| Title | Case study of the CaSil technology at Dieng, Indonesia; Successfully eliminating silica scale |
|---|---|
| Authors | T. Borrmann, H.P. Fraser, J. Johnston, M. Schweig, I. Kardani, D. Singkuang, A.G.A. Sumartha, A.P. Utama, A.Y. Kencana |
| Year | 2024 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Geothermal, Dieng, silica, silica scale, calcium silicate, CaSil, simulated geothermal brine, silica saturation index, electricity generation |
| Abstract | The CaSil technology is a proprietary innovative new technology that eliminates silica deposition and scaling from geothermal brine, supersaturated in silica. The technology has been developed and successfully demonstrated at development plant scale operation over six years in four New Zealand geothermal fields. This paper reports an initial study on the application of the CaSil technology to the silica supersaturated, hyper-saline brine from the Dieng geothermal field, Indonesia. Problematic dissolved silica is rapidly captured as a nanostructured calcium silicate material before silica deposition and scaling can occur. This yields a treated brine that can be cooled to unprecedented low temperatures without silica scaling, thereby enabling more heat energy to be accessed and electricity generated from the same brine flow than is currently possible. Samples of brine from the Dieng-1 well that had been acidified after collection were provided by Geo Dipa Energi to CaSil Technologies for analyses and an initial assessment of the suitability of the CaSil technology to prevent silica scaling. Using atomic absorption and UV visible spectroscopies, electrochemistry, and titrations the main constituents of the brine were identified. Based on this, a simulated brine was generated and used to test and identify the potential of the proprietary CaSil technology to reduce silica levels and the Silica Saturation Index, SSI, of this high silica, hyper-saline brine accordingly. Another intention of these trials was to explore effects from the borate buffer system due to the high boron content of the brine, on the CaSil technology and the reduction of the Silica Saturation Index (SSI) to levels where additional heat can be harnessed and electricity generated without inducing silica scaling. Autoclave reactions were used to simulate field specific high temperature and pressure reaction conditions. The successful laboratory trials using the simulated brine were confirmed using the Dieng brine samples provided in further experiments. These show the pathway for possible field trials, which promise that by incorporating the CaSil technology, additional heat recovery and electricity generation from the Dieng resource can be achieved without silica scale formation, thereby unlocking the full energy potential and utilisation of this geothermal resource. |