1. Introduction
More than 8.1 million people worldwide are now employed by the renewable energy industry—a 5% increase since last year—according to a report released by the International Renewable Energy Agency (IRENA) during its 11th council meeting. The countries with the highest number of renewable energy jobs in 2015 are China, Brazil, the United States, India, Japan and Germany. Within the renewable energy sector, the photovoltaic (PV) solar energy segment remains the largest employer in the world, with 2.8 million jobs (up from 2.5 million at last count) with manufacturing, installation and operations and maintenance jobs. This increase is being driven by the fall in renewable energy technology costs and more favorable public policies. Liquid biofuels account for the world’s second-largest employer with 1.7 million jobs worldwide [
1].
According to a report published recently by the International Renewable Energy Agency (IRENA), nearly half of all jobs in the world generated by the biofuels industry are in Brazil. The Brazilian ethanol and biodiesel industries employed a total of 845.000 workers last year [
2].
The necessities for energy of the modern consuming society have grown tremendously in the last decades. Energy is used to run industrial processes, for domestic consumption in homes, for transportation and for various other purposes. This energy, coming from different sources, forms a system referred to as the energy matrix. The energy matrix represents all the sources available in a country, state or in the world to supply the need (demand) for energy [
3].
The world’s energy matrix is mainly composed of nonrenewable sources, such as coal, oil and natural gas.
Figure 1A shows the world energy matrix in 2020 [
3]. Renewable sources such as solar, wind and geothermal energy, account for only 2.5% of the world energy matrix (marked as “others” in the pie chart of
Figure 1A). Combined with hydraulic energy and biomass, only about 15.0% of the global energy sources are renewable.
Brazil’s energy matrix is very different from that of the rest of the world. In Brazil, although energy consumption from nonrenewable sources exceeds that from renewable sources, it uses more renewable energy than the rest of the world.
Brazil’s consumption of renewable energy is higher than the rest of the world’s renewable energy consumption, with Brazil’s present energy matrix being 48.4% of renewable energy (51.6% of nonrenewable) and the rest of the world’s being 15% of renewable energy (85% non-renewable) [
3].
This characteristic of Brazil’s energy matrix is important. Nonrenewable energy sources are mainly responsible for the emission of greenhouse gas emissions (GHGs). Given that Brazil consumes more energy from renewable sources than other countries, it emits less GHG per inhabitant than most other countries [
3].
The oil crisis that has taken place in recent decades, coupled with the increased demand for fuels and growing concern for the environment, advocates the search for alternative sources in the production of energy [
4]. Alternative sources of renewable energy, such as biomass, are favored over the use of petroleum products because they reduce the emission of gases that cause the greenhouse gas emissions effect.
The main advantages of the renewable energy use (such as palm oil) to produce biofuels are that the plants absorb carbon dioxide in this cycle of production, are biodegradable and present low content of sulfur (S) in the product. The available territorial and climatic conditions in Brazil are favorable to the planting of raw materials necessary for the production of biofuels, which has encouraged investments in public policies in the social sphere to harness regional potential, income generation and employment [
5].
One example of a governmental incentive to produce biofuel (such as biodiesel) in Brazil it is that diesel of fossil origin must have the mandatory addition of 13% of biodiesel, in replacement of the 12% applied since March of 2020. This action was planned in Resolution 16 of 2018 of the national energy policy council (CNPE), that has authorized the ANP to increase this percentage to 15%, which should occur by 2023 [
6].
The are other technologies applied to producing biofuels using palm oil and palm oil neutralization sludge. In the first case, it can be used the transesterification or enzymatic transesterification. In the second case (palm oil neutralization sludge as a raw material), it also can be applied the enzymatic transesterification or microbiological degradation to produce biogas (this may be accomplished due to the characteristics of soap and consequently high pH).
In recent years, several works have investigated the economic feasibility analysis of biofuel production using biomass as raw material (such as palm oil) and residues (such as palm oil neutralization sludge) through pyrolysis followed by the distillation process. A summary of the most recent studies reported in the literature on techno-economic evaluation is presented synthetically as follows.
Abnisa et al. [
7] presented a study on bio-oil production by pyrolysis using palm shell as feedstock in a fluidized-bed reactor at 400, 500, 600 and 800 °C and with N
2 carrier gas at 1, 2, 3, 4 and 5 L/min. In order to optimize palm shell production, the effects of temperature, flow rate of N
2, particle size and reaction time were measured. The maximum yield of bio-oil obtained was 47.3 wt.% (500 °C, 2 L/min of N
2 flow, 60 min reaction time). The most important parameter was the temperature over the bio-oil yield.
Abnisa et al. [
8] investigated the production of bio-oil and biochar using three palm oil residues by pyrolysis in a fixed-bed reactor at 500 °C, N
2 flow rate of 2 L/min and reaction time of 60 min. The yields obtained from bio-oil production were 16.58–43.50 wt.% and of biochar 28.63–36.75 wt.%. These results are affected by the characteristics of the samples, such as ash, fixed carbon, volatiles, hemicellulose and cellulose. The energy density of the biochar was found to be higher than that of the bio-oil. The highest energy density of the biochar was obtained from a palm leaf sample (23.32 MJ/kg), while that of the bio-oil was obtained from a frond sample (15.41 MJ/kg).
Do et al. [
9] presented a study of bio-oil production using empty fruit bunches (EFB) as feedstock, a main residue of the palm oil industry, via fast pyrolysis in a fluidized-bed reactor. It was used a model for commercial process simulations. The total capital investment (TCI) was estimated for five different plant sizes. The EFB bio-oil plant was analyzed in terms of the payback period (PBP), return on investment (ROI), specific capital cost (SCC) and the product value (PV). It was found that 20 kton-dry EFB/yr is the minimum profitable plant size, resulting in a PV of 0.47 USD/kg of bio-oil including 39% water. Sensitivity analysis demonstrated that the plant size and the bio-oil yield are a major influence on the PV. In the most optimistic scenario analyzed, bio-oil can be produced at a PV of 0.27 USD/kg.
Moncada et al. [
10] presented a study on biodiesel, ethanol and poly-3-hydroxybutyrate production using a bio-refinery based palm oil, evaluating the techno-economic and environmental aspects. The results demonstrated an economic margin of 64.5% (1.33-fold higher than standalone ethanol production); the potential environmental impact (PEI) was 156.42 PEI/t products and 0.51 t CO
2 eq/m
3 of biodiesel. In order to measure the footprint indicator and economic impact, feedstock transportation was also included in the analysis. Considering the distance of 300 km, the carbon footprint increased up to 0.59 t CO
2 eq/m
3 of biodiesel and the economic margin was reduced by 1.31%.
Peryoga et al. [
11] investigated bio-oil production using empty fruit bunches (EFBs) as feedstock by pyrolysis. The cost evaluation considered a palm oil mill of 30 metric tons FFB/h capacity. The steps considered in this economic evaluation were chopping, drying, grinding, pyrolysis, solid removal, bio-oil recovery and storage. Sensitivity analysis demonstrated that the raw material price is the most important parameter that affects production cost. The results indicate a promising viability to implement this process in Indonesia. The optimum alternative is to have a bio-oil plant integrated with a palm oil mill.
Mabrouki et al. [
12] investigated the biofuel production using three palm oil residues, namely empty fruit bunch (EFB), palm shell (PS) and mesocarp fiber (MF), using a process simulator called SuperPro Designer (SPD). The simulation includes pretreatment, fast pyrolysis, product collection and upgrading sections. The results were validated with data from the literature of wood oak in a fluidized-bed reactor. Maximum bio-oil production was obtained at 550 °C. The results demonstrated that the PS produced a higher yield of char, while a higher yield of liquid fraction was obtained from the EFB and MF.
Thangalazhy-Gopakumar et al. [
13] studied biochar and bio-oil production using, as feedstock, palm oil sludge by pyrolysis. The bio-oil presented a heating value of 22.2 ± 3.7 MJ/kg, a yield of 27.4 ± 1.7 wt.% and negligible ash content of 0.23 ± 0.01 wt.%. The biochar was investigated for sorption efficiency by adsorbing (Cd
2+ ions) from water and presented a yield of 49.9 ± 0.3 wt.% in the pyrolysis. The removal efficiency of Cd
2+ was similar to a commercially activated carbon (89.4 ± 2%). The adsorption isotherm was well-described by the Langmuir model.
Lee et al. [
14] investigated biochar production using palm oil sludge (POS), palm kernel shell (PKS) and empty fruit bunch (EFB), residues from the palm oil industry, as feedstock by slow pyrolysis (50 mL min
−1 of N
2 at 500 °C). It was identified that higher lignin, carbon, volatiles and HHV were present in PKS and EFB when compared with POS (which also presented lower ash). The thermogravimetric was used to analyze the kinetics of pyrolysis at different heating rates (10–40 °C). The results demonstrated that PKS and EFB are promising sources of biochars.
Li et al. [
15] presented a study of biofuel and biochar production using different biomasses by fast pyrolysis. The raw materials were grouped into five types: husk/shell/pit, organic residue/product, grass/plant, woody, stalk/cob/ear. The results demonstrated that the biochar yield increases from 0.13 to 0.16 kg/kg with ash content (0.3–7.7 wt.%) in the biomass and decreases biofuel yields from 87.3 to 40.7 gallons per ton. The MFSP increases with higher ash content in biomass.
Shemfe et al. [
16] investigated bio-oil production via biomass fast pyrolysis and subsequent bio-oil upgrading via zeolite cracking. The techno-economic assessment was accomplished with two conceptual catalysts’ regeneration for the zeolite cracking process. In the simulations, using the software Aspen Plus, the production of 72 t/day of pine wood was considered. The sensitivity analysis indicates that the operating cost, income tax and fuel yield affect the MFSP the most.
Lam et al. [
17] presented a study of biochar production using banana and orange peels as feedstocks by pyrolysis at 400–500 °C. The pyrolysis generated 30.7–47.7 wt.% yield of a dark biochar, which contained no sulfur, low volatile content (34 wt.%) and high amounts of fixed carbon (72 wt.%). The use of the biochar as adsorbent to treat the palm oil mill effluent (POME) demonstrated a reduction of chemical oxygen demand (COD), concentration of biochemical oxygen demand (BOD) reduction of 57%, oil and grease (O&G) and total suspended solid (TSS) of POME to acceptable standards. The superficial area obtained from the biochar was of 105 m²/g (mesopores), indicating applicability to be used as an adsorbent.
Giwa et al. [
18] presented a study of biochar production using date palm waste and simulations made with SuperPro Designer v8.5. A comparison between production with the conventional process (electric heating-based pyrolysis) and concentrated solar energy was accomplished by analyzing economic and environmental sustainability aspects. Economic analysis demonstrated the most viability from the use of solar energy, with an internal return (IRR) of 14.8% and payback time (PBT) of 4 years and 132 days, and gross margin of 35.5% and return on investment (ROI) of 22.9%. The CO
2 emissions are minor in solar use (38%) when compared with conventional pyrolysis. Sensitivity analysis demonstrated that the cost of date palm waste presents a lower impact in the PBT than changes in biochar sale price.
Lama et al. [
19] investigated fuel production by microwave vacuum pyrolysis compared with conventional pyrolysis, using waste plastic and used cooking oil simultaneously. The results demonstrated short processing time (20 min) and low electrical energy consumption (0.38 kWh). The bio-oil yield obtained was 84 wt., containing higher heating value (49 MJ/kg) than diesel and gasoline, as well as high content of light hydrocarbons. The economic analysis showed a production cost of USD 0.25/L (where in Malaysia the diesel price is USD 0.523/L).
Batlle et al. [
20] studied the utilization of a bio refinery starting from a palm oil mill. Three scenarios were applied: the first (I), the base case, was a traditional palm oil mill; the second (II) was bio-oil and biochar production by fast pyrolysis; and the third (III) considers a bio refinery for biodiesel and glycerin production in a palm oil mill by an extraction/transesterification stage, as well as incorporating the pyrolysis process. The environmental evaluation applied to the scenario (III) demonstrated environmental impacts of 32.5% (climate change category) lower than those when producing electricity and 14.2% lower than environmental impacts from producing biodiesel (resources category), demonstrating that bio-oil production by fast pyrolysis results in lower environmental impacts compared with the other products obtained in a bio refinery. For the three scenarios, the surplus electricity index was calculated, where scenario (III) was the most favorable, achieving 110.23 kW per ton of fresh fruit bunch with an overall efficiency of 82.69%. Finally, the net energy ratio (for the best scenario regarding the thermodynamic performance—scenario (III): 21.17) was calculated and compared with the literature data, resulting in a gain of total energy flow of up to 17.77.
Vasu et al. [
21] presented a study that produced bio-oil with improved pH using blends of palm kernel shell (PKS) and palm oil sludge (POS). The pyrolysis temperature applied was 507 ± 13 °C in a fixed-bed reactor. A reduction in bio-oil yield with the increase of POS in the blend from 0 to 100 wt.% was observed. At a PKS-to-POS mass ratio of 50:50, the pH value of the bio-oil produced was 4.6 ± 0.1. The total acid number (TAN) of bio-oils decreased with increasing POS ratio in the blends.
Yeo et al. [
22] presented a study to develop a bio refinery using as biomass from palm oil industry as feedstock. Techno-economic evaluation of the sustainable circular economy was applied. Three resources were analyzed using Process Graph (P-graph): steam, fertilizer and electricity for regeneration and recycling of biomass. The circular economy model demonstrated potential in reducing 13.469% of the imported electricity and 39.292% of the imported steam, while also presenting 0.642% lower in terms of gross profit.
Yahya et al. [
23] investigated bio-oil, char and burnable gas production using date palm biomass waste of by fast pyrolysis at 525 °C, with results of bio-oil, bio char and gases of 38.8, 37.2 and 24 wt.%, respectively. An economic analysis presented the results of 2.57 years of payback time, with a net saving of USD 556.8 per ton of the date palm waste processed in the pyrolysis unit. It was further estimated that Saudi Arabia could earn USD 44.77 million per annum, approximately, if 50% of the total date palm waste was processed through fast pyrolysis. In addition to that, it would incur a reduction of 2029 tons of greenhouse gas emissions annually.
Kaniapan et al. [
24] presented a review regarding transportation fuel use and energy production of biomass from the palm oil industry (and its residues). A feasibility analysis of palm oil and its residues was made using current valorization methods such as biochemical and thermochemical techniques.
Terry et al. [
25] presented a review of bio-oil production using oil palm biomass (OPB) as lignocellulosic feedstock, as well as presenting a discussion of the chemical compositions of different OPBs and their effects on the bio-oil yield and quality obtained from the pyrolysis process, followed by a discussion on the addition of catalysts and plastics into the pyrolysis process for bio-oil upgrading, and lastly presenting environmental studies and techno-economic analyses regarding the potential use of the process’ integration. Low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropene (PP) have commonly been used in the co-pyrolysis of OPB, which can increase the heating value of bio-oil up to 80.0% compared to that of diesel.
Pires et al. [
26] investigated fuel and chemical production by pyrolysis using biomass as feedstock and the process graph (P-graph) methodology for synthesis in pyrolysis oil refineries. The study demonstrates the profitability of various bio refinery designs. It studies the addition of new unit operations such as a centrifuge for water extraction and a wet oxidation system for acetic acid production, which have profitability ranging from USD 1.650/h to USD 23.66/h with acetic acid and levoglucosan as the main products, respectively.
Detchusananard et al. [
27] presented a study of techno-economic assessment on multibiofuel production using empty fruit brunch (EFB) biomass residual from the palm oil milling process with a pyrolysis–gasification-integrated process. The modeling was accomplished using the Aspen Energy Analyzer and economic performance indicators such as internal rate of return (IRR), payback period (PB) and net present value (NPV). The economic analyses indicate that the proposed process is economically feasible and attractive with 22.0% on IRR, 5.98 years of PB and a USD 249,951.964 NPV.
Attasophonwattana et al. [
28] presented a study of hydrochar’s production using empty fruit bunch (EFB) as feedstock by pilot-scale hydrothermal carbonization (HTC), gasification and washing processes, as well as anaerobic digestion of the HTC’s liquid product. The products regarding gasification were of char (22.7–33.8%) and tar (17.3–28.8%); CO
2/O
2 gasification resulted in 31.3–36.6% for char and 8.5–30.8% for tar. The lower heating value of syngas was in the range of 4.7–6.6 MJ/Nm³ and cold gas efficiency was approximately 39.1–55.1%. Syngas products from air gasification of hydro chars were 39.9–56.5%, 11.4–21.4% and 9.0–14.4% for CO, H
2 and CH
4, respectively, while CO
2/O
2 gasification products yielded 45.1–56.6%, 11.6–24.3% and 9.4–14.0% for CO, H
2 and CH
4, respectively.
Parthasarathy et al. [
29] presented a study of bio-oil production using oil palm wastes (OPW) such as empty fruit bunches (EFB), palm kernel shell (PKS), oil palm frond (OPF) and their blends by pyrolysis. According to the economic analysis, EFB-based pyrolysis has the lowest CAPEX of all tested feedstocks and PKS-based pyrolysis has the highest capital expenses (CAPEX). Furthermore, PKS has the highest operating expenses (OPEX) due to its higher market price as well as higher moisture content. Among the feedstocks, OPF delivers the highest profit at USD 17 M/year, with a 22.0% return on investment (ROI). Regarding the payback period, all OPW feedstocks demonstrated a period of 4–6 years.
In this work, the economic feasibility of the thermal–catalytic process of crude palm oil (CPO) and palm oil neutralization sludge (PONE) followed by the distillation of organic liquid products to produce biofuels was studied not only to evaluate the best investment alternative, but also to evaluate the viability of the project according to the criteria of project evaluation [
30]. The economic feasibility analysis is based on the following economic methods: simple payback criterion, discounted payback, net present value (NPV), internal rate of return (IRR) and index of profitability (IP), as described in detail by Rocha et al. [
30]. The breakeven-point, the minimum sale price (MFSP) and an analysis of sensibility for each process [
30] was also calculated.
4. Conclusions
Starting from the feasibility project criteria indicators, it is possible to affirm that the thermal–catalytic cracking process of crude palm oil to the production of biofuels, coke and methane gas is feasible. This conclusion comes from the results of 4 years for simple payback, 5 years for discounted payback (considering an analysis horizon of 5 years). Additionally, a positive net present value (NPV of USD 3256.57) was obtained, as well as a profitability index higher than 1 (result of 1.02).
Regarding the feasibility assessment for the production of biofuels, coke and methane gas using palm oil neutralization sludge, the same indicators confirm the viability of the project. The simple payback criterion obtained was of 4 years, for discounted payback 5 years, the NPV was USD 28,950.31 and the profitability index was 1.15 (for each dollar invested in the project, a return of 1.15 dollars will occur, within an analysis horizon of 5 years).
The availability used for the project evaluation criteria with crude palm oil and palm oil neutralization sludge was 75% and 56.25%, respectively. This means that the time used to operate the equipment (procedures of load and unload) can be improved. This way, the results of the project´s evaluation indicators can be all improved, starting from the optimization of the pilot plant’s availability (such as use of semi-continuous process, optimization of the time reaction).
The MFSP obtained for the process using palm oil was 1.59 USD/L. The literature reported in this work shows values from 0.68 up to 1.34 USD/L. The main negative aspect that effected this result was the palm oil market price, which affected the costs. The MPSP obtained using palm oil neutralization sludge was 1.34 USD/L; although more stages are necessary in this process, the low estimation of the feedstock contributed to this result.
The internal rate of return (IRR) obtained in both projects was 10% per year, which means that the project is economically feasible. Amaral et al. [
30] presented value a of 10% of IRR.
Sensibility analysis shows that the pyrolysis yield and distillation yield are the parameters that most affect the MFSP in both projects. It also demonstrated that a reduction in electrical energy could reduce the MFSP due to the high consumption of energy in the distillation stage. One alternative is the use of photovoltaic energy.
Another assumption used in this analysis was that only 10% of the total generated gas can provide revenues, which means that this estimation can be improved (such as the use of cogeneration). Other alternatives for producing biofuels, biogas and biochar can also be studied in the group (biomass such as seeds of Amazon fruits, bovine tallow, several vegetable oils of low cost in the Amazon region).
It is important to highlight the fact that several studies in the literature also present applications for biochar products, such as adsorbents, soil improvement and carbon sequestration, as mentioned by Santana Junior et al. [
49].