Geothermal plants are expected to double in the next five years.

The world is fast moving towards utilizing geothermal energy. Fresh concepts for high-temperature wells will speed up the development of geothermal resource across the globe and especially in Europe. EU has funded largely on the innovations and maintenance of the geothermal sector.

Europe saw an increase of 5% in geothermal plants compared to 2019. Currently, 130 plants are functioning in the continent. It is expected that the number could double in the next five to eight years. The EU’s revised Renewable Energy Directive has set the binding renewable energy target for 2030 at 32% with a clause for a possible upwards revision by 2023. By the initiative, a lot of technological breakthroughs are on the way. Geothermal plants use hydrothermal resources that have both water and heat to produce electricity. The process requires high-temperature hydrothermal resources that are obtained from hot water wells or dry steam wells by drilling into the earth. The hot water or steam turbine generates electricity. There are three types of geothermal plants.

• Dry steam plant- This kind of plant uses steam directly from a geothermal reservoir to turn a generator turbine.
• Flash steam plant- It takes high-pressure hot water from deep inside the earth and converts it to steam to drive energy. The process is a cycle as the steam could further be cooled and turned to water. The water can be injected again to the ground for next time use.
• Binary cycle power plant- The transformation of geothermal hot water to another liquid takes place. The heated second liquid is converted to steam to generate turbine.

Taking geothermal energy is a tough act as it involves temperature up to 460°C under earth and the pressure is extremely high. The process of extracting the energy puts enormous pressure on and restricts the lifespan of the equipment and infrastructure used in the process. This stress the equipment involved in energy seeking. It is not just about extracting, sometimes the well needs to be cooled as well.

Flexible coupling for deep earth extensions

A technology developed by scientists of Isor Iceland Geosurvey Institute in Reykjavik as a part of European research project brings in a fully-automated rig. The technology is being tested to minimize the issues of maintenance cost and increase the efficiency of drilling operations.

Isor, established in 2013 is a self-financing, state-owned, non-profit institution. Isor has partnered with European Union’s Geowell Project, along with other renewed research institutions like IRIS in Norway, GFZ in Germany, TNO in Netherlands, etc. Geowell project is focused on developing technologies that could be reliable, cost-effective, environmentally safe and monitoring of high-temperature geothermal wells (HTGWs).

Isor project focuses on developing a flexible coupling that allows the pipe to extend into the coupling. The injection of a coupling means taking away the stress in it. The process is a cycle as the well is cooled and the action continues again. This project is a breakthrough to the geothermal industry as many geothermal plants in mainland Europe need such help. In middle Europe, the energy could be found at greater depths. Flexible couplings in Iceland, where the trial is going on currently, goes up to two kilometres deep. But in Europe, the depth is up to five to six kilometres. The drilling cost for geothermal plants takes around 30-35% of the total revenue. So it is important to find a way to subsidize the issue.

A major challenge that the flexible coupling could face is acceptance among geothermal plants. It is very difficult to convince the management to try something new. They need to be sensitized that by using this technology, it is not just cost-effective but also expands the lifespan of the equipment.

Cement mixture suitable for geothermal application

Another such innovative technology was the production of a cement mixture that is suitable for use in the geothermal application. The cement gets exposed to around 450 °C in thermal projects. The result showed a cement sample from Portland cement mixture apt for the process. The findings resulted in the development of ‘pumpable’ cement with reduced water content without dismissing its sealing properties.

The EU-funded Geowell project has led to the invention of flexible couplings and cement mixtures that can be used in geothermal plants to minimize cost and environmental damages, and monitor HTGWs. The geothermal industry could expect more technological innovations if funding and research keep the pace.