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Significant efforts are being made to produce biofuels to replace fossil fuels and address the issues caused by global climate change. Due to its potential better conversion efficiency to useable power, decreased emission of pollutants, and high energy density, H 2 is one of the prospective options that are seen as a desirable future clean energy carrier. Although there are numerous technologies available for producing H 2 , this review concentrates on fermentative H 2 production techniques, their drawbacks, and current developments. While being a promising method, fermentative strategies still have several drawbacks, including low H 2 production yields. Many approaches have been used to address these issues; among them, the field of metabolic pathway engineering has made enormous strides. To improve H 2 generation, this paper reviewed and discussed several metabolic pathways and modified strains. As well as the challenges involved in H 2 scale-up from a laboratory setting to a commercial scale. • Biohydrogen production via fermentative methods is reviewed and elaborated. • Metabolic engineering methods are proposed for scaling up fermentative biohydrogen. • Challenges of fermentative biohydrogen production and potential solutions. • Bionanotechnology and modified strains enhanced biohydrogen production. [ABSTRACT FROM AUTHOR]

Abstract Considering the overwhelming pressure on worldwide demand of fossil fuels and the climate change caused by air pollution, hybrid electric vehicles have seen a promising future thanks to the development of renewable energy sources. Among various kinds of energy sources that have been used in hybrid electric vehicles, lithium-ion battery and proton exchange membrane (PEM) fuel cell exist to be the most favorable ones owing to their high energy density and power density. However, the degradation issues of the energy sources tend to be neglected when designing the energy management strategies for the hybrid electric vehicles. Concerning existing literature, degradation modelling methods of lithium-ion batteries and PEM fuel cells are reviewed and the possibility of integrating them into health-conscious energy management is discussed. Besides, a variety of energy management strategies that have taken the influence of degradations into consideration are reviewed and classified. The contribution of this paper is to investigate the possibility of developing a health-conscious energy management strategy based on accurate estimation of degradation to improve the durability of the system. Highlights • Degradation modelling and estimation methods for lithium-ion batteries and PEM fuel cells are summarized and compared. • A review of the progress made for involving health management into energy management strategies is provided. • The challenges and unresolved issues for developing health-conscious EMSs are discussed. [ABSTRACT FROM AUTHOR]

Abstract Heavy fossil fuels consumption has raised concerns over the energy security and climate change while hydrogen is regarded as the fuel of future to decarbonize global energy use. Hydrogen is commonly used as feedstocks in chemical industries and has a wide range of energy applications such as vehicle fuel, boiler fuel, and energy storage. However, the development of hydrogen energy in Malaysia is sluggish despite the predefined targets in hydrogen roadmap. This paper aims to study the future directions of hydrogen economy in Malaysia considering a variety of hydrogen applications. The potential approaches for hydrogen production, storage, distribution and application in Malaysia have been reviewed and the challenges of hydrogen economy are discussed. A conceptual framework for the accomplishment of hydrogen economy has been proposed where renewable hydrogen could penetrate Malaysia market in three phases. In the first phase, the market should aim to utilize the hydrogen as feedstock for chemical industries. Once the hydrogen production side is matured in the second phase, hydrogen should be used as fuel in internal combustion engines or burners. In the final phase hydrogen should be used as fuel for automobiles (using fuel cell), fuel-cell combined heat and power (CHP) and as energy storage. Highlights • Biomass and solar pathways for hydrogen production could be feasible in Malaysia. • Hydrogen can be used as transportation fuel, heating fuel and energy storage. • Hydrogen economy in Malaysia faces technical, economic and social challenges. • Renewable hydrogen could be commercialized in 3 phases via the proposed framework. [ABSTRACT FROM AUTHOR]

This paper will introduce the concept of 100% renewable energy and the role hydrogen and fuel cells can play for storage and transportation sectors. The importance, necessity and possibility of an overall global transition from fossil and nuclear-based fuels to renewable energy fuels using electricity and hydrogen as clean energy carriers will be summarized. Polluted, inefficient and unhealthy societies of today are missing energy self-sufficient, better managed, in harmony with nature ecological communities. The possible role of hydrogen fuel cells in fulfilling this target will be demonstrated and the success stories of the leading countries will be given. Renewable energy investments which have started in 2013 increased steadily and reached to 290 billion dollars towards the end of 2015. Today's increasing investments and cheaper supply of renewable energy will in turn effect the hydrogen production costs and increase the diversion from fossil fuels to cheap renewable energy. This reality confirms that hydrogen energy technologies will play an important role in reaching the 100% renewable energy target. [ABSTRACT FROM AUTHOR]

Abstract: It is clear that three of the great challenges facing humanity in the 21st century are energy supply, climate change, and global food security. Although global energy demand is expected to continue to increase, the availability of low cost energy will continue to diminish. Coupled with increasing concerns about climate change due to CO2 release from the combustion of fossil fuels, there is now an urgent need to develop clean and renewable energy system for the hydrogen production. This special issue contains selected papers on photosynthetic and biomimetic hydrogen production presented at the International Conference “Photosynthesis Research for Sustainability-2011”, that was held in Baku, Azerbaijan, during July 24–30, 2011, with the sponsorship of the International Society of Photosynthesis Research (ISPR) and of the International Association for Hydrogen Energy (IAHE). This issue is intended to provide to our readers recent information on the photosynthetic and biomimetic hydrogen production. The web site of this international conference is at: http://www.photosynthesis2011.cellreg.org. At this conference, awards were given to nine young investigators. We have included here some photographs to show the pleasant ambiance at this conference. (Also see http://www.photosynthesis2011.cellreg.org/Photos.php and http://www.life.illinois.edu/govindjee/g/Photo/Baku.html for some additional photographs). We invite the readers to the next conference on “Photosynthesis Research for Sustainability-2013” to be held in May or June 2013, in Baku, Azerbaijan. Information will be posted at: http://www.photosynthesis2013.cellreg.org. [Copyright &y& Elsevier]

Abstract: Energy production and combating climate change are among some of the most significant challenges we are facing today. Whilst the introduction of a hydrogen economy has its merits, the associated problems with on-board hydrogen storage are still a barrier to implementation. Ammonia and related chemicals may provide an alternative energy vector. Besides ammonia and metal amine salts, some other ammonia related materials such as hydrazine, ammonia borane, ammonia carbonate and urea also have the potential for use as alternative fuels. These materials conform to many of the US DOE targets for hydrogen storage materials. Similar to hydrogen, ammonia itself is carbon-free at the end users, although CO2 emission on production of ammonia is dependent on the source of energy. Both hydrogen and ammonia utilised similar energy sources for production: fossil fuels, biomass, renewable electricity, nuclear and solar energy. While a number of papers have been published on the catalytic decomposition of ammonia or related chemicals to produce hydrogen, the use of fuel cells directly fed by ammonia and related chemicals would have a higher efficiency. In recent years significant progress has been made on direct ammonia, hydrazine and urea fuel cells to generate electricity from these materials for transport applications. With the development and application in these technologies, reduction of CO2 emissions in transportation would be possible. In this review, we propose the use of ammonia and related chemicals as potential indirect hydrogen storage materials. The progress on fuel cells using these fuels is also briefly reviewed. [Copyright &y& Elsevier]

Abstract: Hydrogen is potentially the fuel of the future, with the transition to a hydrogen economy driven by the concerns about the climate change and the depletion of fossil fuel resources. Hydrogen is better than almost all other fuels when the fuels are evaluated on the basis of several metrics, including safety and versatility of use. Hydrogen is also presumed to have a superior motivity factor, a performance measure arising out of a combination of acceleration and drag forces. The motivity factor is quantified on the basis of the gravimetric and volumetric energy densities of a fuel. The present paper offers a refinement of the motivity factor which incorporates the effects of the mass of the storage matrix in these energy densities. It is shown that other fuels may have higher motivity factors than hydrogen when quantified on the basis of these refinements. [Copyright &y& Elsevier]