This past project advanced considerably 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 the resulting gas charged waters into the subsurface disposes the captured gases within precipitated minerals that remain stable over geologic time. This method has been demonstrated to be successful and has been running at the Hellisheidi power plant in Iceland for the past three years. Through this industrial scale demonstration, this new method has been demonstrated 1) to offer considerable cost savings compared to other approaches to capture and dispose acidic carbon and sulphur bearing gases; 2) to be far more environmentally compared to other available technologies; and 3) to 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 having a 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 1) by further optimizing gas capture and injection infrastructure at Hellisheidi and thereby further lowering emissions; 2) by implementing lessons learned at Hellisheidi at 3 other field site demonstrations across Europe and 3) by 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. In Hellisheidi, captured and purified CO2 will e.g. be supplied to algae production facilities. 

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. Added value/revenues of utilizing captured streams will further be analysed where applicable. Conversion of H2S to SO2 will cause HSE risks due to pH modification of brines within power plants to be decreased by regulating pH with SO2 instead of H2S. 

The site specific characterisation and modelling of geology, geochemistry and infrastructure for the optimisation of the injection experiments at four distinct geothermal systems located throughout Europe. By applying our approach successfully at 4 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. We will quantify these through a comprehensive modelling program, and using tracers and geochemical data, to gain better understanding of these processes. 

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 to leakages etc. for safer injection procedures. Such demonstrated technology has the potential to be transferred to a large number of other sub-surface applications. 

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 modelling program on a diverse set of geothermal systems we will generate computational tools to predict the behaviour of other systems. 

To help train next generation of scientist 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. This will be done through both the integration of early career scientists into parts of the GECO program through suite of outreach activities.