immobilized area over time,

hydropower presents the highest impact, nuclear, biomass and wind present intermediate impacts, and fossil

fuels present the lowest impacts. Hydropower presents the largest variation, and for biomass, we considered

only 5 % of total immobilized area as due to electricity generation since it usually occurs associated with co-

generation or other economic activities. For use and processing of natural resources, biomass presents thehighest impact and result variation; wind, hydro and nuclear power present the lowest impacts and smaller

variation.

For water consumption, coal and nuclear present the highest impacts, wind and biomass present the

lowest impacts, and natural gas, intermediate impact, but the largest variation due to different type of

technology reported for electricity generation. For population morbidity, coal and oil present the highest

impacts and variation; nuclear, hydro and wind present the lowest impacts.


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For the number of fatalities in accidents it is important to analyze the case of hydropower. If the

accident of Shimantan is considered, this option is by far the one with the largest impact coefficient. Nuclear

power presents number of fatalities similar to the coal and oil alternatives. If the Shimantan and Chernobyl

accidents are excluded from the data by assuming that they were unique, occurred in very special conditions,

and that other accidents of this magnitude did not occur again in the history of the hydro and nuclear power

options, the results are different. Coal and oil present the largest number of fatalities, nuclear power and

hydropower present lower number of fatalities and wind and biomass present the lowest. Natural gas presents

an intermediate number of fatalities.

For cost of electricity generation all alternatives present close figures, natural gas seems to be the

most competitive one, but the cost data present large variation for all options. For energy operational

inefficiency, biomass, oil, nuclear, coal and wind present the highest inefficiency, and hydropower present the

lowest inefficiency but the largest variation.

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tc14 elaee analysis of electricity generation alternatives

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