Evaluation of Life Cycle Assessment of Jatropha Biodiesel Processed by Esterification of Thai Domestic Rare Earth Oxide Catalysts

Abstract

The Thai domestic rare earth oxides, including cerium, lanthanum, and neodymium oxides, with the effects of calcination temperatures (500–1000 °C), were utilized as catalysts for twelve Jatropha biodiesel alternatives via an esterification reaction. This study applied life cycle assessment (LCA) methodology from well-to-wheel analysis to assess energy efficiency and the global warming impact with and without land use change. The results of the life cycle analysis showed that the Jatropha biodiesel alternatives using the La₂O₃ catalyst in all conditions (0.89–1.06) were found to be potential fuel substitutes for conventional diesel (0.86) in terms of net energy ratios; however, the results showed that they generated a higher global warming impact. Considering the improvement process of Jatropha biodiesel in the utilization of waste heat recovery, the Jatropha biodiesel reduced the impacts of the net energy ratios and the global warming impact by 22–24% and 34–36%, respectively. The alternative Jatropha biodiesel using the La₂O₃ catalyst with a calcination temperature of 600 °C was shown to be the most environmentally friendly of all the studied fuels; relatively, it had the highest energy ratios of 1.06–1.37 (with and without waste heat recovery) and the lowest total global warming impact of 47.9–70.7 kg CO₂ equivalent (with land use change). The integration of the material and process development by domestic catalysts and the recovery of waste heat would improve the sustainability choices of biofuel production from renewable resources for transportation fuels in Thailand.

1. Introduction

The increase in fossil fuel consumption is a primary cause of concern in the context of the current climate change. The global carbon dioxide CO₂ emissions in Earth’s atmosphere from land use and the use of fossil fuels was 40,500 million tons of CO₂ in 2022; this is a relatively similar value to that of 40,900 million tons of CO₂ in 2019 [1]. The transportation sector is one of the largest contributors to anthropogenic greenhouse gas (GHG) emissions, at a level of 14%; these emissions come from the burning of fossil fuels for our cars, trucks, ships, railroads, and planes. Almost all, or 95%, of the fuel used for transportation is petroleum-based, largely in the form of gasoline and diesel [2]. In Thailand, diesel fuel accounted for approximately 42% of the total transportation fuel types. To set the alternative energy target (2030–2036), the expected petroleum-based oil and CO₂ reduction targets in the transportation sector are 30.213 million tons of oil equivalent and 37.1 million kg CO₂ per year, respectively [3]. Biodiesel is one of the important renewable energy sources because of its environmental benefits and because it is a very promising alternative to diesel. In practice, Thailand’s government has long-term planning and policies, including the Thailand Integrated Energy Blueprint (TIEB) and the Alternative Energy Development Plan (AEDP) 2015–2036, to continuously support and encourage the alternative energy consumption [4]. It is important to increase the substitution of traditional fossil fuels with biofuels in the transportation sector from 4% in the year 2015 to 20% in the year 2036 [4]. Biofuels in Thailand consist of bioethanol and biodiesel. In this context, the potential feedstock crops for biofuel production are generally sugarcane, cassava, molasses, palm oil, and Jatropha curcas (Jatropha) [4]. Biodiesel is referred to as fatty acid methyl ester (FAME) and is obtained from the transesterification of triglycerides with alcohol and the esterification of free fatty acids (FFA) with alcohol [5,6]. The common basic homogeneous catalytic transesterification reactions using alkaline catalysts for the commercial production are KOH, NaOH, NaOCH₃, and NaOCH₂CH₃. Several homogeneous acid catalysts, such as H₂SO₄ and HCl, have been used successfully in the transesterification of triglycerides containing high FFA due to their strong acidic properties and low cost and the elimination of side reactions such as saponification [7]. Heterogeneous catalysis is advantageous in both esterification and transesterification reactions because it has less sensitivity to FFA and water, a less corrosive character, and a lower number of separations and because it is environmentally friendly [8]. Many studies reported that heterogeneous rare earth oxide (REO) catalysts can be used for both catalyzed esterification and transesterification to produce biodiesel [5,9,10]. Many studies have been related to these issues. Mattos et al. (2012) [9] synthesized rare earth (La, Ce, Sm, and Gd) trisdodecylsulfate materials as Lewis acid–surfactant-combined catalysts for the production of biodiesel from waste soybean cooking oil. The results showed that the La, Ce, Sm, and Gd catalysts could catalyze the transesterification and esterification reactions to obtain FAME yields of 76%, 79%, 81%, and 86% under the optimum conditions. Rattanaphra et al. (2022) [5] have prepared three kinds of REO, cerium (CeO₂), lanthanum (La₂O₃), and neodymium (Nd₂O₃), and investigated the effect of calcination temperatures (500–1000 °C) in the esterification of oleic acid to produce biodiesel. It was found that the CeO₂ catalyst calcined at 1000 °C showed the best catalytic activity, with the highest FAME content of 78.54% under the conditions: 3 wt% catalyst, 20:1 methanol/oil molar ratio, and stirring rate 600 rpm for 5 h. Gnanaserkhar et al. (2020) [11] studied biodiesel production via simultaneous esterification and transesterification over a Ce-modified sulfated catalyst. Their results indicated that a conversion of 93% was achieved under the following conditions: a temperature of 90 °C, a 12:1 methanol/oil molar ratio, a 3 wt% catalyst, and 1 h reaction time. As mentioned above, many studies have reported the use of a rare earth (RE) element as a catalyst to produce biodiesel via esterification reactions. The nonedible oils such as waste oil, valorized agriculture waste, and Jatropha curcas contain high amounts of free fatty acids, which were considered as a prospective feedstock due to the possibility of cultivation in dry/marginal land, a high amount of oil fraction oil (30–40%), and FFA. Alternatively, Jatropha curcas is a potential resource for esterification reactions from oil with a high free fatty acid content. There are several comprehensive studies of the environmental impacts of Jatropha biodiesel obtained from the transesterification of triglycerides with alcohol that were preferable to those of conventional diesel [12,13,14,15]. For the current example, a study by Ajayeb et al. (2013) [16] on the comprehensive life cycle of two different raw materials from biomass, including algae and Jatropha biodiesel, made a comparison with conventional diesel. The non-renewable energy consumption (NRE) and greenhouse gas (GHG) emission reduction were in the range of 6.9–21.7% and 24.7–42.6% compared to conventional diesel. Obligado et al. (2017) [17] studied the GHG reduction potential of biodiesel produced from Jatropha, relative to that of the conventional diesel. The results indicated that the global warming potential of the Jatropha biodiesel is 24.2% lower than that of conventional diesel because of the savings acquired by utilizing the byproducts to produce electricity. Giraldi-Diaz et al. (2018) [18] studied the life cycle energy and carbon footprints associated with the supply chain of Jatropha biodiesel production. The results showed the energy demand and GHG generation of 37.9 MJ/kg biodiesel and 2.16 kg CO₂ eq./kg biodiesel. The environmental impacts of Jatropha biodiesel with waste-to-energy are approximately 35–60% better compared to those of conventional Jatropha biodiesel. However, there is lack of previous life cycle assessment (LCA) studies on the heterogeneous rare earth oxide (REO) catalysts used for catalyzed esterification from oil with high free fatty to produce biodiesel. LCAs are widely used as a valuable tool to quantify the potential environmental performance of products or processes in order to support decision making in production and consumption. This paper attempts to study the LCA of biofuel with a view to outlining ISO 14040/ISO 14044 (2020a) [19] and to consider the implications for policy frameworks in the case of Jatropha biodiesel using REO as catalysts in an esterification reaction in sustainable biofuel production systems. Thus, the aims of this study are (1) to assess the net energy ratio (NER) and global warming impact of twelve types of Jatropha biodiesel processed by the esterification of Thai domestic rare earth oxide catalysts, as carried out by Rattanaphra et al. (2022) [5] and based on the LCA approach; (2) to assess the improvement process of Jatropha biodiesel using waste heat recovery; and (3) to perform the LCA related to the LUC impact of alternative fuels in this study. The results were compared with those of conventional diesel.

2. Materials and Methods

Life cycle assessment (LCA) is a tool (ISO, 2020) [19], which is widely applied to evaluate and compare the environmental performances of products during their entire life cycle. LCA enables the comparison of different products and the identification of the most effective product from conventional diesel and alternative fuels (twelve Jatropha biodiesel types using the REO catalysts: La₂O₃, CeO₂, and Nd₂O₃), as shown in

Table 1. Well-to-wheel analysis: Jatropha biodiesel using REO catalyst options.

Options	Abbreviations	Explanation
1	Biodiesel Ce-500	Jatropha biodiesl-CeO2 at calcination temperature of 500 °C
2	Biodiesel Ce-600	Jatropha biodiesl-CeO2 at calcination temperature of 600 °C
3	Biodiesel Ce-800	Jatropha biodiesl-CeO2 at calcination temperature of 800 °C
4	Biodiesel Ce-1000	Jatropha biodiesl-CeO2 at calcination temperature of 1000 °C
5	Biodiesel La-500	Jatropha biodiesl-La2O3 at calcination temperature of 500 °C
6	Biodiesel La-600	Jatropha biodiesl-La2O3 at calcination temperature of 600 °C
7	Biodiesel La-800	Jatropha biodiesl-La2O3 at calcination temperature of 800 °C
8	Biodiesel La-1000	Jatropha biodiesl-La2O3 at calcination temperature of 1000 °C
9	Biodiesel Nd-500	Jatropha biodiesl-Nd2O3 at calcination temperature of 500 °C
10	Biodiesel Nd-600	Jatropha biodiesl-Nd2O3 at calcination temperature of 600 °C
11	Biodiesel Nd-800	Jatropha biodiesl-Nd2O3 at calcination temperature of 800 °C
12	Biodiesel Nd-1000	Jatropha biodiesl-Nd2O3 at calcination temperature of 1000 °C

. LCA results can provide suggestions for ways to reduce the environmental impact, to improve production processes, and to inform public policy [20,21,22,23]. LCA consists of four major components: (1) goal and scope definition, (2) life cycle inventory analysis (LCI), (3) life cycle impact assessment (LCIA), and (4) interpretation of the results [19].

The net energy ratio (NER) is the ratio of the total energy output of Jatropha biodiesel to the total energy input in the forms of the substrate and energy process requirements needed to produce the product through the life cycle analysis [24,25]. This indicator was used to evaluate and reflect the energy efficiency potential of alternative fuels, as compared with conventional diesel. The NER was calculated using Equation (1). A process was considered technically feasible (net energy gain) if the NER was greater than 1. An NER of less than 1 indicates a low process performance (net energy loss) [12].

$$\mathrm{NER}=\frac{{\mathrm{E}}_{jatropha\mathrm{biodiesel}}}{{\mathrm{E}}_{\mathrm{renewable}\mathrm{energy}}+{\mathrm{E}}_{\mathrm{fossil}\mathrm{energy}}}$$

(1)

where E_{jatropha biodiesel} is the total energy content of the products or Jatropha biodiesel, E_{renewable energy} is the energy inputs from renewable fuel in the process, and E_{fossil energy} is the energy inputs from fossil fuels in the process (

Table 2. Factors for energy calculation along the life cycle of Jatropha biodiesel using REO catalysts.

Subjects	Unit	Energy Factors
Fertilizer production
Fertilizer N	(MJ/kg)	65.0 a
Fertilizer P	(MJ/kg)	29.9 a
Fertilizer K	(MJ/kg)	21.5 a
Herbicides production
Glyphosate	(MJ/kg)	151.0 a
Paraquat	(MJ/kg)	202.0 a
Utilities/Fuels
Water	(MJ/kg)	0.006 a
Methanol	(MJ/kg)	38.08 b
Diesel	(MJ/L)	36.42 c
Electricity	(MJ/kWh)	3.60 d
Products/Co-products
Wood and leaves (dry)	(MJ/kg)	16.54–16.8 d,e
Fruit (dry coat)	(MJ/kg)	11.10–13.07 f
Fruit (seed)	(MJ/kg)	18.81–25.10 f
Seed cake (as fuel)	(MJ/kg)	18.81–25.10 f
Jatropha oil (triolein)	(MJ/kg)	39.03 g
Oleic acid	(MJ/kg)	38.84 h
Glycerol	(MJ/kg)	25.60 c
Jatropha biodiesel	(MJ/kg)	37.30 i

^a Data adapted from Ecoinvent (2006) [26] and Cumulative Energy Demand (CED) provided by SimaPro 8.5.2. ^b Methanol, data obtained from Tobin (2005) [27]. ^c Diesel, data obtained from Silalertruksa et al. (2012) [28]. ^d Electricity, data obtained from Thailand Environment Institute (2003) [29]. Based on 100 MJ of primary energy required to produce 36 MJ or 10 kWh electricity. ^e Wood and leaves (dry), data obtained from Kittiyopas and Ladawa (2006) [30]. ^f Fruit (dry coat), fruit (seed), and seed cake (as fuel), data obtained from Openshaw (2000) [31]. ^g Jatropha oil (triolein), data obtained from Fassinou (2010) [32]. ^h Oleic acid, data obtained from Demirbas (2016) [33]. ⁱ Jatropha biodiesel, data obtained from Becker and Francis (2000) [34].

).

For the global warming impact, the emission factors from the Intergovernmental Panel on Climate Change [2,35] were used to quantify the potential GHG emissions. According to the IPCC Fifth Assessment Report (AR5), the 100-year time horizon for global warming potential has relative values of 1 for CO₂, 265 for N₂O, 30 for fossil CH₄, 28 for CH₄, and 23,500 for SF₆. The global warming potential (GWP) can be calculated by multiplying the quantity of input material for each production activity of the twelve types of alternative Jatropha biodiesel using an REO as a catalyst by the corresponding emission factors (

Table 3. Factors for global warming impact calculation during the life cycle of Jatropha biodiesel using REO catalysts and conventional diesel.

Subjects	Unit	Emission Factors
Fertilizer production
Fertilizer N	(kg CO2 eq./kg N)	6.700 j
Fertilizer P	(kg CO2 eq./kg P)	1.800 j
Fertilizer K	(kg CO2 eq./kg K)	1.290 j
Herbicides production
Glyphosate (g.l.)	(kg CO2 eq./kg g.l.)	10.200 j
Paraquat (p.a.)	(kg CO2 eq./kg p.a.)	7.600 j
Utilities/Fuels
Water	(kg CO2 eq./m3)	0.795 k
Methanol (m.e.)	(kg CO2 eq./kg m.e.)	0.721 k
Diesel	(kg CO2 eq./L fuel)	0.296 k
Diesel (Combustion)	(kg CO2 eq./L fuel)	2.741 l
Electricity	(kg CO2 eq./kWh)	0.599 k
Catalysts
CeO2	(kg CO2 eq./kg CeO2)	4.860 m
La2O3	(kg CO2 eq./kg La2O3)	1.240 m
Nd2O3	(kg CO2 eq./kg Nd2O3)	7.120 m
Transportation
Pickup (4-wheel truck)	(kg CO2 eq./tkm)	0.519 j
10-wheel truck	(kg CO2 eq./tkm)	0.216 j
Use phase
Biodiesel (Combustion)	(kg CO2 eq./L fuel)	0.160 n
Diesel (Combustion)	(kg CO2 eq./L fuel)	2.741 l

^j Data adapted from Ecoinvent (2006) [26] and IPCC (2014) [2] GWP in 100-year timeframe provided by SimaPro 8.5.2. ^k Data obtained from TGO (2021) [35]. ^l Data obtained from TGO (2022) [36]. ^m Data obtained from Ratthanaphra and Suwanmanee (2019) [10]. ⁿ Data obtained from Silalertruksa et al. (2012) [28].

). The GWP was measured using kg CO₂ equivalent and was calculated using Equation (2).

$${\mathrm{GWP}}_{\mathrm{Biofuels}\_\mathrm{i}}={\displaystyle \sum _{\mathrm{k}=1}^{\mathrm{n}}\left({\mathrm{Q}}_{\mathrm{j}}\times \mathrm{Emission}{\mathrm{factor}}_{\mathrm{j}}\right)}$$

(2)

where GWP_{Biofuels_i} is the total GWP of biofuel for each alternative Jatropha biodiesel using an REO as a catalyst i (kg CO₂ equivalent/1000 MJ biofuel); i is the type of Jatropha biodiesel using an REO as a catalyst (La₂O₃, CeO₂ and Nd₂O₃); Q is the quantity of the raw materials, chemicals, and fossil fuels (j) for the different types of alternative Jatropha biodiesel using an REO as catalyst; EF_j is the emission factor j (Table 3); and k to n are the set of GWPs during the production of crops, oil, hydrolysis, esterification, transportation, and use.

There are two major categories for the total GWP assessment for fuel crops, including GHG emissions from the production of input materials into the desired product and the land use change (LUC). The LUC for the fuel crops (Jatropha) of the plantation area is evaluated based on the IPCC guidelines for national greenhouse gas inventories in agriculture, forestry, and other land uses [37]. The total LUC of the fuel crop is evaluated from four main sources of GHG emissions, namely the change in the soil carbon, the change in the carbon stock, the changes in non-CO₂ gases from crop burning, and the GHG emissions from soil management. The LUC was calculated using Equation (3).

$${\mathrm{LUC}}_{\mathrm{Biofuels}\_\mathrm{i}}={\mathrm{C}}_{\mathrm{soil}\mathrm{carbon}}+{\mathrm{C}}_{\mathrm{stock}}+{\mathrm{C}}_{\mathrm{crop}\mathrm{burning}}+C_{\mathrm{soil}\mathrm{management}}$$

(3)

where LUC is land use change (kg CO₂ equivalent per 1000 MJ biofuel), C_{soil carbon} is a change in the soil carbon, C_stock is a change in the carbon stock, C_{crop burning} is a change in non-CO₂ gases from crop burning, and C_{soil management} is a change in soil management.

2.1. LCA Goal, Scope, and Functional Unit

This work applied the LCA technique for the assessment of the energy efficiency and global warming impact of twelve types of alternative jatropha biodiesel using REO catalysts such as La₂O₃, CeO₂ and Nd₂O₃, with the effect of calcination temperature, and compared them with conventional diesel, based on the international standards (ISO 14040/ISO 14044, 2020) [19]. The functional unit (FU) of the study is the production of 1000 MJ of Jatropha biodiesel from cradle-to-biodiesel production and well-to-wheel LCIA with the influence of the calcination temperature (500–1000 °C) on the catalyst activity in the esterification for biodiesel production. The studied alternative Jatropha biodiesel types using REO catalysts for calcination temperature are presented in Table 1. The well-to-wheel scope of this LCA study is shown in Figure 1. The scope of the Jatropha biodiesel types encompassed Jatropha plantation, Jatropha oil production, the hydrolysis of Jatropha oil triglycerides production, and the esterification of fatty acid production; the transportation of Jatropha fruit was also included.

2.2. Data Sources and Assumptions

The secondary data were retrieved from previous research, including data on the production of diesel (the National Metal and Materials Technology Center or MTEC, 2009). The data of the diesel and the Thai electricity grid were adopted from the Thai National Life Cycle Inventory Database by the MTEC. The information on biodiesel production was described in the previous study for each process involved. The Jatropha plantation and Jatropha oil production data were adopted from the works of Prueksakorn and Gheewala (2008) and Prueksakorn et al. (2010) [12,38]. The data for the hydrolysis of Jatropha oil triglycerides into oleic acid were adopted from Phuenduang et al. (2012) [39]. The information on esterification for biodiesel production was described in the study by Rattanaphra et al. (2022) [5]. The assumptions for the LCIA in this study are summarized as follows:

• This study applied the energy allocation method, which allocates the environmental impacts of all products and co-products based on the energy value of the Jatropha plantation (the fruit and the co-products), the Jatropha oil production (Jatropha oil and seed cake) [12,38], and the hydrolysis of the Jatropha oil (oleic acid and glycerol) [28,33].
• Energy consumption and CO₂ emissions from manual labor are not included in this analysis.
• The CO₂ adsorption of the Jatropha plantations and the CO₂ emissions from the combustion of biodiesel were considered carbon neutral because they were of biogenic origin [37,38].
• The total amount of waste heat was converted into electricity with the average energy efficiency of 35% [40,41].

3. Results and Discussion

3.1. Life Cycle Inventory (LCI) Analysis

The energy and material flows of Jatropha curcas Linnaeus biodiesel (Jatropha biodiesel) production using CeO₂ (biodiesel-CeO₂), La₂O₃ (biodiesel-La₂O₃), and Nd₂O₃ (biodiesel-Nd₂O₃) as solid catalysts are illustrated in Figure 1. The LCI from the cradle-to-grave or well-to-wheel analysis of conventional diesel and the three types of Jatropha biodiesel production using REO as catalysts were considered and involved the materials, energy inputs, and all emissions in the life cycle. There were six main processes of the alternative fuels, including the productions of the Jatropha plantation, the Jatropha oil (triolein), the extraction, the hydrolysis of triolein, the esterification of oleic acid, the transportation of materials, and the use. The following sections provide the details of each stage, as described below.

3.1.1. Jatropha curcas Linnaeus (Jatropha) Plantation

The details on the inventory of the Jatropha plantation in Thailand were retrieved from Prueksakorn and Gheewala (2008) and Prueksakorn et al. (2010) [12,38]. The plantation period of the trees used in this study was 20 years. The trees were planted at a 1 m × 1 m spacing for the first year. In the second year, the crop density was then reduced to 2 m × 2 m to facilitate photosynthesis. The amount of crop density is in the range of 1100–3300 plants per ha [38]. As shown in Figure 1, in the Jatropha plantation stages, the fertilizer formula 15-15-15 comprises the main substances used to plant the Jatropha trees at the rate of 625 kg/ha/year. The weeds are removed and controlled by the farmer through the use of herbicides. This study assumes an average of 2.5 L of glyphosate per ha every year [38]. The harvesting of Jatropha is possible in the first years after plantation; the main product is Jatropha fruit, and the co-products include Jatropha wood. The average yield of a Jatropha plantation is 7 tons of fresh fruit per ha and 24.7 tons of Jatropha wood per ha [38]. The energy values of Jatropha fruit (coat) and Jatropha fruit (seed) are 12.09 and 21.96 MJ/kg [31], respectively. The average energy value of Jatropha wood is 16.67 MJ/kg [30,42]. The allocation factor of Jatropha fruit (seed) obtained from the Jatropha plantation step was 0.145.

3.1.2. Jatropha Oil Extraction

The products and co-products from Jatropha oil extraction consist of Jatropha oil (triolein) and seed cake. This step comprises cracking, pressing, and filtrating processes. The Jatropha fruit and seed were first separated from the peels by a 2 hp cracking machine with a 100–120 kg seed/h capacity. The Jatropha seeds were then pressed by a 5 hp screw press machine with a 12.5–20 L oil/h capacity. The Jatropha oil was purified with a 2 hp filtration machine with a 150–170 L oil/h capacity [38]. The energy values of Jatropha oil and seed cake are 39.03 MJ/kg [32] and 18.81–25.1 MJ/kg [31], respectively. The allocation factor of Jatropha oil obtained from the Jatropha oil extraction step was 0.352.

3.1.3. Hydrolysis of Jatropha Oil Triglycerides

In this work, Jatropha oil (triglycerides) was used to produce fatty acids. The information on this process was retrieved from Phuenduang et al. (2012) [39] and carried out in two main stages. The first stage, the hydrolysis reaction of triglycerides with water, utilizes a high temperature and pressure of 290 °C and 11 MPa, respectively. Triglyceride was reacted with water to obtain the main product acid (oleic acid) and the co-product (glycerol), as shown in Figure 2a. The conversion obtained was 99.99 mol% and the amount of heat required for this stage was 2347.75 kW. In the second stage, oleic acid and glycerol were separated and cooled down to a temperature of 160 °C and 1 atm. The amount of waste heat from this stage was 4284.97 kW. The products yielded by this process were 1.00 kg oleic acid and 0.108 kg glycerol [39]. The energy values of the oleic acid and glycerol were 38.84 MJ/kg [33] and 25.6 MJ/kg [28,30], respectively. The allocation factor obtained for the oleic acid was 0.933.

3.1.4. Esterification of Fatty Acid

The energy and material flows of Jatropha biodiesel production using CeO₂ (biodiesel-CeO₂), La₂O₃ (biodiesel-La₂O₃), and Nd₂O₃ (biodiesel-Nd₂O₃) as solid catalysts are illustrated in Figure 1. The esterification of oleic acid was carried out in a 600 mL Parr stirred batch reactor (model 4568). Oleic acid was mixed with the catalyst and charged into the reactor. After heating the mixture to 200 °C, methanol was charged into the reactor, and the esterification reaction was started. Upon the completion of the reaction, the reaction mixtures were cooled and centrifuged at 3000 rpm for 30 min to separate the biodiesel product; subsequently, the biodiesel product was heated at temperatures of 110 °C for 24 h to remove any remaining water and methanol. The operation parameters were as follows: a molar ratio of oil to methanol of 1: 20; a catalyst loading of 3 wt%; a stirring rate of 600 rpm, and a reaction time of 5 h [5]. The free fatty acid (FFA) reacted with the methanol, as shown in Figure 2b. The products from this step were fatty acid methyl ester (FAME) and water. The FAME content (biodiesel) was analyzed by gas chromatography (GC) according to the EN 14103 standard [43], using SHIMADZU GCMS-QP2020 equipped with a SHRxi-5Sil MS capillary (Shimadzu, Tokyo, Japan) [5]. The FAME contents using different catalysts (cerium, lanthanum, and neodymium oxide) at different calcination temperatures (500–1000 °C) in the esterification for the biodiesel production of 1000 MJ of Jatropha biodiesel are illustrated in

Table 4. The parameters for the production, net energy input, and net energy ratio (NER) of 1000 MJ Jatropha biodiesel.

Parameters	Jatropha Biodiesl-CeO2				Jatropha Biodiesl-La2O3				Jatropha Biodiesl-Nd2O3
Options	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)
Materials/Chemicals
Jatropha, kg	58.611	69.269	60.112	52.459	59.567	55.348	61.093	64.945	63.968	67.004	65.607	78.899
Jatropha oil, kg	38.139	45.073	39.115	34.135	38.761	36.015	39.753	42.260	41.625	43.600	42.691	51.340
Oleic acid, kg	45.195	45.073	39.115	34.135	36.938	36.015	39.753	42.260	42.154	43.600	42.691	51.340
Methanol, kg	8.927	8.903	7.726	6.743	7.296	7.114	7.853	8.348	8.327	8.612	8.433	10.141
Solid catalyst, kg	1.356	1.352	1.173	1.024	1.108	1.080	1.193	1.268	1.265	1.308	1.281	1.540
Utilities/Fuels, kWh
n Electricity (Hydrolysis)	43.338	51.218	44.448	38.788	44.045	40.925	45.173	48.021	47.299	49.544	48.510	58.339
O Electricity, (Calcination)	12.642	15.216	17.733	19.427	10.332	12.158	18.022	24.051	11.791	14.719	19.354	29.219
p Electricity, (Esterification)	10.528	10.500	9.112	7.952	8.605	8.390	9.261	9.844	9.820	10.157	9.945	11.964
Q Electricity (Purification)	4.487	4.481	4.291	3.999	4.123	4.082	4.247	4.357	4.352	4.416	4.376	4.757
Products
Biodiesel yield	0.593	0.595	0.685	0.785	0.725	0.744	0.678	0.634	0.636	0.615	0.628	0.522
Energy efficiency
Summation of energy input (MJ)	1220	1273	1106	967	980	943	1056	1128	1270	1316	1290	1551
NER	0.819	0.785	0.904	1.034	1.020	1.060	0.946	0.886	0.787	0.759	0.775	0.645

ⁿ The electricity use for hydrolysis of Jatropha oil triglycerides production, as presented in Figure 2a. ^O The electricity use for the different calcination temperatures (500–1000 °C) and different catalysts (cerium, lanthanum, and neodymium oxides) in esterification for Jatropha biodiesel production. ^p The electricity use for esterification of fatty acid and the reaction conditions of 200 °C, 39 bars, for 5 h, as presented in Figure 2b. ^Q The electricity use for purification of FAME at temperatures of 110 °C, 1 atm, for 24 h.

. The energy use of this stage consists of three parts: the electricity use for the calcination of the catalysts, the esterification reaction, and the purification of the FAME. The LCI data from the cradle-to-catalyst production gate of the CeO₂, La₂O₃, and Nd₂O₃ catalysts were adopted from Rattanaphra and Suwanmanee (2019) [10]. The energy values of the CeO₂, La₂O₃, and Nd₂O₃ catalysts were 77.10 MJ/kg, 24.60, and 143.0 MJ/kg [10], respectively.

3.1.5. Transportation

All the materials (fertilizer, fuels, etc.), including the product/co-product (Jatropha fruit, wood, etc.) and others, involved in the life cycle of Jatropha biodiesel were transported by pickup (4-wheel truck) and 10-wheel trucks [12,38]. This study presumed that the Jatropha cultivation areas were located in the central part of Thailand, in Nakhonpathom province. The Jatropha fruit was transported from the plantation to the oil refinery and hydrolysis plants with an average distance of 100 km. It was assumed that the hydrolysis production would be sited close to the oil refinery. Then, the hydrolysis production was also conveniently located close to the location of the esterification production process. The other assumptions regarding the transportation are available in Prueksakorn and Gheewala (2008, 2010) [12,38].

3.1.6. Use in Vehicle Engines

The carbon adsorption and emissions from the combustion of biodiesel were not considered in the calculations due to their biogenic nature of their origin [37]. With few exceptions, the fossil carbon of FAME originates from the methyl group of methanol, which constitutes about 5.6% of the total carbon content in the FAME [28,44]. Therefore, the use phase GHG emissions of biodiesel from the fossil fraction of the CO₂ emissions of biofuels were 0.16 kg CO₂/liter of biodiesel [30]. The use phase emissions from the on-road mobile combustion per liter of diesel were 2.70 kg CO₂, 1.42 × 10⁻⁴ kg CH₄, and 1.04 × 10⁻³ kg N₂O, when accounting for the 2.74 kg CO₂ equivalent [36,37].

3.2. Life Cycle Impact Assessment (LCIA) Analysis

The assigned categories from the well-to-wheel analysis were global warming and the energy efficiency of three types of Jatropha biodiesel: biodiesel-CeO₂, biodiesel-La₂O₃, and biodiesel-Nd₂O₃, as compared with that of conventional diesel. This part includes the impact of land use change on the life cycle assessment study.

3.2.1. Energy Efficiency

The analysis of the energy inputs of biodiesel-CeO₂, biodiesel-La₂O₃, and biodiesel-Nd₂O₃ is illustrated in Figure 3 and Figure 4a. For the same performance, the comparison of the NERs between the production of 1000 MJ of biodiesel (37.3 MJ per kg) [30] and that of 1000 MJ of conventional diesel (38.6 MJ per kg) was considered [39]. A comparison of the total energy input and the NERs for twelve types of Jatropha biodiesel with that of conventional diesel is presented in Figure 3 and Table 4. This indicated that the total energy input for conventional diesel was lower than that from the production of the Jatropha biodiesel (options 1–2 and 9–12) by 4–25% because of the high amount of materials/chemicals (oleic acid, methanol, and solid catalysts) and electricity usage and the low amount of biodiesel yield (0.52–0.64), based on the basis of an energy output of 1000 MJ (Table 4 and Figure 4a). The total energy use of Jatropha biodiesel (options 3–8) was lower than that of the conventional diesel by 4–24% owing to the relatively low amounts of oleic acid, methanol, solid catalyst input, and the relatively high biodiesel yield (0.63–0.78). Note that the reduction in energy input for Jatropha biodiesel in options 5–6 was primarily due to the moderately low amount of energy used (electricity) for the calcination solid catalyst. The order of the high energy efficiency of alternative Jatropha biodiesel is as follows: Biodiesel La-600 (option 6) > Biodiesel Ce-1000 (option 4) > Biodiesel La-500 (option 5) > Biodiesel La-800 (option 7) > Biodiesel Ce-800 (option 3) > Biodiesel La-1000 (option 8) > Biodiesel Ce-500 (option 1) > Biodiesel Nd-500 (option 9) > Biodiesel Ce-600 (option 2) > Biodiesel Nd-800 (option 11) > Biodiesel Nd-600 (option 10) > Biodiesel Nd-1000 (option 12). Comparing the values of the energy ratio of Jatropha biodiesel from well-to-wheel, options 3–8 (biodiesel-La₂O₃) showed higher energy ratio values (0.89–1.06) than the values of the energy ratio of conventional diesel (0.83–0.84) obtained in the study by USDA and USDE (1998) [45].

3.2.2. Global Warming Impact Assessment

The comparative study of the environmental profiles of biodiesel-CeO₂, biodiesel-La₂O₃, and biodiesel-Nd₂O₃ is illustrated in Figure 5 and Figure 4b. Based on the basis of the energy output of 1000 MJ, the global warming impact resulting from conventional diesel was 89.8 kg CO₂ equivalent. The results indicated that the twelve types of Jatropha biodiesel had global warming impacts that were 18–44% greater than that of conventional diesel. Similar life cycle energy and GHG emission results from conventional diesel were reported by Rattanaphra and Suwanmaee (2019) and Suwanmaee et al. (2020) [10,25]. Considering Jatropha biodiesel production using CeO₂, La₂O₃, and Nd₂O₃ as catalysts, the main contribution from the hydrolysis production to the total global warming impact was 52–79%, followed by Jatropha oil production (23–35%), esterification production (14–28%), and Jatropha plantation (7–11%). The transportation stage and the exhaust emissions from the use of Jatropha biodiesel slightly affected the global warming impact, as shown in Figure 4b. Note that the global warming impact of Jatropha biodiesel production was also dominated by electricity at 76–81%; the largest contribution was from the use of electricity for the hydrolysis and oil extraction, at 64–66% and 25–30%, and the smallest contribution was from the use of electricity for the esterification production, at 5–9% of the total global warming impact. This is because the hydrolysis reaction (triglyceride with water) consumes high energy at a moderate temperature and pressure (290 °C and 11 MPa) (Section 3.1.3).

The main GHG emission of diesel was primarily due to the combustion stage at 80.68 kg CO₂ equivalent (89.84% of the total global warming impact). In the case of Jatropha biodiesel, the use phase GHG emission was 4.90 kg CO₂ equivalent, which contributed approximately 3.02–4.55% of the total global warming impact (see Figure 4b). This indicated that alternative Jatropha biodiesel had a use phase global warming impact that was 94% lower than that of conventional diesel because biodiesel avoids CO₂ emissions from combustion [37]. The comparisons of the global warming impacts of biodiesel–CeO₂, biodiesel–La₂O₃, and biodiesel–Nd₂O₃ were evaluated. With a similar life cycle energy (Section 3.2.1), the biodiesel–CeO₂ (133–140 kg CO₂ equivalent) and biodiesel–Nd₂O₃ (134–162 kg CO₂ equivalent) have a higher global warming impact than the biodiesel–La₂O₃ (109–127 kg CO₂ equivalent) by 22–28% and 22–48%. The cases of a global warming impact by biodiesel Ce-800 (option 3) and biodiesel Ce-1000 (option 4) were exceptions. This is mainly due to the fact that biodiesel–La₂O₃ (0.63–0.74) had a higher FAME yield performance than the biodiesel–CeO₂ (0.59–0.68) and biodiesel–Nd₂O₃ (0.59–0.68), except for biodiesel Ce-1000 (option 4) (0.78).

3.2.3. Process Analysis: Improvement of Waste Heat Recovery

The main energy use and the generation of GHG emissions from the well-to-wheel analysis of the Jatropha biodiesel production using CeO₂, La₂O₃, and Nd₂O₃ as catalysts (Section 3.2.1 and Section 3.2.2) are presented in Figure 4a,b. The main contributor to the energy use and GHG emissions is the electricity use for the hydrolysis production, which contributed approximately 30.71–35.59% of the total energy input and 48.46–52.88% of the total global warming impact, respectively. The improvement of waste heat recovery from the hydrolysis production was considered. The energy recovery was determined using two sources. The first was the utilization of the waste heat of oleic acid and glycerol. The second was the integration of hydrolysis production and biodiesel production by utilizing the heat source from oleic acid for preheating (160 °C to 200 °C). It was assumed that the total amount of waste heat was converted into electricity at the average energy efficiency of 35% [35,41], and the electricity produced by waste heat was used to replace Thailand’s grid electricity. The parameters for the production of 1000 MJ of Jatropha biodiesel with waste heat recovery are illustrated in

Table 5. The different parameters for production, net energy input, net energy ratio (NER) of 1000 MJ Jatropha biodiesel with waste heat recovery.

Parameters	Jatropha Biodiesl-CeO2				Jatropha Biodiesl-La2O3				Jatropha Biodiesl-Nd2O3
Options	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)
Utilities/Fuels, kWh
p Electricity, (Esterification)	3.969	3.959	3.436	2.998	3.244	3.163	3.492	3.712	3.702	3.829	3.749	4.511
Energy efficiency
Summation of energy input (MJ)	928	981	853	746	760	729	801	855	997	1034	1014	1218
NER	1.078	1.019	1.172	1.341	1.315	1.372	1.249	1.170	1.003	0.967	0.986	0.821

^p The electricity use for esterification of fatty acids and the reaction condition of 200 °C, 39 bars, for 5 h, as presented in Figure 2b.

. The study of the environmental profiles of biodiesel-CeO₂, biodiesel-La₂O₃, and biodiesel-Nd₂O₃ with waste heat recovery is illustrated in Figure 6 and Figure 7.

Comparing the total energy requirement of the hydrolysis production, the integration of the waste heat recovery (Table 5) shows a lower energy use value (0.935 kWh/kg oleic acid) than that of the conventional process (Table 4) without utilizing waste heat recovery (2.59 kWh/kg oleic acid). Therefore, the increase in the NER by 21.42–24.26% was primarily due to the moderately high amount of waste heat recovery from the hydrolysis production of 56–85 kWh per 1000 MJ of Jatropha biodiesel (Table 5). Note that the values of NER obtained in options 1–8 with the improvement process (1.08–1.37) were higher than 1, indicating a high process performance (net energy gain) (Table 5). This was because the energy input in this Jatropha biodiesel decreased with a waste heat recovery from the hydrolysis production that led to a reduction of 21.45–23.97% in the total energy input and 33.77–36.36% of the total global warming impact for Jatropha biodiesel production, respectively. The NERs of the Jatropha biofuels in options 1–8 with the improvement process (1.08–1.37) were higher than that of conventional diesel (0.86), except for the NER obtained in option 12 (0.82). The values of the energy ratio obtained in our study (0.82–1.37) were in line with that reported by Varadharajan et al. (2008) [46], who reported NERs of Jatropha biodiesel of 0.67–1.3. The results show the competitiveness of the use of Jatropha biofuels using CeO₂ and La₂O₃ as catalysts over conventional diesel in terms of energy efficiency and global warming impact. The global warming impact for conventional diesel was 89.8 kg CO₂ equivalent, which was higher than those for biodiesel-CeO₂ (71.1–85.2 kg CO₂ equivalent), biodiesel-La₂O₃ (70.7–81.9 kg CO₂ equivalent), and biodiesel-Nd₂O₃ (88.6 kg CO₂ equivalent) production, except for the global warming impact in options 2, 10, 11, and 12.

3.2.4. Impacts on Land Use Change

This work examined the GHG emissions from the three types of previous land use considered possible for biofuel crop expansion in Thailand, namely abundance land, tropical forests, and cropland (sugarcane field) [28,47,48]. The LUC of each option is reported in

Table 6. The land use change to Jatropha biodiesel.

Case Descriptions	Units	Abundance of Land to Sugarcane	Abundance of Land to Jatropha	Forest Land to Jatropha	Sugarcane to Jatropha
Soil carbon	kg CO2 equivalent/hectare	−1210	−1210	6197	0
Soil carbon stock	kg CO2 equivalent/hectare	−6270	−917	18,316	5353
Non-CO2 gases from crop burning	kg CO2 equivalent/hectare	0 r	0 r	5240 s	0 r
Emissions from soil management	kg CO2 equivalent/hectare	−527.70	0.31	−3331	528.01
Total LUC	kg CO2 equivalent/hectare	−6952	−2126	26,421	5881
	kg CO2 equivalent/kg crop	−0.102	−0.425	5.284	_

^r Assuming there are no CO₂ gases from burning in crop change. ^s Assuming there is a 50% level of CO₂ gases from burning in crop change.

. The theoretical calculation of carbon impact (LUC) from the land conversion to Jatropha was analyzed in the studies by Bailis and Baka (2010) and Cherubin et al. (2018) [48,49]. The total LUCs were evaluated from the four main sources of GHG emissions and are shown in Table 6. The change in soil carbon and carbon stock was calculated based on the IPCC (2006) [37] and the obtained crop yield. The average sugarcane yield was 65 tons per hectare and included the obtained crop yield from Jatropha (Section 3.1.1). The non-CO₂ and nitrous oxide (N₂O) emissions were evaluated from the burning of the crop fields before harvest and the amount of fertilizer used for the managed soil.

The results obtained from the three types of LUC are as follows. With the crop change from abundance land to Jatropha, the total GHG emissions decreased at a rate of 2.12 tons of carbon per hectare. The largest contribution to the global warming impact reduction was the change in soil carbon and carbon stock (2.12 tons of carbon per hectare), and the smallest contribution was from the change in the nitrous oxide formation from the fertilizer (0.31 tons of carbon per hectare). This is due to the low amount of N-fertilizer used in the studies of Jatropha and crop productivity (0.074 tons N/tons Jatropha or 0.37 tons/hectare). When the abundance land was converted into the Jatropha crop, the total global warming impact of Jatropha biodiesel with the waste heat recovery with the LUC was 5–45% lower than that of conventional diesel (Figure 8) and showed a 47–58% reduction relative to the reference system of Jatropha biodiesel (Figure 5). The typical LUC from the forest land to Jatropha was considerable (Figure 8 and Figure 9); the global warming impact of Jatropha biodiesel (with and without waste heat recovery) with LUC was dramatically higher than that of conventional diesel (79–84%) and the Jatropha biodiesel process (68–81%). For the forest land to crop (Jatropha) field, the loss of carbon stocks increased at a rate of 26.42 tons of carbon per hectare (5.28 kg CO₂ equivalent/kg Jatropha) when Jatropha was planted to replace forest land. With the crop change from sugarcane to Jatropha, the total GHG emissions increased significantly, at a rate of 18.3 tons of carbon per hectare. The change in the carbon stock was primarily influenced by the overall total LUC as a result of the shifts from sugarcane to Jatropha. This is due to the fact that sugarcane (65 tons per hectare) [50] is more productive (crop yield) than Jatropha (7 tons per hectare) [38]. The evaluated results represent the importance of the issue of expanding crop production for biofuel and use to support the achievement of the Thailand Integrated Energy Blueprint (TIEB) and Alternative Energy Development Plan (AEDP) 2015–2036.

4. Conclusions

The LCA of the energy efficiency and global warming impact of the twelve types of Jatropha biodiesel using cerium (CeO₂), lanthanum (La₂O₃), and neodymium (Nd₂O₃) oxides as catalysts and the effects of the calcination temperatures (500–1000 °C) were assessed. The process improvement and the LUC impact were established to identify the variation in the LCA results of alternative Jatropha biodiesel and conventional diesel.

In the first part, the net energy ratios from the well-to-wheel Jatropha biodiesel production using the La₂O₃ catalyst with calcination temperatures of 500–1000 °C (0.89–1.06) were better than that of conventional diesel (0.86). However, the global warming impact of Jatropha biodiesel was 107.8–162.5 kg CO₂ equivalent/1000 MJ, which was greater than that of conventional diesel by 18–44%. This is due to the high electricity use in the hydrolysis reaction for converting Jatropha oil triglyceride to fatty acid.

In the second part, with the utilization of the waste heat of the hydrolysis reactor for the esterification reaction condition, the energy efficiency of the alternative Jatropha biodiesel significantly increased by 22–24% and decreased the global warming impact by 33–36%, compared to the reference system of Jatropha biodiesel.

In the third part, this study accounted for the global warming impact with three types of previous land use for biofuel crop expansion in Thailand, including abundance land, tropical forests, and the sugarcane crop. The total global warming impact of Jatropha biodiesel, including the LUC of typical abundance land to Jatropha crop was lower (10–15%) than the reference system of Jatropha biodiesel, but the results were found to be 4–49% greater in terms of the total global warming impact than that of conventional diesel. Regarding the LUC, the typical previous forest land and sugarcane crop were accounted for; the global warming impacts of Jatropha biodiesel (with LUC) were dramatically higher than that of conventional diesel, at 76–84% and 88–89%, respectively.

In conclusion, the study highlighted the fact that Jatropha biodiesel (with and without waste heat recovery), using La₂O₃ as a catalyst with a calcination temperature of 600 °C, was shown to be the most superior choice of all the studied alternative biofuels in terms of energy efficiency and that it had the lowest total global warming impact, including that of the LUC of the typical abundance land, compared to using CeO₂ and Nd₂O₃ catalysts and conventional diesel. This LCA intended to provide and recommend relevant policy information on the assessment of the environmental sustainability of the aspects of biofuel development with regard to the future potential substitution of conventional diesel in Thailand and in other countries.