Unlocking the full geothermal potential: How the CaSil technology can eliminate silica scaling and create new business opportunities

Abstract

Silica scaling continues to pose a worldwide challenge in the full exploitation of geothermal reservoirs. As dissolved silica precipitates during cooling and steam production, it forms an intractable scale that blocks pipework, heat exchangers and reinjection wells. These deposits significantly lower the efficiency of heat exchangers, resulting in a direct reduction in electricity and revenue generation over time. Regular and costly maintenance is required which leads to plant downtime. Conventional silica scale mitigation techniques are not wholly successful and come with drawbacks such as high cost or corrosion risks.
The innovative and proprietary CaSil technology introduces a disruptive method of transforming dissolved silica entities into a novel calcium silicate (CaSil) product, forming discrete particles that remain suspended and do not adhere to metal surfaces. This process achieves a significant reduction in the silica saturation index to well below 1 within seconds. The robust technology is adaptable to a wide range of brine compositions, regardless of the initial silica concentration, ensuring dependable elimination of silica scaling. Moreover, the CaSil technology facilitates the safe reduction of brine temperatures beyond current limits without inducing any silica scaling. This presents novel business prospects for utilising additional process heat in sectors like greenhouses, aquaculture, or milk powder production, supporting the efforts to decarbonise industrial processes. The CaSil technology can seamlessly integrate with existing geothermal operations, or greenfield plants, offering a versatile solution.
This paper presents updated data from our development plant which was successfully operated across four different geothermal resources in New Zealand. The effectiveness and robustness of the technology which can unlock the full potential of geothermal resources are highlighted. Additionally, data based on laboratory experiments are discussed, addressing the applicability of the technology to high silica, hypersaline geothermal brines such as the Dieng field in Indonesia.