**3. Conversion technologies for biodiesel production**

Biodiesel derived from domestic renewable sources such as animal fats, vegetable oils, and algal oil has considerably similar properties and characteristics to petroleum-based diesel, making it a promising alternative fuel [12]. Edible oils are commonly produced from edible feedstocks such as coconut oil, soybean oil, palm oil, rapeseed oil, olive oil, corn oil, etc. Different non-edible oils including jatropha oil, petroleum nut oil, and castor oil can also be used for biodiesel production. In the case of waste oils, the possible feedstocks are waste cooking oil, fish oil, animal tallow oil, and pyrolysis oil while algal oil is usually sourced from *Chlorella vulgaris* algae [13]. Generally, the process flow for biodiesel production includes feedstock production and harvesting, oil extraction, oil refining, transesterification, and distillation (**Figure 5**).

Oil can be extracted from the raw material using mechanical extraction or solvent/ enzyme extraction. Mechanical extraction usually uses a screw type machine to expel the oil through pressing (**Figure 6**). This process is relatively simple and is applicable to almost any kind of nuts and oilseeds, though, oil yield or recovery is oftentimes quite low [14]. Unlike mechanical extraction, solvent/enzyme extraction can result to significantly higher oil yields with oil reduction in meal to less than 1% by weight (**Figure 7**). However, this method has higher energy requirement and takes longer time. Another method that can be used for oil extraction is the enzymatic extraction method which uses suitable enzymes. As compared to other methods such as the

**Figure 5.** *General process flow for biodiesel production.*

*Comparative Analysis of Biodiesel Production from Different Potential Feedstocks… DOI: http://dx.doi.org/10.5772/intechopen.102724*

**Figure 6.**

*General process flow of oil extraction via mechanical extraction.*

**Figure 7.** *General process flow of oil extraction via solvent extraction.*

solvent extraction method, it is more environment-friendly but disadvantageous in terms of costs and processing time [15].

Crude oil, a product of oil extraction, is then refined to further improve the quality of the oil. Typically, oil refining process consists of several stages such as degumming, centrifugation, neutralization, oil bleaching, filtration, deaeration, and deodorization (**Figure 8**). Phospholipids are commonly removed by acid degumming using concentrated phosphoric acid at a temperature below 100°C. Phospholipids precipitated into gums are separated through centrifugation. Removal of free fatty acids (FFA) is done in the neutralization stage where alkaline solution such as sodium hydroxide is made to react with FFA forming soap stock which is removed again by centrifugation. Bleaching using adsorbents is employed to further improve the quality of the oil through the removal of other impurities and contaminants such as residual soap and gums, chlorophyll, oxidation products, and trace metals causing impurity reduction from 1.2 to 0.84% by mass. The recommended dosage loading of adsorbents used in the bleaching process are 17 kg bleaching earth and 5 kg activated carbon per metric ton of oil fed. These adsorbents are then removed by filtration while the bleached oil undergoes deaeration and deodorization. These last two stages of refining process aid in moisture and FFA removal to attain the desired 0.15% by mass moisture content and 0.025% by mass maximum FFA content of refined oil to be fed for biodiesel production [14, 16].

Transesterification is the main conversion technique for biodiesel production. This process involves the reversible reaction of oil or triglyceride to alcohol in the

#### **Figure 8.** *General process flow of oil refining.*

#### **Figure 9.**

*General process flow of biodiesel production.*

presence of a base catalyst forming fatty acid methyl esters (FAME) or biodiesel and glycerol. The process is usually carried out in a series of two batch transesterification reaction at 60°C (**Figure 9**). The initial reaction takes place for two hours causing a

#### *Comparative Analysis of Biodiesel Production from Different Potential Feedstocks… DOI: http://dx.doi.org/10.5772/intechopen.102724*

96% conversion of triglycerides to biodiesel. Glycerol, a by-product of the reaction, is immiscible with biodiesel and eventually settles forming a layer below the biodiesel. The glycerol layer along with 60% of the unreacted methanol is allowed to settle for an hour before being withdrawn out of the reactor and processed for purification. The biodiesel layer is then subjected to the second reaction to convert the remaining triglyceride to biodiesel with about 99.95% conversion [14, 16].

Conversion technologies have a significant impact on the competitiveness of biodiesel as alternative fuel since it relates to quality and productivity. Hence, development of advanced processing technologies for biodiesel has been the focus of many researches. More so, selection of a good complementary feedstock is important to bridge the gaps in the Philippine biodiesel industry.

### **4. Feedstock development**

Looking into feedstock development, three generations of biodiesel have been classified. The first-generation biodiesel is generally related to edible biomass sources such as food crops. However, with concerning issues and risks on food security, its implementation appears to have certain restrictions. Drawbacks of first-generation feedstocks led to growing interest on fuels produced from non-edible lignocellulosic biomass sources which are classified as second-generation biodiesel. These include fuels derived from forest and agricultural residues, animal wastes, and municipal solid wastes. Third generation biodiesel, on the other hand, include fuels that are produced from algal biomass or feedstocks which do not compete with food and arable lands [15].

#### **4.1 First-generation biodiesel**

#### *4.1.1 Coconut as biodiesel feedstock*

The Philippines is known as the world's second largest coconut producer and the top exporter of coconut products such as coconut oil. According to the Philippine Statistics Authority (PSA), 348 million coconut trees can be found in around 70 out of more than 80 provinces in the country in 2019, covering approximately a quarter of the total agricultural lands in the Philippines [17].

Biodiesel from coconut is derived specifically from the extracted oil from *copra. Copra* is the dried kernel part of the fruit which can be scooped out of the shell after drying up to a moisture content of about 6%. C*opra* is heated to 104–110°C in a conditioning unit to further improve oil extraction [14]. Crude coconut oil then undergoes oil refining process to increase the efficiency of the transesterification reaction for biodiesel production.

In the Philippines, a hectare of coconut plantation can yield 100 trees with an average nut yield per tree using the tall variety of 70 nuts annually. Equivalently, 1305 kg of *copra* is produced per hectare of coconut plantation per year. For an average yield of 605 liters of coco biodiesel per metric ton of *copra*, about 38,000 ha coconut plantation is needed to supply the nuts requirement of about 266 million per year for a commercial scale 30 million liter per year biodiesel capacity [16].

#### *4.1.2 Soybean as biodiesel feedstock*

In the Philippines, soybean is used primarily as a main ingredient in livestock feed because of its high protein content. However, due to insufficient domestic production, the country has been importing huge amounts of soybeans to meet the local demand. In 2019, the country's soybean gross supply was 178,772 metric tons in which only 659 metric tons or about 0.36% of the total supply was produced locally, and the remaining 178,113 metric tons (99.64%) was imported by the country. Domestic production of soybeans was reported to decrease at an average rate of −0.57% growth per year from 2017 to 2019 [18].

Aside from soybean meal, soybean processing also produces soybean oil as secondary product, making it one of the potential alternative feedstocks for biodiesel production. Solvent extraction is usually employed for an integrated soybean meal and biodiesel production system for a higher oil recovery and a more preferred soybean meal grade for animal feeds.

On the average, threshed soybean yield in the Philippines can reach 2.5 metric tons per hectare per cropping with a biodiesel potential of 100–129 liters per metric ton depending on the oil extraction method used. A total of 93,000–121,000 ha of soybean plantation, yielding about 233,000–302,000 metric tons threshed soybean per year is needed to supply the feedstock requirement for a commercial scale 30 million liter per year biodiesel plant [19].

#### *4.1.3 Oil palm as biodiesel feedstock*

Oil palm is a tropical tree crop typically grown in areas where rain is abundant. Normally, wild palms have a life span of up to 200 years while commercial palms only have 20–30 years economic life span [20]. Oil palm as a plantation crop is a highyielding source of two distinct oils such as palm oil and palm kernel oil (lauric oil) which can be obtained from the fibrous mesocarp or flesh of the fruit and kernel of the nut, respectively.

Similar to coconut oil, oil palm is identified as one of the alternative feedstocks for biodiesel production because it contains highly saturated vegetable fats [21]. Processing of oil palm includes bunch reception followed by sterilization and threshing to remove the fruit from the bunch. The fruitlets are then digested and pressed to extract the crude palm oil which undergoes clarification before the oil refining process.

The average yield of oil palm is 135 trees per hectare. About 20 metric tons of fresh fruit bunches (FFB) per hectare is harvested annually with a biodiesel potential of 188 liters per metric ton. For a 30 million liters per year biodiesel capacity, about 8000 ha of oil palm plantation is required to produce 160,000 metric tons of FFB per year [20, 21].

#### **4.2 Second-generation biodiesel**

#### *4.2.1 Jatropha curcas as biodiesel feedstock*

Jatropha is locally known as tubang-bakod and is considered as a potential source for biodiesel production due to its suitability in tropical and subtropical regions as well as its higher seed productivity and rapid growth [22]. On the average, it has a productive life span ranging from 35 to 50 years. Unlike other crops such as palm and coconut which takes about eight and four years, respectively before the first harvest, jatropha can be harvested in just 14 months [23]. Since this crop is not used for food applications, its potential as a biodiesel feedstock in the Philippines has grown interest. With an oil content of about 20–60%, jatropha is found to have a higher oil content than that of other oilseed crops such as palm oil. However, the high content of free fatty acids (FFA) in jatropha is seen as a disadvantage for biodiesel production since this requires an additional transesterification reaction to improve the biodiesel quality [24].

*Comparative Analysis of Biodiesel Production from Different Potential Feedstocks… DOI: http://dx.doi.org/10.5772/intechopen.102724*

On the average, the yield of jatropha is 2500 plants per hectare, producing about six to eight metric tons of seeds. With its biodiesel potential yield of 185 liters per metric ton, about 23,000 ha of jatropha plantation to produce approximately 160,000 metric tons of seeds is needed to supply the feedstock requirement for a commercial scale 30 million liter per year biodiesel plant [25, 26].

#### *4.2.2 Used cooking oil as biodiesel feedstock*

Used cooking oil has drawn considerable interest as a potential alternative source for biodiesel production due to its low cost and its availability at a huge quantity as waste. Though waste cooking oil has been used in soap production, most of its volume is discarded into the environment. Since feedstock cost is one of the primary concerns in biodiesel production, utilization of used cooking oil as feedstock can significantly contribute to cost savings.

At the optimum conditions of 6.51 mol/mol methanol-to-oil molar ratio, 0.171 mol/mol sodium hydroxide-to-oil molar ratio, 47.0°C, and 30-minute reaction time for the sodium hydroxide-catalyzed transesterification of used cooking oil, the percent mass yield of biodiesel is around 80. This means that approximately 8 kg of biodiesel can be produced from 10 kg of used cooking oil [27]. This results to a biodiesel potential yield of approximately 905 liters per metric ton. Hence, for a commercial scale 30 million liter per year biodiesel plant, about 34,000 metric tons of used cooking oil is required as feedstock annually.

#### **4.3 Third-generation biodiesel**

#### *4.3.1 Microalgae as biodiesel feedstock*

Microalgae have emerged as a suitable feedstock for biodiesel production due to its high lipid content, rapid biomass growth, and cultivation which does not compete with food crops for arable land [28]. As compared to other crop-based biodiesel feedstocks, microalgae appear to have the highest oil productivity [29].

Parametric studies on microalgae (*C. vulgaris)* as feedstock for biodiesel production revealed that maximum oil extraction efficiency of around 15% can be obtained using a biomass-to-solvent ratio of 1:14 at a 24-hr duration and a 1:2 (v/v) ratio of methanol-to-chloroform as solvent via Soxhlet method. Moreover, the optimum conditions for base-catalyzed transesterification for biodiesel production are 1:6:0.2 oil-to-methanol-sodium hydroxide molar ratio at 55°C reaction temperature and five minutes reaction time [30]. Meanwhile, the biodiesel potential yield of microalgae is 896 liters per metric ton. Hence, a total of 263 ha of cultivation area, yielding an annual biomass production of 34,000 metric tons is needed to supply the feedstock requirement for a commercial scale 30 million liter per year biodiesel plant.

### **5. Suitability assessment of biodiesel production from different feedstocks**

#### **5.1 Feedstock availability and biodiesel potential yield**

As shown in **Table 2**, in terms of biodiesel productivity which assumes maximum biomass conversion to biodiesel for the given possible available land area, coconut has the highest potential among the potential feedstocks considering the huge


#### **Table 2.**

*Biodiesel potential yield of different biodiesel feedstocks in the Philippines.*

plantation area for this crop of about a quarter of the total agricultural lands in the country. Even at a 5% blending mandate by 2025, the existing cropping area for coconut is almost four times greater than the area requirement to produce enough feedstock.

Moreover, oil palm is the second crop-based feedstock with the highest biodiesel productivity. Its utilization for biodiesel production in the Philippines has already been proposed as alternative to coconut oil, however, a more comprehensive study for its viability still needs to be conducted before its implementation as required by the Department of Energy (DOE) [31]. Once allowed as alternative feedstock, the potential available area for this crop can sustain almost half of the biodiesel requirement for a 5% blending rate in 2025.

Looking into the biodiesel potential, used cooking oil and microalgae have the highest maximum yield among the possible feedstocks. However, oil extraction from microalgae is still performed in lab-scale and no technology has been confirmed yet as to its practical application in large scale lipid extraction [15, 32]. Nonetheless, only around 6150 ha will be required as biomass cultivation area to achieve the biodiesel requirement in 2025 if microalgae will be used as feedstock. Similarly, utilization of used cooking oil for biodiesel production still requires further studies specifically on process optimization and raw material quality control [11]. Meanwhile, with the available quantity of used cooking oil, this feedstock can contribute about 4.50% of the total biodiesel requirement in 2025.


 *Carbon footprint and GHG reduction potential of different biodiesel feedstocks at varying blending rates.*

*Comparative Analysis of Biodiesel Production from Different Potential Feedstocks… DOI: http://dx.doi.org/10.5772/intechopen.102724*


#### **Table 4.**

*GHG savings of different biodiesel feedstocks at varying blending rates.*

#### **5.2 Carbon footprint and GHG reduction potential**

Along with issues on energy security considering the continuously increasing energy demand and diminishing fossil reserves, the alarming impacts of climate change also call for the adoption of sustainable development options. In response to this, the country committed for a 75% greenhouse gas (GHG) emissions reduction by 2030, in which 2.71% is unconditional and 72.29% is conditional based on the 2021 Nationally Determined Contribution (NDC). This is established against the forecasted business-as-usual cumulative emission of 3340.3 metric tons CO2e for the period 2020–2030 [33]. Hence, use of technologies that can substantially curb emissions, such as biofuels, is targeted. Compared to fossil fuel, biofuels can significantly lower carbon dioxide and carbon monoxide emissions by 78 and 50%, respectively [33].

In the Philippine setting, the biodiesel industry carbon footprint results to 1.4634 kg CO2e per liter. This was obtained by conducting Life Cycle Assessment (LCA) and taking into account a cradle-to-grave system boundary starting from feedstock cultivation up to biodiesel end-use. In Ref. to the GHG emission of petroleum diesel equal to 3.12 kg CO2e per liter, a GHG reduction potential of about 53.05% can be achieved upon full displacement of petroleum diesel by pure coconut methyl ester or coco biodiesel [14]. Correspondingly, at varying blending rates of 2, 5, 10, and 20%, the GHG reduction potential that can be attained are 1.06, 2.65, 5.31, and 10.61%, respectively. In 2021, 2% biodiesel blending has a potential GHG savings of 289,380 metric tons CO2e per year considering the total diesel demand of 8750 million liters. Implementing the 5% blending rate in 2025 will result to a significant hike in the potential avoided GHG emissions to nearly 1.32 million metric tons CO2e per year from the diesel demand projection of 16,000 million liters.

**Table 3** shows the carbon footprint and GHG reduction potential at varying blending percentages of different potential biodiesel feedstocks. Comparing the different feedstocks, biodiesel production from coconut has the lowest carbon footprint and highest GHG reduction potential, followed by oil palm. Oil palm biodiesel has a carbon footprint of 1.80 kg CO2e per liter and GHG reduction potential of 42% [20, 21]. This corresponds to a GHG savings of about 1.047 million metric tons CO2e per year for a 5% blending mandate in 2025 (**Table 4**). On the other hand, jatropha biodiesel and biodiesel derived from soybeans using solvent extraction results to a carbon footprint of 2.34 kg CO2e per liter and 1.93 kg CO2e per liter, which contributes about 25% and 38% reduction in GHG emissions, respectively [19, 34]. Potential GHG savings of the other feedstocks at varying biodiesel blending rates are also shown in **Table 4.**

*Comparative Analysis of Biodiesel Production from Different Potential Feedstocks… DOI: http://dx.doi.org/10.5772/intechopen.102724*

#### **5.3 Economic viability**

The cost of biodiesel production is highly affected by the feedstock which typically accounts for 70–80% of the total production cost [28, 32]. This led to a usually higher cost of biodiesel than petroleum-based diesel which is a major drawback for biodiesel commercialization in the country. Hence, selection of a more economically viable feedstock is a great advantage to boost the biodiesel industry in the Philippines.

In 2020, the average local price of crude CNO is Php 48.83 per liter. The price of biodiesel in the same year ranges from Php 35.00 to Php 71.00 per liter, whereas the diesel price is only around Php 35.16 per liter [11]. If sourced directly from copra based on farmgate price, a relatively lower biodiesel price can be achieved, ranging from Php 27.67 to Php 52.62 per liter [35]. In the case of oil palm as feedstock, a price equivalent to Php 22.72 per liter of commercially available crude palm oil results to a lower minimum selling price for biodiesel of Php 33.26 per liter, a return on investment of 14.44%, and a payback period of 5.75 years. Assuming the case of an integrated oil palm plantation and biodiesel plant, where the plantation is established from oil palm seeds, the biodiesel selling price is Php 33.53 per liter while the return on investment and payback period are 22.04% and 9.33 years, respectively [20, 21].

For jatropha biodiesel, sensitivity analysis revealed that at a seed price of Php 5.00 per kg, the selling price of biodiesel is Php 35.00 per liter to have a return on investment of 17.26% and a payback period of 3.85 years. However, use of crude jatropha oil as a bunker fuel is found more economically feasible than trans esterified crude Jatropha oil [36]. Similarly, biodiesel production from soybean appears to be economically unattractive as biodiesel price can go as high as Php 87.34 per liter depending on the crop yield and the prices of commodities. Soybean biodiesel production via solvent extraction results to a biodiesel price range of Php 48.49 to Php 84.52 per liter for manual farming and Php 33.36 to Php 67.71 per liter for mechanized farming. Using mechanical extraction, a price range of Php 38.93 to Php 87.34 per liter and Php 19.35 to Php 65.59 per liter can be obtained for manual and mechanized farming, respectively [19].

### **6. Conclusion**

The use of biofuels in the Philippines, in pursuant to Republic Act 9367 (also known as the Biofuels Act of 2006), is a valuable initiative as the country envisions action plans towards energy security and climate change mitigation. However, feedstock availability and pricing concerns remains the primary challenges hampering the growth of the biofuels industry. At present, biodiesel in the country is solely sourced from coconut. The mandated biodiesel blending to petroleum diesel remains stagnant at 2% due to marginally higher pump prices at increased blending of coco biodiesel. Hence, research and development studies on the viability of different potential feedstocks for biodiesel has been initiated.

In this chapter, potential feedstocks for biodiesel such as coconut, oil palm, soybean, jatropha, used cooking oil, and microalgae were assessed in terms of feedstock availability and biodiesel potential yield, carbon footprint and GHG reduction potential, and economic viability. Among the feedstocks, oil palm (first generation), used cooking oil (second generation), and microalgae (third generation) have the highest biodiesel potential yield. Considering the potential available area, oil palm is the most recommended feedstock having the second highest biodiesel productivity of 376 million liters per year, next to coconut. It also has a relatively lower carbon footprint of 1.80 kg CO2e per liter and a GHG reduction potential of 42% which is higher than the other sources. Moreover, its economic viability makes it a good complementary feedstock to coconut for biodiesel production since it results to a potentially lower biodiesel selling price of Php 33.26 per liter. Although other sources such as used cooking oil and microalgae have emerged as suitable alternative feedstocks, more comprehensive validation studies still need to be conducted for its practical application in biodiesel production.

Hence, ensuring economic and environmental sustainability is the challenge facing the biodiesel industry in the Philippines. It is therefore crucial to develop and establish appropriate and efficient processing technologies and pricing mechanisms, as well as to utilize low cost and readily available feedstocks to sustain the industry's growth.
