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Solar carbothermic production of Zn from ZnO (SOLZINC)

Objective

Objectives and problems to be solved: The technical feasibility of a solar thermal chemical reactor for producing Zn from ZnO and carbon as a reducing agent in about a 0.5 MW plant is investigated for i) the production of Zn as a commodity with very low CO2 emissions and ii) the realisation of a cyclic process where Zn is produced from ZnO in a solar reactor and the Zn is used as a "solar fuel" for electricity production in Zn-air fuel cells. This work includes optimising the Zn-air fuel cells for solar Zn and optimising the interfaces between the solar reactor and the zinc-air cells. The CO2-mitigation potential for producing Zn as a commodity is assessed as well as the specific costs for producing electricity from concentrated solar light stored as Zn. Description of the work: First a 10 kW version of the solar reactor chosen for scale-up for about a 0.5 MW plant is build and tested. Quantified performance variables include the specific conversion rate of ZnO to Zn as a function of temperature and the amount of carbon as a reducing agent. The lower the specific amount of carbon the larger the fraction of stored solar energy in the products, but the more difficult is to condense the zinc without re-oxidisation. The experimental results are used to develop a numerical model that predicts performance as a function of operating conditions and to finalise the design concept for the large-scale reactor. A reactor including feeding system and off-gas handling unit for the about 0.5 MW plant is designed, constructed, and tested. The numerical model used to predict reactor performance is validated. Furthermore, a Zn-air fuel cell system suited for up scaling for small electric power plants based on Zn will be designed, build and tested. The large-scale tests are done in a 1 MW solar facility. The 10 kW tests are performed in a large solar simulator. Two industrial partners insure that the project maintains industrial viability. One has vast experience in Zn-smelting and the treatment of off-gas containing Zn vapour without major re-oxidation of the Zn: they develop the condensing unit and the off-gas treatment equipment. The Zn/air fuel cell manufacturer is responsible for optimising the cell modules for the requirements of the solar ZnO-Zn cycle. Expected Results and Exploitation Plans: A detailed economic study of the technology costs and a determination of how economically the solar process mitigates CO2 emissions and produces electricity via the ZnO-Zn cycle is conducted. The experimental, numerical, and eco-efficiency results are used to develop a conceptual design for the reactor and the other components of the ZnO-Zn cycle paving the path to a demonstration at an industrial scale. Numerous exploitation scenarios for a solar ZnO to Zn plant are studied conceptually including the option to produce H2 from Anther expected long-term benefits of the technology include the following: a reduction of CO2 emissions, a saving of fossil fuel resources, an opportunity for a nearly emission free urban transport system, and an expansion of work opportunities in the field of renewable energy.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Address
Avenue De Villeneuve 52
66860 Perpignan
France

Participants (5)

PAUL SCHERRER INSTITUT
Switzerland
Address
Paul Scherrer Institut
5232 Villigen
SCANARC PLASMA TECHNOLOGIES AB
Sweden
Address
Vaernavaegen 7
Hofors
SWISS FEDERAL INSTITUTE OF TECHNOLOGY ZUERICH
Switzerland
Address
Sonnegstrasse 3 Eth Zentrum Clt
8092 Zurich
WEIZMANN INSTITUTE OF SCIENCE
Israel
Address
Herzel Street 2
76100 Rehovot
ZOXY Energy Systems AG
Germany
Address
Attenbergstrasse 23
75038 Oberderdingen