assessment of energy production options in lieu of orange cultivation in ribera baixa (valencia)

International Journal of Energy Science (IJES) Volume 4 Issue 4, August 2014 www.ijesci.org

doi: 10.14355/ijes.2014.0404.01

109

Assessment of Energy Production Options in

Lieu of Orange Cultivation in Ribera Baixa

(Valencia), Spain Enrique A. Navarro1, Alfred Wong*2

1Instituto de Robótica y Tecnologías de la Información y Las Comunicaciones (IRTIC), Universitat de València,

Paterna (València), Spain.

2Arbokem Inc., Vancouver, Canada.

* Correspondence to: P.O. Box 34173, Vancouver V6J 4N1, Canada.

E‐mail: [email protected]

Received 17 March 2014; Revised 22 April 2014; Accepted 24 April 2014; Published 3 July 2014

© 2014 Science and Engineering Publishing Company

Abstract

The Comunitat Valenciana is the largest orange producing

area in the European Union. During the past decade, orange

cropping has been under severe economic stress arising from

increasing competition from less‐costly foreign imports.

Consequently, farm‐gate prices are depressed to the extent

that it has effectively fallen to the same or below the cost of

production. Orange groves are being abandoned in many

instances. Preliminary assessment showed that conversion of

orange grove in Ribera Baixa to produce energy does not

appear to be a viable option. Electric power generation is not

practicable in the absence of government feed‐in tariff

subvention. Photovoltaic power generation might however

be practicable for self consumption under certain

circumstances. Use of crude microalgal oil does not provide

sufficient economic benefits to the prospective on‐road end

uses, in absence of any excise tax exemption. The production

yield of crude moringa oil is far below that of crude

microalgal oil to be of competitive interest.

Keywords

Biofuel; Economy; Energy; Oranges; Ribera Baixa; Valencia

Introduction

Orange (Citrus sinensis (L.) Osbeck), one of the most

widely grown tree fruit crop in the World, is native to

southern China (Morton, 1987). Cultivation of oranges

in eastern coastal Spain began during the Islamic Era.

In the 1970s, there was a major rapid expansion of

orange production in both Comunitat Valenciana and

Andalusia. In 2010, Comunitat Valenciana produced

~1.51 million tonnes of sweet oranges, accounting for

about 57% of the total orange production in Spain (IVE,

2012). Most of the oranges are grown in the province

of Valencia. Orange is cropped in about 19% of the

land area of Ribera Baixa, the highest among all the

comarcas of the Comunitat Valenciana (GVA, 2010;

IVE, 2012). The geographic location of Ribera Baixa is

given in Figure 1. The land holdings in Ribera Baixa

are highly fragmented (Wong and Navarro, 2013). The

typical size of a single orange‐grove holding is in the

range of 0.2 to 1.0 hectare. It has been evident for

many years that the net revenue from such small scale

orange cropping does not provide sufficient living

income for the land owner. Indeed many growers

have alternative wage‐paying off‐farm employment. It

may be noted that there are also significant number of

farmers who combine rice cropping and orange

cropping activities to achieve sufficient income for

sustenance.

During the past few years, the orange cropping

economy in Spain has been in significant decline. The

underlying causes are well known: higher input costs,

and long‐term decrease in the price of fresh oranges

imported into the vital EU markets from overseas.

Both causes are difficult to resolve. Labour is and will

continue to be a significant cost factor in the

production of fresh oranges. And the labour cost in

Spain is substantially higher than that in off‐shore

countries such as Brazil, Egypt, Morocco and South

Africa. Freer trade with these producing countries into

the EU is increasing irreversibly year by year.

Nevertheless, direct government subvention for

www.ijesci.org International Journal of Energy Science (IJES) Volume 4 Issue 4, August 2014

110

orange growers has been solicited actively during the

past few years (Anon., 2011). In view of the continuing

national budgetary problems and the lack of priority

assigned to this agricultural sector under the EU’s

Common Agricultural Policy, the outlook for off‐

setting financial support is dismal.

Up until about 2008, conversion of orange groves to

housing estates has been a particularly attractive

option for many farmers who wish to leave the

business permanently. However, the economic crash

since that time has halted this exit strategy abruptly.

A new strategy of agricultural production and

distribution is needed to rectify this dismal economic

situation (Wong and Navarro, 2014). This project was

undertaken to determine if energy production in lieu

of orange cropping might be a viable practical

alternative for Ribera Baixa farm land.

Methods

Public‐domain documents, including reports, statistics

and journal publications were used for the present

development and analysis of various energy‐

production scenarios for the remediation of the

declining orange‐cropping economy in Ribera Baixa.

On an as‐required basis, USA cost data were adjusted

to 2012 by using the Consumer Price Index calculator

published by the US Bureau of Labor Statistics

(http://www.bls.gov/data/ inflation_calculator.htm).

The US currency was converted to Euro using

reference values published by the European Central

Bank (ECB; http://sdw.ecb.europa.eu/) for the

indicated time. Typically, US‐dollar cost (or price) was

first adjusted for inflation (or deflation), and then the

inflation/deflation‐adjusted value would be converted

to Euros for the specified time period.

Results and Discussion

In view of the high incident solar radiation and

generally warm climatic conditions available at the

latitude of Ribera Baixa, it is logical to consider its

deployment to produce portable energy. Figure 2

shows the candidate schemes evaluated. In particular,

liquid fuel might be produced to offset the purchase of

petro‐diesel fuel for on‐farm as well as off‐farm uses.

FIG. 2 CANDIDATE ENERGY PRODUCTION OPTIONS

~ 5,000 hectares of land in

use for orange production

in Ribera Baixa in 2011

Cultivation of microalgae

to produce crude oil

Photovoltaic cells to

produce electricity

Cropping of oil‐bearing trees

to produce crude oil

Direct use in on‐farm

and off‐farm diesel

engines

Sale to national

power grid or to

local users directly

Annual average incident solar

radiation on a horizontal surface

= 4.49 kWh/m2/day (ASDC, 2012)

Map: http://en.wikipedia.org/wiki/File:Mapa_de_la_Ribera_

Baixa.png

FIG. 1 GEOGRAPHIC LOCATION OF RIBERA BAIXA IN THE

COMUNITAT VALENCIANA

0.3 ºW

39.2 ºN


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Power Generation

During the past decade, Spain had an exceptional

large expansion in power generation capacity based

on renewables. This expansion was fuelled by

generous government subsidies and readily available

bank financing. As of December 31, 2013, about 30% of

the installed power capacity was based on renewables,

notably solar and wind (Red Eléctrica de España, 2014:

7). Since the start of the economic recession beginning

in 2008, the Spanish government has terminated all

subventions for the installation of new renewables

power production (Morales and Sills, 2012). Moreover,

it has cut previously‐promised feed‐in tariff subsidies

successively to leave the investors of renewable power

generation in increasingly serious financial difficulties.

Although the operating cost of power production from

renewables such as wind and solar is inherently low,

the recurring significant cost of capital borrowing had

to be continually financed. One of the consequences is

the substantial steady rise in the price of (grid) power

delivered to consumers to cover the financial shortfall.

It is very plausible that grid power generators as well

as the distribution network operator are also

exploiting the present subvention turmoil for

additional price increases. In order to quell the

growing public discontent about steadily rising power

cost in times of economic recession, the government

has now intervened in the market in a reversal of its

standing policy of energy‐market liberalization (Anon.,

2013a; Minder, 2013; Anon. 2014). This pre‐tax price

relief may be temporary as the government still needs

higher tax revenue and lower financial subvention to

re‐balance the national finance. The evolving political‐

economic situation has a considerable impact on the

ultimate viability of small‐scale private power

generation for sale to the national grid or to local users

directly.

1) Large‐scale Electric Power

In theory, orange cropland could be converted

easily to produce electricity using the photovoltaic

(PV) technology. Unlike concentrated solar power

(including coupling to Stirling engines)

technologies, there would be no need for cooling

water. In the simplest configuration, there would

be no storage of heat or electricity during no‐sun

periods. For this preliminary analysis, highly

idealized conditions of PV power generation were

used.

The annual revenue of a solar photovoltaic power

generation option for Ribera Baixa was estimated

as follows:

R = P * D * E * T (1)

where R= revenue (€/ha per year), P = peak unit

power (MWp/ha), D = maximum daylight time

(hours/year), E = inverter efficiency (%) and T =

wholesale tariff (€/MWh).

The simple payout time was calculated as follows:

P = C/R (2)

where C = capital cost of installation (€) and R =

gross pre‐tax revenue (€ per year). The

assumptions used in these calculations are given in

Table 1. The maximum net output per hectare was

calculated to be 2,525 MWh for sale annually to the

grid. This value could be considered to be highly

idealized. In an evaluation of 26 fixed‐tilt

photovoltaic installations in the USA, the US

Department of Energy (2012) has found the direct

land use by annual electricity production to range

from 400 to 1,250 MWh per hectare. It may be

noted that most of the surveyed US installations

are located in desert‐like regions of southwestern

United States. The production capacity of the

Moura project in Portugal had cited 2,685 MWh

generated per hectare of collector surface mounted

on trackers (Acciona, 2008).

Under the highly idealized conditions used in the

present estimation, the maximum gross pre‐tax

revenue would be €80,116 annually. At a capital

cost of €3.642 million per hectare given in Table 1,

the simple payback time is calculated to be about

45 years. It is evident that there is inadequate

economy in the conversion of orange grove to

produce electricity (for the grid) by photovoltaic

means, in the absence of significant State

subvention.

2) Small‐scale Electric Power

Retail prices of PV panels and subsystems fell

substantially during the year, due in part to the

Spanish government’s termination of all

subventions for new solar power production

(Morales and Sills, 2012). The other factor causing

lower retail prices was the entry of many low‐cost

PV hardware manufacturers into the EU market. In

retrospect, the generous subvention provided by

past Spanish governments had induced exuberant

expansion of solar power generation. At present,

PV panels (240 W/24 V) are retailing at about €200

per unit. And PV kits (5‐kWpeak power, including


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TABLE 1 ASSUMPTIONS USED IN THE CALCULATION OF SOLAR PHOTOVOLTAIC POWER GENERATION UNDER HIGHLY IDEALIZED CONDITIONS

Parameter Representative value Remarks

P Power (peak) per unit

surface area

0.71 MWp (peak, direct current) per

hectare

In an evaluation of 26 fixed tilt photovoltaic installations in the USA, the US

Department of Energy (2012) has found the direct land use by capacity to

range from 0.23 to 0.71 MW per hectare.

The Andosol solar photovoltaic power station near Guadix [37.2 °N,

3.1 °W], Andalucia reported 50 MW installed capacity from 51 hectares

gross fixed‐tilt collector surface (Solar Millennium, 2009).

D Daylight hours available

at the specific location 2,821 hours net available

Total 4,445 daylight hours annually at Sueca (ASDC, 2012). Assumed 20

rainy days. Deduction of 2 hours after sunrise and 2 hours before sunset.

E Inverter efficiency 80% Typical value for losses incurred in the converting of direct current to

alternating current. Transformer efficiency is assumed to be 100%.

T Tariff at pre‐tax

wholesale level €50 per MWh

Representative First Quarter, 2012 price (DG, 2012). Feed‐in tariff in Spain

will be cancelled as of December 31, 2012 (DG Energy, 2012).

C

Cost of installation of

photovoltaic power

system

€3.642 million per hectare, without

any thermal storage capacity (=

€5,130 per kW‐peak, installed)

The US‐EIA (2010) value was adjusted for inflation (1.06 multiplier) from

2010 to 2012, and then converted at US$1.2502 to €1.00 using ECB 3rd

Quarter, 2012 reference exchange rate.

The Andosol Project reported a capital cost of €6,000 per kW installed,

including thermal storage and extensive infrastructure (Solar Millennium,

2009).

€5,460 per kW with tracker system but without thermal storage, cited for

the Moura solar photovoltaic power station, near Amareleja [38.2 °N,

7.2 °W], Portugal (Acciona, 2008).

panels wiring, controller, batteries and inverter) are

available in the retail market at ~€ 7,900, exclusive

of 21% VAT. The pre‐tax cost such a kit would be

about €1,580 per kW. According to the vendor (see

http://www.kitsolar.com), the kit could provide

sufficient for the need of a modern house with full

complements of electrical appliances.

Commentators and lobbyists have noted that the

renewable energy sector can ʺhelp end the crisis

with investment in self consumption” (Anon.,

2013b). But in the pursuit of acquiring new tax

revenue, the government has imposed an excise tax

on PV electricity generated for in‐home personal

use in mid‐2013 (Government of Spain, 2013). In

view of this new tax, private PV‐generated power

has instantly become uneconomical, even for self

consumption. In effect, the simple pay‐out time for

an average size house installed with simple PV‐

panels has now increased by 60% (Anon., 2013c).

This regressive taxation policy has effectively

deterred about 30% of the households with roofs

for PV panel installations from supplying own

pollution‐free electricity. The same Real Decreto Ley

9/2013 also applies to any installation of PV panels

in privately‐owned orange orchards for the

generation of power for own use. In essence,

everyone is being taxed for using the Sun!

As shown in Figure 3, the pre‐tax retail price of

electricity for medium‐size households has been

rising rapidly since 2007. For comparison, in

December, 2012, the cost of electricity at the

household level in Ribera Baixa was €0.161 per

kWh, exclusive of taxes and fees. The Instituto para

la Diversificacion y Ahorro de la Energía reported

the average consumption of electricity of a

detached medium‐size house in the Mediterranean

region (including Ribera Baixa) to be 8,363 kWh per

year (IDAE, 2013). If the representative pre‐tax

price was €0.15 per kWh, the potential valuation of

PV electricity to be generated (for a house located

within an orange orchard) could be €1,254 annually.

The simple payout time for the installation of the

above‐described PV system would thus be about 6

years, on a pre‐tax basis.

0.00

0.05

0.10

0.15

0.20

2000 2002 2004 2006 2008 2010 2012 2014Average price (without taxes), Euro

per kWh

Spain EU‐15 EU‐27

Basis: Annual household consumption: 2,500 to 5,000 kWh

Source: EUROSTAT, 2014.

FIG. 3 AVERAGE NATIONAL ELECTRICTY PRICES (WITHOUT

TAXES) FOR MEDIUM‐SIZE HOUSEHOLDS IN SPAIN

AND THE EU

Without consideration of any standby power

demand and/or possible export of a small amount


113

of surplus power to the grid, these preliminary

calculations would suggest that the “power

generation for self‐consumption” scenario might be

economically feasible.

If an “energy cooperative” of self consumers was to

convert one hectare of “orange grove” for PV

power generation, the potential pre‐tax value of

electricity generated would be as much as €3

million on the basis 710 kWpeak per hectare (from

Table 1). The un‐surprisingly high valuation would

certainly tempt the “energy cooperative” to sell

surplus power outside the farm gate, to exploit the

apparent large pre‐tax price differential between

retail and wholesale electricity. It should be

cautioned however that the apparently favourable

economics is predicated on the assumption that

there is no cost incurred for transmission and

distribution to houses of self‐consumers located

virtually adjacent to the hypothetical PV power

generation site. In practice, this scenario may not be

practicable as many existing houses within orange

groves are not fully occupied on a year round basis,

and not sufficiently clustered to render shared PV

production of electric power.

TABLE 2 AVERAGE RATIO OF NETWORK PRICE TO ENERGY PRICE FOR

RETAIL ELECTRICITY DELIVERED TO DOMESTIC CONSUMERS

2007 2008 2009 2010

Spain No data 0.39 0.39 0.82

EU‐15 1.13 0.64 0.67 0.71

Sweden* 0.91 0.44 0.88 0.86

* inserted for comparison

Source: Adapted from EUROSTAT, 2012.

If surplus power generated was to be exported

outside the farm gate of the “energy cooperative”,

there would definitely be a substantial addition of

network cost. Table 2 illustrates the magnitude of

the network cost relative to the base (≈ wholesale)

cost of electricity for Spain, Sweden and EU‐15.

With the addition of a network cost, the pre‐tax

price differential between retail and “wholesale +

network” would narrow substantially for the

planned power‐export business of the “energy

cooperative”.

Furthermore, unfettered reasonable fee‐for‐service

access to existing transmission and distribution

network may not be a certainty for the small

electric power producer such as the hypothetical

“energy cooperative”. Recent EC directives (e.g.,

Directive 2009/72/EC) have mandated the complete

segregation of power transmission business from

power generating companies to afford greater

market competition. The small independent power

producers still encounter the problem of un‐

availability of volume discount for network usage.

The economic viability of prospective export of

surplus power by the “energy cooperative” would

thus be degraded further.

Biomass Oils

The conceptual plan is to produce crude triglyceride

oil from microalgae or oil‐bearing tree crops. The

crude triglyceride oil would then be used directly in

diesel engines with little or no engine modifications.

Baquero et al. (2010) have reported successful

experimental use of straight vegetable (triglyceride) oil

in farm diesel engines. In this fashion, the costly

refining of the crude triglyceride oil into approved

EN590 diesel fuel or EN14591 ester diesel blending

stock could be avoided.

As given in Table 3, the demand of diesel fuel for

orange production is relatively small, at ~90 litres per

hectare under orange cropping conditions which are

similar to those of Ribera Baixa. In comparison, the

demand for fuel (95% diesel + 5% gasoline) is given to

be about 300 litres per hectare for rice cropping (Greer

et al., 2012). For an orchard size of one hectare, the

annual diesel fuel expense would be less than €100 for

stand maintenance, if the farm‐use diesel fuel was

available for purchase at nominal €1.00 per litre (with

excise tax exemption and reduced value‐added tax).

This small expenditure certainly does not justify any

on‐purpose production of liquid fuel for this purpose.

TABLE 3 FOSSIL FUEL USAGE REPORTED FOR ORANGE FARMS IN SEVERAL DIFFERENT COUNTRIES

Location Reference Diesel fuel, litres/ha Yield*, kg/ha Remarks

Antalya, Turkey Ozkan et al., 2004 338 None cited; about 300

trees per ha

100% diesel; including tillage (land preparation)

and delivery of irrigation water

Florida, USA Pimentel, 2006 186 46,000 (field?) 50% vol. diesel + 50% vol. gasoline

Manzadaran, Iran Namdari et al., 2011 300 32,500 (field?) 100% diesel; including tillage (land preparation)

and delivery of irrigation water

San Joaquin Valley ‐

South (California), USA O’Connell et al., 2009 87 28,845 (field) Diesel + gasoline; stand maintenance only.

* In the case of fresh oranges, packing‐house yield is typically 80% of field yield.


114

Nitrogen and phosphorus from

municipal liquid wastes

Incident solar radiation

Make‐up

H2O

CO2

Source: Adapted from Wong et al., 2013

FIG. 4 CONCEPTUAL SCHEME TO PRODUCE CRUDE MICROALGAL OIL (CMO) IN RIBERA BAIXA

However, production of biofuel for on‐road uses

might be economically more attractive, in view of

continued rise in the base petroleum price globally.

1) Microalgal Oil

In view of the abundant amount of sunlight and

warm ambient temperatures available annually,

microalgal oil production could be an attractive

candidate. As in the case of rice cropping in the

same geographic region, it has been estimated that

a production of 17,000 litres of crude microalgal oil

(CMO) per hectare might be feasible (Wong et al.,

2013). As given in Figure 4, the proposed

processing scheme would result in no effective

discharge of process effluents or solid wastes into

the receiving environment.

In order to implement open‐pond production of

microalgae, a means to control the infiltration of

water through the soil would be required.

Moreover, an effective water management scheme

would also need to be established to account for

the high evaporation of water from the open pond

during the hot summer months.

The scenario of producing CMO for on‐road uses is

examined in Table 4. The two principal

assumptions used in this analysis are that a) CMO

could be used directly in place of petro‐diesel with

minor engine modification to account lower

calorific value, b) the cost ready‐to‐use CMO

would be equivalent to the base pre‐tax price of

petro‐diesel, and c) excise tax for on‐road usage

could not be avoided. The European Commission

(2012) has specific rules and regulations governing

the collection of minimum excise tax on fuel in all

EU member states.

Depending on the final organizational structure of

the production facility, it may be possible to avoid

the payment of value‐added tax (VAT). For

example, each member of a “biofuel cooperative”

could use its own‐produced crude bio‐oil, after

isolation and filtration at a centralized processing

facility. It could be argued that there was no

transfer of ownership of any goods to cause any

imposition of VAT.

0

100

200

300

400

500

600

0.000 0.200 0.400 0.600 0.800 1.000

CMO production cost, € per litre

Cost saving at pump,

€ per year

Excise tax at €0.331 per litreExcise tax exempted

FIG. 5 EFFECT OF EXCISE TAX AND CMO PRODUCTION COST

ON ANNUAL COST SAVINGS IN A MODEST‐SIZE DIESEL

VEHICLE USING 100% CMO

At the anticipated yield of 17,000 litres CMO per

year, conversion of ~330 m2 of present orange grove

would be sufficient to produce ~560 litres of CMO

CMOCultivation of

example Chlorella

spp. in open pond

Mechanical

isolation and

filtration

Ready‐to‐use fuel

to replace petro‐

diesel

Anaerobic

digestion

Digestate to be used

as fertilizer

supplement

Fuel to boiler for

generation of

steam for in‐

factory uses.

solidsbiogas

Partial recycling of wet biomass

Flue gas

Oil‐depleted biomass

wet

biomass

Base case set to be

equivalent to the

prevailing base pre‐tax

price of petro‐diesel


115

for the operation of a single model diesel vehicle (at

10,000 km usage per year) each year. But the

annual saving that could be accrued from

operating the model diesel vehicle would be €95.

The level of saving could be realized only after

expending considerable cost to convert the orange‐

producing land for self‐production of CMO as

petro‐diesel substitute.

Figure 5 shows the impact of excise tax and CMO

production cost on the realizable saving in motor

fuel cost. Note that the cost saving for the operation

of a single diesel model car could reach ~€550

annually, if there was no excise tax on the CMO

and if the CMO production was 25% of the base

case. There is no practicable means to avoid paying

the excise tax for on‐road motor vehicles. It may be

noted that all tax exemption for biofuel sold to the

public will be terminated in Spain as of December

31, 2012. In view of continuing Spanish national

budget crisis, there is essentially no prospect of any

resumption of “biofuel subsidy” in Spain in the

immediate future.

TABLE 4 CRUDE MICROALGAL OIL (CMO) PRODUCTION OPTIONS

Assumptions:

o CMO can be used in conventional diesel engines with minor engine modifications (Wong et al., 2012).

o CMO productivity = 17,000 litres/ha/year (Wong et al., 2012)

o Fuel properties:

Calorific value: 42.3 MJ/kg petro‐diesel; 38.0 MJ/kg CMO

Density: 0.833 kg/litre petro‐diesel; 0.920 kg/litre CMO

o Reference automobile: KIA Rio – 2011 UK model 1.1 CRDi Manual (1.12‐litre; 5‐passenger) with lowest emission (viz., 85 g CO2 per km) of

any internal‐combustion motor vehicles sold in the UK. http://www.kia.co.uk/~/media/specifications/rio_spec_sheet_updated.ashx

3.50 litres petro‐diesel/100 km urban; 123 MJ/100 km urban

3.53 litres CMO/100 km urban at the same 123 MJ/100 km urban

Typical 14,000 km/year automobile usage

o Fuel pricing:

Farm use: €1.000/litre petro‐diesel, including €0.07871/litre excise tax and 18.0% VAT (EC, 2012). The calculated base pre‐tax

petro‐diesel price at pump = €0.769/litre

Road use: €1.298/litre petro‐diesel at pump, calculated from base pre‐tax price to include €0.331/litre excise tax and 18.0% VAT

(EC, 2012).

CMO production options

1‐hectare individual orchard in Ribera Baixa Ribera Baixa

CMO‐Zero CMO‐20 CMO‐100 CMO‐Max

CMO production % land use 0 20 100 100

hectares 0 0.2 1.0 5,139 (a)

litres/year 0 3,400 17,000 87,363,000

GJ/year 0 119 594 3,054,210

Petro‐diesel required (b) litres/year 87 70 0 0

€/year (c) 87 70 0 0

CMO surplus GJ/year 0 116 594 3,054,210

litres/year 0 3,330 17,000 87,363,000

Private cars fuelled (d) number/year 0 7 33 171,982

€ cost/car/year (e) 654 559 559 559

€ savings/car/year ‐‐‐ 95 95 95

Gross farm‐gate revenue €/year – oranges (f) 6,250 5,000 0 0

€/year – CMO (g) 0 2,560 13,069 67,160,099

€/year total 6,250 7,560 13,069 67,160,099

Notes:

(a) Total area of land used for orange cropping in Ribera Baixa in 2011 (GVA, 2011).

(b) for orange farming

(c) market price at €1.00/litre for farming uses (Daniel Buguera, personal communications, 2012)

(d) adjusted for lower CMO calorific value

(e) Calculated pump price of petro‐diesel at €1.298 per litre; Calculated pump price of CMO fuel = €1.100/litre (i.e., €0.769 per litre pre‐tax base

price + €0.331 per litre excise tax, without any VAT)

(f) Oranges: 25 tonnes/hectare x €250/tonne x hectares allocated for orange cropping

(g) CMO: 17,000 litres/ha x €0.769/litre (excluding excise tax) x hectares allocated for biofuel production


116

The commitment of Spain to comply with the EU

biofuel objectives by 2020 (EC, 2007) would be met

by decree. In the absence of government subsidies,

there may be no further expansion of production of

biodiesel blending stock inside Spain. In the

fulfillment of this EU‐wide motor fuel composition

requirements, biofuel blending stock could be

imported perhaps more economically from other

EU member states such as France and Germany.

However, this negative economic projection could

be mitigated substantially if the prevailing base‐

case pre‐tax price of petrol‐diesel rose significantly,

due to real‐term rapid increases in global crude

petroleum prices.

2) Tree oil Crops

Cultivation of jarak (Jatropha curcas L.) as an energy

crop has been studied at several field trial locations

in the Comunitat Valenciana by the Instituto

Valenciano de Investigaciones agrarias in about

2007 (IVIA, 2008; IVIA, 2009). Jarak grows best

under humid tropical conditions (DECD, 2005;

Daniel, 2006). This IVIA research project appeared

to have since abandoned, possibly because of the

intractable problem of supplying large quantities of

irrigation water for the mass production of a liquid

biofuel product that has no direct Spanish

government subvention in the market place (EC,

2012).

In contrast, moringa (Moringa oleifera Lam.) is

highly valuable multi‐purpose small tree found in

tropical and subtropical regions of the World. All

parts of the tree, viz., leaves, pods, roots, bark,

stems and twigs have highly‐nutritious alimentary

uses (Hsu et al., 2006). Moringa is drought tolerant.

Typically, it can be grown in areas with 250 to 1,500

mm rainfall annually (Radovich, 2011). Thus, with

the annual precipitation in Ribera Baixa rainfall

being about 500 mm, no irrigation would be

required. The best mean annual temperature range

is 25 to 35 °C (Palada and Chang, 2003). Established

moringa trees can survive low temperature of 0 °C

and high temperatures up to 48 °C (Price, 2007), for

short periods. Moringa is a fast growing plant

which is responsive to irrigation and fertilization.

Foidl et al (2001) have reported that moringa shrub

would grow typically to 1.5 to 2 metres before

extensive branching starts. The corresponding

diameter at breast‐height would be 20 to 40 cm.

Under intensive culture, green pods as well as

leaves could be harvested 6 to 7 months after

seeding (Schabel, 2003). Full productivity could be

attained by the fourth year after seeding (Rajangam

et al., 2001). The conceptual scheme to produce

crude moringa oil is shown in Figure 6. Note that

all solid wastes are managed gainfully.

The productivity of moringa oil is estimated to be

in the range of 685 to 1,141 litres per hectare per

year, on the basis of the following assumptions:

o Planting density = 400 trees/ha (Radovich, 2011,

p.9)

o Productivity at maturity = 15,000 to 25,000

seed/tree/year (Foidl et al., 2001, Table 1)

o Seed weight = 300 milligrams/seed (Foidl et al.,

2001, Table 1)

o Oil content of seed = 35% by weight (Rashid et

al., 2008)

o Crude oil density = 0.920 kg/litre

It may be noted that Radovich (2011) has suggested

a yield of only ~225 litres per hectare per year for

“natural” cropping of moringa in Hawaii. If the

maximum output of 1,141 litres per hectare per

year was assumed, conversion of 1/2 of one hectare

of orange grove would be sufficient for the

operation of a single model diesel car. The annual

demand of one motor vehicle would be ~500 litres

of crude moringa oil per year.

Incident solar radiation CO2 (from air)

FIG. 6 CONCEPTUAL SCHEME TO PRODUCE CRUDE MORINGA OIL IN RIBERA BAIXA

Moringa

cropping

H2O (from

rainfall)

Mechanical separation of

seeds from mechanically‐

harvested pods

Mechanical crushing of seeds

and oil filtration

Ready‐to‐use fuel

to replace petro‐

diesel Solid residues as agricultural mulch

Optional irrigation


117

There is no reliable information available for

moringa cropping in northern‐latitude regions. The

cropping of almonds in the Sacramento Valley

(Connell et al., 2012) was used as the surrogate to

estimate the possible production cost of moringa

oil. The climatic conditions and farm labour cost

structure of the Sacramento Valley (California) are

largely similar to those of Ribera Baixa (Wong and

Navarro, 2013). Harvesting of moringa pods would

be made by mechanical shaking in a similar fashion

as the harvesting of almonds from mature trees. In

the transcription to the Ribera Baixa location,

moringa cropping was assumed to be practicable

without the use of fertilizers, pest control chemicals

and irrigation water, and without any interest on

operating capital.

At the highest probable yield of 1,141 litres per

hectare per year cited above, and using the

production cost for almonds, i.e., US$3,923 per

hectare (Connell et al., 2012), the estimated 2012

production cost would be €2.75 per litre of crude

moringa oil (at ECB reference currency exchange

rate of €1.00 = US$1.2502 for 3rd Quarter, 2012).

Note that the additional cost of expressing crude

oil from the harvested moringa seeds has been

omitted in the present calculation of production

cost.

If the farm‐gate price was €2.50 per litre of crude

moringa oil after deducting nominal €0.25 per litre

for in‐farm cost of expressing harvested moringa

seeds to produce ready‐to‐use crude oil, the

maximum gross revenue would only be ~€2,853 per

hectare annually. This figure can be compared to

~€13,000 per hectare for the CMO option, and

~€6,250 per hectare for the present orange cropping.

Even in the best‐case scenario, the conversion of

land for the production of crude moringa oil for

transportation uses would not be an attractive

alternative to currently‐practiced orange cropping

in Ribera Baixa.

However, in view of the potential demand for a

“natural” nitrogen fertilizer for proposed organic

orange farming, there could be a business case for

the implementation of moringa cropping, albeit on

a small scale, among the orange groves. In this

instance, moringa cropping could be undertaken

solely to provide young foliage for the preparation

of “green manure”.

Table 5 shows moringa leaves to have similar

nitrogen (N) content as farm animal manures. With

the exception of rice straw, olive oil mill wastes

(mainly found in Andalusia or Catalunya), farm

animal manures (from livestock rearing in Asturias)

and fish meals (available largely from Galicia) are

not readily available locally for composting in

Ribera Baixa. Thus, cultivation of moringa

specifically for leaf production appears to be an

attractive proposition for boosting the nitrogen

content of rice straw (Ayuntamiento de Valencia,

2004) for the local preparation of a natural fertilizer

for organic tree cropping. Furthermore, microalgae

solids might be available if a crude microalgal oil

production project was realized separately in the

Albufera rice cropping area of Ribera Baixa (Wong

et al., 2013). The cost of “natural” nitrogenous

fertilizer for organic cropping of oranges and tree

nuts could thus be reduced substantially.

TABLE 5 COMPARATIVE NITROGEN CONTENT WITH SELECTED NATURAL

FERTILIZERS

% total N of

dry matter*References

Moringa

leaves 3 ‐ 5

Foidl et al., 2001; Kakengi et al.,

2007; MAG, 2010; Peréz et al., 2012.

Rice straw 0.5 ‐ 0.9

Juliano, 1985; Marimuthu et al.,

2002; Goyal and Sindhu, 2011; El‐

Akshar et al., 2012.

Olive oil mill

wastes 0.8 – 1.6

Khatib et al., 2010; López Piñeiro et

al., 2010.

Farm animal

manure 2 ‐ 5

Pratt and Castellanos, 1981; Khatib

et al., 2010.

Fish meal 9 ‐ 12 Sujeewa, 2000; Kakengi et al., 2007.

Microalgae 8 ‐ 10 González López et al., 2010.

* Where applicable, N was calculated as “reported protein/6.25”.

Perennial Energy Crops

Several perennial plants such as miscanthus

(Miscanthus giganteus), switch grass (Panicum virgatum)

and giant reed (Arundo donax L.) have been suggested

as potential energy crops for the EU to meet the

mandated long‐term goal of reducing the emission of

greenhouse gases. In particular, C4 plants are

recognized to be highly efficient in photosynthesis;

they are tolerant to drought as well as high

temperature conditions (Bower and Leegood, 1997).

Nevertheless, intensive water and fertilization

management were required to achieve maximal

growth of both C3 and C4 energy crops (Angelini et al.,

2005; Mantineo et al., 2009; Nassi o Di Nasso et al.,

2010; Dopazo et al., 2010). It is also instructive to note

the caution given by Ericsson et al. (2009) that high

profitability of energy crops (especially with generous

government subvention) will lead to high land and

production costs for food crops, especially in the

cereal‐grain producing regions of the EU.


118

Angelini et al. (2009) have reported an average yield of

~38 tonnes dry matter/hectare per year for giant reed

and ~29 tonnes dry matter/ha per year for miscanthus

in a 12‐year field trial in central Italy (43.67 ºN, 10.32 ºE;

2 metres above sea level). In a separate shorter 5‐year

field trial in Sicily (37.38 ºN, 14.35 ºE; 550 metres above

sea level), Mantineo et al (2009) reported average yield

of giant reed and miscanthus to be 33 tonnes/ha/year

and 22 tonnes/ha/year, respectively. Interestingly, a C3

plant (i.e., giant reed), afforded substantially higher

average yield than a C4 plant (i.e., miscanthus) in both

independent Italian studies. Zhu et al. (2008) have

estimated that continual rise in the average global

temperature as a result of higher atmospheric CO2

concentration would narrow the difference in solar

energy conversion efficiency between C3 and C4 plants.

Dopazo et al. (2010) have cited that short‐term trials of

several selected cultivars of miscanthus in Portugal

under conditions of intense irrigation had provided

practical yields of only 10 to 25 tonnes dry matter per

hectare.

Sugar cane (Saccharum officinarum), a ubiquitous C4

plant, has been grown routinely, but not as mass‐scale

monoculture, in southeastern Spain during medieval

Islamic time. Triana et al. (2008) has reported the

practicality of a new Cuban variety of sugar cane

which could provide proportionally higher yield of

fibrous biomass relative to the customary sugar juice.

Exceptionally high yield of up to 80 tonnes per hectare

has been reported for experimental cultivation under

optimized conditions in Cuba (Alejandro Abril,

personal communication, 2013). Using the

methodology described by Weyer et al. (2010), the

theoretical practicable biomass yield from

phtotosynthesis under tropical conditions was

estimated to be 85 to 110 dry tonnes per hectare per

year. As shown in Table 6, average incident solar

radiation and temperature at Sueca are substantially

lower than those in Matanzas (Cuba), for example. If

the “80 tonnes per hectare” yield was transcribed into

the prevailing Sueca meteorological conditions

without consideration of other growth factors such as

different rainfall pattern and soil structure, the

expected annual yield would be decreased to between

20 to 60 tonnes per hectare, at about the same range of

biomass yield as miscanthus or giant reed reported in

above‐cited Italian field trials.

The fundamental obstacle to the implementation of the

“energy‐cropping” approach is that the pattern of

highly fragmented holdings in Ribera Baixa is not

conducive to mass‐scale field crop production. Even if

the above issue could be overcome, there are no local

end users, i.e., suitable solid‐fuel thermal power

generation facilities, to purchase the biomass

produced by these energy crops. Transportation of

compressed dried biomass, as a commodity, from

Valencia to thermal power plants in northern EU

countries is financially impractical. It may however be

noted that many Dutch thermal power plants have

been importing wood pellets from Canada as well as

Eastern Europe for co‐firing with coal for many years.

The mandated strategic goal is to reduce the emission

of greenhouse gases.

Conclusions

The problem of orange cropping in Ribera Baixa is

persistent and difficult to solve in view of continued

globalization of freer trade with competitive fresh

oranges arriving into the EU market from low‐wage

producing countries. The solar‐energy capture of

selected approaches was evaluated without

consideration of economics. Moreover, cultivation

activities were assumed to be under optimal

conditions in which cultivar selected, soil fertility,

appropriate year round temperatures, water supply,

TABLE 6 METEOLOGICAL CONDITIONS FOR SUGAR‐CANE CROPPING IN SUECA, SPAIN AND IN MATANZAS, CUBA

Basis: 1 year Matanzas

(23.1 ºN)

Sueca

(39.2 ºN)

Average annual full‐spectrum incident solar radiation, MJ/m2 (a) 7,551 5,911

Maximum theoretical yield (b), dry matter, kg/ha 114 89

Calculated full‐spectrum solar energy conversion efficiency, % (c) 5.5 5.5

Average daily temperature, ºC (a) 21.3 – 26.8 8.4 – 24.0

Degree‐days above 18 ºC (a) minimum for biomass growth (d) 2,462 652

Maximum theoretical yield of dry matter, relative to “Matanzas”, %

Due to lower incident solar radiation

Due to fewer degree‐days available

‐‐‐‐

‐‐‐‐

78

26

(a) ASDC (2012) data

(b) Based on the calculation model of Weyer et al. (2010) for primary production.

(c) Cf. Zhu et al. (2008) had cited 4.6% and 6.0% full‐spectrum solar energy conversion efficiency for C3 plants and C4 plants, respectively.

(d) Deerr (1921: 24‐30) had commented >70 ºF (21 ºC) for adequate biomass growth and maturation.


119

etc. are available without limit. The production of

energy, in the form of photovoltaic electricity or plant

oil as diesel fuel substitute, does not appear to have

sufficient economic advantages in lieu of present

orange cropping. The production of photovoltaic

electricity for self consumption might be practicable

under certain circumstances. The hurdle is not

technology, but government fiscal and regulatory

policies.

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assessment of energy production options in lieu of orange cultivation in ribera baixa (valencia)

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