Graphene-Based Assemblies for Moist-Electric Generation

Moisture is a ubiquitous and clean resource in nature, which continuously diffuses in the atmosphere and demonstrates huge chemical potential energy that is difficult to be utilized. Recently, the generation of power from interactions between graphene and gaseous water molecules in moisture has triggered great research interest that could provide a novel energy conversion system for our society. graphene-based assemblies have been considered as ideal platforms for moist-electric generation (MEG) in many studies, because of the abundant of functional groups, controllable microstructure and diverse macro morphologies. Therefore, in this short review, we will first state the preparation techniques of graphene-based assemblies for MEG. Then, the fundamental mechanisms of MEG are discussed and the latest advances on graphene MEG are reviewed. Finally, an overview of the current challenges and future development trends in graphene MEG is provided.

Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching

Spin Hall effect, an electric generation of spin current, allows for efficient control of magnetization. Recent theory revealed that orbital Hall effect creates orbital current, which can be much larger than spin-Hall-induced spin current. However, orbital current cannot directly exert a torque on a ferromagnet, requiring a conversion process from orbital current to spin current. Here, we report two effective methods of the conversion through spin-orbit coupling engineering, which allows us to unambiguously demonstrate orbital-current-induced spin torque, or orbital Hall torque. We find that orbital Hall torque is greatly enhanced by introducing either a rare-earth ferromagnet Gd or a Pt interfacial layer with strong spin-orbit coupling in Cr/ferromagnet structures, indicating that the orbital current generated in Cr is efficiently converted into spin current in the Gd or Pt layer. Our results offer a pathway to utilize the orbital current to further enhance the magnetization switching efficiency in spin-orbit-torque-based spintronic devices.

Techno-Economic Analysis of Municipal Solid Waste Gasification System for Electric Generation, Case Study: City at Central Java

Municipal Solid Waste (MSW) management is a problem in Indonesia because of the rapidly increasing volume and limited land. The Waste to Energy (WTE) concept is a concept that will be carried out for municipal solid waste management where the solid waste will be managed into electrical energy and reduce the volume of solid waste significantly by building a Gasification – engine system, one of which in Surakarta Central Java. MSW management infrastructure in one of the infrastructures that can be cooperated with the scheme of Public Private Partnership (PPP) in the form of investment project with a 20-years concession period and the BOOT (Build, Own, Operate, and Transfer) method. Downdraft Fixed bed gasification from Ankur scientific Energy Technologies Pvt, Ltd used for electric generation. Around 300 tons/day new municipal solid waste and 700 tons/day old waste as fuel resources. Potential power generating capacity of 8 MW (Gross) with an investment cost of Rp. 367.622.450.000. Techno economic analysis used the Capital Budgeting method. Result calculations obtained NPV is positive, IRR on project of 14,5%. Operation of MSW gasification system can reduce CH4 emission with equivalent 85.126,86 tCO2/year.

Separator-less Amino Acid-powered Biofuel Cell Through an Artificial Multi-enzyme Cascade Reaction

Objective This study was aimed at constructing a highly stable one-compartment enzymatic biofuel cell (EFC) without a separator through a multi-enzyme cascade reaction pathway. Results A separator-less EFC composed of a multi-enzyme cascade anode containing four dehydrogenases from a thermophile and a cathode devised using a multi-copper oxidase mutant with enhanced enzyme activity from a hyperthermophile was developed. To fabricate an EFC without a separator, redox mediators utilized in the enzymatic cascade reaction were also immobilized on the anode. In the presence of the fuel 100 mM L -proline, the separator-less EFC with four thermophilic dehydrogenase-modified anode achieved a maximum power density of 11.3 υW/cm 2 at 37°C, which was 1.6-fold higher than that of a similar EFC fabricated with a one enzyme-modified anode. The separator-less EFC composed of a multi-enzyme modified anode maintained approximately 57% of the load current at 0.3 V measured on the first day of EFC fabrication, even after 4 days.Conclusion Efficient L-proline electric generation utilizing a separator-less EFC composed of a multi-enzyme modified anode through a multi-step fuel oxidation reaction and a highly stable multi-copper oxidase mutant-modified cathode was successfully achieved over a long period. The long-term stability of the separator-less EFC can facilitate its application as an efficient power source for implantable medical devices requiring continuous operation.

Generation of Electricity from Waste Heat

Thermo electric generation converts heat energy into electrical energy . Power generated from TEG depends on the temperature difference between hot and cold surface . To improve the efficiency of TEG, MPPT algorithm with boost converter is used . Maximum power is obtained in the system when the output resistance of the system matches with the input resistance of TEG. By modelling the power variations generated from TEG system in series and parallel were minimized . The proposed system consists of TEG with boost converter having P& O MPPT . This paper presents simulation model of TEG module using MATLAB and is successful in generating a stable output.