Woody and herbaceous biomasses have been utilized as biomass energy plant feedstocks that generat... more Woody and herbaceous biomasses have been utilized as biomass energy plant feedstocks that generate electricity for years. The coconut tree, classified as woody biomass, flourishes throughout tropical regions. Every year, each tree can produce an average of 70 nuts or a maximum of 150 nuts, with each fruit consisting of 15.18% shell. The Philippines has approximately 2.2 million tons of coconut shells each year. The study aims to determine the energy yield of the coconut shells when torrefied. The coconut shells were crushed, torrefied, and analyzed elementally. Initially, the calorific value of raw coconut shells was 30.79 MJ/kg and improved to 34.37 MJ/kg after torrefying at 275°C and held for 30 minutes. The optimal mass yield was 90.10%, while the energy density was 111.64%, resulting in an energy yield of 100.59%. Torrefaction improved the calorific value of coconut shells by 11.63% and optimized the energy yield to 100.59%.
Concentrated solar power is an alternative renewable energy technology that converts solar energy... more Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis approach that is widely used in energy and environmental engineering applications. In this paper, we review previous work on the applications of computational fluid dynamics in the design of concentrated solar power technology. We performed a bibliometric analysis of journal articles relevant to applications to analyze the current trend of utilization of computational fluid dynamics in these technologies. Then, we conducted a comprehensive analysis focused on the design of solar dish technology using computational fluid dynamics. Furthermore, we reviewed in detail the optical modeling of solar concentrators and solar receivers. Of the 83 retrieved publications from Scopus database, 80 ...
International Journal of Renewable Energy Research, 2022
Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and c... more Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and carbon-neutral plants, algae, and animals that can potentially be used as a bioenergy resource to replace fossil fuels. Coconut is one of the biomass feedstocks that are plentiful in tropical countries. The 347 million coconut trees planted in the Philippines produced 14.7 MT of nuts in 2020. The coconut shells (endocarp) comprise 15.18% of each coconut fruit, accounting for 2.2 MT of the total volume of coconuts. Torrefaction, the slow heating process from 200°C to 300°C, is a vital preprocessing step for improving biomass's physical qualities and chemical content. Coconut shells were torrefied using 200°C, 225°C, 250°C, 275°C, and 300°C at a residence time of 10mins, 15mins, and 30mins. At 275°C and residence time of 30mins, it was found that the moisture content was 2.00%, ash content was 0.60%, the volatile matter was 0.66%, fixed carbon was 96.70%, and the optimal high heating value (HHV) of 34.37 MJ/kg was achieved. The improvement indicates an increase of 11.64% from the heating value of raw coconut shells (RCS) at 30.79 MJ/kg. The study concurs with other researchers on the positive effect of torrefying biomass feedstock, particularly the coconut shells. It is concluded that torrefaction at 275°C and residence time of 30 mins will significantly improve the HHV of the coconut shells.
Engineering, Technology and Applied Science Research, 2022
Coconut is a biomass resource that is abundant in tropical countries. In 2020, the Philippines pl... more Coconut is a biomass resource that is abundant in tropical countries. In 2020, the Philippines planted 347 million coconut trees that produced 14.7 million tons of coconuts. The coconut shells (endocarp) are considered a waste material, which comprise 15.18% of each fruit and account for 2.2 million tons. The calorific value of raw coconut shells is 30.79MJ/kg. When torrefied at 275°C for 30 minutes holding time, the calorific value reached the optimal of 34.37MJ/kg, representing an increase of 11.64%. The mass yield (My) was 90.10% and the energy density was 111.64%, resulting in an energy yield of 100.59%.
International Journal of Renewable Energy Research , 2022
Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and c... more Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and carbon-neutral plants, algae, and animals that can potentially be used as a bioenergy resource to replace fossil fuels. Coconut is one of the biomass feedstocks that are plentiful in tropical countries. The 347 million coconut trees planted in the Philippines produced 14.7 MT of nuts in 2020. The coconut shells (endocarp) comprise 15.18% of each coconut fruit, accounting for 2.2 MT of the total volume of coconuts. Torrefaction, the slow heating process from 200°C to 300°C, is a vital preprocessing step for improving biomass's physical qualities and chemical content. Coconut shells were torrefied using 200°C, 225°C, 250°C, 275°C, and 300°C at a residence time of 10mins, 15mins, and 30mins. At 275°C and residence time of 30mins, it was found that the moisture content was 2.00%, ash content was 0.60%, the volatile matter was 0.66%, fixed carbon was 96.70%, and the optimal high heating value (HHV) of 34.37 MJ/kg was achieved. The improvement indicates an increase of 11.64% from the heating value of raw coconut shells (RCS) at 30.79 MJ/kg. The study concurs with other researchers on the positive effect of torrefying biomass feedstock, particularly the coconut shells. It is concluded that torrefaction at 275°C and residence time of 30 mins will significantly improve the HHV of the coconut shells.
Concentrated solar power is an alternative renewable energy technology that converts solar energy... more Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis approach that is widely used in energy and environmental engineering applications. In this paper, we review previous work on the applications of computational fluid dynamics in the design of concentrated solar power technology. We performed a bibliometric analysis of journal articles relevant to applications to analyze the current trend of utilization of computational fluid dynamics in these technologies. Then, we conducted a comprehensive analysis focused on the design of solar dish technology using computational fluid dynamics. Furthermore, we reviewed in detail the optical modeling of solar concentrators and solar receivers. Of the 83 retrieved publications from Scopus database, 80 were journal articles, and only three were review papers. Among these 80 journal articles, only 54 were relevant to this study, and 23 were relevant to solar dish technology. The documents were analyzed according to their number of citations, journal sources, and keyword evolution and network map. The information presented in this paper is useful to further recognize the contributions of computational fluid dynamics to the development of concentrated solar power, particularly to solar dish technology. In addition, we also discuss the challenges and future research directions to make solar energy a more sustainable source of renewable energy.
Concentrated solar power (CSP) is an alternative approach to harnessing the sun's power to genera... more Concentrated solar power (CSP) is an alternative approach to harnessing the sun's power to generate renewable energy. As the requirement for the generation of energy grows, the demand for concentrated solar power also increases. Recently, efforts in using CSP technology to generate renewable energy have been adopted globally, with a 6.45 GW capacity installed. With plans of the Philippines to further strengthen the country's energy production and enhance the production of renewable energy in Mindanao, this study proposes to design a CSP specifically for Davao City using a computational fluid dynamics approach. The parabolic dish and a receiver can accommodate a concentrator dish of 10 meters in aperture diameter for installation in Davao City. The design scale-up of the concentrator is then assessed with its efficiency using ANSYS Fluent. In addition, SolTrace and the fluent discrete ordinates radiation model can predict the potential thermal energy extracted from solar radiation. The results show the heat flux pattern in the CSP receiver entrance.
2021 IEEE International Conference on Environment and Electrical Engineering and 2021 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2021
Energy security is a very important requirement for economic growth and stability. Renewable ener... more Energy security is a very important requirement for economic growth and stability. Renewable energy (RE) growth is one of the key elements of this area. The utility-type or the large-scale use of solar photovoltaic (PV) panels to produce electricity is becoming one of the most cost-effective energy sources. Solar generation costs have declined over the past few years, driven by an explosion in PV cell output and production. The objective of this study was to present the viability – both the technical and the economic feasibility of a 5 MWp solar photovoltaic (PV) farm in a specific location in Butuan City, Philippines. This paper performed the technical and economic analysis based on present market conditions and the availability of local materials from solar panels to power inverters, the build-on-systems (BOS), and cost considerations in putting up the large-scale PV utility using the PVSyst Software as the simulation tool. For a 5 MWp system, the investment could reach close to 300 million pesos (or USD6.25M). However, the results of the simulations revealed very promising financial benefits over a long period or in the lifespan of the solar power farm. The payback period is at 4.23 years, the return of investments or the ROI is at 506.2%, and other economic indicators are all positives and great support for establishing the solar PV farm. Over the lifetime of the PV farm, a total of 109,828.4 tons of CO2 will be avoided using the solar farm project. The authors highly recommend the proposed solar farm project to be implemented based on the results of this study.
This paper analyzes the impending water and energy crisis in Davao City. Three statistical models... more This paper analyzes the impending water and energy crisis in Davao City. Three statistical models namely linear, exponential, and cubic were used to predict future water and energy demands. The Tamugan River offers a potential source to address this looming problem, yet, it has become a source of conflict mainly between the Davao City Water District and Hedcor, Inc. The former is bent on harnessing the river which is known to have an abundance of high-quality surface water, while the latter proposes to establish cascaded hydropower plants given the river's immense volume of flowing water. Notwithstanding the sincerity of both parties, the current conflict on who should harness the Tamugan River and how it be harnessed has to be resolved to avoid forestalling Davao City's development.
Woody and herbaceous biomasses have been utilized as biomass energy plant feedstocks that generat... more Woody and herbaceous biomasses have been utilized as biomass energy plant feedstocks that generate electricity for years. The coconut tree, classified as woody biomass, flourishes throughout tropical regions. Every year, each tree can produce an average of 70 nuts or a maximum of 150 nuts, with each fruit consisting of 15.18% shell. The Philippines has approximately 2.2 million tons of coconut shells each year. The study aims to determine the energy yield of the coconut shells when torrefied. The coconut shells were crushed, torrefied, and analyzed elementally. Initially, the calorific value of raw coconut shells was 30.79 MJ/kg and improved to 34.37 MJ/kg after torrefying at 275°C and held for 30 minutes. The optimal mass yield was 90.10%, while the energy density was 111.64%, resulting in an energy yield of 100.59%. Torrefaction improved the calorific value of coconut shells by 11.63% and optimized the energy yield to 100.59%.
Concentrated solar power is an alternative renewable energy technology that converts solar energy... more Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis approach that is widely used in energy and environmental engineering applications. In this paper, we review previous work on the applications of computational fluid dynamics in the design of concentrated solar power technology. We performed a bibliometric analysis of journal articles relevant to applications to analyze the current trend of utilization of computational fluid dynamics in these technologies. Then, we conducted a comprehensive analysis focused on the design of solar dish technology using computational fluid dynamics. Furthermore, we reviewed in detail the optical modeling of solar concentrators and solar receivers. Of the 83 retrieved publications from Scopus database, 80 ...
International Journal of Renewable Energy Research, 2022
Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and c... more Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and carbon-neutral plants, algae, and animals that can potentially be used as a bioenergy resource to replace fossil fuels. Coconut is one of the biomass feedstocks that are plentiful in tropical countries. The 347 million coconut trees planted in the Philippines produced 14.7 MT of nuts in 2020. The coconut shells (endocarp) comprise 15.18% of each coconut fruit, accounting for 2.2 MT of the total volume of coconuts. Torrefaction, the slow heating process from 200°C to 300°C, is a vital preprocessing step for improving biomass's physical qualities and chemical content. Coconut shells were torrefied using 200°C, 225°C, 250°C, 275°C, and 300°C at a residence time of 10mins, 15mins, and 30mins. At 275°C and residence time of 30mins, it was found that the moisture content was 2.00%, ash content was 0.60%, the volatile matter was 0.66%, fixed carbon was 96.70%, and the optimal high heating value (HHV) of 34.37 MJ/kg was achieved. The improvement indicates an increase of 11.64% from the heating value of raw coconut shells (RCS) at 30.79 MJ/kg. The study concurs with other researchers on the positive effect of torrefying biomass feedstock, particularly the coconut shells. It is concluded that torrefaction at 275°C and residence time of 30 mins will significantly improve the HHV of the coconut shells.
Engineering, Technology and Applied Science Research, 2022
Coconut is a biomass resource that is abundant in tropical countries. In 2020, the Philippines pl... more Coconut is a biomass resource that is abundant in tropical countries. In 2020, the Philippines planted 347 million coconut trees that produced 14.7 million tons of coconuts. The coconut shells (endocarp) are considered a waste material, which comprise 15.18% of each fruit and account for 2.2 million tons. The calorific value of raw coconut shells is 30.79MJ/kg. When torrefied at 275°C for 30 minutes holding time, the calorific value reached the optimal of 34.37MJ/kg, representing an increase of 11.64%. The mass yield (My) was 90.10% and the energy density was 111.64%, resulting in an energy yield of 100.59%.
International Journal of Renewable Energy Research , 2022
Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and c... more Biomass is biodegradable and non-fossilized organic materials derived from abundant, clean, and carbon-neutral plants, algae, and animals that can potentially be used as a bioenergy resource to replace fossil fuels. Coconut is one of the biomass feedstocks that are plentiful in tropical countries. The 347 million coconut trees planted in the Philippines produced 14.7 MT of nuts in 2020. The coconut shells (endocarp) comprise 15.18% of each coconut fruit, accounting for 2.2 MT of the total volume of coconuts. Torrefaction, the slow heating process from 200°C to 300°C, is a vital preprocessing step for improving biomass's physical qualities and chemical content. Coconut shells were torrefied using 200°C, 225°C, 250°C, 275°C, and 300°C at a residence time of 10mins, 15mins, and 30mins. At 275°C and residence time of 30mins, it was found that the moisture content was 2.00%, ash content was 0.60%, the volatile matter was 0.66%, fixed carbon was 96.70%, and the optimal high heating value (HHV) of 34.37 MJ/kg was achieved. The improvement indicates an increase of 11.64% from the heating value of raw coconut shells (RCS) at 30.79 MJ/kg. The study concurs with other researchers on the positive effect of torrefying biomass feedstock, particularly the coconut shells. It is concluded that torrefaction at 275°C and residence time of 30 mins will significantly improve the HHV of the coconut shells.
Concentrated solar power is an alternative renewable energy technology that converts solar energy... more Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis approach that is widely used in energy and environmental engineering applications. In this paper, we review previous work on the applications of computational fluid dynamics in the design of concentrated solar power technology. We performed a bibliometric analysis of journal articles relevant to applications to analyze the current trend of utilization of computational fluid dynamics in these technologies. Then, we conducted a comprehensive analysis focused on the design of solar dish technology using computational fluid dynamics. Furthermore, we reviewed in detail the optical modeling of solar concentrators and solar receivers. Of the 83 retrieved publications from Scopus database, 80 were journal articles, and only three were review papers. Among these 80 journal articles, only 54 were relevant to this study, and 23 were relevant to solar dish technology. The documents were analyzed according to their number of citations, journal sources, and keyword evolution and network map. The information presented in this paper is useful to further recognize the contributions of computational fluid dynamics to the development of concentrated solar power, particularly to solar dish technology. In addition, we also discuss the challenges and future research directions to make solar energy a more sustainable source of renewable energy.
Concentrated solar power (CSP) is an alternative approach to harnessing the sun's power to genera... more Concentrated solar power (CSP) is an alternative approach to harnessing the sun's power to generate renewable energy. As the requirement for the generation of energy grows, the demand for concentrated solar power also increases. Recently, efforts in using CSP technology to generate renewable energy have been adopted globally, with a 6.45 GW capacity installed. With plans of the Philippines to further strengthen the country's energy production and enhance the production of renewable energy in Mindanao, this study proposes to design a CSP specifically for Davao City using a computational fluid dynamics approach. The parabolic dish and a receiver can accommodate a concentrator dish of 10 meters in aperture diameter for installation in Davao City. The design scale-up of the concentrator is then assessed with its efficiency using ANSYS Fluent. In addition, SolTrace and the fluent discrete ordinates radiation model can predict the potential thermal energy extracted from solar radiation. The results show the heat flux pattern in the CSP receiver entrance.
2021 IEEE International Conference on Environment and Electrical Engineering and 2021 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2021
Energy security is a very important requirement for economic growth and stability. Renewable ener... more Energy security is a very important requirement for economic growth and stability. Renewable energy (RE) growth is one of the key elements of this area. The utility-type or the large-scale use of solar photovoltaic (PV) panels to produce electricity is becoming one of the most cost-effective energy sources. Solar generation costs have declined over the past few years, driven by an explosion in PV cell output and production. The objective of this study was to present the viability – both the technical and the economic feasibility of a 5 MWp solar photovoltaic (PV) farm in a specific location in Butuan City, Philippines. This paper performed the technical and economic analysis based on present market conditions and the availability of local materials from solar panels to power inverters, the build-on-systems (BOS), and cost considerations in putting up the large-scale PV utility using the PVSyst Software as the simulation tool. For a 5 MWp system, the investment could reach close to 300 million pesos (or USD6.25M). However, the results of the simulations revealed very promising financial benefits over a long period or in the lifespan of the solar power farm. The payback period is at 4.23 years, the return of investments or the ROI is at 506.2%, and other economic indicators are all positives and great support for establishing the solar PV farm. Over the lifetime of the PV farm, a total of 109,828.4 tons of CO2 will be avoided using the solar farm project. The authors highly recommend the proposed solar farm project to be implemented based on the results of this study.
This paper analyzes the impending water and energy crisis in Davao City. Three statistical models... more This paper analyzes the impending water and energy crisis in Davao City. Three statistical models namely linear, exponential, and cubic were used to predict future water and energy demands. The Tamugan River offers a potential source to address this looming problem, yet, it has become a source of conflict mainly between the Davao City Water District and Hedcor, Inc. The former is bent on harnessing the river which is known to have an abundance of high-quality surface water, while the latter proposes to establish cascaded hydropower plants given the river's immense volume of flowing water. Notwithstanding the sincerity of both parties, the current conflict on who should harness the Tamugan River and how it be harnessed has to be resolved to avoid forestalling Davao City's development.
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Papers by Randell U Espina