An international firm credited with supporting the development of one of the world’s largest geothermal powered utilities has underlined the potential for harnessing the Sultanate’s geothermal resources for applications such as water desalination, district cooling and low pressure steam generation.
RG Thermal Energy Solutions (RG-TES), a UAE-based firm focused on developing geothermal projects in the Middle East and Africa, outlined opportunities for the commercial exploitation of this largely untapped energy resource at a key conference held in the city recently.
While any geothermal resources in the Sultanate are essentially low-enthalpy (temperature) reservoirs, which make them unsuitable for power generation, these resources are ideal for a range of applications that currently depend on conventional energy, say RG-TES’s experts. According to the company, the Middle East is a “unique geothermal market”, endowed with far greater low-enthalpy resources than most people are aware of. These resources, it argues, can power a substantial share of the region’s thermal desalination capacity.
Moreover, heat from low-enthalpy geothermal fields can be used to pre-heat water for steam generation, thereby contributing to significant energy savings. In particular, the potential for low-enthalpy geothermal energy in Oman appears to be significant, the company insists, citing the findings of a 1996 study of geothermal resources in the Sultanate. In that study, temperature maps of boreholes drilled within Petroleum Development Oman’s (PDO) concession revealed that the highest underground temperature was around 174 deg C. While deemed far below the minimum temperature (of around 300 deg C) required for direct use of hot water in steam power generation, these reservoirs are ideal for direct applications, such as heating, cooling, desalination, and steam generation, according to the experts.
In fact, Oman and the wider region has an abundance of low-enthalpy geothermal reservoirs, they maintain. To buttress its claim, the company says it has drilled the first low-enthalpy geothermal wells in the Middle East at Masdar City in the UAE. The project consists of a closed loop of two geothermal wells yielding an average temperature of 95 deg C. These wells will be used for district cooling for the Masdar City development. Separately, Saudi oil giant Saudi Aramco has commissioned RG-TES to undertake a study of geothermal resources.
“The team’s findings have shown that the geothermal resource in the region is much greater than previously estimated. Work continues on the project with the overall aim of developing 2-3 geothermal cooling and desalination plants,” the company said. Low-enthalpy geothermal reservoirs in the Middle East, according to RG-TES, can be typically found near anticlines — a geological term for areas in the ground that host oil and gas traps, and synclines — deep aquifers filled with hot water. Geothermal energy is typically accessed through a ‘triplet’ closed loop well configuration involving two production wells and one re-injection well drilled to depths of 2-3 km.
Heat from the water is extracted for use in applications that require direct thermal heat, offering substantial energy savings as a result. Such savings can be upwards of 45 per cent when geothermal capacity is added to district cooling systems operating on thermal chillers as opposed to electric chillers. Based on these savings, one geothermal well in a cooling application replaces approximately 1 MW of power plant capacity, according to RG-TES. Likewise, energy savings can be as high as 85 per cent when using geothermal desalination via Multi-Effect Distillation (MED), compared with conventional MED, according to the company.
Dubai-based RG-TES is a joint venture of Ambata Capital Partners, which specialises in funding the development of clean energy, and Reykjavik Geothermal, a leading geothermal power development company, which develops high temperature geothermal resources into geothermal power plants globally.
