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Economic analysis on the enhancement of citrus wastefor energy productionMaurizio Lanfranchi aa Faculty of Economics, University of Messina, Messina, ItalyPublished online: 31 Oct 2012.

To cite this article: Maurizio Lanfranchi (2012): Economic analysis on the enhancement of citrus waste for energyproduction, Journal of Essential Oil Research, 24:6, 583-591

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Economic analysis on the enhancement of citrus waste for energy production

Maurizio Lanfranchi*

Faculty of Economics, University of Messina, Messina, Italy

(Received 12 December 2011; final form 31 July 2012)

In the last few decades, industrialized nations have become aware of the extent of how unsustainable some of theproduction models used are and have therefore adopted policies that aim both to save energy and to safeguard theenvironment through the use of alternative energy sources and, among these, biomass. The use of these alternativeenergy sources is very important: for example, this allows the saving of 200 g of CO2 per product, in addition toavoiding the emission of sulfur and other pollutants. The energy produced from biomass can be recovered by burningthe material directly for heat, and turning it into fuel, to make it more convenient to use. The choice of destination ofbiomass depends on the characteristics of the biomass available, because the content of carbon and nitrogen, moistureand volatile substances influence the choice of energy conversion. The aim of this work is to briefly outline ananalysis on the importance that biomass can have especially ‘pastazzo’, which is the squeezed pulp (of the processedcitrus fruits), for the enhancement of a sustainable economy, sought after in recent years not only by the EU but inan entire international context. The study is conducted by a research group as part of the Department Sefisast,Section of Agricultural Economics and Policy, specifically directed by Prof. M. Lanfranchi. The research is based onthe assumption that one can obtain both energy and bio-ethanol, not only from agricultural waste but also from thewaste products of the citrus industry arising from the processes of extracting juice and oil from skins. The use of the‘squeezed pulp’ could possibly help solve some of the serious environmental problems especially in the Mediterra-nean basin, particularly in Sicily, which is a major citrus producing region. This particular study aims to assess thecost of producing ethanol from squeezed pulp, with particular attention to the processing of lemons, a product inwhich the province of Messina has a leading role in terms of utilized agricultural area. The first part of this workpresents a discussion on the evolutionary aspects of EU energy policy; in the second part, it explains the importanceof biomass and its potential uses, and the last part contains data on the potential calories that can be obtained fromthe processing of squeezed pulp.

Keywords: agro-energy policy; biomass; bio-fuel; citrus waste processing

1. Introduction

The evolution that has accompanied the economicsystems of Western countries over the last thirty years,following the radical social, economic and technologi-cal changes, has also inevitably involved agriculture,which has undergone significant changes in productionsystems and also within the social structure of ruralareas. In particular, the agricultural sector has shownover the period a European trend in terms of GDP– which on average does not exceed 3% of the total –and in terms of employment. On average, agricultureaccounts for no more than 5% of the total labor forceemployed, but nevertheless it is called upon to play akey role, since it affects 80% of the land in the EU andstill provides employment for just under 20 millioncitizens.

The reading of this data helps to understand howagriculture is potentially able to attract additional labor.In light of this, it is easy to believe that the rural sector,better than other manufacturing sectors, can realize thepotential benefits from energy derived from renewable

sources in order to adapt the increasing energy demand,while limiting the negative effects on the ecosystem (1).

The current scenario of European agriculture ischaracterized by pressing technological evolution, in anattempt on one hand to compensate for the lack ofland, taken from the area through urbanization, and onthe other hand to replace the productive factor withcapital, which in terms of cost is cheaper (2).

Such a situation, which dominated the industrializa-tion of agriculture, resulted in the long run in aconsiderable increase in demand for energy, which to besatisfied has required heavy reliance on fossil energysources. The constant role of external energy, whichstands at approximately 3% of total needs, causes aserious negative impact on the environment; it isestimated that the contribution of agriculture to theemission of greenhouse gases comes to approximately15% of the total emissions, resulting mainly from the useof fossil fuels for transport and for heating.

The agricultural sector, although responsible forhaving contributed to the accumulation of greenhouse

*Corresponding author. Email: mlanfranchi@unime.it

The Journal of Essential Oil ResearchVol. 24, No. 6, December 2012, 583–591

ISSN 1041-2905 print/ISSN 2163-8152 online� 2012 Taylor & Francishttp://dx.doi.org/10.1080/10412905.2012.739788http://www.tandfonline.com

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gases in the atmosphere, to a fluctuating figure around10% of total greenhouse gas emissions attributable tothe EU, can play a key role in containing theseemissions that harm our planet. This role can be givento agriculture and carried out, mainly through theproduction of agro-forestry biomass to be allocated tothe production of substitute energy derived fromtraditional fossil fuels; in this way, it will contribute toreducing emissions of CO2.

In this work, after a brief discussion on the agro-energy policy of the EU, the intent is to highlight therole that sustainable agriculture can play towardsproduction and use of energy derived from renewableand clean sources, especially from biomass to producesecond-generation bio-fuel. The article presents asummary of data in the ongoing research on the studyof the feasible production of bio-ethanol obtained fromcitrus waste in the province of Messina, Italy.

2. The EU policy in support of agro-energy

The world consumption of primary energy sources is ataround 10 billion tonnes of oil equivalent (toe), ofwhich about 3.8 billion tonnes of oil, about 2.3 billiontonnes of natural gas that are flanked by coal consump-tion, which amounts to about 2.8 billion toe, thedemand for nuclear at 0.7 Mtoe and that of hydrogen isabout 0.28 million toe. As can be seen, among thehydrocarbons, oil and gas account for more than 60%of world energy demand. The trend of energyconsumption has increased dramatically compared withthe first two decades of the last century, during whichthe world demand for primary energy sourcesamounted to just over 1 billion toe, while today it hasexceeded to 10 billion toe and predictions indicate thatin the next two decades it will exceed 16 billion toe.All this justifies the concerns of governments, publicopinion and mass media, which in turn indicates atrend of unsustainable development that leads to therealistic expectation that the continued increase inconsumption in a short time will not be met by oil andgas resources currently active. The shadows that darkenthe energy future of our planet not only concern thereformulation of demand, but also the environmentalunsustainable of this huge energy consumption. It isexpected that emissions of carbon dioxide in the firstquarter of this century will increase according to thesame trend in energy consumption.

In a scenario this alarming, the use of renewableenergy sources can contribute on one hand to preservingthe stock of fossil resources, on the other to reducingthe negative impact on the environment.

The alarm about the amount of available reserves ofconventional energy is real, because the estimatesregarding the availability of natural gas amount to

180,000 billion cubic meters; therefore, according tothis data the indication is that the current consumptionrate means that resources will be sufficient to meetenergy demand for about another seventy years. How-ever, when taking into account the growth of theworld’s population and the growing energy demand ofcountries like China and India, this will inevitably affectthe level of reserves and will reduce further the time ofself-sufficiency in energy. Currently, the USA, the EUand Japan consume about 4.6 billion toe – just underhalf of the world’s demand of energy. If the consump-tion is compared with the world population, whichstands at around 6.5 billion people, one can infer aworld average energy consumption per capita of 1.62toe, compared with that of the EU of 3.9 toe per capita,Japan 4 toe per capita and the USA 7.9 toe per capita.The scenario on energy consumption within the UE isalso alarming, given that the member countries import75% of the oil they need, 57% of natural gas and 40%of coal, percentages destined to increase in future years,further contributing to the energy dependence of aunited Europe. The situation in Italy is particularlyalarming, because it imports 85% of its energy needs.

The events, which have succeeded in time, havegradually pushed the governing bodies of the Commu-nity to adopt an integrated energy policy. The journeystarted way back in 1952 with the establishment of theCZECH, followed by Euratom, and has been slow andtortuous, and to this day has yet to achieve the objectiveof an integrated energy policy capable of positivelyeffecting the future market of energy resources. The firstexample of EU energy policy dates back to the 1970swith the resolution on ‘A new approach to energypolicy’, in which the first Community energy objectiveswere defined. They were divided into four sections:

• develop electronuclear energy;• develop the domestic energy resources of the

Community;• diversify energy supplies from abroad;• promote investments in technological research to

develop renewable energy.

In the 1980s, a second ten-year energy plan waslaunched, geared to pursue the following objectives:

• reduce use of oil from 50% to 40% of totalenergy consumption;

• improve energy efficiency by 20% through themaintaining of the share of natural gas and aprogram of alternative supplies.

Even this energy plan failed, basically for the samereasons as the previous one, related to the fact that therealization of it passed through the instrument of the

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Resolution, which as everyone knows, is not a bindingdocument for the recipients but only for the MemberStates.

In the 1990s, the European Energy Charter wasdrawn up, signed at The Hague on December 17, 1991.This is an important tool for the study of issues inenergy between the states of the ex-Soviet bloc, Centraland Eastern Europe and the European Community.Among the objectives that the Charter intends to pursueare to contribute to the economic development of theformer USSR and the COMECON, and the diversifica-tion of energy sources of supply. Three years later inLisbon, on December 17, 1994, the Energy CharterTreaty was signed, which entered into force on April16, 1998. In 1995, the Green Paper on Energy waspublished, which sought to ensure the free movementof the resource ‘power’ within the boundaries of theCommunity. That same year, reflecting the importancethat the EU had given to issues related to energy needs,the White Paper on Energy was adopted, describing thepriorities of Community action for the realization of theinternal energy market, in order to ensure security ofsupply and environmental protection.

In most recent years, a second Green Paper wasadopted: ‘Towards a European strategy for energy sup-ply security’. This is the most important documentalong the path to achieving an energy policy that canenhance and build upon the potential abundance ofrenewable energy, through a system of incentives thatpartially offset the high cost of production. The energypolicy should aim at halting the current trend, which ina few years could bring an energy dependence beyondthe borders of 90%.

Italy is in a situation even more problematical,because, as the importer of energy for a share of 85%,compared with a European average of 50%, it will needto implement all the actions necessary aimed at develop-ing renewable energy, even through tax incentives,focusing primarily on the productive use of waste prod-ucts, and the waste product thus from being a problembecomes a resource. To reduce energy dependence, Italywould do well to focus on one hand on promotingenergy savings, in terms of energy consumption inbuildings and transport infrastructures, and on the otherstimulating the production of bio-fuels.

The EU in this direction has laid down the principle20 20 20, ‘which indicates that the target-bond policythat the Community has set itself to reduce itsgreenhouse gas emissions by 20% and increase energyefficiency by 20% by 2020’; also in the sametimeframe, the European partners will have to be ableto adopt a ‘sustainable’ energy mix, 20% coming fromrenewable sources, and of those 8% will be generatedfrom biomass and bio-fuels, so as to establish aminimum standard for the mandatory use, in 10% of

the fuel market, and promoting ‘second-generation’bio-fuels, a minor environmental impact, coming fromforest material and grasses. All this in harmony withthe objectives enshrined in the Kyoto Protocol.

3. The importance of second-generation bio-fuelsin the management of the world energy crisis

First-generation bio-fuels, based on food crops such ascorn, soybeans and sugar cane, not from food crops,cause problems of food supply, while second-generationbio-fuels that use the biomass of agricultural residues arestill available in limited quantities. However, they haveadvantages in terms of environmental sustainability,because they involve the reuse of waste, therefore mini-mizing negative environmental externalities, which arelinked to competition between food crops and non-foodcrops that cause fear due to the risk of food safety.

Biomass is any compound of biological origin –plant or animal – produced by photosynthesis, whichcan be burned to produce energy, digested by specificbacteria to produce biogas and bio-diesel, or subjectedto a process for producing ethanol. The conversion ofbiomass occurs, as well as for direct combustion,through a biochemical process, anaerobic digestion, i.e.in the absence of oxygen, or fermentation, or through athermo-chemical process, combustion and pyrolysis gas-ification, where the energy is obtained from the transfor-mation into heat, unlike the biochemical processes inwhich the energy produced results from chemicalreactions. In particular, during anaerobic digestion,microorganisms cause the demolition of complex sub-stances such as lipids and carbohydrates and producebiogas. From a chemical point of view, biogas iscomposed of methane with a percentage between 55%and 70%, and for the remainder of carbon dioxide. Thevariation in the amount of methane present is justifiedby the different origin of the biomass, such as biogasfrom the livestock sector, which is strongly influencedby the type of animal feed and the residence time ofmanure in the stable. Therefore the highest percentageof methane is found in biomass from pig farms, with alower production of biogas per cubic meter.

It is a form of indirect solar energy produced fromagricultural residues, forestry, industrial waste, etc.

Energy from biomass is certainly the one that ismore strongly linked to agriculture and forestry; now itis possible to analyze the advantages and disadvantagesarising from the use of this alternative energy source,considered a renewable type and virtually inexhaustibleresource, if the normal vegetative reproduction cycle ofplants can be respected.

The source of biomass is different, in fact, it stemsfrom any organic compound: forests, plants grown forenergy purposes, be that woody plants or grasses,

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residues from food production, catering and fromorganic waste. Herbaceous energy crops are rapeseed,sunflower, sorghum fiber, kenaf and miscanthus.Energy crops of woody origin are predominantly ofcoppice, poplar, willow, eucalyptus, etc., and thesecultures are referred to as SRF (short rotation forestry).Many applications are now in being: examples are theuse of waste from orujillo, olive oil, allowing Spain togenerate significant quantities of electricity.

The energy produced from biomass comes from astrong interaction between two subsystems: one, agro-forestry, which underpins the production of fuel, theother industrial, which is responsible for energyconversion. The use of energy derived from biomass issuitable for a wide range of uses, ranging from solidfuels for civil heating to those for industrial use, for thegenerating of electricity to those for urban districtheating, to liquid fuel for machinery to the use of gas toproduce electricity. These energy products are consid-ered good substitutes for fossil fuels; methane and dieselare replaced by the burning of straw and scraps of wood,gasoline and diesel fuel for machinery could be replacedby bio-ethanol and bio-diesel, respectively.

Bio-fuels are therefore a direct substitute for fossilfuels in transport and can be integrated rapidly into thefuel supply systems. They can be considered a substi-tute fuel in the transport sector, which affects the totalconsumption of energy for 21%.

Energy from biomass can also be achieved fromwaste sugar (bagasse) and this process is particularlycommon in tropical countries, major producers of sugarcane. Another method of production of biomass is thatwhich tends to use the waste from the process ofindustrial processing of citrus fruits. Such wastes arecommonly referred to as ‘pastazzo’ (squeezed pulp).

A characteristic of biomass is absorption of the car-bon dioxide before release to the point of significantlyreducing the emission of carbon dioxide by 90%compared with traditional fossil fuels. It is roughlyestimated that the reduction of carbon dioxide releasedinto the atmosphere following the use of biomass isabout 200 g per kilowatt hour of energy produced (3).

The biogas production is obtained through the use ofanimal sewage in special plants apt to produce methane,so this helps to solve the serious problem of pollution ofunderground water and that of the associated use ofchemical fertilizers, as part of the sewerage can be usedas natural fertilizers.

The energy coming from the exploitation ofbiomass accounts for approximately 10–12% of theaggregate worldwide production. The long-termforecasts foresee a substantial increase in the role ofbio-energy. According to some estimates conductedworldwide, by mid-century bio-fuels will reach a quotaof 17% of electricity and 38% of total fuel.

In agriculture, one of the items of costs that has asubstantial impact on the agricultural budget isundoubtedly related to electricity, and, in cases wherethe management provides for the activity of a cattlefarm, the annual expenditure for energy increasesdramatically. Whenever agricultural entrepreneurs areconfronted with an investment program aimed at savingenergy it is almost always unproductive because thecapital required is always prohibitive.

Nevertheless, it is possible to find a solution tosignificantly cut energy costs in agriculture and in somecases to draw an additional income. This solution isprecisely the use of biomass, present in satisfactoryamounts on the farm, and with the use of a cogenerationplant gives a saving of approximately 20%.

The real technological revolution seems feasible inmultifunctional farms where it is possible to generateenergy in excess to be sold to the supplying body, thusobtaining an additional profit. As for profits, the percent-age in favor of the farmer, on average, fluctuates around10% of the selling price of electricity. It is easy to seethe importance of this opportunity for the world ofagriculture that, in addition to having enough electricityfor the management of the company, allows entrepre-neurs to earn an additional income and save money onthe disposal of wastewater, which is estimated at about 5euros cents per kilogram of biomass withdrawn.

At present, biomass accounts for 15% of globalenergy needs, with an output of 55 million TJ equal to1230 Mtoe per year. The distribution of energy frombiomass on a global scale is quite uneven. In fact,while in developing countries the use related to thisenergy source is around 38% of the total needed withalmost 90%, as in the case of Nepal; on the other hand,in industrialized countries the contribution of biomassis negligible (3%), although in some countries, likeFinland and Sweden, the rate of use exceeds 15%.

It is estimated that in the space of 100 yearsmethane can be considered a greenhouse gas 23 timesmore powerful than carbon dioxide.

Figure 1. Traditional fuels used in the EU.

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However, in the EU the exploitation of fossil energyis still very high. Figure 1 shows how meaningful theenergy dependence on traditional sources is.

4. The contribution of the second-generation fuelsto environmental sustainability

It should be pointed out that there is an ever broaderspreading of bio-energy model farms around the world,and any farm that is able to provide for its own energyneeds, by redeploying waste arising from agriculturaland livestock, can produce enough power for its needsand sell the excess electric energy produced to thesupplier. Doing so helps to reduce significantly the neg-ative impact on the environment and reduce theproduction of greenhouse gases.

A review on the environmental impact consequent tothe use of biogas also clearly highlights the advantagesof reducing the excessive load of sewage on agriculturalland with the well-known deleterious implications forcrops: reducing the pathogenic load of sewage that facil-itates their use in crops, natural reduction in emissionsof odors just bearable and, above all, a considerable cutin the emission of methane, which is a greenhouse gasfar more aggressive than carbon dioxide (1).

Another interesting opportunity is directly linked tothe production of ethanol, alcohol fuel produced fromthe starch in corn, the scraps of grape skins and thesqueezed pulp of citrus fruits. The characteristic ofethanol is to generate greenhouse gases in an amountof about 40% less than those produced from oil. Thefurther use of biomass is in fact in the production ofethanol made from agricultural waste such as cellulosewaste, in which case the ethanol from biomass cancompletely eliminate the contents of the greenhousegases.

The development of this alternative eco-combustiblehas been hampered in the past by powerful multinationaloil companies worried about losing significant marketshare thanks to the special properties of ethanol, whichhas a higher octane level than gasoline; this octane isparticularly important because it prevents ignitionengines of cars from having combustion problems,which is why the multinationals have introduced anadditive, lead, subsequently banned because of its hightoxicity and because it is responsible, to a great degree,for air pollution.

The gradual introduction of ethanol, which todaycovers about 20% of the content of petrol, the remain-der is represented by an oil polluter of undergroundwater, falls into existing and future policies of EUagro-energy. The use of biomass is not limited to themost well-known application that has so far beenreported, but hydrogen can also be obtained and in thefuture, if this alternative renewable energy source is

encouraged, it might be possible to think of convertingbiomass into plastic, paper, clothing, etc. (4).

From the above it is clear that the use of biomasscan counteract the greenhouse effect, as indicated inthe guidelines of the Conferences of Rio De Janeiro in1992 and Kyoto in 1997, as it lowers the emissions ofpollutants of fossil origin, such as CO2, sulfuric acidand benzene.

Therefore, renewable energy sources seem toassume a prominent role in combating air pollution.Among the sources of energy, undoubtedly the biomassenergy resource has the most potential, though currentlyin Western countries about 60% of agricultural wastegoes for landfill instead of being reused as an energysource.

The advantages of the use of biomass energy arenot only environmental but economical. Indeed the costof collection and disposal of waste is quite expensiveand is relevant to the economic system of a country;therefore, through the process of combustion of waste,it could be possible to solve the problem of wastemanagement with positive effects on the environment.

5. Using biomass and the positive externalities

The biomass used to produce energy can be materialfrom residual sources, or the result of dedicated work,grown specifically for energy purposes and called‘energy crops’. Because of this classification, the sourcesare identified as residual sources or non-residual. Thefirst include the residues of agricultural production(divided into production waste, processing waste),forestry residues and wood production, animal waste(manure), or waste of by-products of agro-food, chaindistribution waste and final consumption (organicwaste). Among the sources that are not consideredresidual are aquatic energy crops; energy crops onsurplus agricultural land, energy crops on degraded landor derived from deforestation.

A portion of what is collected includes agriculturalproducts; the remainder includes derivatives that can beused to produce energy, which increases the profitabilityof the crop without heavily affecting the cost of produc-tion or harvest. Therefore it is important to evaluate exante the energy source to be used, which involves a cer-tain balance in the analysis of cost-benefit. The decisionon which source of most biomass to adopt is not simpleand in general a choice should be made in relation tothe particular situation of the territory in which it is. Inany case, the factors to be evaluated and taken intoaccount when determining the availability of biomass ina given area are: the future food needs, as determinedby the expected growth and diet of the population, thefood production system that can be adopted worldwidein the following years, the productivity of forests and

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energy plantations, the use of biomaterials in industryand in constructions, the availability of degraded land,and the use of land in competition with one another (e.g. surplus agricultural land used for reforestation).Biomass can have various uses, the crude one can beconverted directly into heat and power (bio-energy) withprocesses similar to those used for fossil fuels, but itcan also be used as fuel (bio-fuels) to be converted laterinto energy or products for the chemical industry(bio-products). All the conversion technologies used toobtain these three types of products fall into three broadcategories: biochemical conversion (anaerobic digestion,hydrolysis and fermentation), chemical conversion(esterification); thermo-chemistry conversion (combus-tion, pyrolysis and mass).

The solid products (charcoal) are intended mainlyfor boilers to produce heat and electricity, while fromthe synthesis gas and pyrolysis, after an appropriatetreatment, electricity is produced using engines, gasturbines or fuel cells, and it is also possible to derivebio-fuels with particular processes of synthesis. Bio-fuels such as bio-ethanol and bio-diesel are destined forthe transport sector.

Therefore, a bio-fuel is a fuel to replace fossil fuelscompletely, as well as being a renewable source. Bio-fuel as the object of the research is the resulting pelletfrom the drying the pulp.

The processes that allow the conversion of biomassinto energy are biochemical and thermo-chemical:aerobic digestion, anaerobic digestion, combustion,pyrolysis, co-firing and gasification. The first producedenergy is due to the chemical reaction given by theactivity of enzymes, fungi and microorganisms that areformed in biomass under specific conditions, andapplicable to some farming by-products within thelivestock manure and certain waste processing, andbiomass heterogeneous storage in controlled landfills.The thermo-chemical conversion processes, however,are based on the action of heat, which creates thechemical reactions necessary to turn the matter intoenergy. These are used to treat wood and its deriva-tives, the most common type of crop by-products andcertain lignocellulose waste processing. Among thethermo-chemical processes, gasification is the mostinteresting: it provides greater efficiency comparedwith direct combustion, and has reached a moreadvanced stage of development compared with fastpyrolysis.

Today, biomass energy covers 9–14% of worldenergy consumption and is used mainly in developingcountries to meet the daily energy needs. In thesecountries, biomass produces an average of 38% ofprimary energy consumed, with peaks up to 90% insome cases, but often is used inefficiently. In developedcountries, conversely, with certain exceptions (Austria

and Scandinavian countries), it is a niche market andprovides only 3% of the energy needs (3.5% in EUcountries).

In the USA, biomass covers 4% of energy needsbut could have the potential to reach at least 20% evenwithout competing with food production, by simplyusing to the best advantage the land and agriculturalinfrastructure available. Therefore, in developed coun-tries, biomass can bring many benefits especially to theenvironment, while in the developing countries effortscould well be directed to promote a more modern andsustainable use, in which the growth of welfare can besustained over the long term allowing the recovery ofthe resources used and at the same time preserving theability of future generations through new technologiesor through the use of alternative energies.

In the light of these considerations, it can easily beimagined that if biomass is efficiently used it cancertainly provide a beneficial effect not only to theindividual firm but a reflection on the whole Communitythat receives a positive externality.

6. The biomass obtained from citrus wasteprocessing

The term pastazzo means all waste by-products fromthe industrial processing of citrus fruits such as peel andsqueezed pulp. It is composed of peel and albedo ofcitrus, which are present inside d-limonene, pectin,polymers, cellulose and hemicellulose, simple andcomplex sugars. It has been, from the earliest times,used both in Italy (especially Sicily in view of theconsiderable annual production of citrus fruit) and inother foreign countries as food for farm animals, butrecently this particular biomass has been used in theprocess of anaerobic digestion for the production of gasand energy. The use of pastazzo could be a potentialsolution to the disposal of organic material, which is

Figure 2. Use of biomass compared with the energy needs.

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still a problem, due to a significant lack of suitable dis-posal sites. The energy costs are so high that sometimescompanies are forced to use the processing waste asfuel. It is to be noted that this use is far from being eco-nomically viable. In fact, pastazzo contains on averagemore than 90% water, and to burn must first be sub-jected to drying, and this increases the cost of energybecause, among other things, the rotary kilns are used.There may be several uses for this product, which flowsfrom residues of processing citrus in particular, toproducing biogas, bio-fuel and bio-ethanol.

The process involves the drying of the waste, inorder to have as final product a usable pellet as a sourceof energy, as a result of its combustion. Its calorie valueis about 12–13 MJ/kg dry weight, slightly lower thanthat generated by other biomass and about a quarter ofthat compared with fossil fuels. The higher the level ofdrying the higher the calorie value, since it will not takea lot of energy to evaporate the remaining water.

If from the fruit the initial 40% approximately ofjuice and 0.005% of essential oil are extracted, the gapwill be the remaining 60%. The water present in thepeel corresponds to approximately 85% of the total; theaim of the drying process is to reduce the humidity to15%, guaranteeing a product with very low levels ofwater content that can be used as fuel.

The production of pastazzo is around 50–60% byweight of the original produce to be transformed,therefore, for every tonne ‘put in for processing’ thereis 400–500 kg of juice produced (and derivatives) and600–500 kg waste with a dry matter content of around17–18%.

The pulp produced by processing industries has led,over the years, to many problems related to theeconomic and environmental disposal. The businessdecision to consider this product not a ‘waste’ but aresource could overcome the obstacles and the costsassociated with its disposal, allocating large amounts ofproduct to the production of quality compost andespecially the production of bio-fuel.

Table 1 shows the volume in tonnes produced in2011 in Italy, with reference to the citrus industry. Thisdata refers to ISTAT of May 2012.

Considering that 25% of the total citrus productionis destined for processing, the data in Table 2 can beinferred.

Analysis conducted shows that the production lea-der in the national territory is represented by orangeswith 2,520,659.1 tonnes, followed by clementines with730,564.3 tonnes and 509,663.2 tonnes of lemons. Theremaining operations are minor and relate to mandarins,grapefruit (though the production is minimal), bergamotand other citrus fruit (citron, Chinotto). The volume intonnes of citrus fruit at the national level for industryamounted to 985,268, while the transformation intonnes of oranges and lemons alone came to 757,580.According to data previously reported (50–60% of totalconversion), it can be seen that each year pastazzoproduced could amount to 460,000/550,000 tonnes, butif the production of oranges and lemons only is takeninto account, the amount of pastazzo goes to 385,000/455,000 tonnes. On the other hand, Table 3 describesthe tonnes of citrus fruit that were produced in 2011 inSicily.

With regards to the processing industry, Table 4shows the quantities of citrus fruits.

Table 1. Production of citrus in Italy, 2011.

Tonnes

Oranges 2,520,659.1Mandarin 146,163.7Clementines 730,564.3Grapefruit 7,595.0Bergamot 25,473.6Lemons 509,663.2Other citrus 955.0Total 3,941,073.90

Source: Our elaboration on ISTAT data (2011).

Water (on average 75-85% by weight) polysaccharides (pectin, cellulose and hemicellulose) approximately 1.5-3%

mono and disaccharides (glucose, fructose and sucrose) for a 6-8%

organic acids (citric, isocitric and malic) for a content of 0.5-1.5%

amino acids, vitamins, pigments, enzymes and mineral salts

Figure 3. Chemical composition of citrus pulp.

Table 2. Quantity of citrus fruits for processing, 2011.

Tonnes

Oranges 630,164.78Mandarin 36,540.93Clementines 182,641.08Grapefruit 1,898.75Bergamot 6,368.40Lemons 127,415.80Other citrus 238.75Total 985,268.49

Source: Our elaborations on ISTAT data (2011).

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With 457,073 tonnes, 228,536/274,243 tonnes ofpastazzo can be obtained, but if only the production ofSicilian oranges and lemons are taken into account, andthe transformation is worth around 422,403 tonnes witha production of pastazzo amounting to 210,000/250,000 tonnes.

The analysis also quantified the production in tonnesof citrus fruit produced in the province of Messina in2011 to outline the positive impact on the economicenvironment and provide decision support to politicalleaders for local development in the area (Table 5).

Considering 25% of the total production is destinedfor processing, namely for the production of juices,canned food, essential oils and other products, the datain Table 6 can be inferred.

In total, 13,000/15,000 tonnes of pastazzo can beproduced, but if only the processing of oranges andlemons is taken into account, then it is possible toextract 11,000/ 13,500 tonnes.

However, even today, despite the large quantities ofpastazzo constantly produced, a profitable way ofemploying it has yet to be found, that is, a use that

through a policy of low cost may help to improveenvironmental conditions and to ensure that industrygains from the processing and at the same time have asustainable activity. The machines that carry out thedrying of the pastazzo consume, in fact, for every kgof dry biomass, approximately 268 cubic decimeters ofmethane. The dry by-product produced is able torelease 186 MJ of heat with an energy cost for theremoval of water equal to 138 MJ. Therefore, for everykilogram of pastazzo, it is possible to obtain 48 MJ ofheat. Through a study of the data previously men-tioned, it can be seen that in Italy it is possible toobtain through the use of pastazzo, taking into accountonly the production of oranges and lemons, about21,600,000,000 MJ of heat (6,000,000,000 kWh);Sicily 12,000,000,000 MJ of heat (3.33 � 109 kWh),and in the province of Messina 648,000,000 MJ heat(180,000,000 kilowatt hour). Whereas the price of akWh is about e0.25, in the province of Messina alone,there could be a potential revenue of e45,000,000. Tominimize the loss of energy for transformation, a natu-ral pre-drying of the product would seem appropriate.However, it is to be specified that in this work, onlythe expected cost and consequently revenue, or calorievalue, which can be inferred from a given quantity ofpastazzo that was analyzed, and the costs (and anyrevenue) and economic factors facing the company forprocessing or use of this important biomass were nottaken into account.

Recently, the initiation of different researchthroughout the world, to try to make the best use ofthis resource, has been witnessed. Another example isthe University of Valencia, which has developed aunique technology to reuse the skins of oranges inorder to produce bio-ethanol. Research conducted inAustralia found that if the minimum content ofessential oils is reduced, eliminating the liquid resultingfrom the pressing of the peel before sending to thereactor of anaerobic digestion, for each kilogram offresh pastazzo, 77 liters of biogas are produced. Thismeans that in Italy, taking into account only theprocessing of oranges and lemons, it could be possibleto obtain approximately 34,650,000,000 liters of biogas(34,650,000 m3), in Sicily 19,250,000,000 liters

Table 3. Production of citrus in Sicily, 2011.

Tonnes

Oranges 1,251,811Mandarin 71,759.7Clementines 66,918.1Lemons 437,806.6Grapefruit 7,525.0Total citrus 1,835,820

Source: ISTAT (2008).

Table 5. Production of citrus in Messina, 2011.

Tonnes

Oranges 30,000Mandarin 7,500Clementines 900Lemons 60,000Total citrus 98,400

Source: ISTAT (2011).

Table 6. Quantity of citrus fruit for processing in Messina,2011.

Tonnes

Oranges 7,500Mandarin 1,875Clementines 225Lemons 15,000Total citrus 24,600

Source: Our elaborations on ISTAT data (2011).

Table 4. Quantity of citrus for processing in Sicily, 2011.

Tonnes

Oranges 283,905Mandarin 18,344Clementines 15,569Lemons 85,820Grapefruit 1,881.2Total citrus 457,073.8

Source: Our elaborations on ISTAT data (2011).

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(19,250,000 m3) of biogas, and in Messina1,039,500,000 liters (1,039,500 m3) of biogas.

7. Conclusions

As has been seen in recent years, the Community’senergy policy has set the targets in line with the KyotoProtocol and with relevant International Agreements onenergy saving and in the research of renewable sources.The achieving of these goals to reduce energy depen-dence and the consequent consumption of fossil fuelshas provided an important impetus to the production offuel derived from agricultural non-food crops, knownas the ‘first-generation bio-fuels’.

Despite the cost of production of such fuels stillbeing higher than those of fossil fuels, their use hasbecome, following the impulses and strategiesundertaken by the international policy, a growing trendworldwide. In fact, it is currently estimated that theworldwide production of bio-fuels exceeds 35 billionliters.

It is realistic to presume that there are well foundedfears according to which first-generation bio-fuels maythreaten and undermine food security and contribute toincrease the volatility of agricultural prices. Thisconcern, which affects all states of the world, has nodoubt concrete foundations; in fact, the production ofbio-fuels obtained from non-food crops requires largesurface areas. According to some estimates, it iscalculated that, at Community level, to pursue the goalset for 2020 to reach a 10% share of bio-fuels to beallocated to the transport sector in the most optimisticassumptions it would be necessary to have an AA ofabout 20 million hectares, slightly less than 20% of thetotal area devoted to arable land in the Community. Inremembering that in 2011 the EU used 3 millionhectares of land to grow bio-fuels, it is understandablehow this has contributed to the prices of agriculturalcommodities, combined with the rise in oil prices,resulting in soaring costs in transport and a growth indemand for agro-food in emerging Asian countries. Itwould therefore seem necessary to explore alternativesthat can restrict the massive demand for land to be usedfor energy purposes, in order to avoid the gradualremoval of land from the cereal producing companies,because in that case, there would be a particularly para-doxical scenario characterized by an energy policy thatencourages the production of energy from non-food

crops, and a PAC that protects the production of qualityEuropean food. Indeed in such a scenario, parallel com-petition between the market of first-generation bio-fuelsand food products would be created, which in turnwould cause farmers to abandon extensive crops infavor of energy. A comprehensive analysis willprobably lead to the result showing an increase inimports of agricultural products with the consequentcontraction of exports and the emergence of foodsecurity risk, in terms of food self-sufficiency withinthe EU.

The High Level Group CARS 21, formed in 2005to examine the competitive challenges that the Europeancar industry is facing, said that second-generation bio-fuels are particularly promising and has recommendedsignificant support for the development.

Therefore it would be wise to look at possiblealternatives and, among these, the second-generationbio-fuels derived from waste in processing and agro-food processing, such as the production of biomassfrom the pastazzo of citrus fruits, which has beenhighlighted in this work. Even for a reality such as theprovince of Messina, it could represent an interestingopportunity in the process of implementation of inte-grated and multifunctional farming. The opportunitiesoffered by the rural development policy provide for thepossibility of financing investments on the farm itselfor nearby to it, for example for the processing ofbiomass and for the mobilization of unused biomass inforestry. The PSR 2007/2013 for Sicily sets out theobjectives of Axis II as ‘the increase in biomassproduction and diffusion of practices/activities for thereduction of greenhouse gases’.

References1. P. Marzullo and M. Lanfranchi, Il contributo dell’agricol-

tura alla sostenibilità attraverso la produzione e l’utilizzodi energia rinnovabile. Annali facoltà di Economia,Messina (2003).

2. M. Lanfranchi, Sulla multifunzionalità dell’agricoltura,aspetti e problem. Antonino Sfameni Editore, Messina(2002).

3. E. Crabbe, C. Nolasco-Hipolito, G. Kobayashi, K.Sonomoto and A. Ishizaki, Biodiesel production fromcrude palm oil and evaluation of butanol extraction andfuel properties. Proc. Biochem., 37, 65–71 (2001).

4. H. Fukuda, A. Kondo and N. Hideo, Biodiesel fuelproduction by transesterification of oils. J. Biosci. Bioeng.,92, 405–416 (2001).

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