• Energy Research
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• 13. Climate action close
• University of North Sumatra close

Abstract Bottlenecks on the development of biodiesel production could be eliminated using direct transesterification (DT). This review presents a comprehensive overview for DT from oleaginous seed crops (edible and non-edible), microalgal and fungal/yeast biomass. Effects of key operational parameters, affecting the yield of biodiesel, such as feedstock, feedstock processing technologies, feedstock water content, catalyst choice, temperature, co-solvent and reaction time are summarised and critically assessed. 15% and 68% of published data showed high fatty acid (FA) yields and FA to fatty acid methyl ester (FAME) conversion efficiencies, respectively. Highest fatty acid yielding feedstock were Jatropha and a novel non-edible Mediterranean crop, Cynara cardunculus, the microalgae Chlorella and Nannochloropsis, and the fungi/yeast Trichosporon oleaginosus, Rhodosporidium toruloides, Lipomyces starkeyi, Mortierella isbellina, and Pichia guilliermondi. For wet microalgal biomass, a preference for acid-catalysed direct transesterification was determined, while base-catalysed DT was more suitable for dry biomass, except for turbo-thin film-assisted DT of microalgal biomass. The data highlight that DT operational parameters and technologies need optimisation for feedstock and water content and outcomes may be strongly strain-dependent for microalgal feedstock. To bring commercial biodiesel potential of some high-yielding feedstock to reality, comprehensive life cycle – and techno-economic analyses are required for intensified and non-intensified DT processing, taking feedstock production and possibilities of biorefinery concepts into account whilst also focussing on those processing platforms that can esterify fatty acids in wet biomass.

AbstractDeveloping countries located in the tropics have favorable climates to develop modern agriculture and agriculture‐based industry. Peru and Indonesia are examples of two developing countries located in the tropics with economies based on the export of agricultural products. The generation of agricultural and forest residues has continuously increased in these countries. In this paper, we analyze the availability of agricultural and forest products in Peru and Indonesia in order to calculate the number of residues that could potentially be used for different applications such as energy generation and composite materials production. A single index taking into account the technical, economic, and environmental performance of these residues‐based products was utilized to compare them. The results showed that, in addition to the generation of energy, the production of plastic bio‐based composites and activated carbon are viable alternatives for the use of these residues.

The long-term use of fossil energy has expected to be exhausted if there is no breakthrough for renewable energy. Energy source future will become extinct along with the increasing energy needs and population, which impacts on energy consumption. Electrical energy sources by industry, households, offices, and schools are needed. For this reason, the development of biomass produced from rice husk as organic waste with developed through the biobriquette method has expected to provide a solution to overcome future energy scarcity. Besides, it can also be utilized for the development of adequate electrical energy in rural areas of Indonesia. As an agrarian country, most of its population depends on livelihoods in the agricultural sector. The biobriquette has developed used rice husk as the main of raw material plus other components as an adhesive. Therefore, to create high-quality briquettes and produce charcoal as fuel in driving steam turbines within power plants, further analysis is needed. The advanced method is necessary to develop in Indonesia. The rice husk has easily obtained and able to supply raw materials for processing briquette biomass at a more economical and efficient cost compared to biomass using gasification, pyrolysis, liquefaction, and biochemical methods. So far, rice husk only turns into a waste of rice refinery production without any use as electrical energy.

Turning off the electric lamp during available daylight will save electricity, while at the same time thermal energy from solar radiation transmitted through the window will increase the space-cooling load. Therefore, it is necessary to evaluate the whole system that includes not only the room space with the windows and the electric lighting systems, but also the air conditioning system. For analysis of the whole system using different types of energy (i.e. electricity, solar radiation, light emitted by lamps and thermal energy), it is important to take into account the quality of these different types of energy. The concept of entropy and exergy were applied in this analysis. The purpose of this study is to show the energy use for daylighting, electric lighting, and space cooling systems as a series of exergy input, output, and consumption and reveal how a daylighting system consumes solar exergy and how electric lighting and space cooling systems consume exergy from fossil fuel. The methodology to calculate the exergy consumption of the system during a given time was developed first. This method was then applied to the lighting and cooling for a typical room. The study found that electric lighting consumes the lowest amount of exergy while the space cooling consumes the highest amount of exergy for the system.

The motorcycle is one of the most vehicles as a means of transportation for Indonesians today. It can be said that almost all motorcycles use gasoline. Overall, this condition is quite large and absorbs national fuel consumption. This study aims to develop a technique in order to save fuel consumption on a motorcycle by installing microcontroller equipment. Tests are carried out on the highway in at varying speeds from 30 km/h to 80 km/h. Testing is done by comparing the consumption of gasoline fuel on a motorcycle before and after using a microcontroller. The research results show that there is saving in gasoline fuel consumption on a motorcycle after using a microcontroller. The fuel saving ranges from 15% to 45% for each variation in engine speed.