Future Power Technology Research Articles

Bifunctional electrolyte regulation towards low-temperature and high-stability Zn-ion hybrid capacitor

Aqueous Zinc-based energy storage devices are considered as one of the potential candidates in future power technologies. Nevertheless, poor low temperature performance and uncontrollable Zn dendrite growth lead to the limited energy storage capability. Herein, an anti-hydrolysis, cold-resistant, economical, safe, and environmentally friendly electrolyte is developed by utilizing water, ethylene glycol (EG), and ZnCl2 with high ionic conductivity (7.9 mS cm−1 in glass fiber membrane at −20 °C). The spectra data and DFT calculations show the competitive coordination of EG and Cl- to induce a unique solvation configuration of Zn2+, conducive to effectively inhibiting the hydrolysis of Zn2+, suppressing the dendrite growth, and broadening the working voltage range and temperature range of ZnCl2 electrolyte. The isotope tracing data confirm that Cl- could effectively destroy the ZnO passivation film, promoting the formation of Zn nuclei and improving its reaction activity. Compared to the corresponding ZnSO4 electrolyte, the Cu/Zn half-cell with the ZnCl2 electrolyte exhibits a stable cycle life of more than 1600 h at −20 °C, even at the current density of 5 mA cm−2. The assembled Zn-ion hybrid capacitor possesses an average capacity of 42.68 mA h g−1 under −20 °C at a current density of 5 A g−1, 3.5 times than that of the modified ZnSO4 electrolyte. Our work proposes a new approach for optimizing aqueous electrolytes to meet low temperature energy storage applications.

Analysis of operational characteristics of biomass oxygen fuel circulating fluidized bed combustor with indirect supercritical carbon dioxide cycle

Biomass have serve as a sustainable fuel source to mitigate environmental concerns in power generation. Developments in advanced coal combustion technologies have presented several promising solutions probable to be integrated with biomass combustion. Indirect supercritical carbon dioxide cycle incorporated with oxygen fuel circulating fluidized bed combustor was proposed to improve the power efficiency for domestic waste biomass resources, such as waste paper, waste wood, and cow manure. The thermodynamic analysis of the proposed cycle was analysed using Aspen Plus software within the excess oxygen ratio ranged between 0.97 and 1.05 and compared with coal fuelled supercritical carbon dioxide cycle. As excess oxygen ratio reached 1.01, with approximation of 27% of inlet oxygen concentrations, energy penalty by the compression and purification unit was minimized. The maximum net efficiency was 35.76% for waste paper, 27.74% for waste wood, and 31.12% for cow manure. The stored carbon dioxide at the same excess oxygen ratio for waste wood, waste paper and cow manure was 92.60%, 92.33% and 90.91% respectively. The proposed power cycle fuelled with waste paper resulted in a net efficiency slightly lower than coal fuelled power cycle. This work highlighted the potential of proposed biomass oxygen fuel circulating fluidized bed combustor integrated supercritical carbon dioxide cycle to serve as a future power technology for negative carbon dioxide emission.

Analysis of radial-outflow turbine design for supercritical CO2 and comparison to radial-inflow turbines

Cycles using supercritical carbon dioxide have been recognized as potential future power technology. However, the turbines in these systems tend to experience very high rotational speeds and entail small physical sizes, which can affect on the overall feasibility. One turbine type having potential to overcome some of the described challenges is the radial outflow turbine. However, its use in supercritical carbon dioxide power systems has not yet been extensively studied since typically axial or radial inflow turbines are considered instead. In this paper, the design of radial-outflow turbines with supercritical carbon dioxide is carried out and the results are compared to the respective radial inflow turbine designs. The analysis was carried out with turbine inlet temperature of 600 °C, inlet pressure of 200 bar and outlet pressure of 78 bar. Designs with four mass flow rates were investigated to study the effect of the power scale on the turbine design and losses. The geometry, efficiency, rotor stress and axial force were defined and analyzed for each design case. The results show that both the investigated turbine types can reach high isentropic efficiencies ranging from about 85% to over 90%. The radial outflow turbines can reach high efficiencies at wider specific speed range whereas the efficiency of radial inflow turbine is reduced more steeply, as the design speed is changed from its optimal value. Radial outflow turbines also reach high efficiencies with lower design speeds and that can be considered advantageous, since it helps to reduce the challenges related to turbomachinery rotordynamic and mechanical design. As a conclusion of the study, it is suggested that the use of radial outflow turbines can increase the feasibility of supercritical carbon dioxide power systems at the examined power scales.

Prognostics of Proton Exchange Membrane Fuel Cells Using A Model-based Method

Proton exchange membrane fuel cells (PEMFCs) are becoming one of the most popular future power technologies with the advantages including low operating temperature, high power conversion efficiency, and zero pollution. However, there are still many shortcomings restricting the large scale commercialization of PEMFCs, such as the short lifetime and high cost. Accurate prognostics of PEMFCs are very significant for its life and cost management. This paper presents an efficient semi-empirical model-based prognostics method estimating the health state and the remaining useful life of PEMFCs based on the adaptive unscented Kalman filter (AUKF) algorithm. AUKF algorithm can automatically adjust the system process covariance and observation covariance according to the estimation residuals, and it also solves the initial parameters setting problem of conventional UKF algorithm. Finally, simulation results demonstrate that the proposed model-based prognostics method using the AUKF algorithm has better prognostics performance than using the UKF algorithm.

Imagining socio-technical futures – challenges and opportunities for technology assessment

ABSTRACTAn increasing orientation of technology assessment (TA) and adjacent fields toward future socio-technological developments is leading scholars to examine, assess and adapt different approaches of future studies on various levels. In this special issue of the Journal of Responsible Innovation, a number of members of the extended TA community in Europe seek to advance different approaches to handling the unpredictable, to consider various possible socio-technical futures and to explore a more active role in technology design and shaping of the future as required by concepts such as responsible innovation (RI) or responsible research and innovation (RRI). The three German words ‘Zukunft Macht Technik’ (the title of a TA conference in Vienna in 2015) make a nice little pun in German: they can either be interpreted as the short sentence ‘Future shapes technology’ or as the assembly of the three nouns ‘future power technology.’ Both readings are borne in mind in this special issue. A main insight of this special issue is that we need to explore how the debate on imagined socio-technical futures is enriched by concepts such as R(R)I, taking into account that no future can exist without an awareness of the present setting of innovation processes and technology development.

A bright future power technology in 2008 [from the editor

Presents the editorial for this issue of the publication.