Macroporous carbon foam with high conductivity as an efficient anode for microbial fuel cells

In this work, we demonstrate graphitized mesophase pitch-based carbon foam as anode for microbial fuel cells for the first time. Graphitized mesophase pitch-based carbon foam (GMCF), mesophase pitch-based carbon brush (MCB), pitch-based carbon felt (CF) with the different structures are investigated. Among them, GMCF-MFC exhibits excellent power generation property of 1800 mW/m², which is 1.33 and 2.65 times that of MCB-MFC and CF-MFC. GMCF is a graphitized material with a high electrical conductivity that accelerates extracellular electron transport (EET) between microorganisms and the surface of the material, thereby improving the electrochemical performance of MFCs. Besides, GMCF has well-developed macroporous (almost 300 μm in diameter) and through-pore structures, which could facilitate the enrichment of microorganisms and the diffusion of ions. And the staggered through-pores fix exoelectrogens in the pores, preventing them from “swimming out” and promoting the formation of microbial communities in these pores. More importantly, GMCF is a low-cost rigid carbon foam that can be easily fabricated into large-sized electrodes, which is beneficial for application to MFC amplification tests.     

Dynamic energy and mass balance model for an industrial alkaline water electrolyzer plant process

This paper proposes a parameter adjustable dynamic mass and energy balance simulation model for an industrial alkaline water electrolyzer plant that enables cost and energy efficiency optimization by means of system dimensioning and control. Thus, the simulation model is based on mathematical models and white box coding, and it uses a practicable number of fixed parameters. Zero-dimensional energy and mass balances of each unit operation of a 3 MW, and 16 bar plant process were solved in MATLAB functions connected via a Simulink environment. Verification of the model was accomplished using an analogous industrial plant of the same power and pressure range having the same operational systems design. The electrochemical, mass flow and thermal behavior of the simulation and the industrial plant were compared to ascertain the accuracy of the model and to enable modification and detailed representation of real case scenarios so that the model is suitable for use in future plant optimization studies. The thermal model dynamically predicted the real case with 98.7 % accuracy. Shunt currents were the main contributor to relative low Faraday efficiency of 86 % at nominal load and steady-state operation and heat loss to ambient from stack was only 2.6 % of the total power loss.     

Optimization of power allocation for wind-hydrogen system multi-stack PEM water electrolyzer considering degradation conditions

Hydrogen production from wind power has become one of the most important technologies for the large-scale comprehensive development and utilization of wind power, but the randomness of wind power has a large negative impact on the stability and cost of such wind-hydrogen hybrid energy systems. In this work, we initially analyze the relationship between electrolyzer efficiency and degradation with a three-dimensional multi-physics field model of PEMWE single-cell. Optimization of a power allocation strategy for wind-hydrogen system with a multi-stack PEM water electrolyzer (PEMWE) is proposed by considering degradation conditions. The multi-stack PEMWE power allocation strategy consists of the control module and execution module. In the control module, the degradation of PEMWE is quantified using the voltage degradation rate under different operating conditions. By setting the turning power point and external power supply and calculating the power allocation order online to reduce the degradation of PEMWE. In the execution module, the extended duty cycle interleaved buck converter (EDCIBC) based on fuzzy PID control is used to power each PEMWE single-stack. Case studies are carried out via computer simulation based on the configuration and experimental data for a specific wind farm located in Cixi, Zhejiang, China. Our results show that the energy efficiency of the wind-hydrogen system is 61.65% in a one-year operation, the voltage degradation of the PEMWE single-stack is 7.5 V, and the maximum efficiency is 6.29% lower than that when it is not aged. The EDCIBC output current ripple is as low as 0.053%, which rapidly and accurately follows the generated power allocation signal.     

Designing for an imagined user: Provision for thermal comfort in energy-efficient extra-care housing

Regarded as one solution to the problem of how to enable older people to retain their independence, extra-care housing, where each resident has their own self-contained dwelling and access to communal facilities and to care, has received extensive funding in recent years. Implicit in the concept of specialist housing is the notion of ‘special’ occupants, imagined older people. Adopting a socio-technical approach, this paper considers how ideas about ageing inform those aspects of extra-care-housing-design that relate to thermal comfort. The paper draws on semi-structured interviews with 13 people involved in the design, development and management of UK-based extra-care housing. Participants characterised imagined occupants as vulnerable to cold, at risk from fuel poverty and liable to be burned by hot surfaces or fall from high windows. These user representations were reportedly inscribed into the design of extra-care housing schemes through the inclusion of building features such as communal heating, under-floor heating, restricted window opening and heated corridors. The utilisation of stereotypical user representations of older people raises questions, given that older people's thermal comfort needs can be highly diverse. The paper explores the implications for energy demand.     

A novel design for humidifying an open-cathode proton exchange membrane fuel cell using anode purge

The low performance of open-cathode proton-exchange-membrane fuel cells (OCPEMFCs) is attributed to the low-humidity ambient air supplied to the cathode using electric fans. To improve the OCPEMFC performance, this paper proposes a novel humidification method by collecting water purged from the anode and supplying it to the open cathode. The OCPEMFC performance is evaluated at various humidifier distances from the cathode inlet, and it is compared with that where no humidifier is used when the OCPEMFC operates under three different current levels of 1, 5, and 8 A. The results show that the novel design improves the stack power, and optimal performance is achieved at a humidifier distance of 2 cm. The energy efficiency achieves an improvement between 1.4% and 1.8% when a humidifier is used.