The world faces the threat of an energy crisis that is exacerbated by the dominance of fossil energy sources that negatively impact the sustainability of the earth’s ecosystem. Currently, efforts to increase the supply of renewable energy have become a global agenda, including using solar energy which is one of the rapidly developing clean energies. However, studies in solar photovoltaic (PV) modelling that integrates geospatial information of urban morphological building characters, solar radiation, and multiple meteorological parameters in low-cost scope have not been explored fully. Therefore, this research aims to model the urban rooftop solar PV development in the Global South using Bandung, Indonesia, as a case study. This research also has several specific purposes: developing a building height model as well as determining the energy potential of rooftop solar PV, the energy needs of each building, and the residential property index. This study is among the first to develop the national digital surface model (DSM) of buildings. In addition, the analysis of meteorological effects integrated with the hillshade parameter was used to obtain the solar PV potential value of the roof in more detail. The process of integrating building parameters in the form of rooftop solar PV development potential, energy requirements, and residential property index of a building was expected to increase the accuracy of determining priority buildings for rooftop solar PV deployment in Bandung. This study shows that the estimated results of effective solar PV in Bandung ranges from 351.833 to 493.813 W/m², with a total of 1316 and 36,372 buildings in scenarios 1 and 2 being at a high level of priority for solar PV development. This study is expected to be a reference for the Indonesian government in planning the construction of large-scale rooftop solar PV in urban areas to encourage the rapid use of clean energy. Furthermore, this study has general potential for other jurisdictions for the governments focusing on clean energy using geospatial information in relation with buildings and their energy consumption.

This article presents an engineering study of an integrated system to produce bio-oil from microalgae biomass. The analysis is based on a pilot plant located at Minami-soma Fukushima, Japan, which further simulates 1 ha based-cultivation. Municipal wastewater and flue gases were utilized as nutrient sources for the microalgae culture of the proposed design. A flow sheet diagram of the integrated plant was synthesized by process engineering software to allow simulation of a continuous system. The design and sizing of the process equipment were performed to obtain a realistic estimation of possible production cost. The results demonstrated that nutrient savings was achieved by wastewater and CO₂ utilization to the polyculture of native microalgae. Process simulation gave an estimated CO₂ sequestration of 82.77 to 140.58 tons ha⁻¹year⁻¹ with 63 to 107 tons ha⁻¹year⁻¹ of potential biomass production. The integrated process significantly improved the energy balance and economics of biofuel production and also the wastewater treatment plant (WWTP). The economic analysis confirmed that higher biomass production and technology improvement were required to achieve operational feasibility and profitability of the current microalgae-based bio-oil production.

Microalgae is a biofuel crop that needs large amounts of water and nutrients in cultivation stage and requires excessive energy at the downstream processes. This study presented an integrated plantation concept to accomplish these issues by material and energy balance optimization of microalgae based biodiesel production cycle. Significant potency of positive energy balance by utilizing agriculture waste water from Palm Oil Mill Effluent (POME) was comprehensively investigated. However, POME has rich nutrient compounds for microalgae growth and its utilization reduces energy penalty. The total energy balance indicated substantial figures, in range of 2.66 up to 3.05 or even higher following the system efficiency. Meanwhile, total energy output for 1 production cycle in 10ha microalgae pond approximately 160 GJ and net energy produced reaches 100 GJ. Based on current best available methods or technologies, microalgae cultivation for biofuels by using wastewater provide a positive energy return and might be economically viable