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Geothermal Emission Gas Control

Periodic Reporting for period 1 - GECO (Geothermal Emission Gas Control)

Reporting period: 2018-10-01 to 2020-03-31

GECO is an innovative project aiming at providing clean geothermal energy with a lower cost. It builds upon the success of the recently completed Carbfix project.

This past project has advanced our ability to clean the exhaust gases emitted by geothermal power plants based on a novel water dissolution method in a dedicated scrubbing tower. The injection of these gas charged waters into the subsurface disposes the captured gases within precipitated minerals that remain stable over geologic time. This method has been running at the Hellisheidi power plant in Iceland for the past three years. It has been demonstrated to; 1) offer considerable cost savings compared to other approaches to capture and dispose of acidic carbon and sulphur bearing gases, 2) be far more environmentally friendly compared to other available technologies, and 3) aid in the long-term viability of geothermal systems by enhancing the permeability of fluid injection wells.

The goal of this GECO Innovation Action is to adopt this approach, together with emission gas reuse schemes, to become a standard to the geothermal power industry worldwide through its application to three new sites across Europe. Moreover, the detailed monitoring and chemical modelling of this injection has provided novel insights into the reactions that occur in the subsurface in response to flowing fluids in geothermal systems. By consistently monitoring the reactions that occur in the four GECO field sites, each with distinct geology, we will be able to generalise these findings to create a tool for predicting the chemical behaviour of a large number of other systems before they are developed for geothermal energy. Such tools have the potential to decrease both the risk and the cost of future geothermal energy projects.

To lower emissions from geothermal power generation by capturing them for either reuse or storage. This will be done by; 1) further optimizing gas capture and injection infrastructure at Hellisheidi and thereby further lowering emissions, 2) implementing lessons learned at Hellisheidi at three other field site demonstrations across Europe, and 3) combining the success of the Carbfix approach with corresponding gas re-use approaches.

To turn captured emissions into commercial products, allowing for cost reductions through increased revenues. By producing pure enough gas streams for utilisation processes, products like hydrogen gas and pure CO2 can be used as an added value to help offset the costs of cleaning exhaust gases.

To demonstrate cost competitiveness of developed gas capture and injection methods through a comprehensive economic analysis of gas capture, injection and monitoring at each field site.

To characterise and model the geology, geochemistry and infrastructure of the four distinct geothermal systems located throughout Europe with the aim of optimising the injection experiments. By applying our approach successfully at four diverse locations we will aid in the public acceptance of geothermal energy throughout the continent.

To quantify the rate and extent of subsurface reactions occurring in response to induced fluid flow during and after the injection of fluids into the subsurface.

To integrate new technology, such as detecting CO2 fluxes via remote sensing, in-situ laser isotope analyser and corrosion monitoring system, for improved monitoring of the injections leading to decreased risks associated with leakages etc. for safer injection procedures.

To generate an improved understanding of the response of subsurface rocks to induced fluid flow in the subsurface. Notably by combining the results of a consistent chemical monitoring and a modelling program on a diverse set of geothermal systems, we will generate computational tools to predict the behaviour of other systems.

To help train the next generation of scientists and engineers in the current best practice work-flow for lowering emissions from deep geothermal operations and thereby moving the GECO technology into the future.
The tasks carried out during this first period have focused on data acquisition, modelling and laboratory experiments that form a basis for the forthcoming pilot demonstrations during the project’s later stages. At the onset of the project, a detailed project management plan was constructed with a Gantt chart and a work breakdown structure along with a schedule per task, responsible partner, related subtasks, deliverables and dependencies on other tasks. An internal communication plan and visual identity was put in place including communication tools and a website. Training and outreach activities have been carried out and are detailed in the periodic dissemination report. Also, an annual report on the communication process and performance for year one was submitted.

The modelling work under WP2 has been largely completed. We have characterised each demonstration site based on local geology, lithostratigraphy, mineral alteration, tectonics, structural features, and hydrological conditions. This was followed by detailed reservoir modelling and sensitivity study of the demo-sites that included numerical simulations under steady state conditions and geophysical data constraints of the characterised reservoirs of each demonstration site. Finally, properties of the steady state flow module were determined for different gas mixtures to be used to form the basis for optimal CO2 and water injection.

In WP3, the characteristics of both the amine-based CO2 purification system characteristics and the burn and scrub purification system have been analysed in preparation for the demonstration system design. Basic design and integration of these systems was also completed. In addition, details on the specification and validation of purified gas were provided.

In WP4 we have prepared several reports in preparation for injection in the later stages of the project. First, a synthesis report on thermodynamic models of CO2/H2S/brine systems describing the reference database that will be used for modelling the Castelnuovo injection well. Second, a report on precipitation/dissolution effects of CO2/brine on different rock types and materials at different temperature and pressure conditions. Calibrated modelling predicts intermediate and long-term reservoir rock-fluid interactions and the efficiency of CO2 storage. Third, a synthesis report on experimental measurements of CO2 absorption in pure water and the dissolution kinetics, under variable temperature and pressure conditions.

All demonstrations, WP5-WP8 have entered the design and engineering phases (apart from WP6). The procurement and construction of the demonstrations will start during the next period.

In WP9, preliminary activities concerning the IPR management, environmental and economic evaluation have been initiated.
Most of the work carried out in the first period involves state of the art modelling, laboratory experiments and pre-design, in order to prepare for the project‘s pilot demonstrations in the forthcoming periods. Most of the progress beoynd the state of the art is expected at later stages of the project.