Electrolytic Silicon and Iron Powders as Alternatives to Hydrogen as Energy Carrier and Store
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Chemical and Environmental Eng
Abstract
The hydrogen technology is at present regarded as a potential solution to the problems resulting from using fossil fuels, particularly CO2 emission. However, the development of the hydrogen technology has encountered a number of difficulties, of which the need to reversibly store the hydrogen gas is a major challenge. Particularly, the reversible storage capacities achievable even in the best materials or devices are too low, for example, LaNi5H6 (< 1.5 wt%, ~300K) and high pressure or liquid hydrogen tank (< 4 wt%), but the high storage capacity in some others, e.g. NaAlH4 (> 7 wt%, >520K) and LiBH4 (>18.4 wt%, >553K), does not allow convenient reuse of the stored hydrogen.In fact, hydrogen gas is not an energy source because it does not exist in nature. In any energy application, the hydrogen gas only plays the roles of the energy store when the hydrogen gas is produced using another form of energy, such as electricity from the renewable or nuclear energy, and of the energy carrier when the gas is combusted in an internal combustion engine or fed into a fuel cell. These two roles of hydrogen can be well played by other pure elemental substances, such as silicon and iron. Like hydrogen, the energy stored in silicon and iron can be released through a chemical or an electrochemical reaction with oxygen. The products from these reactions, i.e. silicon and iron oxides, are the natural components of the Earth and will have zero environmental impact. One of the reasons why hydrogen has been so far the research and public focus is its high specific energy (energy per unit mass). Unfortunately, hydrogen is a gas under ambient conditions and the need for storage by any known method significantly reduces hydrogen's real specific energy. For example, the specific heat from the combustion of hydrogen gas in air is 122.8 kJ/g (425 degC), but it reduces to 30.7 kJ/g when hydrogen is stored at 25wt% (the theoretical maximum hydrogen storage capacity), but to a disappointing low value of 8.0 kJ/g when hydrogen is stored at 6.5 wt% (the targeted reversible hydrogen storage capacity of the US Department of Energy). On the contrast, iron and silicon are stable solids under ambient conditions and there is no storage problem. For combustion in air, the specific heat of silicon is 32.4 kJ/g and that of iron is 7.3 kJ/g. The other consideration for energy application is the energy density (energy per unit volume). Using the mass density of the three elements, it can be shown that, again for combustion in air, the heat density is only 8.6 kJ/cm3 for liquid hydrogen, but 75.5 kJ/cm3 for silicon and 57.5 kJ/cm3 for iron. Therefore, silicon and iron are thermodynamically better than hydrogen when storage is considered. On the technical side, the combustion of silicon and iron powders has long been proven in research, and it is now the time to develop a technique in which silicon and iron powders can be produced easily using renewable energy, particularly solar energy. This proposed research aims to experimentally demonstrate the thermodynamically predicted feasibility of using silicon and iron powders as the alternatives to hydrogen as the energy store and carrier. Particularly, it is intended to produce and regenerate the silicon and iron powders from their oxides using molten salt electrolysis under solar energy workable conditions (electricity and heat). The applicant and co-workers have already performed preliminary tests and produced successfully fine silicon and iron powders using the novel FFC Cambridge Process (co-invented by the applicant in the UK) at relatively high temperatures (800 degC ~ 900 degC). It is intended to lower the molten salt temperatures in this project (< 500 degC) so that solar heat can be used in the process. The products will be investigated by TG and DSC and tested for combustion in air. The optimal powder particle morphology and its correlation with the electrolysis conditions will be identified
Organisations
Publications
Peng J
(2008)
Electrochemical Conversion of Oxide Precursors to Consolidated Zr and Zr-2.5Nb Tubes
in Chemistry of Materials
Wang D
(2008)
Solid state reactions: an electrochemical approach in molten salts
in Annual Reports Section "C" (Physical Chemistry)
Li G
(2009)
Affordable electrolytic ferrotitanium alloys with marine engineering potentials
in Journal of Alloys and Compounds
Peng J
(2009)
Cyclic voltammetry of electroactive and insulative compounds in solid state: A revisit of AgCl in aqueous solutions assisted by metallic cavity electrode and chemically modified electrode
in Journal of Electroanalytical Chemistry
Wang H
(2009)
An alumina membrane reference electrode for molten chloride salts applications
in NA
Wei X
(2009)
Solar-thermochromism of Pseudocrystalline Nanodroplets of Ionic Liquid-Ni II Complexes Immobilized inside Translucent Microporous PVDF Films
in Advanced Materials
Peng J
(2009)
Direct and low energy electrolytic co-reduction of mixed oxides to zirconium-based multi-phase hydrogen storage alloys in molten salts
in Journal of Materials Chemistry
Peng J
(2009)
Phase-Tunable Fabrication of Consolidated (a+ß)-TiZr Alloys for Biomedical Applications through Molten Salt Electrolysis of Solid Oxides
in Chemistry of Materials
Xiao W
(2010)
Rationalisation and optimisation of solid state electro-reduction of SiO2 to Si in molten CaCl2 in accordance with dynamic three-phase interlines based voltammetry
in Journal of Electroanalytical Chemistry
Li W
(2010)
Metal-to-oxide molar volume ratio: the overlooked barrier to solid-state electroreduction and a "green" bypass through recyclable NH4HCO3.
in Angewandte Chemie (International ed. in English)
Peng J
(2010)
Cyclic Voltammetry of ZrO[sub 2] Powder in the Metallic Cavity Electrode in Molten CaCl[sub 2]
in Journal of The Electrochemical Society
Shi X
(2011)
Processing nanomaterials in molten salts: partially electrometallized TiO2 as Pt support for enhanced catalytic oxidation of CO and CH3OH.
in Chemistry (Weinheim an der Bergstrasse, Germany)
Huang Q
(2011)
Chloride ion enhanced thermal stability of carbon dioxide captured by monoethanolamine in hydroxyl imidazolium based ionic liquids
in Energy & Environmental Science
Siambun N
(2011)
Utilisation of Carbon Dioxide for Electro-Carburisation of Mild Steel in Molten Carbonate Salts
in Journal of The Electrochemical Society
Wang H
(2012)
A Robust Alumina Membrane Reference Electrode for High Temperature Molten Salts
in Journal of The Electrochemical Society
Xiao W
(2013)
Up-scalable and controllable electrolytic production of photo-responsive nanostructured silicon
in Journal of Materials Chemistry A
Hu D
(2013)
Near-Net-Shape Production of Hollow Titanium Alloy Components via Electrochemical Reduction of Metal Oxide Precursors in Molten Salts
in Metallurgical and Materials Transactions B
Gao H
(2013)
Liquid diffusion of the instantaneously released oxygen ion in the electrolytic porous Fe from solid Fe2O3 in molten CaCl2
in Electrochimica Acta
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(2013)
Manganese oxide based materials for supercapacitors
in Energy Materials
Igunnu E
(2014)
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in International Journal of Low-Carbon Technologies
Zhang J
(2014)
Electrochemical fabrication of porous Sn/SnSb negative electrodes from mixed SnO2-Sb2O3
in Electrochemistry Communications
Ijije H
(2014)
Carbon electrodeposition in molten salts: electrode reactions and applications
in RSC Adv.
Chen G
(2014)
The FFC Cambridge process and its relevance to valorisation of ilmenite and titanium-rich slag
in Mineral Processing and Extractive Metallurgy
Rong L
(2014)
Investigation of electrochemical reduction of GeO2 to Ge in molten CaCl2-NaCl
in Electrochimica Acta
Yu L
(2014)
Cryo-solvatochromism in ionic liquids
in RSC Adv.
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(2014)
Achieving low voltage half electrolysis with a supercapacitor electrode
in Energy Environ. Sci.
Ijije HV
(2014)
Electro-deposition and re-oxidation of carbon in carbonate-containing molten salts.
in Faraday discussions
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(2014)
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in SCIENTIA SINICA Chimica
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(2014)
A sunlight assisted dual purpose photoelectrochemical cell for low voltage removal of heavy metals and organic pollutants in wastewater
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Akinwolemiwa B
(2015)
Redox Electrolytes in Supercapacitors
in Journal of The Electrochemical Society
Siambun N
(2015)
Influence of CO2 Gas in the Electro-Carburisation Process of Mild Steel
in International Journal of Chemical Engineering and Applications
Weng Y
(2015)
Titanium carbide nanocube core induced interfacial growth of crystalline polypyrrole/polyvinyl alcohol lamellar shell for wide-temperature range supercapacitors
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(2015)
Preface
in Progress in Natural Science: Materials International
Peng J
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Electrochemical Preparation of Fine Powders of Nickel-Boron Alloys in Molten Chlorides for Magnetic Hydrogenation Catalysts
in Journal of The Electrochemical Society
Chen G
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Supercapacitor and supercapattery as emerging electrochemical energy stores
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(2016)
Nitrogen-doped graphene guided formation of monodisperse microspheres of LiFePO 4 nanoplates as the positive electrode material of lithium-ion batteries
in Journal of Materials Chemistry A
Akinwolemiwa B
(2016)
Highlights from liquid salts for energy and materials - Faraday Discussion, Ningbo, China, 11-13 May 2016.
in Chemical communications (Cambridge, England)
Chong B
(2016)
Highly efficient photoanodes based on cascade structural semiconductors of Cu 2 Se/CdSe/TiO 2 : a multifaceted approach to achieving microstructural and compositional control
in Journal of Materials Chemistry A
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(2016)
Esterification of fatty acids from waste cooking oil to biodiesel over a sulfonated resin/PVA composite
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Liu X
(2016)
Bipolarly stacked electrolyser for energy and space efficient fabrication of supercapacitor electrodes
in Journal of Power Sources
Zhao Y
(2016)
Polypyrrole/TiO2 nanotube arrays with coaxial heterogeneous structure as sulfur hosts for lithium sulfur batteries
in Journal of Power Sources
Yu L
(2016)
High energy supercapattery with an ionic liquid solution of LiClO4.
in Faraday discussions
Gao Y
(2017)
Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO2-CaO-MgO-Al2O3 molten slag at 1723 K.
in Physical chemistry chemical physics : PCCP
Description | REFINE |
Amount | £445,520 (GBP) |
Funding ID | EP/J000582/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 12/2011 |
End | 11/2015 |
Title | Carbon production (main sponsor: Royal Society) |
Description | Electrochemical capture and utilisation of CO2 in molten salts and the process can be driven by solar energy (heat and electricity). |
IP Reference | |
Protection | Protection not required |
Year Protection Granted | 2007 |
Licensed | No |
Impact | The PI has been invited to give keynote lectures at various international conferences (e.g. EUCHEM, July 2014 Tallin), and also in the Parliament (19 November 2014) |
Description | Seminar in Parliament |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Policymakers/politicians |
Results and Impact | I will report this later here. I will report this later |
Year(s) Of Engagement Activity |