Biodiesel and Hydrogen Production in a Combined Palm and Jatropha Biomass Biorefinery: Simulation, Techno-Economic, and Environmental Evaluation.

The biodiesel from lignocellulosic materials has been widely recognized as an alternative fuel to meet energy requirements worldwide, facing fossil fuel depletion, and emerging energy policies. In this work, the biorefinery approach was applied for biodiesel production from jatropha and palm oils in order to make it economically competitive by the utilization of residual biomass as the feedstock for obtaining hydrogen via steam reforming of glycerol and gasification. The linear chains for hydrogen and diesel were simulated using UniSim software and main stream properties were collected from the literature or predicted by correlations. The proposed scheme of biorefinery was analyzed through environmental and techno-economic assessment to identify the feasibility of this process to be implemented. Three different blends of oils (JO10-PO90, JO20-PO80, and JO30-PO70) were considered in the environmental analysis to determine alternatives for reducing potential environmental impacts (PEIs). It was found that the acidification potential highly contributed to the environmental impacts attributed to the use of fossil fuels for heating requirements, and JO30-PO70 blend exhibited the lowest PEI value. The economic indicators were calculated to be 8,455,147.29 $USD and 33.18% for the net present value and internal rate of return, respectively. These results revealed that the proposed combined biomass biorefinery is feasible to be scaled up without causing significant negative impacts on the environment.

Introduction

Recently, the development of clean energy sources has become necessary in order to meet energy demands because of the rapid population increase, massive industrialization worldwide, and environmental concerns.[1,2] In addition, energy policies have encouraged the use of renewable sources to assure sustainable development and energy security.[3] Biodiesel from lignocellulosic biomass seems to be an attractive alternative for fossil fuel substitution because of its favorable emission profiles, renewability, nontoxicity, high cetane number, and good lubricity.[4,5] Several raw materials derived from forestry, agriculture, and agro-industrial wastes exhibit good properties as feedstocks for biodiesel production.[6] Vegetable oils from palm, coconut moringa, and soybean, among others, have been widely used as alternative fuels because they do not contribute to the global carbon dioxide buildup.[7] The transformation of these oils into biodiesel is carried out by the transesterification process using alcohol (methanol or ethanol).[8,9]

The oil palm is a perennial tree that remains competitive because of the increment of the yield per unit area.[10] The high oil content of this crop allows being used as a potential source of renewable energy.[11] The Jatropha curcas L. is a drought-resistant crop that grows in the tropical and subtropical world.[12] It is a poisonous, semi-evergreen shrub reaching a height up to 6 m that may cause gastrointestinal issues after human ingestion.[13] Despite its high toxicity, oil content of the jatropha seed is about 300–400 g/kg which makes it an appropriate alternative feedstock for bioenergy production.[14] However, the low conversion and energy utilization inefficiencies concerning biodiesel production from jatropha seeds represent a drawback that can be solved by forming oil blends as palm and jatropha oils.[15] The use of these lignocellulosic feedstocks reduces the biodiesel production costs because of its low price and abundance.[16]

The single biodiesel-oriented manufacturing plants are not economically competitive against oil refineries and alternative utilization paths have been investigated in order to overcome these drawbacks.[17] The biorefinery concept represents an alternative for the integrated use of the biodiesel industry-derived wastes generating a suite of products as hydrogen.[18] This concept is based on biomass conversion processes to produce power, fuel, and chemicals such as biodiesel, biohydrogen, and biomethane.[19] For example, the crude glycerol obtained during biodiesel production is used to produce gaseous fuels by steam reforming and biomass gasification.[20,21] The application of biorefinery for biomass valorization offers several benefits because of the diversification in feedstocks and products while addressing sustainability goals.[22]

The scheme of a biorefinery requires to be evaluated by different computer-aided tools such as techno-economic analysis and environmental assessment. These tools allow to assess the potential economic feasibility of bioenergy chains and understand its environmental performance.[23] Numerous methodologies have been developed to assess the performance of chemical processes in the early conceptual design phase under a sustainability concept. Moreno-Sader et al.[24] applied the tool for the reduction and assessment of chemical and other environmental impacts to quantify the environmental impacts of palm oil production based on the emission media. Romero-Perez et al.[25] used the techno-economic sensitivity analysis to identify operating variables that most contributed to the economic performance of palm oil biorefinery. Meramo-Hurtado et al.[26] used the waste reduction algorithm (WAR) to determine the potential environmental impacts (PEIs) related to the industrial production of levulinic acid via acid-catalyzed dehydration.

Several works have addressed the synthesis and evaluation of biorefineries from J. curcas L. and oil palm in order to face the drawbacks of biodiesel industries using lignocellulosic materials. Table summarizes recent contributions found in the literature about these feedstocks in biorefinery approaches. For example, Navarro-Pineda et al.[27] developed a conceptual design of biorefinery for the exploitation of J. curcas considering traditional biodiesel production with glycerin as the co-product as well as thermochemical transformation of biomass into bio-oil, bio-char, and heat. The authors evaluated the sustainability of this design under renewability, economic, environmental, and community development categories and reported promising results. Herrera-Aristizábal et al.[28] performed environmental assessment of a palm-based biorefinery in North Colombia using WAR and found negative values for total generation of PEI as well as significant impacts on atmospheric categories. According to this literature review, there is a knowledge gap on the use of combined J. curcas and oil palm under a biorefinery approach to obtain high value products such as biodiesel blends.

Table 1

Recent Works on J. curcas L. and Oil Palm-Based Biorefineries

biorefinery feedstock	environmental analysis	techno-economic analysis	references
J. curcas	x	x	Navarro-Pineda et al.[27]
oil palm	x		Batlle et al.[29]
J. curcas			Navarro-Pineda et al.[30]
J. curcas	x		Martinez-Hernandez et al.[31]
J. curcas			Vivas and Collado[32]
J. curcas	x	x	Martinez-Hernandez et al.[33]
J. curcas and microalgae		x	Giwa et al.[1]
oil palm	x	x	Garcia-Nuñez et al.[34]
oil palm	x		Herrera-Aristizábal et al.[28]
oil palm		x	Romero-Perez et al.[25]

The aim of this work is to apply the biorefinery concept for biodiesel production from J. curcas and palm oils and utilization of processing wastes to convert residual biomass and glycerol into hydrogen. To this end, a combined biomass biorefinery was simulated using UniSim software to obtain extended mass and energy balances. After the conceptual design and simulation, the feasibility of the process was evaluated using a techno-economic analysis tool. The PEIs were quantified via WAR under the atmospheric and toxicological categories of impacts. These assessments provided insights about the sustainability of the biodiesel production from both biomasses.

Methods

The methodology followed in this work addressed the conceptual design of the combined biomass biorefinery based on the information available in the literature for these types of biomasses (J. curcas and African oil palm). The chemical composition of biomasses and main operating conditions for biomass transformation into high-value products were collected from several contributions. In this case, hydrogen and biodiesel were the products of the biorefinery. After designing the entire process, the biorefinery was simulated in UniSim software, which provided extended mass and energy balances. To validate simulation results, production yields provided by software were compared with those reported in the literature at the experimental level. These process data were entered into the computer-aided tools selected for the evaluation of economic and environmental performance of the entire biorefinery.

Process Description

The general scheme of the combined biomass biorefinery from jatropha and palm oils is shown in Figure . The selected feedstocks exhibit a high content of free fatty acids (FFAs) that are transformed into biodiesel by alkaline transesterification. For African palm oil, the FFA content was 1.25% wt, while J. curcas oil accounted for 15.04% wt of FFA. The extraction of both oils generates a huge amount of lignocellulosic wastes, which can be used for producing high-value products. The proposed biorefinery involves the utilization of these lignocellulosic materials for producing hydrogen via a gasification technique. The glycerol obtained from the transesterification reaction is also considered for energy production by steam reforming. In this context, the conceptual design of the combined biorefinery includes four main sections: (i) biodiesel production from oils through alkaline transesterification, (ii) steam reforming of glycerol, (iii) biomass gasification, and (iv) hydrogen purification.

Figure 1

Scheme of the combined biomass biorefinery.

The process of extracting oils is not covered in this work, hence, the amount of the residual lignocellulosic material generated during oil extraction was estimated according to the information reported by Ganduglia et al.[35] For jatropha, it has been reported that the fruit shells are composed of 36.3, 63.07, and 56% of husks, seeds, and oil, respectively.[36] The lignocellulosic material exhibits different complex biopolymers such as cellulose, lignin, and hemicellulose, whose composition varied depending on the extraction process and plant nature. The composition of these residues after oil recovery from palm and jatropha is listed in Tables and 3, respectively. The elemental analysis of both biomasses was also collected from the open literature and summarized in Table .

Table 2

Composition of the Lignocellulosic Residual Biomass from African Palm

component	EFB (% wt)[37]	PPF (% wt)[37]
cellulose	38.8	32.7
hemicellulose	35.64	28.5
lignin	25.25	38.7

Table 3

Composition of the Lignocellulosic Residual Biomass from Jatropha

component	de-oiled cake (% wt)[38]	fruit (% wt)[39]
cellulose	53.5	56.31
hemicellulose	16.6	17.41
lignin	24.9	23.91
others	5	2.37

Table 4

Elemental Composition of Palm and J. curcas Residual Biomasses

component	palm bagasse (%)		Jatropha bagasse (%)
C	45a	78.20b	45.76c	45.50d
H	6.4a	8.90b	6.30c	7.20d
N	0.25a	3.56b	0.42c	4d
O	47.3a	8.04b	47.44c	43.30d
S	1.06a	1.3b	0.07c

Ref (40).

Ref (41).

Ref (42).

Ref (39).

Biodiesel Production from Oils through Alkaline Transesterification

The transesterification method was used to obtain the biodiesel by reacting alcohol (methanol) and fatty acids in the oil feedstock.[43] In brief, sodium hydroxide (NaOH) was used to catalyze this reaction and glycerol was obtained as a co-product, which are required to be separated from diesel. Then, liquid–liquid extraction was used to separate the products and send them to further purification stages. The biodiesel was purified using a flash separation stage in order to remove the remaining water and traces of methanol. The sodium hydroxide removal from the glycerol stream was carried out through neutralization with H3PO4, in which Na3PO4 was obtained and centrifuged. Afterward, methanol was recovered using a distillation column and was mixed with the methanol of makeup to reach the process requirements. The biodiesel production from palm and jatropha oil was simulated in UniSim Design software assuming a capacity of 100,000 t/y of oil. The composition of both oils used as the feedstock is reported by Sanford et al.[44] and Berchmans and Hirata.[45] As shown in Table , the unavailable properties in the simulator were determined by correlations found in the literature,[46−50] which are based on fuel property measurements as stated by Samuel and Gulum.[51]

Table 5

Main Equations for Property Estimation

property	mathematical expression	references
viscosity		Krisnangkura et al.[46]
cloud point	Pcloud = 0.526(%yC16:0) – 4.992	Sarin et al.[47]
POFF	POFF = 0.5111(%yC16:0) – 7.823	Sarin et al.[47]
index of iodine	II = 6.9512 + (−0.1825(%yC16:0)) + (1.01984(%yC18:0)) + (1.145(%yC18:1)) + (1.7248(%yC18:2))	Filho et al.[48]

The Peng–Robinson–Twu model was used as property package because of its accuracy for density predictions of hydrocarbons and polar components.[52] However, other streams in biodiesel production were simulated using a non-random two liquid model. The operating conditions were collected from the information available in the literature and summarized in Table .

Table 6

Operating Conditions for Biodiesel Production from Palm and Jatropha Oils

	transesterification		methanol recovery		glycerol separation
palm oila	catalyst	NaOH	reflux	2	stages	3
	reactor type	CSTRc	stages	18	water mass flow (kg/h)	1000
	temperature (°C)	60	distillate mass flow (kg/h)	1345	temperature (°C)	35
	pressure (kPa)	400c	distillate composition	0.997	pressure (kPa)	120
	MeOH/oil ratio	06:01		neutralization (kmol/h)	0.92
	residence time (h)	1
	conversion (%)	99
J. curcas oilb	catalyst	NaOH	reflux	2.5/4.5	stages	3
	reactor type	CSTRc	stages	43,282	water mass flow (kg/h)	1000
	temperature (°C)	65	distillate mass flow (kg/h)	2425/2245	temperature (°C)	35
	pressure (kPa)	400c	distillate composition	0.994/0.99	pressure (kPa)	120
	MeOH/oil ratio	5:1/6:1		neutralization (kmol/h)	0.92
	residence time (h)	1.5/1.0
	conversion (%)	99/99

Ref (54).

Ref (55).

Ref (53).

Steam Reforming of Glycerol

In order to simulate the production of hydrogen via steam reforming, operating conditions and properties found in the literature were considered.[56] A Gibbs reactor was used for the decomposition of glycerol into carbon monoxide and hydrogen. An adiabatic reactor was also required for performing water gas shift (WGS) reactions that convert CO into H2. The effect of temperature was evaluated to determine the most suitable condition for increasing the hydrogen production yield. The glycerol/water (G/W) molar ratio selected was 1:9 reducing the production of carbon monoxide as reported by Sad et al.[57]

Biomass Gasification

This process for hydrogen production was based on assumptions and operating conditions reported by many authors such as Bassyouni et al.[58] and Gonzalez Laguado and Quintanilla Prada.[59] The empty fruit bunches (EFBs) and palm pressing fiber (PPF) were considered as useable oil palm biomass, which were simulated separately with different chemical compositions. For jatropha, the residues were de-oiled cake (DOC) and fruit without seeds (F). The gasification and WGS reactions using steam as the gasifying agent were considered and steam/biomass (S/B) mass ratio = 2 was selected according to the work carried out by Khan et al.[60] The thermodynamic package recommended for these processes is Peng–Robinson and the chemical composition of feedstocks was found in many works.[39−42] The operating conditions for biomass gasification are summarized in Table .

Table 7

Operating Conditions for Biomass Gasification

operating condition	bagasse	steam	gasification reaction
temperature (°C)	25	400	1000
pressure (kPa)	2000	2000	2000

Hydrogen Purification

It is required to separate hydrogen from syngas components such as CO2, CO, and CH4, and hence, pressure swing adsorption (PSA) technology is used for hydrogen purification. The syngas is fed into an adsorption column under high pressure to obtain hydrogen with a purity of around 98–99.99% mol.[61] The simulation of this stage considers real operating conditions of a typical industrial plant. The adsorption process occurs at room temperature (25 °C) and an inlet pressure of 40 atm. The adsorption column is represented as a black box allowing to separate the stream components in the mass percentage reported by Song et al.[62]

Environmental Analysis

To assess environmentally the proposed combined biomass biorefinery, the WAR was developed. This tool describes the PEIs considering different categories of impacts divided into atmospheric and toxicological.[28] The PEI output provides information related to the external environmental efficiency, which refers to the capacity of a process for obtaining final products under a minimum discharge of potential. The total output rate of PEI is calculated by eq 1, where iout(cp), ioutep, iweep, and iwecp represent the rate of PEI leaving the system due to chemical interactions, the rate of PEI out of the system due to energy generation processes, and PEI out of a system as a result of the release of waste energy due to energy generation and chemical processes, respectively.[63]

The effect of blend composition was evaluated by varying the contents of jatropha and palm oils in order to analyze alternatives for reducing PEIs related to feedstock conditions.

Techno-Economic Feasibility Analysis

The techno-economic feasibility analysis enables to compare both technical and economic efficiencies of many processes.[64] The total capital investment (TCI) involves the funds needed to purchase and install the biodiesel manufacturing plant including equipment, facilities, and raw materials, among others. The TCI is described by eq 2, where FCI is the fixed capital investment, WCI is the working capital investment, and SUC is the start-up investment.

The net cash flow (NCF) was calculated by eq 3, where AOC represents the annualized operating costs and ∑mCv is the annual income.

The economic profitability indicators selected to assess the combined biomass biorefinery are the net present value (NPV) and internal rate of return (IRR). The IRR is the interest rate at which the NPV is equal zero. The NPV is one of the most insightful profitability criteria that is calculated by eq 4, where ACF is the net income for the nth year.

Results and Discussions

Process Simulation

Biodiesel Production via Transesterification of Jatropha and Palm Oils

This simulation is shown in Figure . As can be observed, palm oil and jatropha oil enter the mixer (MIX-102), while methanol and sodium hydroxide are mixed in MIX-101. The resulting mixtures are heated before entering the reactor (CRV-100), in which the transesterification reaction takes place. Then, the products of the reaction are sent to the liquid–liquid tower (T-100) that works with water in order to separate the biodiesel from the glycerol and unreacted methanol. The stream containing biodiesel is sent to the flash separator (V-101) to remove water and methanol from the product. The stream containing glycerol (105A) is sent to the reactor CRV-101, in which neutralization is performed by adding H3PO4. The product stream from neutralization is subjected to centrifugation (X-100) to remove Na3PO4. Then, the supernatant stream (108) is fed into a distillation tower T-102 in order to separate glycerol and methanol. The methanol stream (MeOHr) is sent back to the transesterification reactor. The required inlet streams for obtaining an oil blend of jatropha oil–palm oil in 30–70% wt (JP30-PO70) is listed in Table .

Figure 2

Simulation flow sheet for biodiesel production via alkaline transesterification.

Table 8

Feedstock Streams for Biodiesel Production

oil blend (% wt)	Jatropha oil (kg/h)	Jatropha bagasse (kg/h)	palm oil (kg/h)	PPF (kg/h)	EFB (kg/h)	total bagasse (kg/h)
JP30-PO70	3300	6035	7700	9411	14,861	30,307

Table lists the fuel properties of both biodiesels from palm oil and jatropha oil, which were provided by the process simulation and compared with the standard EN 14214. The biodiesels were in the desirable ranges based on this standard. The biodiesel from palm oil exhibited a higher cetane number than the biodiesel from jatropha oil which indicates shorter ignition delay periods in the diesel engine.[51] The higher value for biodiesel from jatropha oil in the iodine index affects stability against oxidation and hydrolysis processes.[47]

Table 9

Fuel Properties from Simulation of Produced Biodiesel

property	biodiesel from palm oil	biodiesel from jatropha oil	JP30-PO70	EN 14214
ester content (% wt)	97.74	98.83	96.53	min 96.5
density@15 °C (kg/m3)	878.65	879.33	878.77	860–900
viscosity@40 °C (cSt)	4.34	4.23	4.21	3.5–5
cetane number	62.15	53.27	58.73	>51
iodine index	52.29	105.70	66.75	<120

Hydrogen Production through Steam Reforming of Glycerol

The simulation of steam reforming of glycerol to hydrogen is based on complex chemical reactions.[65] The overall steam reforming reaction is the result of glycerol decomposition (reaction 5) and WGS (reaction 6).[57]

Figure shows the hydrogen process simulation by the glycerol steam reforming technique, which consists of a steam reformer (GBR-100), a WGS reactor (ERV-101), water–gas separation vessel (V-102), and molecular sieves to separate hydrogen from syngas. The system is operated at the atmospheric temperature and steam to a carbon (S/C) ratio = 3. The reformed water is heated in E-110 to obtain reformed steam, which is fed into the reformer (GBR-100) along with glycerol (GlyceM1). The products of the reforming reaction are cooled (E-111) and sent to the WGS reactor (ERV-101) that operates in an equilibrium model. The resulting syngas is separated from water in the V-102, and hydrogen is collected in the molecular sieves. Table summarizes the composition and operating conditions of main inlet and outlet streams involved in this process.

Figure 3

Simulation flow sheet for hydrogen production through glycerol steam reforming.

Table 10

Composition of Main Streams for Glycerol Steam Reforming

	inlet streams		outlet streams
properties	reformed steam	glycerol/water	water	H2	gas
temperature (°C)	200	200	100	100	126
pressure (kPa)	101.3	101.3	4053	3881	3881
molar flow (kmol/h)	55.02	69.16	71.88	84.3958	41.44
mass flow (kg/h)	991.35	2166.10	1298.23	170.40	1688.82
composition (wt)
H2	0.0000	0.0000	0.0000	0.9983	0.0006
CO	0.0000	0.0000	0.0000	0.0000	0.0009
CO2	0.0000	0.0000	0.0045	0.0000	0.9532
CH4	0.0000	0.0000	0.0000	0.0001	0.0047
C2H6	0.0000	0.0000	0.0000	0.0000	0.0000
H2O	1.0000	0.4720	0.9955	0.0016	0.0406
glycerol	0.0000	0.5280	0.0000	0.0000	0.0000

The effect of reaction temperature on the reforming process was studied in order to maximize the production of hydrogen. Martin et al.[66] reported that higher temperatures significantly reduce the formation of coke during steam reforming. Figure shows the influence of temperature on hydrogen production yield under specific operating conditions previously described. It was found that the highest hydrogen/glycerol mass ratio was achieved at 650 °C.

Figure 4

Effect of temperature on hydrogen production through steam reforming.

The Gibbs free energy minimization method was used to predict the production yield of H2, CO, CO2, and CH4 and compared with the results reported by Soto.[56] It has been pointed out that this thermodynamic study concluded that hydrogen production is favored by high temperature, low pressure, and high water/glycerol ratio.[57] In fact, Wang et al.[67] concluded that temperatures above 750 °C and S/C between 2 and 3 are suitable for hydrogen production. Table summarizes the gas production through steam reforming of glycerol.

Table 11

Production Yield of Gases Using Steam Reforming Technique

production yield (gas/glycerol, mass ratio)	H2	CO2	CO	CH4
simulation	0.130	1.001	0.263	0.0069
experimental[56]	0.149	1.334	0.162	0.000

Hydrogen Production through Biomass Gasification

The oil extraction process generates several wastes and some of them are not being used for obtaining high-value products. The bagasse, EFB, PPF, DOC, and fruits without seed residual biomasses were sent for gasification in order to obtain the syngas required to produce hydrogen. Table presents the syngas composition for a blended jatropha oil–palm oil (JO30-PO70). Nipattummakul et al.[68] reported similar values for the molar composition of syngas as follows: H2 (0.52% mol), CO (0.30% mol), CO2 (0.14% mol), and CH4 (0.001% mol). Li et al.[69] also obtained an approximated volumetric composition: 53.6, 20.5, 20.9, and 4.4% vol for H2, CO, CO2, and CH4, respectively. The simulation results fitted the compositions obtained experimentally by other authors suggesting a good prediction for the real process.

Table 12

Syngas Composition Produced through Biomass Gasification

components	composition (% mol)	composition (% vol)
H2	0.596	49.82
CO	0.228	23.09
CO2	0.174	26.92
CH4	0.001	0.16

The route for biomass gasification to hydrogen is shown in Figure . As can be observed, the biomasses are mixed and sent to a gasifier (GBR-100-2), in which gasification reactions took place. The biomass thermal gasification produces a gas called syngas or synthesis gas that is mainly CO and H2 along with a minor amount of CO2 and CH4.[70] Then, the CO content is converted into hydrogen and carbon dioxide via WGS in adiabatic reactors at thermodynamical equilibrium (ERV-100, ERV-101-2, ERV-102) and the resulting gas is feed into a separation vessel (V-100) to remove condensates from the syngas stream. Afterward, this stream is compressed and sent to a PSA unit (X-100-2). Table presents the composition of the main inlet and outlet streams involved in hydrogen production through biomass gasification.

Figure 5

Simulation flow sheet for hydrogen production via biomass gasification.

Table 13

Composition of Main Streams for Biomass Gasification

	inlet streams					outlet streams
properties	EFB	PPF	Jatropha bagasse	H2O bagasse	condensates	liquid wastes	hydrogen	gasses
temperature (°C)	20	20	20	25	25	150	25	46.04
pressure (kPa)	2000	2000	2000	2000	4053	2000	3881	3881
molar flow (kmol/h)	1252.43	793.14	509.26	2169.16	1185.91	786.53	2315.76	1157.55
mass flow (kg/h)	14,860.7	9411.11	6034.56	39,077.65	21,535.23	14,181.30	4668.87	50,099.31
composition (wt)
H2	0.064	0.089	0.063	0.000	0.0000	0.0000	1.000	0.001
O2	0.469	0.080	0.475	0.000	0.0000	0.0000	0.000	0.000
C	0.449	0.782	0.458	0.000	0.0000	0.0000	0.000	0.000
N2	0.002	0.035	0.004	0.000	0.0000	0.0000	0.000	0.002
H2O	0.000	0.000	0.000	1.000	0.9865	0.9983	0.000	0.001
CO	0.000	0.000	0.000	0.000	0.0000	0.0000	0.000	0.002
CO2	0.000	0.000	0.000	0.000	0.0135	0.0017	0.000	0.994
CH4	0.000	0.000	0.000	0.000	0.0000	0.0000	0.000	0.001
S	0.016	0.013	0.000	0.000	0.0000	0.0000	0.000	0.000

Global Energy Balance of the Biorefinery

The global energy balance around the combined palm and jatropha biomass biorefinery was performed in order to calculate the net energy gain of the system. As shown in Figure , caloric content of biomasses and oils were considered for the calculation of energy inputs. The utilities were estimated with the process simulation at 2987.99 kW. The energy output included biodiesel (JP30-PO70) and hydrogen from both reforming and gasification. The higher heating value (HHV) of oil palm biomasses as well as jatropha bagasse were found in the literature.[71,72] The HHV of jatropha and palm oils were simulated properties provided by software. The net energy ratio (NER) was calculated as the ratio between the net energy output and net energy input. A value of NER > 1 indicates that the fuel system has a net energy gain, that is, the energy given for the production of biodiesel and hydrogen is higher than the energy obtained in the use of biodiesel and hydrogen.

Figure 6

Energy balance of the biorefinery.

The PEIs of the processes involved in combined biomass biorefinery were determined by the WAR algorithm. The PEI categories considered in this work were based on the results reported by Young and Cabezas[73] as follows: human toxicity potential by ingestion, human toxicity potential by exposure, aquatic toxicity potential (ATP), terrestrial toxicity potential, global warming potential (GWP), ozone depletion potential, smog formation potential, and acidification potential (AP). Figure shows the PEI for three different blends (JO10-PO90, JO20-PO80, and JO30-PO70), palm oil, and J. curcas oil. As can be observed, the AP most contributes to environmental impacts, followed by ATP and GWP categories. These results can be attributed to the consumption of fossil fuels in order to supply the heating energy requirements for steam reforming and biomass gasification of residual lignocellulosic materials. Palm oil exhibited the highest value for AP and ATP categories, which could be assigned to the sulfur content in palm bagasse (0.029 wt) producing acids over the process. The JO30-PO70 blend generated lower PEIs (1100 PEI/h) than other blends. Hence, it was expected that the blend with a lower palm oil amount showed lower environmental impacts.

Figure 7

PEI for combined biomass biorefinery.

Techno-Economic Feasibility Analysis

The equipment costs were calculated according to the characteristic dimensions provided by simulation software. However, the hydrogen purification stage was dimensioned according to the recommendations found in the literature related to the use of three packed-bed adsorption columns.[62] The cost estimation was performed through several plots reported by Peters and Timmerhaus,[74] which were updated with the CEPSI index. Table summarizes the total cost of equipment used for operating the biorefinery.

Table 14

Equipment Cost Estimation

equipment	cost (USD)
heat exchangers	$444,663.51
compressors	$507,512.18
pumps	$40,715.72
reactors	$456,152.37
drums	$204,391.05
columns	$523,859.21
total	$2,177,294.03

As is listed in Table , the raw material costs considered the inflation per year in Colombia and involved the cultivation and oil extraction costs. The selling price for different products obtained in this biorefinery were collected from Han et al.[75] and are summarized in Table .

Table 15

Raw Material Costs

raw material	cost (USD/kg)
NaOH	0.337
methanol	0.466
H3PO4	0.68
oil-bagasse	0.604

Table 16

Selling Price of Products

product	selling price (USD/kg)	product	selling price (USD/m3)
biodiesel	0.89	H2	2.7
Na3PO4	0.75	CO2	0.3

The fixed capital investment and working capital were calculated assuming product sale for one month. The TCI refers to funds invested to begin a product manufacture for at least one month. The proposed combined biomass biorefinery reported a FCI of 12,715,397.16 $USD, WC of 2,050,423.75 $USD, and TCI of 14,765,820.91 $USD. The total operating cost estimation was performed based on annualized raw material costs, utility costs, administrative expenses, and labor, among others. This information was useful to calculate the cash flow of over a year, which is defined as the difference between incomes and expenses. The total operating cost, sales revenue, and NCF were calculated to be 82,760,321.68 $USD, 87,726,871.58 $USD, and 4,966,549.90 $USD, respectively. The techno-economic feasibility of combined biomass biorefinery was analyzed by economic indicators (NPV and IRR) for a useful life of 15 years and annual interest rate of 20%. The economic indicators were calculated to be 8,455,147.29 $USD and 33.18% for NPV and IRR, respectively. These results revealed that the proposed combined biomass biorefinery is feasible to be implemented. In addition, similar values for IRR were obtained in other works using lignocellulosic materials.[76,77]

Conclusions

This work was focused on applying the biorefinery concept to the biodiesel production from J. curcas and palm oils with the aim of taking advantage of biodiesel industry-derived residues to generate high-value products such as hydrogen. The process simulation of linear chains provided information concerning process streams (temperature, pressure, mass flow, and composition), which were required for performing environmental and techno-economic analyses. The residual biomass conversion into hydrogen was carried out through gasification, which is one of the most used thermochemical technology. The glycerol produced as a co-product in the transesterification reaction was used in steam reforming for hydrogen production. The incorporation of these linear chains into the biodiesel production process was expected to be an alternative for making it more economically competitive. The environmental analysis results revealed that AP most contributes to environmental impacts, followed by ATP and GWP categories. The AP category also shown to be significantly high for a single biomass biorefinery reported in previous works such as oil palm-based biorefinery,[28] which suggests similar environmental performance of the combined biomass design in this impact category. The blend JO30-PO70 exhibited the lowest PEIs; hence, it was selected for further studies. The NPV and IRR indicators were calculated to be 8,455,147.29 $USD and 33.18%, respectively, suggesting the feasibility of the proposed combined biomass biorefinery. The combination of both jatropha and palm oils for biodiesel production was shown to be an attractive tecno-economic alternative, supporting the study performed by Sarin et al.[49] The main drawback of this biorefinery design was the high energetic demand for transforming both biomasses into valuable products. Hence, the application of process integration techniques to the simulated biorefinery is recommended in order to reduce the consumption of energy during preheating for the transesterification reaction and biomass gasification. Besides, the process safety evaluation of this design features a key aspect to be considered in future studies to assess the viability of the biorefinery in terms of fire and explosion hazards.