Wed, 02 June, 2021
The Horizon 2020-funded Geo-Pro Project has been working to improve the accuracy and consistency of thermodynamic and kinetic input data as well as the accuracy of the equations of state to provide robust, flexible and accessible tools to optimise sustainable geothermal reservoir management, power and heat production, and reinjection strategies.
The key to doing this is through the understanding of the chemical and physical properties of geothermal fluids.
We spoke with Maria Eleni Mitzithra, Senior Project Leader, to find out more about the project, its aims, and the benefits for industry…
Can you start by introducing yourself and letting us know how you are involved in the Geo-Pro Project?
I joined TWI in November 2014 and currently I am a Senior Project Leader in the Surface, Corrosion and Interface section within TWI’s Materials and Structural Integrity group. My main working areas are corrosion testing, corrosion behaviour, and materials in aggressive environments.
As for Geo-Pro, from a technical point of view, TWI is responsible for the design and manufacture of a geothermal multiphase flow loop, with the aim of investigating the interactions between the properties of geothermal fluids and multi-phase flow. The purpose of the designed capability is to demonstrate feasibility of the flow loop test concept for the specific sector, which will help in identifying and ranking the most important parameters. The flow loop will be fed with fluid compositions, simulating those found in geothermal fields in GEOPRO case studies (Insheim-Pfalzwerke Geofuture GmbH and Kilzidere- Zorlu). The flow loop test capability will be used for performing both multi-phase and cavitation flow loop tests, for conditions relevant to those faced in the GEOPRO case studies (up to 230°C and 40bara). It contains a number of instruments that will allow for liquid and steam/gas flow rate measurements, pressure and temperature measurements at different locations, density and distribution of phase fractions of the multiphase fluids, visualisation of flow pattern, cavitation measurements, enthalpy measurements, and corrosion rate measurements. Different test pipe configurations will be employed for the above tests at three different inclination angles.
Why are the chemical and physical properties of the geothermal fluids such a key factor for optimising site developments and operation?
GEOPRO strives to deliver a better understanding of the chemical and physical properties of geothermal fluids as transport media to aid the optimisation of site development and operation. The development and operation of geothermal systems are affected by a lack of understanding of such fluid properties, as below:
- Scale formation/ clogging (such as silica and calcium carbonate scaling) occurs through the geothermal plant, as well as within borehole and surface pipes and equipment, and can have serious economic consequences, arising from energy loss, loss of production, increased cost of cleaning and maintenance, or even shut down of productions/re-injection wells. The great complexity of predicting scale formation processes results from the complexity of the fluids. Improved thermodynamic formulation for H2O-salt-CO2 fluids (Equations of State-EoS) combined with flow assurance simulations and tests are expected to aid predictive modelling of the causes of scaling and optimise, in real time, the inhibitor dosage.
- Local corrosion/erosion phenomena due to CO2 outgassing can have a significant impact on the structural integrity and the service life of the pipe and equipment systems of geothermal power plants. This is due to current thermodynamic models failing to predict accurately the correct CO2 outgassing pressure. Improved CO2 solubility models and EoS for H2o—salt-CO2 fluids will be obtained and implemented into geochemical models and flow assurance simulations, in to order to assess the causes of gas outgassing and options for optimising pressure/gas outgassing control.
- Superhot geothermal resources are a relatively recently detected, new type of geothermal resource that reach temperatures significantly in excess of the critical temperature of water (374°C). Producing superhot fluids leads to flow scaling and corrosion phenomena that can strongly differ from those encountered when producing from conventional systems. Current conventional thermodynamic models cannot be used for the prediction of the chemical content and properties of the superhot fluids. No relevant experimental data are available either. State-of-the-art reservoir modelling and flow assurance simulations targeting such superhot resources will aim to develop relevant data and thus assess the optimum utilisation of these fluids.
What are the benefits for end users from this project, and who is GEOPRO aimed at?
Among the aims of the GEOPRO project is to develop models and technologies that will contribute to making geothermal energy generation more accessible and affordable. Impact for the end users in the geothermal industry is expected to arise in four main areas; exploration, system design and installation, more efficient plant operation, and maintaining plant outputs. All of these are expected to potentially lead to reductions in the levelised cost of electricity (LCOE) through geothermal energy, and increase its competitiveness and penetration of the energy mix towards the EU2030 / 2050 targets.
Through reducing scaling formation and reinjection temperature, controlling CO2 outgassing, decreasing degradation of material, and increasing energy production from exploitation of superhot resources, the GEOPRO impact is expected to be as follows:
- Reduction of capital costs from equipment oversizing
- Reduction in pumping costs
- Reduction in costs for equipment related to corrosion
- Optimum inhibitor usage
- Increased enthalpy extraction and efficiency in power generation
By having much better understanding of the fluids’ properties and relevant reaction kinetics, as well as better EoS, the GEOPRO approach can be used for many more geothermal environments in the world, apart from the specific GEOPRO case studies (ZOREN, PFALZWERKE GEOFUTURE GMBH, ORKUVEITA REYKJAVIKUR SF (OR)).
There are also environmental benefits from the GEOPRO Project, can you explain more about these?
Assessment of the environmental impact of the developed thermodynamic and flow assurance tools on the GEOPRO case studies will be carried out following a ‘cradle-to-grave’ life cycle approach. Data from the GEOPRO power plant operators are required for the validation of the environmental benefits of the GEOPRO concepts. It is expected that the developed GEOPRO knowledge/tools/concepts and their impact can lead to a significant reduction in the CO2 emissions; for example, it is expected that increased enthalpy extraction (by reducing the re-injection temperature) can lead up to 50% of reduction in current CO2 emissions for the Kilzidere-Zorlu case.
In addition, the knowledge obtained from GEOPRO will contribute to helping achieve the relevant EU targets on renewable energies. The capacity factor of geothermal power is 70-95% and, unlike other renewables, its availability does not depend on seasonal variation or climatic conditions. For that reason, it is considered as a constant and secure source of energy production. The use of the GEOPRO tools and knowledge would contribute to optimising the production and exploitation of geothermal wells, along with the operation of the plants, enhancing even further the security that geothermal energy provides as a sustainable energy source.
How is the Project developing and what are the next steps to be taken?
All relevant tasks are progressing to plan and the project is heading towards its first periodic review. The project has another year to go and the outcomes/deliverables of most of the tasks are expected towards the end of the project.
The Geo-Pro project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 851816