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Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO2) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO2 concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO2 gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L−1 day−1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min−1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg−1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment.

With the increasing awareness of green energy, electric vehicles have become the future trend, with lithium-ion batteries (LIBs) regarded as the most suitable energy storage carrier. Therefore, more and more research topics are focused on LIBs, and all parties are working hard to improve the performance of LIBs. Yet, the safety concerns caused by the failure of LIBs cannot be ignored. LIBs themselves are energetic materials, and the causes of accidents often go through multistage irreversible reactions. Several studies have also pointed out that the electrolyte has a significant correlation with the response characteristics because, in the process of LIBs thermal runaway, the electrolyte participating in the oxidation of the entire battery leads to a considerable amount of heat and even runaway reaction as well. Accordingly, it is necessary to obtain a safer electrolyte by modification. In this study, a significant flame retardant (FR) additive, tris (2,2,2-trifluoroethyl) phosphite (TTFP), is used to suppress lithium-ion battery fires or even explosions and maintain typical battery performance. The performance of the electrolyte was tested by differential scanning calorimetry and thermogravimetric analyzer, and the electrolysis was examined on liquid flash point (FP), self-extinguishing time (SET), and conductivity. During the heating process, adding TTFP to the electrolyte effectively delayed the exothermic peak, reduced the amount of heat, improved the FP, and curtailed the SET. The hazard degree of the electrolyte under high-temperature environment was much lower than before adding the additives, and the additives were finally obtained. It can conclusively prove the safety of lithium batteries without lessening the practical performance of the batteries.

Solar energy is a renewable energy source that can be utilized for different applications in today’s world. The effective use of solar energy requires a storage medium that can facilitate the storage of excess energy, and then supply this stored energy when it is needed. An effective method of storing thermal energy from solar is through the use of phase change materials (PCMs). PCMs are isothermal in nature, and thus offer higher density energy storage and the ability to operate in a variable range of temperature conditions. This article provides a comprehensive review of the application of PCMs for solar energy use and storage such as for solar power generation, water heating systems, solar cookers, and solar dryers. This paper will benefit the researcher in conducting further research on solar power generation, water heating system, solar cookers, and solar dryers using PCMs for commercial development.

Biodiesels have gained much popularity because they are cleaner alternative fuels and they can be used directly in diesel engines without modifications. In this paper, a brief review of the key studies pertaining to the engine performance and exhaust emission characteristics of diesel engines fueled with biodiesel blends, exhaust aftertreatment systems, and low-temperature combustion technology is presented. In general, most biodiesel blends result in a significant decrease in carbon monoxide and total unburned hydrocarbon emissions. There is also a decrease in carbon monoxide, nitrogen oxide, and total unburned hydrocarbon emissions while the engine performance increases for diesel engines fueled with biodiesels blended with nano-additives. The development of automotive technologies, such as exhaust gas recirculation systems and low-temperature combustion technology, also improves the thermal efficiency of diesel engines and reduces nitrogen oxide and particulate matter emissions.

Petroleum-based plastics are associated with environmental pollution problems owing to their non-biodegradable and toxic properties. In this context, renewable and biodegradable bioplastics possess great potential to replace petroleum-based plastics in mitigating these environmental issues. Fabrication of bioplastic films involves a delicate mixture of the film-forming agent, plasticizer and suitable solvent. The role of the plasticizer is to improve film flexibility, whereas the filler serves as a reinforcement medium. In recent years, much research attention has been shifted toward devising diverse methods for enhancing the performance of bioplastics, particularly in the utilization of environmentally benign nanoparticles to displace the conventional hazardous chemicals. Along this line, this paper presents the emergence of nanofillers and plasticizers utilized in bioplastic fabrication with a focus on starch-based bioplastics. This review paper not only highlights the influencing factors that affect the optical, mechanical and barrier properties of bioplastics, but also revolves around the proposed mechanism of starch-based bioplastic formation, which has rarely been reviewed in the current literature. To complete the review, prospects and challenges in bioplastic fabrication are also highlighted in order to align with the concept of the circular bioplastic economy and the United Nations’ Sustainable Development Goals.

Global energy sources are being transformed from hydrocarbon-based energy sources to renewable and carbon-free energy sources such as wind, solar and hydrogen. The biggest challenge with hydrogen as a renewable energy carrier is the storage and delivery system’s complexity. Therefore, other media such as ammonia for indirect storage are now being considered. Research has shown that at reasonable pressures, ammonia is easily contained as a liquid. In this form, energy density is approximately half of that of gasoline and ten times more than batteries. Ammonia can provide effective storage of renewable energy through its existing storage and distribution network. In this article, we aimed to analyse the previous studies and the current research on the preparation of ammonia as a next-generation renewable energy carrier. The study focuses on technical advances emerging in ammonia synthesis technologies, such as photocatalysis, electrocatalysis and plasmacatalysis. Ammonia is now also strongly regarded as fuel in the transport, industrial and power sectors and is relatively more versatile in reducing CO2 emissions. Therefore, the utilisation of ammonia as a renewable energy carrier plays a significant role in reducing GHG emissions. Finally, the simplicity of ammonia processing, transport and use makes it an appealing choice for the link between the development of renewable energy and demand.

Biodiesel is gaining prominence as a superior alternative source of energy to replace petroleum-based fuel in transportation. As of today, the biodiesel market continuous to rise up as the biofuel has been introduced to more than 60 countries worldwide. The aim of the present review is to highlight on the scenario of the biofuel implementation in transportation sector towards sustainable development in Colombia and Malaysia. Colombia serves as an ideal comparative case for Malaysia in terms of biodiesel development since the country is the main palm oil producer in Latin America region and the pioneer in bioethanol industry. The first section shows an overview on the biodiesel as an alternative fuel in transportation. The next section will focus on a comparative study between Malaysia and Colombia biodiesel sector in terms of energy supply, resource, production and consumption, standards, techno-economic cost and their biodiesel policies. A comprehensive review was studied to discuss on the sustainability of palm cultivation and biodiesel, impact of palm industry and biodiesel policy in transportation sector and potential international collaboration between Malaysia and Colombia to improve their existing policies, strategies and blueprints related to the palm biodiesel industry, thus overcoming the challenges when dealing with global energy issue.

Biodiesel is a clean, renewable, liquid fuel that can be used in existing diesel engines without modification as pure or blend. Transesterification (the primary process for biodiesel generation) via heterogeneous catalysis using low-cost waste feedstocks for catalyst synthesis improves the economics of biodiesel production. Heterogeneous catalysts are preferred for the industrial generation of biodiesel due to their robustness and low costs due to the easy separation and relatively higher reusability. Calcium oxides found in abundance in nature, e.g., in seashells and eggshells, are promising candidates for the synthesis of heterogeneous catalysts. However, process improvements are required to design productive calcium oxide-based catalysts at an industrial scale. The current work presents an overview of the biodiesel production advancements using calcium oxide-based catalysts (e.g., pure, supported, and mixed with metal oxides). The review discusses different factors involved in the synthesis of calcium oxide-based catalysts, and the effect of reaction parameters on the biodiesel yield of calcium oxide-based catalysis are studied. Further, the common reactor designs used for the heterogeneous catalysis using calcium oxide-based catalysts are explained. Moreover, the catalytic activity mechanism, challenges and prospects of the application of calcium oxide-based catalysts in biodiesel generation are discussed. The study of calcium oxide-based catalyst should continue to be evaluated for the potential of their application in the commercial sector as they remain the pivotal goal of these studies.

Microalgae have received widespread interest owing to their potential in biofuel production. However, economical microalgal biomass production is conditioned by enhancing the lipid accumulation without decreasing growth rate or by increasing both simultaneously. While extensive investigation has been performed on promoting the economic feasibility of microalgal-based biofuel production that aims to increase the productivity of microalgae species, only a handful of them deal with increasing lipid productivity (based on lipid contents and growth rate) in the feedstock production process. The purpose of this review is to provide an overview of the recent advances and novel approaches in promoting lipid productivity (depends on biomass and lipid contents) in feedstock production from strain selection to after-harvesting stages. The current study comprises two parts. In the first part, bilateral improving biomass/lipid production will be investigated in upstream measures, including strain selection, genetic engineering, and cultivation stages. In the second part, the enhancement of lipid productivity will be discussed in the downstream measure included in the harvesting and after-harvesting stages. An integrated approach involving the strategies for increasing lipid productivity in up- and down-stream measures can be a breakthrough approach that would promote the commercialization of market-driven microalgae-derived biofuel production.

Biodiesel is an alternative to fossil fuels for diesel engines, yet actual biofuel properties need to be tuned to comply with fuel standards. In particular, fuel stability is required for efficiency and commercial use. Fuel stability varies with the nature and proportion of chemical functional groups of biodiesel. Optimum oxidation stability is required because degradation by oxidation gives products that compromise fuel properties and impair fuel quality and engine performance. For instance, oxidation induces the formation of short-chain corrosive acids and deposits. Here, we review techniques to improve the oxidation stability of biodiesel. For instance, stability is improved by additives such as antioxidants. Factors influencing oxidation stability include composition of fatty acids, acid content, peroxide content, iodine content, viscosity, insoluble impurities, external conditions, and storage material. Antioxidants reduce lipid peroxidation at the beginning of the chain reaction and increase the onset temperatures.