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New StOrage Latent and sensible concept for high efficient CSP Plants

Periodic Reporting for period 2 - NewSOL (New StOrage Latent and sensible concept for high efficient CSP Plants)

Reporting period: 2018-01-01 to 2019-06-30

NEWSOL project addresses the specific challenge towards high efficiency solar energy harvesting by advanced materials solutions and architectures that are in line with those specified in SET-plan (https://ec.europa.eu/energy/en/topics/technology-and-innovation/strategic-energy-technology-plan). Its main objective is to develop advanced materials solutions based on innovative storage media and concepts for Concentrated Solar Power (CSP) up to validation in field of their performance by real time monitoring. This will be supported by an innovative thermal energy storage design based on the combination of new functional and advanced materials, like heat thermal fluid, sensible and latent energy storage media and insulating materials, into two innovative plant architectures: single tank thermocline storage and concrete type module.

The main challenges of NEWSOL are the development of two new system Architectures:
I) Thermocline Concrete Tank, (combining sensible and latent heat up to 550ºC), and
II) Concrete module tank (sensible heat up to 550ºC).

The scope to fulfil the challenges is to validate four new advanced materials:
1) Two different new high thermal performance concrete
1a) high thermal conductivity and
1b) high thermal insulation
2) Molten Salts (including nanoparticles)
3) Filler Material re-usage.

From the careful combination of the materials solutions within the two concept solutions six high relevant impacts are expected:
a) Reduced LCOE,10-12cEuro/kWh via higher material performance,
b) New designs that enable a reduction of CAPEX and OPEX,
c) Increase material understanding enabling long term performance,
d) Deployment of high tech monitoring technologies included in the demo activities,
e) Environmental re-usage of materials
f)Through innovative materials, higher world market penetration of European materials supply sector.

Moreover, investments foreseen at prototype level will be integrated into the Évora Molten Salts Platform site (EMSP.s) part of the European Research Infrastructure Network.
Overall in terms of Project Management following activities have been developed::
• Project handbook and templates
• Data Management Plan and Quality Management Plan
• Project Management Collaborative Space
• Project Corporate Image and website

For the Material and new Design following activities have been achieved:
• A pre-selection of material compositions to be used in the thermocline tank and concrete module
• Definition of KPIs required to evaluate the materials and TES (thermal energy system)
• A predesign of the thermocline tank and the module
• An evaluation of the actual implementation for the CSP technology and definition of business cases
Material development activities had a strong laboratorial component, namely:
High performance concrete
• CAC and OPC+FA concretes and compatible thermal aggregates
• Selection and optimum combination of aggregates, combining basalt, calcareous, slag and calcium alumina clinker aggregate, with better chemical and physical stability characteristics at high temperatures, when compared to siliceous type aggregates.
Molten Salt:
• Innovative low-melting point and high stability new ternary mixture NaNO3–KNO3–Ca(NO3)2 (1kg done,100kg testing ongoing)
• A novel Li-salt system, LiNO3-NaNO3-KNO3 obtained at lab scale, has been characterized and is being used as a benchmark to assess the thermal performance compared to the selected Ca-ternary mixture.
• MS incorporating two types of nanoparticles to increase the specific heat capacity of molten salts.

Slag re-usage from past mining activity with high metallic content suitable to be used as a heat storage material. Selection of material, long term stability and characterization (DRX, SEM, etc.) was done, the mineralogic composition identified and a study in terms of grain size and chemical stability was performed.

Insulating concretes for the isolation of the walls and foundation of the tank and module, in order to improve the current solutions based on mineral wool and expanded clay bed.
• Foam concrete-aerogel composites with low density and low thermal conductivity
• Lightweight high thermal aggregate concretes to achieve lower densities by decreasing the ratio of aggregates

Concerning the compatibility of materials following activities took place:
• Compatibility between Ca-ternary Molten Salts and CAC concrete mixtures
• Interaction between Molten Salts and 5 different Filler samples (slag type) were performed with full characterization
• Isothermal static corrosion tests for two stainless steels in Ca(NO3)2-NaNO3-KNO3 eutectic mixture were carried out
• Incorporation of calcium nitrate into concrete

Concerning the developments in terms of Thermal simulation and Sensor technology:
• Start setting up numerical models for the Thermocline concrete tank, investigating the designs for the optimum configuration
• Investigation of trade-off between thermal performance and cost for the basic module design
• Setting up numerical models for investigation of designs with enhanced heat transfer
• Sensor development for materials and system monitoring
• Adaptation of monitoring technology for multiple sensors
• Preparation of the EMSP facilities for prototypes start-up phase

Activities achieved related to dissemination activities:
• Website and communication strategy was implemented
• Workshops planned
• Scientific communications

Activities achieved related to ethics:
• NEC and EPQ Requirement
"Several technological areas have reached significant results that go beyond state of the art:
Molten Salts:
• Innovative low-melting point (131ºC) and high stability (up to 525ºC) Molten Salt ternary have been investigated: NaNO3 – KNO3 – Ca(NO3)2. Corrosion experimental work with stainless steel shows a lower velocity rate than with Solar Salt. This mixture has a lower cost than current solar salt or oil used in power plants, thus using such a mixture would have an important socio-economic impact
• ""NaNO3 – KNO3 – Ca(NO3)2"" safety sheets produced from the laboratorial tests
• A novel Li-salt system, LiNO3-NaNO3-KNO3 obtained at lab scale was verified to be stable up to 490ºC has been characterized and its advantages highlighted
Slag:
• Slag re-usage has been validated that it is suitable to be used as a heat storage material. A significant environmental advantage was identified, meaning an important positive environmental impact would occur in Sao Domingos area where this slag is currently accumulated next to a river stream in SE Portugal.
Sensor Development
• Sensors have been successfully developed to be embedded into concrete up to 500ºC
"
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