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Physical Storage
Lithium combustion 30.9.2015

Lithium reactor for the examination of the gaseous and solid reaction products in the combustion of atomized molten lithium in air, nitrogen and carbon dioxide.
© Siemens AG

Lithium, the renewable coal

Lithium can be used for chemically storing electricity as part of a cycle in which it is first generated electrochemically using surplus electricity and then combusted as required in a power plant-compatible process to release the energy again. In the “LiKohle” project, researchers are investigating and assessing the possible reaction processes, for example in a carbon dioxide or nitrogen atmosphere. Valuable chemical raw materials can be generated as a by-product of the energy conversion.

Project status Project completed
Project duration June 2012 until September 2015

With the exception of the battery technology, the potential of lithium to store overproduction electricity from renewable energy sources has not been studied. The fundamental aspects of the lithium combustion in a power plant relevant process, as well as concepts for the energy efficient possibility for the recycling of the solid reaction products are to be examined within the project. The project consortium includes the following partners: Siemens AG, as project leader and industrial partner, the research group of professor Scherer (Ruhr-Universität Bochum, specialists in combustion processes) and the research group of professor Katharina Kohse-Höinghaus and professor Andreas Brockhinke (Universität Bielefeld) with an extensive experience in the analysis of reaction kinetics and flame characterization.

  • Experimental setup of the laminar flow reactor, which is used for the observation of single burning Lithium particles for fundamental investigation of the ignition and combustion process. Pure or mixed gaseous atmospheres are continuously heated-up in a gas preheater and guided in a quartz-glass tube. Simultaneously, the quartz tube is fed with single Lithium particles with a size fraction of 50-250 µm. Being exposed to the hot gas, the particles ignite and burn in the optical accessible quartz-glass tube. The Combustion is analyzed with a two-color pyrometer, which measures particle temperatures and diameters at the same time. In addition, the particle burn-out will be extracted by a testing probe and investigated with X-ray diffraction. © Ruhr-Universität Bochum
  • A streak of combusting Lithium particles. The Lithium burns in the quartz-glass tube reactor in an exhaust atmosphere of a methane-air flame. The temperature of the exhaust gas is approx. 1200 K.  Initial results indicate that the temperatures of the combusting particles are much higher than 2000 K. © Ruhr-Universität Bochum
  • Lithium flame of atomized molten Lithium (Lithium flow rate of 1 g/s, narrow particle size distribution, mean particle size of 100 µm) under air atmosphere (Tg = 450°C). © Siemens AG
  • Lithium reactor for the examination of the gaseous and solid reaction products in the combustion of atomized molten lithium in air, nitrogen and carbon dioxide. © Siemens AG
  • Lithium flame characterization - Combustion of molten lithium under air atmosphere in a low pressure reactor. © Universität Bielefeld
  • Energy and material cycle based on lithium as a highly dense material energy store with a depiction of two possibilities for the energy discharge: (a) Combustion in a carbon dioxide atmosphere (comparable thermal level with the combustion of fossil fuels in oxygen) and a valuable reaction product (carbon monoxide which can be converted with hydrogen to form fossil fuel); (b) Combustion with nitrogen (comparable thermal level with the combustion of fossil fuels in oxygen) and lithium nitride as a solid reaction product, which can be hydrolysed energy efficiently to produce ammonia. © Siemens AG

The target of the present project consortium is the study and evaluation of the potential of a closed energy loop on the basis of electropostive metals and in particular lithium as high density, seasonal, energy storage material. Thereby lithium is produced using an electrochemical process (electrolysis of lithium chloride) by use of stranded, overproduction electricity from renewable energy sources. The conversion / release of the stored renewable energy in to thermal energy by use of a power plant compatible combustion process in a carbon dioxide or nitrogen atmosphere is to be examined. According to its position in the standard reduction potential table, lithium can reduce even very low reactive gases. The strongly exothermic reaction of lithium with CO2 and nitrogen (N2) yields thermal energy comparable to the combustion of coal in an oxygen atmosphere. Furthermore lithium can reduce thereby CO2 to valuable carbon monoxide (CO), which can be further converted with hydrogen (H2) from renewable sources to methanol or gasoline. The lithium nitride, as product of the combustion in nitrogen, can offer in an exothermic reaction with water an energy efficient access to ammonia, an important chemical product obtained otherwise with a large energy comsumption.

Key aspects of research

  • Reaction mechanism and reaction kinetics of the exothermic reaction of lithium with carbon dioxide, nitrogen and gas mixture
  • Combustion parameters (ignition characteristics, particle temperature, flame characteristics)
  • Reaction products in dependence of the reaction parameters
  • The present project is not to be seen as an alternative to hydrogen as energy storage material, but as an addition to the energy storage materials topic

Project Progression

At the current stage of the project (first project year) the partners are developing reactors with lithium particles, lithium spray as well as low pressure reactors for the caracterisation of the combustion in carbon dioxide or nitrogen atmosphere. Up to the present date no study on lithium combustion reactors for energy conversion and usage in an power plant relevant process was published. The reactor design activities are supported by experiments in order to determine relevant material properties of electroposite metals and numerical simulation. The fundamentals of the lithium combustion in carbon dioxide and nitrogen will be determined as part of the activities of the second and third project year: single particle raction, ignition, flame and particle temperature, reaction kinetics and mechanism, reaction products in dependence of the reaction paramters. Technical relevant lithium combustion concepts will be developed based on the experimental results. The investigation of the lithium availableness, enviromental impact and effciency of the energy storage concept based on litium (electropositive metals) complete the presented study.

The first project milestone was successfully completed. The fulfillment of the other defined milestones is not at risk.

Supported by: The Federal Government on the basis of a decision by the German Bundestag


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Research funding

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