This article was downloaded by: [Abu Yousuf]On: 05 August 2014, At: 18:33Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

International Journal of SustainableEnergyPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/gsol20

Assessment of organic acid-rich bio-sapto generate electricitySreejon Dasab, Abu Yousufbc, Maksudur Rahman Khanc, SalmaAkhter Iqbalb & Md. Nasir Uddina

a Department of Chemical Engineering, University of Malaya,50603 Kuala Lumpur, Malaysiab Department of Chemical Engineering and Polymer Science,Shahjalal University of Science and Technology, Sylhet-3114,Bangladeshc Department of Chemical and Natural Resources Engineering,University Malaysia Pahang, 26300 Gambang, Kuantan, MalaysiaPublished online: 01 Aug 2014.

To cite this article: Sreejon Das, Abu Yousuf, Maksudur Rahman Khan, Salma Akhter Iqbal & Md.Nasir Uddin (2014): Assessment of organic acid-rich bio-sap to generate electricity, InternationalJournal of Sustainable Energy, DOI: 10.1080/14786451.2014.943758

To link to this article: http://dx.doi.org/10.1080/14786451.2014.943758

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoever as tothe accuracy, completeness, or suitability for any purpose of the Content. Any opinionsand views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Contentshould not be relied upon and should be independently verified with primary sourcesof information. Taylor and Francis shall not be liable for any losses, actions, claims,proceedings, demands, costs, expenses, damages, and other liabilities whatsoever orhowsoever caused arising directly or indirectly in connection with, in relation to or arisingout of the use of the Content.

This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

International Journal of Sustainable Energy, 2014http://dx.doi.org/10.1080/14786451.2014.943758

Assessment of organic acid-rich bio-sap to generate electricity

Sreejon Dasa,b, Abu Yousufb,c∗, Maksudur Rahman Khanc, Salma Akhter Iqbalb andMd. Nasir Uddina

aDepartment of Chemical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia;bDepartment of Chemical Engineering and Polymer Science, Shahjalal University of Science and

Technology, Sylhet-3114, Bangladesh; cDepartment of Chemical and Natural Resources Engineering,University Malaysia Pahang, 26300 Gambang, Kuantan, Malaysia

(Received 27 March 2014; accepted 4 July 2014)

The study has focused on electricity generation from organic acid-rich bio-substrate like star fruit (Averrhoacarambola). The sap of star fruit was selected as an electrolyte due to the presence of significant amountsof organic acids such as citric acid and ascorbic acid. To preserve the sap, 2% phenol by volume was used toreduce the growth of microorganisms, and the addition of phenol did not affect the initial pH. It was observedthat due to an increase in the electrode surface area, reaction rate and current generation had been amplified.Internal resistance also decreased rapidly because of the large electrode surface area. Furthermore, internalresistance was the significant barrier in electricity generation, which was also successfully controlled by thebaffle flow agitation system. Moreover, the baffle flow agitation system reduces the formation of dead zonesand increases the total dissolved solids inside the electrochemical cell compartments during operation.

Keywords: bio-electrochemical cell; star fruit; bio-electricity; acid-rich sap; baffle agitation

1. Introduction

Energy is one of the driving forces in the socio-economic development of any country. Developingcountries like Bangladesh have been facing a power crisis for about a decade, mainly becauseof inadequate power generation capacity compared with demand and the ageing infrastructure ofmany existing power generation facilities. Only 20% of the total population is connected with gridelectricity. Currently, most of the power plants in Bangladesh (representing 84.5% of the totalinstalled capacity) use natural gas – the main commercial primary energy source, with limiteddomestic reserves as a fuel (Hossain and Badr 2007). Though solar and wind energies are thepromising renewable sources in Bangladesh, but these are characterised by high investment cost,seasonal and site dependency. However, biomass is a major energy source in Bangladesh, whichcan be used for decentralised electricity generation (Kennes, Parikh, and Stolwijk 1984). World-wide, biomass-to-electricity and biofuel production have gained importance due to employmentopportunity, reduction in reliance on fossil fuels and positive environmental benefits. At present,the dependence on primary energy sources such as natural gas, coal and oil is increasing sig-nificantly. These three non-replenishable energy sources are consumed very fast by the global

∗Corresponding author. Email: ayousufcep@yahoo.com

© 2014 Taylor & Francis

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

2 S. Das et al.

people, approaching a stage where the demand of these fuels is becoming alarmingly. The bio-electrochemical cell offers a potential solution to mitigate the problems. It uses the availablesubstrates from renewable sources with a modified electrode, and converts them into harmlessby-products with simultaneous production of electricity (Gupta et al. 2011; Ma et al. 2009). Bio-electricity is a new term in the field of bio-energy. The technology of bio-electricity generationin the form of a fuel cell is a microbial fuel cell (MFC). In an MFC, wastewater are managed toconvert microorganism into fuel such as ethanol, methane and hydrogen from organic matter, andthese cells are designed with the anode and cathode, separated by a membrane. These fuel cellsare applied where dual activity could significantly reduce the cost associated with the electricitygeneration and wastewater treatment methods (Chaurasia, Ando, and Tanaka 2007; Strik et al.2008). It produces very low power electricity. Fuel cell stack design with these methods is verycomplicated (Sadiq Al-Baghdadi 2007). A suitable substrate for microorganism in wastewateris not always available (Cindrella, Fu, and Ho 2014). These methods are applicable where dualactivities are beneficial like wastewater treatment and small-scale electricity production, and themajor purpose sits on water treatment.

Not having these kinds of limitations, this technology has been shown to be a very promisingsource of bio-electricity generation from organic acid-rich bio-sap, which can be found frominedible fruits or leaves, and these bio-substrates are also renewable. From the literature, theself-ordering conditions of anodic porous alumina grown in solutions of various organic acids,such as citric acid, malonic acid, maleic acid and tartaric acid, were also studied (Ono, Saito, andAsoh 2005). In these acid electrolytes, a relatively large cell is available upon the application of ahigh anodisation voltage due to their low acidity. These organic acids are all carbonic acid, whichis similar to oxalic acid. In the present paper, the sap is selected as an electrolyte as it containstwo vital organic acids, such as citric acid (0.98 g per cent) and ascorbic acids (0.0252 g per cent)which contain acidic hydrogen shown in Figure 1. This technology has shown very economical,environmentally safe and the possibility of small-scale electricity generation in rural or remoteareas. A simple electrochemical cell is charged with selective organic acid-rich bio-sap (star fruit)with the insertion of two different metals of having different places in the reactivity series togenerate significant amounts of electricity as direct current (DC). The novelty of this researchwork is the incorporation of the baffle flow agitation system and use of the organic acid-rich bio-sap as an electrolyte in a typical electrochemical process. The electrochemical cell is modified bythe baffle flow agitation system, which is more effective to increase the electricity generation rate

C

C

C

C

O

O

O

O

H

H

HC

OC

H

H

O H

H

H

three acidic hydrogens

C

H

H C

O

O H

COH CO

O H

C

CH3

C

O

O H

H

two acidic hydrogens

Citric acid Ascorbic acid

Figure 1. Chemical structure of citric acid and ascorbic acid with highlighted acidic hydrogen.

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

International Journal of Sustainable Energy 3

than the ordinary electrochemical cells. Progresses of the preservation technique, construction ofbio-electrochemical cell and the feasibility study of electricity generation from selected acid richbio-substrates were also studied in this research.

2. Materials and methods

2.1. Bio-electrolyte processing

Number of bio-substrates such as star fruit (Averrhoa carambola), patharkuchi leaves (Kalanchoepinnata) and lemon (Citrus limonium) were screened out to select a suitable source of bio-sap.Finally, star fruit was selected as the bio-electrolyte because of some properties such as low pH,high electrical conductivity, economic value and availability. Star fruits were washed with normalwater to remove dust from the surface of the fruits, and also washed with distilled water for morecleaning. Star fruits were cut into small pieces (Figure 2(a)) and disrupted (Figure 2(b)) in ablander to obtain the sap.

The sap was filtrated with a filter paper to remove the fibrous portion. The filtrate was treatedas an electrolyte/bio-electrolyte. Like other biological broth, it was difficult to prevent the bio-electrolyte from the attack of microorganisms. Here, the antibacterial reagent (2% phenol byvolume) was subjected to a bio-electrolyte for preservation. Phenol is a water-soluble weak acid,which is freely absorbed by microorganisms when sufficient mineral nutrients are present in thesoil. Enzymes or selected organisms can degrade individual phenolic acids (Blum and Shafer1988). Therefore, there is no significant adverse impact on the soil when the exhausted phenolicbio-electrolyte is discharged after electricity generation (Kuiters and Denneman 1987). Moreover,the exhausted bio-electrolyte could be used as a bio-fertiliser because of its organic contents.Thermal treatment at 70 ◦C about 5–7 min was another way to preserve the bio-electrolyte, but itwas observed that thermal treatment saved the bio-electrolyte from microbial attack for less thantwo days; it might be due to the formation of easily digestible compounds for microbes. On theother hand, 2% phenol by volume is more effective for preserving the bio-electrolyte for morethan four days. Table 1 shows two different types of preservation techniques.

BA

Figure 2. Pieces of star fruit (A) and organic sap (B).

Table 1. Preservation procedures of bio-electrolyte.

No. Preservation techniques Procedures

I Preserving fresh bio-electrolyte withantimicrobial reagent

By adding 2% phenol by volume

II Preserving fresh bio-electrolyte with thermaltreatment

Thermal treatment at 70 ◦C about 5–7 min(without adding any antimicrobial reagent)

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

4 S. Das et al.

2.2. Reaction mechanism of the bio-electrochemical cell

The principle of electricity generation using bio-electrolyte is the same as a simple electrochemicalcell which converts chemical energy into electrical energy. The basic difference in the presentstudy with electric cell theory is only the utilisation of organic acid (citric acid, iso-citric acid,ascorbic acid, oxalic acid including other weak organic acid, etc.), which is found in acid-richfruits or leaves as electrolyte. This is a renewable source for producing energy. In the case ofcitric acid, the organic sap contains about 90%–95% water. Dissociation of organic acid in thisaqueous solution, according to Equation (1), consequently increases the H+ ions. In the meantime,the Zn plate dissolves in the organic electrolyte as Zn2+ ion, sacrificing two electrons. Electronspass through the external circuit, and salts of Zn are produced. On the other hand, H+ ions areadsorbed on the surface of the Cu plate, and receiving electrons those evolve as H2 gas (Fontana andGreene 1978).

Approximately 9 L of the bio-electrolyte was used for the baffle agitation system during 100-hoperation. Electrolyte solution was prepared in such a way that contained raw sap and water witha proportion of 1:8. After pouring the mixture into a cell, zinc (Zn) and copper (Cu) plates weremerged into the electrolyte with a proportion of 1:1 and 2:1. Immediately, chemical reaction tookplace, which in turn created positive and negative potentialities. As a result, the conduction ofelectricity was started. Citric acid reacts with Zn to produce zinc citrate, Equation (2), and releasedhydrogen ions.

HOOC−CH2−C(OH)(COOH)−CH2−COOH(aq) → HOOC−CH2

−C(OH)(COOH)−CH2−COO− + H+ (1)

2[HOOC−CH2−C(OH)(COOH)−CH2−COO−] + Zn2+ → [HOOC

−CH2−C(OH)(COOH)−CH2−COO−]2Zn (2)

In this way, the Zn plate became negatively charged and H+ contacted the Cu plate to becomepositively charged. As these two plates were connected by wire, current flowed from Cu to Znthrough the outer circuit, and from Zn to Cu through the bio-electrolyte. Therefore, the circularpath of the cell generated DC. By applying the inverter, DC was converted into alternating current.

At the anode, two electrons are then released from each zinc atom, Equation (3), giving theZn2+ ion.

Zn(s) → Zn2+(aq) + 2e− (3)

At the cathode, the other reaction is called reduction, when positively charged hydrogen ionsaccept electrons and evolve as hydrogen gas, Equation (4).

2H+(aq) + 2e− → H2(g) (4)

2.3. Bio-electrochemical cell design and measurements

To prepare the cost-effective cell, empty battery boxes are collected from a local market. Afterwashing the boxes, electrodes of copper and zinc having dimensions of height: 10.8 cm, length:5.4 cm and weight: 12 g were inserted with sap of star fruits into the boxes. A multi-meter wasconnected for measuring the current and voltage.A box of four compartments is shown in Figure 3,where each compartment has the following dimensions – width: 4 cm, length: 8.4 cm, height:10.5 cm and effective height of the electrolyte: 9.5 cm. For achieving high voltage and highcurrent yield, several types of cell connections had been observed. Among these observations, thecombination of series and parallel connections had been found capable of producing maximum

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

International Journal of Sustainable Energy 5

Figure 3. Arrangement of a bio-electrochemical cell (anode:cathode ratio 2:1) where dotted and plane lines indicateseries and parallel connections, respectively. Symbols ‘a’ and ‘b’ denote effective height of the electrolyte and cell height,respectively.

power (Figure 3). The generation of electricity needs to be continued until the anode plate getstotally corroded (Fontana and Greene 1978). A meaningful arrangement of the electrode (2:1anode–cathode ratio) was added to generate the maximum yield by increasing the anodic surfacearea. The polymeric separator that had been used in between anode and cathode was chemicallystable to the electrolyte.

Both open circuit voltage (Voc) and short circuit current (Isc) are measured precisely by a digitalmulti-meter. After that a resistor of 1950 k� is connected in parallel and series to measure voltageand current, respectively. The accuracy and maximum operating range of multi-meter, pH meterand conductivity meter used during the measurements are given in Table 2.

An advanced baffle flow agitation system has been introduced here to circulate the bio-electrolyte continuously through cell boxes by using potential energy difference (Figure 4). Adesign is fabricated using a wood frame and four empty battery cases (cell boxes) of 16 cells.A diaphragm pump (TYP-2000) is used for handling organic electrolyte continuously, and cellboxes are connected with plastic pipes for the circulation of the bio-electrolyte. A regulator isconnected with a diaphragm pump to control the flow rate of the bio-electrolyte. The bold spiralpath shows the movement of the bio-electrolyte within the cell boxes. This type of flow patternprevents the formation of dead zones and distributes the bio-electrolyte evenly throughout thecell boxes. About 9 L of the organic bio-electrolyte is loaded in this baffle agitation system andcirculated continuously for an 80-h operation. All experiments have been accomplished repeat-edly a minimum of three times, and the average values of the operating variables such as voltage,current, pH change and internal resistance from repeated data were taken.

Table 2. Accuracy of measuring instruments.

Measuring instruments Measuring range Accuracy

pH meter (HI 98130) 0.0–14.0 pH ±0.05 pHConductivity meter (HI 8033) 0.0–199.9 μS/cm ±1%Digital multi-meter (FLUKE-87-V) 0.0–10A (AC and DC) ±0.05% DC

0.0–1000V (AC and DC)

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

6 S. Das et al.

Figure 4. Advanced design of bio-electrochemical cell with baffle agitation system.

3. Results and discussion

3.1. Bio-electrolyte analysis

Any kind of fruit or leaf sap can be used when there is an evidence of significant percentage ofacids present in juice with suitable pKa value. The tendency of an acid to release a proton is calledthe acid dissociation constant (pKa) of that substance. pKa gives the acidity of a given hydrogenatom and pH gives the concentration of hydrogen ions. The pH measurement (Table 3) showsthe results that both the extracted juice is suitable to produce sufficient voltage and current in anelectrochemical cell. It is observed that the lower value of pH indicates the generation of highervoltage and current. Acids having lower pKa value have high dissociation in aqueous solutionof low pH (Chang 2003), which refers to the highly reactive affinity to the metal (electrode).Conductivity (σ ) and viscosity (μ) are the other important parameters of electrolyte which are

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

International Journal of Sustainable Energy 7

Table 3. pH, conductivity and viscosity measurement of A. carambola (AC), K. pinnata(KP) and C. limonium (CL).

Measured value Uncertainty

Parameters AC KP CL AC KP CL

pH 2.82 4.63 2.13 ±0.03 ±0.02 ±0.03σ (μS/cm) 4.1 3.13 2.3 ±0.3 ±0.25 ±0.2μ (cP) 5.1 4.3 9.0 ±0.1 ±0.1 ±0.15

Table 4. Chemical compositions of green star fruit (Averrhoacarambola).

Contents Per cent (g)

Moisture 90.65Protein 0.39Lipid 0.31Crude fiber 0.92Reducing sugars 2.80Total sugars (as gram reducing sugars) 2.91Pectin 1.64Starch 1.92Titratable acidity (as gram anhydrous citric acid) 0.98Ascorbic acid 0.0252Tannin 0.0028

given in Table 3. Viscosity of the bio-electrolyte has a significant effect on electricity generation,and higher current density can be obtained with the optimum electrolyte concentration (Ono,Saito, and Asoh 2005). Highly viscous sap does not have a desired state for the present baffleagitation system because it needs a continuous flow of the electrolyte. It was clear from Table 3that A. carambola (AC) gave low pH, 2.82, denoting a high acid content, whereas it was 4.63for K. pinnata (KP), though viscosity and conductivity of KP are comparatively better than AC.Here, the availability and rich amount of acidic hydrogen ion (low pH) are the most importantfactors for the selection of the organic bio-electrolyte. On the other hand, C. limonium (CL) isbetter than AC and KP electrolytes according to pH, μ, and σ values, but CL is not feasible forelectricity generation due to its food value.

Another most important factor is the composition of the extracted sap. Composition of the saphas an impact on electric resistance of a bio-electrochemical cell. In this study, star fruit has beenused as an electrolyte to inspect electricity production capability in this baffle agitation systemwhich was connected in series and parallel combination for acquiring maximum electrical energy.Chemical compositions of green star fruit of per 100 g (Narain et al. 2001) are given in Table 4.

3.2. Effects of the anode surface area

Electrochemical reaction depends on the initial pH of electrolyte and the area of the electrodesurface. The larger electrode surface area enhances not only current density (Yang, Mul, andMoulijn 2007), but also the pH of the electrolyte. In Figure 5, it is observed that the rate of pHchange increases significantly with the addition of electrode surface area (2:1 anode–cathodesystem) compared with the 1:1 anode–cathode system during 80-h operation. Moreover, thecurrent generation was expressively higher in the 2:1 anode–cathode system than in the 1:1anode–cathode system for the same operating conditions.

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

8 S. Das et al.

0

1

2

3

4

5

6

7

8

9

1.4 1.9 2.4 2.9 3.4

I–1(A

–1)

pH

1:1 anode–cathode

2:1 anode–cathode

Figure 5. Effect of anode surface area on pH and current generation.

Acids react with the anode and produce complex salts (solid corrosion products) forming alayer on the inserted surface of the anode, acting as a barrier to further oxidation (Jones 1996).The presence of solid corrosion products resists proton transport through the electrolyte causinginternal resistance in the cell (Moran and Labine 1986). Every electrochemical cell contains someamount of internal resistance due to the electrodes and the electrolyte.A larger electrochemical cellhaving a large electrode contact area with the electrolyte means less internal resistance. If the areaof the electrode is too small, a large internal resistance can be established, possibly because of thesolid corrosion product. Such resistance can decrease the amount of current generation (Moran andLabine 1986). The major problem of the electrochemical cell is an increase in internal resistancewithin the electrolyte. According to Wiedeburg’s theory, the current generation decreases with anincrease in internal resistance (Guthe 1898). Therefore, electrolyte resistance plays an importantrole in case of electrolyte selection. The lower internal resistance enhances better performance ofthe cell. For this reason, the effect of internal resistance was observed precisely, and a fixed resistor(2 k�) is connected in parallel and series with the cell while voltage and current are measured,respectively. Figure 6 illustrates that internal resistance is initially high for the 1:1 anode–cathodesystem compared with that of 2:1 system. After 80 h of operations, it was observed that there wasa significant difference between the 2:1 and 1:1 anode–cathode system. Therefore, it is clear thatless surface area and slow reaction rate are responsible for the increase in the internal resistancein the 1:1 anode–cathode system.

3.3. Effects of the baffle agitation system

Since only the sap was used as the bio-electrolyte, the stagnancy might interrupt the ionic move-ment and anodic–cathodic reactions. It is reported that the conversion of the current is high enoughwith an increase in the agitation rate (Raju and Basha 2005). Therefore, a flow type baffle agitationsystem was developed for the present bio-electrochemical cell.

In Figure 7, the effect of agitation is shown on the current generation. Current generation washigher when the 2:1 anode–cathode cell arrangement was subjected to a baffle agitation systemcompared with the bio-electrochemical cell without agitation. With the influence of agitation,hydrogen ions are distributed evenly throughout the cell, and hereafter reduces the concentration

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

International Journal of Sustainable Energy 9

0

300

600

900

0 30 60 90

Rin

tern

al (

W)

t (h)

1:1 anode–cathode

2:1 anode–cathode

Figure 6. Influence of anode surface area on internal resistance.

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 20 40 60 80 100 120

I–1 (

A–1

)

t (h)

without agitationwith agitation

Figure 7. Effect of baffle agitation on current generation with 2:1 anode–cathode cell arrangement.

polarisation (Guthe 1898). This agitation system also helps to reduce the suspension of the solidinto the bio-electrolyte.

For a better function of the electrochemical cell, internal resistance is one of the importantfactors. In the present study, internal resistance was increased rapidly, and reached a higher valuearound 19 k� when no agitation was applied. However, this value is remarkably reduced to around9 k� when the system was agitated (Figure 8). Thus, it is clear that agitation was the influentialfactor on the current generation and internal resistance minimisation. The maximum output ofpower, voltage, current and internal resistance with uncertainty is highlighted in Table 5 for A.carambola electrolyte with the agitation-assisted 2:1 anode–cathode system.

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

10 S. Das et al.

0 20 40 60 80 100 120t (h)

without agitation

with agitation

Rin

tern

al (

W)

Figure 8. Influence of baffle agitation on internal resistance with 2:1 anode–cathode cell arrangement.

Table 5. Maximum power, current, voltage andinternal resistance measurement for A. caram-bola electrolyte with the agitation-assisted 2:1anode–cathode system.

Operating Experimentalvariables maximum output Uncertainty

Power (P) 9.24 W ±0.7 WCurrent (I) 2.2A ±0.1AVoltage (V ) 4.2V ±0.2VRinternal 9000 � ±1.5�

4. Conclusions and future prospect

Electrode surface area, initial pH, baffle agitation, viscosity and conductivity significantly influ-ence the generation of bio-electricity. The main challenge of handling bio-electrolyte is themicrobial attack. The present study proved that the addition of 2% phenol was quite sufficientto preserve the electrolyte from the attack of microorganism. Maximum power 9.24 W, voltage4.2V and current 2.2A were obtained from 9 L of the bio-electrolyte, when the 2:1 anode–cathode baffle agitation system was applied. Moreover, the evolution of hydrogen gas can bea promising source of energy in terms of hydrogen fuel engine, but it needs more research tocapture hydrogen gas from this bio-electrochemical cell. As there is no emission of carbon diox-ide to the environment, it can be a possible technology to minimise environmental pollutionby avoiding fossil fuel technologies. The exhausted bio-electrolyte can be a possible source ofbio-fertiliser after the electricity-generation process. The greenhouse effect can be reduced bythe plantation of trees containing acid-rich fruits and leaves. Eventually, the development of thisnew approach will make a significant contribution towards the achievement of effective greenenergy.

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014

International Journal of Sustainable Energy 11

Funding

The authors acknowledge financial support from Research Center of Shahjalal University of Science & Technology,Sylhet-3114, Bangladesh.

References

Blum, U., and S. R. Shafer. 1988. “Microbial Populations and Phenolic Acids in Soil.” Soil Biology and Biochemistry20 (6): 793–800.

Chang, R. 2003. General Chemistry: The Essential Concepts. 3rd ed. New York: Mc Graw Hill.Chaurasia, P., Y. Ando, and T. Tanaka. 2007. “Investigation on Proton Exchange Membrane Fuel Cell for Solar Power

Generation.” International Journal of Sustainable Energy 26 (2): 107–119.Cindrella, L., H.-Z. Fu, and Y.-S. Ho. 2014. “Global Thrust on Fuel Cells and Their Sustainability – An Assessment of

Research Trends by Bibliometric Analysis.” International Journal of Sustainable Energy 33 (1): 125–140.Fontana, M. G., and N. Greene. 1978. Corrosion Engineering. 2nd ed. New York: McGraw Hill Book.Gupta, G., C. Lau, B. Branch, V. Rajendran, D. Ivnitski, and P. Atanassov. 2011. “Direct Bio-Electrocatalysis by Multi-

Copper Oxidases: Gas-Diffusion Laccase-Catalyzed Cathodes for Biofuel Cells.” Electrochimica Acta 56 (28):10767–10771.

Guthe, K. 1898. “Polarization and Internal Resistance of Electrolytic Cells.” Physical Review (Series I) 7 (4): 193.Hossain, A. K., and O. Badr. 2007. “Prospects of Renewable Energy Utilisation for Electricity Generation in Bangladesh.”

Renewable and Sustainable Energy Review 11 (8): 1617–1649.Jones, D. A. 1996. Principles and Prevention of Corrosion. 2nd ed. Upper Saddle River, NJ: Prentice Hall.Kennes, W., J. K. Parikh, and H. Stolwijk. 1984. “Energy From Biomass by Socio-Economic Groups – A Case Study of

Bangladesh.” Biomass 4 (3): 209–234.Kuiters, A., and C. Denneman. 1987. “Water-Soluble Phenolic Substances in Soils Under Several Coniferous and

Deciduous Tree Species.” Soil Biology and Biochemistry 19 (6): 765–769.Ma, Y., G. G. Karady, A. Winston, P. Gilbert, R. Hess, and D. Pelley. 2009. “Economic Feasibility Prediction of the

Commercial Fuel Cells.” Energy Conversion and Management 50 (2): 422–430.Moran, G. C., and P. Labine. 1986. Corrosion Monitoring in Industrial Plants Using Nondestructive Testing and

Electrochemical Methods (Vol. 908). Montreal, Canada: ASTM International.Narain, N., P. Bora, H. Holschuh, and M. D. S. Vasconcelos. 2001. “Physical and Chemical Composition of Carambola

Fruit (Averrhoa carambola L.) at Three Stages Maturity.” CYTA-Journal of Food 3 (3): 144–148.Ono, S., M. Saito, and H. Asoh. 2005. “Self-Ordering of Anodic Porous Alumina Formed in Organic Acid Electrolytes.”

Electrochimica Acta 51 (5): 827–833.Raju, T., and C.A. Basha. 2005. “Process Optimization Studies on Mediated Electrooxidation.” Portugaliae Electrochimica

Acta 23 (3): 367.Sadiq Al-Baghdadi, M. A. 2007. “A Simple Mathematical Model of Performance for Proton Exchange Mmbrane Fuel

Cells.” International Journal of Sustainable Energy 26 (2): 79–90.Strik, D. P., H. Terlouw, H. V. Hamelers, and C. J. Buisman. 2008. “Renewable Sustainable Biocatalyzed Electricity

Production in a Photosynthetic Algal Microbial Fuel Cell (PAMFC).” Applied Microbiology and Biotechnology81 (4): 659–668.

Yang, K. S., G. Mul, and J. A. Moulijn. 2007. “Electrochemical Generation of Hydrogen Peroxide Using Surface Area-Enhanced Ti-mesh Electrodes.” Electrochimica Acta 52 (22): 6304–6309.

Dow

nloa

ded

by [

Abu

You

suf]

at 1

8:33

05

Aug

ust 2

014