• Energy Research

Biofuel production by oleaginous microalgae is a promising alternative to the conventional fossil fuels. Many microalgae species have been investigated and deemed as potential renewable sources for the production of biofuel, biogas, food supplements and other products. Oleaginous microalgae, named for their ability to produce oil, are reported to store 30–70% of lipid content due to its metabolic properties under nutrient starvation conditions. This review presents the assortment of the research studies focused on biofuel production from oleaginous microalgae. The new methods and technologies developed for oleaginous microalgae cultivation to improve their biomass content and lipid accumulation capacity were reviewed. The production of renewable, carbon neutral, bio-based or microalgae-based transport fuels are necessary for environmental protection and economic sustainability. Microalgae are a significant source of renewable biodiesel because of their ability to produce oils in the presence of sunlight more efficiently than that of crop oils. This review will provide the background to understanding the bottlenecks and the need for improvement in the cultivation or harvesting process for oleaginous microalgae.

Abstract Microalgae are promising sustainable energy sources for biodiesel production due to their rapid photosynthesis growth rate and capacity to be cultivated in wastewater, seawater, or freshwater. Moreover, microalgae could complete the entire growth cycle via photosynthesis reactions that convert light energy into renewable energy. The closed photobioreactor, PBR is resistant to infection from uninhabited algae species and allows frequent monitoring of various factors such as temperature, light intensity, and pH during the cultivation phase. Thus, this study focuses on continuous cultivation technology which produces higher biomass productivity with sustainable energy-saving operation as compared to batch culture. High productivity of microalgae biomass tends to accumulate higher concentrations of lipid and carbohydrates composition which is essential for the production of biofuels. The energy balance of numerous microalgae-based biofuels was discussed, and it was discovered that the net-energy ratio was greater than 1, indicating that the process is both commercially feasible and environmentally friendly. This study also summarizes the most recent discoveries on continuous cultivation constraints through photobioreactors, PBRs as well as potential challenges to tackle in scaling up the continuous sustainable culture mechanism. The research gaps, market opportunities, and future development directions of continuous photobioreactor systems are discussed to explore future development opportunities. A continuous photobioreactor, architecture is recommended for a pilot-scale trial, as a cost-benefit comparison would be beneficial in commercializing the framework.

The management of solid waste presents a challenge for developing countries as the generation of waste is increasing at a rapid and alarming rate. Much awareness towards the sustainability and technological advances for solid waste management has been implemented to reduce the generation of unnecessary waste. The recycling of this waste is being applied to produce valuable organic matter, which can be used as fertilizers or amendments to improve the soil structure. This review studies the sustainable transformation of various types of biomass waste such as animal manure, sewage sludge, municipal solid waste, and food waste, into organic fertilizers and their impact on waste minimization and agricultural enhancement. The side effects of these organic fertilizers towards the soil are evaluated as the characteristics of these fertilizers will differ depending on the types of waste used, in addition to the varying chemical composition of the organic fertilizers. This work will provide an insight to the potential management of biomass waste to be produced into organic fertilizer and the advantages of substituting chemical fertilizer with organic fertilizer derived from the biomass waste.

Abstract Southeast Asia is vulnerable to climate change with over half of its population already being impacted by drought, flooding, and rise in sea levels recently. This work reviews the current water resource challenges in Indonesia, prone to the rising impacts of climate change. A baseline assessment of Indonesia's water and drinking water resources related to its original sources is presented. In response to a growing concern over chronic challenges that undermine water supply nationwide, this study analyses drinking water safety supervision. To accomplish this, a literature survey (100 studies published during the 2000–2023 period) was performed to identify regional groundwater resources sustainability and water security issues. Among the main findings of this study, only 10% of rainfall infiltrates to the groundwater, while 70% of its rivers are heavily polluted by domestic waste. During the study period, water availability decreased to 1,200 m3/year in 2020, with only 35% of the resources being economically feasible for reuse. The water supply deficit in Indonesia was estimated to be 5.5 hm3/year with roughly 67% of the population's water demand satisfied in 2021. Although this deficit might be fulfilled with private vendors, water supply/demand forecasts in 2030 suggest that the gap could not be closed by increasing water supply.

The non-renewable nature of fossil energy and the environmental pollution caused by its use, such as haze, make it very urgent to develop clean and efficient renewable energy. By using microalgae biomass as an alternative raw material energy sources like biohydrogen, methane can be produced through fermentation and photosynthesis. Unlike solar energy, which has the disadvantages of low energy density, instability and difficulty in storage, biohydrogen and biogas are one of the novel ideal energy sources at present. The utilization of microalgae has various attractive prospects in their production due to its cost-effectiveness, renewable biomass and ease of scaling-up technology. This paper discusses the latest microalgae biomass biohydrogen and biogas production technology including integrated biorefinery systems, co-production or mixed production techniques and puts forward the key problems to be solved in the development of microalgae biohydrogen production technology.

In this present study, microalgal phycobiliproteins were isolated and purified via potential biphasic processing technique for pharmaceutical as well as food applications. The algal pre-treatment techniques were studied to enhance the yield of microalgal phycobiliproteins from the biomass. The proposed methods were optimised to obtain the best recovery yield of phycobiliproteins that can be isolated from the biomass. The phycobiliproteins were further purified using liquid biphasic system. The results showed that microalgal phycobiliproteins of high purity and yield was achieved using sonication treatment (20% power, 50% duty cycle and 7 min of irradiation time) with the biphasic system, where the purification fold of 6.17 and recovery yield of 94.89% was achieved. This work will provide insights towards the effective downstream processing of biomolecules from microalgae.

The pursuit of carbon neutrality confronts the twofold challenge of meeting energy demands and reducing pollution. This review article examines the potential of gasifying plastic waste and biomass as innovative, sustainable sources for hydrogen production, a critical element in achieving environmental reform. Addressing the problem of greenhouse gas emissions, the work highlights how the co-gasification of these feedstocks could contribute to environmental preservation by reducing waste and generating clean energy. Through an analysis of current technologies, the potential for machine learning to refine gasification for optimal hydrogen production is revealed. Additionally, hydrogen storage solutions are evaluated for their importance in creating a viable, sustainable energy infrastructure. The economic viability of these production methods is critically assessed, providing insights into both their cost-effectiveness and ecological benefits. Findings indicate that machine learning can significantly improve process efficiencies, thereby influencing the economic and environmental aspects of hydrogen production. Furthermore, the study presents the advancements in these technologies and their role in promoting a transition to a green economy and circular energy practices. Ultimately, the review delineates how integrating hydrogen production from unconventional feedstocks, bolstered by machine learning and advanced storage, can contribute to a sustainable and pollution-free future.

Il existe une forte demande pour une source d'énergie propre, abordable et durable en raison de la limitation de l'approvisionnement en combustibles fossiles. Les révolutions industrielles des algues se sont avérées être une étape importante pour réaliser le besoin croissant d'énergie et atteindre les objectifs de développement durable (ODD). Dans cette revue, la production et le traitement des algues d'un point de vue industriel et le traitement des algues dans l'industrie 4.0 ainsi qu'un changement de paradigme de l'industrie 4.0 à l'industrie 5.0 ont été bien délimités. De plus, de nombreux aspects de l'industrie des algues ont été discutés, notamment l'analyse économique et environnementale de la production de bioénergie des algues, la personnalisation de la bioénergie dérivée des algues, la culture des algues et les modifications de l'approche culturale. Les outils de génie génétique mis en œuvre dans la culture d'algues pour la production de bioénergie et de sous-produits ont également été étudiés, ainsi que des domaines de concentration tels que la souche d'algues souhaitée et sa détection par manipulation génétique automatisée et modification génétique. En outre, les impacts de l'Industrie 5.0 sur les nouvelles opportunités de marché et l'aspect environnemental ainsi que la possibilité d'atteindre les ODD ont été étudiés de manière significative. Existe una gran demanda de fuentes de energía limpias, asequibles y sostenibles debido a la limitación en el suministro de combustibles fósiles. Las revoluciones industriales de las algas han demostrado ser un paso significativo para darse cuenta de la creciente necesidad de energía y lograr los objetivos de desarrollo sostenible (ODS). En esta revisión, la producción y el procesamiento de algas desde el punto de vista de la industria y el procesamiento de algas en la Industria 4.0, así como un cambio paradigmático de la Industria 4.0 a la Industria 5.0, estuvieron bien delineados. Además, se han discutido numerosos aspectos en la industria de las algas, incluido el análisis económico y ambiental de la producción de bioenergía de las algas, la personalización de la bioenergía derivada de las algas, el cultivo de algas y las modificaciones en el enfoque de cultivo. También se estudiaron las herramientas de ingeniería genética implementadas en el cultivo de algas para la generación de bioenergía y subproductos, y el área de enfoque como la cepa de algas deseada y su detección a través de la manipulación genética automatizada y la modificación genética. Además, se estudiaron significativamente los impactos de la Industria 5.0 en el aspecto de nuevas oportunidades de mercado y medio ambiente, así como la posibilidad de alcanzar los ODS. There is a high demand for clean, affordable and sustainable source of energy due to the limitation in fossil fuel supplies. The algae industrial revolutions have proved to be a significant step to realize the growing need for energy and achieving the sustainable development goals (SDGs). In this review, the production and processing of algae from an industry point of view and the algae processing in Industry 4.0 as well as a paradigmatic shift from Industry 4.0 to Industry 5.0 were well-delineated. Moreover, numerous aspects in the algae industry have been discussed, including economic and environmental analysis of algae bioenergy production, customization of the algae-derived bioenergy, algae cultivation and modifications in the cultivating approach. Genetic engineering tools implemented in the algae culture for bioenergy and by-products generation was also studied, and area of focusing such as the desired algae strain and its detection through automated genetic manipulation and genetic modification. Furthermore, the impacts of the Industry 5.0 on the new market opportunities and environment aspect as well as the possibility of achieving SDGs were significantly studied. هناك طلب كبير على مصادر الطاقة النظيفة والميسورة التكلفة والمستدامة بسبب محدودية إمدادات الوقود الأحفوري. أثبتت الثورات الصناعية للطحالب أنها خطوة مهمة لتحقيق الحاجة المتزايدة للطاقة وتحقيق أهداف التنمية المستدامة (SDGs). في هذه المراجعة، تم تحديد إنتاج ومعالجة الطحالب من وجهة نظر الصناعة ومعالجة الطحالب في الصناعة 4.0 بالإضافة إلى التحول النموذجي من الصناعة 4.0 إلى الصناعة 5.0 بشكل جيد. علاوة على ذلك، تمت مناقشة العديد من الجوانب في صناعة الطحالب، بما في ذلك التحليل الاقتصادي والبيئي لإنتاج الطاقة الحيوية للطحالب، وتخصيص الطاقة الحيوية المستمدة من الطحالب، وزراعة الطحالب والتعديلات في نهج الزراعة. كما تمت دراسة أدوات الهندسة الوراثية المنفذة في استزراع الطحالب للطاقة الحيوية وتوليد المنتجات الثانوية، ومجال التركيز مثل سلالة الطحالب المرغوبة واكتشافها من خلال التلاعب الوراثي الآلي والتعديل الوراثي. علاوة على ذلك، تمت دراسة تأثيرات الصناعة 5.0 على فرص السوق الجديدة والجانب البيئي بالإضافة إلى إمكانية تحقيق أهداف التنمية المستدامة بشكل كبير.