Electrical energy storage technologies for stationary applications are reviewed. Particular attention is paid to pumped hydroelectric storage, compressed air energy storage, battery, flow battery, fuel cell, solar fuel, superconducting magnetic energy storage, flywheel, capacitor/supercapacitor, and thermal energy storage. Comparison is made among these technologies in terms of technical characteristics, applications and deployment status.

http://promexico.me/Rubenius/WhitePapers/sdarticle%20(1).pdf

Progress in electrical energy storage system: A critical review

Zinc–air is a century-old battery technology but has attracted revived interest recently. With larger storage capacity at a fraction of the cost compared to lithium-ion, zinc–air batteries clearly represent one of the most viable future options to powering electric vehicles. However, some technical problems associated with them have yet to be resolved. In this review, we present the fundamentals, challenges and latest exciting advances related to zinc–air research. Detailed discussion will be organized around the individual components of the system – from zinc electrodes, electrolytes, and separators to air electrodes and oxygen electrocatalysts in sequential order for both primary and electrically/mechanically rechargeable types. The detrimental effect of CO2 on battery performance is also emphasized, and possible solutions summarized. Finally, other metal–air batteries are briefly overviewed and compared in favor of zinc–air.

/pdf/recent-advances-in-zinc-air-batteries-5fiw4wwwgg.pdf

Recent advances in zinc–air batteries

Innovation in concentrated solar power

This work focuses on innovation in CSP technologies over the last decade. A multitude of advancements has been developed during this period, as the topic of concentrated solar power is becoming more mainstream. Improvements have been made in reflector and collector design and materials, heat absorption and transport, power production and thermal storage. Many applications that can be integrated with CSP regimes to conserve (and sometimes produce) electricity have been suggested and implemented, keeping in mind the environmental benefits granted by limited fossil fuel usage.

Innovation in Concentrated Solar Power

The high power density, ease of transportation and storage and many years of development of internal combustion engine technologies have put liquid hydrocarbon fuels at a privileged position in our energy mix. Therefore processes that use renewable energy sources to produce liquid hydrocarbon fuels from H2O and CO2 are of crucial importance. Concentrated Solar Power (CSP) can be employed as the only energy source for the renewable production of hydrogen from water either indirectly, e.g. by supplying the electricity for electrolysis, or directly by supplying the necessary heat for thermochemically producing hydrogen. Among the various thermochemical cycles tested so far for CSP-driven hydrogen production via water splitting (WS), those based on redox-pair oxide systems, are directly adaptable to carbon dioxide splitting (CDS) and/or combined CO2/H2O splitting for the production of CO or syngas, respectively. The acknowledgement of this fact has recently revived the interest of the scientific community on such technologies. The current article presents the development, evolution and current status of CSP-aided syngas production via such redox-pair-based thermochemical cycles. At first the various redox oxide material compositions tested for water/carbon dioxide splitting are presented and their redox chemistries are discussed. Then the selection of suitable solar reactors is addressed in conjunction with the boundary conditions imposed by the redox systems as well as the heat demands, technical peculiarities and requirements of the cycle steps. The various solar reactor concepts proposed and employed for such reactions and their current status of development are presented. Finally, topics where further work is needed for commercialization of the technology are identified and discussed.

A review on solar thermal syngas production via redox pair-based water/carbon dioxide splitting thermochemical cycles

In the framework of the EU-project SOLZINC, a 300-kW solar chemical pilot plant for the production of zinc by carbothermic reduction of ZnO was experimentally demonstrated in a beam-down solar tower concentrating facility of Cassegrain optical configuration. The solar chemical reactor, featuring two cavities, of which the upper one is functioning as the solar absorber and the lower one as the reaction chamber containing a ZnO/C packed bed, was batch-operated in the 1300–1500 K range and yielded 50 kg/h of 95%-purity Zn. The measured energy conversion efficiency, i.e., the ratio of the reaction enthalpy change to the solar power input, was 30%. Zinc finds application as a fuel for Zn/air batteries and fuel cells, and can also react with water to form high-purity hydrogen. In either case, the chemical product is ZnO, which in turn is solar-recycled to Zn. The SOLZINC process provides an efficient thermochemical route for the storage and transportation of solar energy in the form of solar fuels.

A 300kW Solar Chemical Pilot Plant for the Carbothermic Production of Zinc

By using concentrated sunlight for the production of zinc from zinc oxide, it is possible to recharge the spent electrodes of zinc–air fuel cells/batteries with renewable energy. Several innovative processes for the solar production of zinc are under investigation. These include the direct thermal dissociation of zinc oxide (ZnO) or the use of reducing agents for the carbothermal reduction of zinc oxide. Most advanced is the carbothermic SOLZINC process (European research project (2001–05) for the development of a pilot-scale solar carbothermic process for co-producing zinc and carbon monoxide (CO) by reacting zinc oxide and carbon), in which a small amount of carbon is used as a reducing agent for zinc oxide dissociation, whereas in the high-temperature process heat is delivered by concentrated solar radiation. A SOLZINC pilot plant producing about 50 kg h−1 of zinc dust has been successfully operated and a conceptual design of a solar demonstration plant producing 1.7 t h−1 of zinc serves as the database for cost estimates. Several scenarios for the application of solar-based technologies for zinc production technologies including the cyclic ZnO–Zn process for renewable electricity production in zinc–air batteries have been studied. Further development is required prior to the commercialization of this renewable process for recharging zinc–air batteries.

SECONDARY BATTERIES – ZINC SYSTEMS | Zinc Electrodes: Solar Thermal Production

Solar Carbothermic Production of Zinc From Zinc Oxide: Solzinc

The reduction of ZnO with a carbonaceous material using concentrated solar radiation as energy source is an innovative concept (1) for the storage of solar energy in Zn as a "solar fuel" prior to its use for the production of electricity in Zn-air fuel cells or of hydrogen by splitting water with Zn. In both cases ZnO is formed, which can be reprocessed to Zn in the solar plant, creating a cyclic process (2) for the production of metallic Zn as a commodity with drastically reduced CO2-emissions compared to conventional fossil-fuel based Zn-production. This paper gives an overview over the SOLZINC-project, in which we investigate the scientific and technological problems of scaling up this novel technology. Based on the small scale investigations a batch process (1 batch per day) using a concentrated beam down radiation heating the ZnO-C mixture has been selected for upscaling. The choosen furnace concept using concentrated solar irradiation to react ZnO and a solid carbon material to produce gaseous Zn has been further optimized on 5-10 kW scale. The necessary input data for upscaling have been generated. The results with respect to operation temperature requirements, overall reaction rates, choice of specific C-material for reduction and of construction materials of the furnace are used to design and build a pilot plant at a scale of several hundred kW. The use of Zn-dust as to be produced from the offgas of the solar reactor for mechanically rechargable Zinc-air fuel cells has been demonstrated.

S. Santén

Papers

A 300kW Solar Chemical Pilot Plant for the Carbothermic Production of Zinc

SECONDARY BATTERIES – ZINC SYSTEMS | Zinc Electrodes: Solar Thermal Production

Solar Carbothermic Production of Zinc From Zinc Oxide: Solzinc

Solar Carbothermic Production of Zinc and Power Generation via ZnO-Zn Cyclic Process