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Technologies for geothermal to enhance competitiveness in smart and flexible operation

Periodic Reporting for period 2 - GeoSmart (Technologies for geothermal to enhance competitiveness in smart and flexible operation)

Reporting period: 2020-06-01 to 2022-11-30

The GeoSmart project aims to optimise and demonstrate innovations to improve the flexibility and efficiency of geothermal heat and power systems, specifically:
• Energy storage and power block management innovations to provide daily flexibility for “dispatchability’’- to ramp up and down to the extent and speed required to fill the gaps between the sporadic and “duck curve” demand curves and the supply curves from solar and wind;
• Integration of more flexible organic Rankine cycle (ORC) systems that can cope with variations in needs in the electricity markets;
• Innovative methods to allow a combined heat and power (CHP) supplier to extract more heat from the post-generator (“waste” heat) brine outflows when required for increased heating supply during colder weather, using aquifer heat storage/re-cooling, and by removing the scale-formation constraints to cooling in high-silicate brines.
The proposed innovations will be implemented and tested at demonstration sites in Insheim (Germany) and KZD2 (Turkey) against four technology pillars:
• Provision of Thermal Energy Storage (TES), tailored to a site's conditions, to provide buffered supply against stochastic and 'duck curve' peak and ramping needs;
• Redesign of ORC generation system to optimise for flexibility of operation and maximise efficiency across the ramp rates and "off-design" operating conditions required to work with TES;
• Increase ORC efficiency during warm days through an aquifer based hybrid cooling system;
• The Carnot efficiency of the exergy extraction will be increased by removing the brine re-injection temperature constraint caused by silica scaling.
The main achievements in the reporting period were as follows:
• Formalisation of end user specifications for the two demonstration sites in Balmatt (Belgium) and Zorlu (Turkey) (WP1);
• User workshops to generate the integration document with site specific data and proposed innovations at the demonstration sites (WP1 & WP10);
• Development of safety and risk register for demonstration sites to include information on equipment safety legislation codes, operational conditions and specification designs (WP1).
• Identification and selection of phase change materials in accordance with the site requirements (WP2);
• Design of thermal storage units for demonstration sites based on input data from the demonstration sites (WP2);
• Development of physical models for the different components of the ORC including the pump, heat exchangers, expander and piping (WP3);
• Work on preliminary design and control strategy for the aquifer-based hybrid cooling of the ORC (WP3);
• Work on production of the individual and overarching energy management and control systems and optimisation of the combined flexible ORC, thermal energy storage and aquifer-based hybrid cooling system for application at the Balmatt demonstration site (WP3 & WP6);
• Design of retention tank unit following the heat exchange unit to allow for silica scale formation prior to re-injection (WP4).

The main achievement in the RP2 were as follows:
• Following the change of demo sites, the key performance indicators (KPIs) were re-evaluated for relevance;
• New site specific (Insheim and KIZILDERE 2) integration documents including Process flow diagrams (PFD) and Piping and Instrumentation diagrams (P&IDs) were formalised to define the integration of the GeoSmart innovations on the demo sites;
• Previously established site specific safety and risk registers were updated to include information on relevant equipment safety legislation codes, operational conditions and specification designs.
Insheim site
• Design of pressurized water thermocline storage (10 MWh) as the TES of choice;
• Development of adiabatic cooling system specifications for air cooled condenser;
• Development in progress for implementation of a flexible energy management of ORC and district heating using a secondary cycle with industrial water.
Kizildere 2 site
• Finalization of design of two types of storage systems:
o Steam accumulator (5 MWh) and a Phase Change Material (PCM) module (2 MWh).
• Decision on final material choice (HITEC salt) for PCM module;
• Design and development of a small scale test module (PCM and HX) for laboratory testing in CEA and Fraunhofer respectivley;
• Design, development and delivery of a scaling reduction system for installation at Kizildere 2 site;
• Formalisation of detailed planning document for procurement of materials (tendering) to fabrication, installation and demonstration of the storage and retention tanks on Kizildere 2 site.
The GeoSmart technology concept will allow the geothermal plant to be operated in a flexible mode to produce power and heat in a cost competitive way. This will be elaborated via case studies addressing a wide range of geothermal power opportunities.
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