In 2007, the US Department of Energy recommended a no-go on NaBH4 hydrolysis for onboard applications; however, the concept of a NaBH4-H2-PEMFC system has the potential to become a primary source for on-demand power supply. Despite the many efforts to study this technology, most of the published papers focus on catalytic performance. Nevertheless, the development of a practical reaction system to close the NaBH4-H2 cycle remains a critical issue. Therefore, this work provides an overview of the research progress on the solutions for the by-product rehydrogenation leading to the regeneration of NaBH4 with economic potential. It is the first to compare and analyze the main types of processes to regenerate NaBH4: thermo-, mechano-, and electrochemical. Moreover, it considers the report by Demirci et al. on the main by-product of sodium borohydride hydrolysis. The published literature already reported efficient NaBH4 regeneration; however, the processes still need more improvements. Moreover, it is noteworthy that a transition to clean methods, through the years, was observed.

Finding stable solutions for hydrogen storage is one of the main challenges to boosting its deployment as an energy vector and contributing to the decarbonization of the energy sector. In this context, sodium borohydride (NaBH4) has been largely studied as a hydrogen storage material due to its significant advantages, such as low pressure, stability, and high hydrogen storage density. The development of catalysts and additive materials for the on-demand hydrolysis of NaBH4 for hydrogen release is a key research area. This work studies the effects of non-toxic and environmentally friendly additives for the hydrolysis process in terms of yield, lag time, hydrogen generation rate, and gravimetric density. Specifically, four additives, including sodium carboxymethylcellulose (CMC), polyacrylamide (PAM), sodium dodecyl sulfate (SDS), and β-cyclodextrin (BCD), were studied for their application in the storage and release of hydrogen. The best results were provided by the use of sodium carboxymethyl cellulose and polyacrylamide. In the first case, a hydrolysis yield of 85%, a lag time of 70 s, a hydrogen production rate of 1374 mL·min−1·gcat−1, and a storage capacity of 1.8 wt% were obtained. Using polyacrylamide as additive, a hydrolysis yield of almost 100% was achieved, although it required a significantly higher time period for complete conversion.

Resumo-A Linha Digital do Assinante (DSL) é uma tecnologia de transmissão de dados em banda larga que aproveita as redes telefônicas existentes. A linha telefônica possui varias limitações, sendo a principal o crosstalk, o qual limita a taxa de transmissão de dados do DSL. Novas técnicas de alocação de potência estão sendo desenvolvidas, as quais são conhecidas como Gerenciamento Dinâmico do Espectro (DSM -Dynamic Spectrum Management). Testes em uma linha real foram realizados e os resultados foram comparados com valores padronizados através de simulações. Por fim, o uso de técnicas de DSM foram testadas através de simulações para o ambiente real.