6.b) List and explain the problems associated with geothermal system operations.
Answer:
Problems associated with geothermal system operations:
1. Induced Seismicity (Human‑Caused Earthquakes)
- Enhanced geothermal systems (EGS) involve injecting fluids under pressure to stimulate reservoirs, which can trigger seismic events.
- Notable cases include Basel (Switzerland), where over 10,000 tremors (up to M3.4) occurred after injection, leading to project cancellation.
- Pohang (South Korea) experienced a damaging M5.5 quake tied to EGS operations.
2. Scaling, Corrosion, and Clogging
- Geothermal fluids often contain dissolved minerals, which precipitate as scale (e.g., silica, calcium) in pipes and equipment.
- The fluids may also be chemically aggressive, leading to corrosion of pipes, heat exchangers, and casings.
- Clogging and fines migration (tiny particles entering the system) further degrade performance.
3. Groundwater Contamination & Fluid Disposal
- Extracted geothermal fluids often contain toxic elements like mercury, arsenic, boron, and antimony. If not properly reinjected, these can contaminate water and soil.
4. Land Subsidence & Uplift
- Removing large volumes of fluid reduces reservoir pressure, causing the ground to sink (subsidence).
- Example: Wairakei (New Zealand) experienced subsidence.
- In Germany, a geothermal project caused uplift due to mineral swelling.
5. High Capital and Maintenance Costs
- Front-end costs—like deep drilling and exploration—are very high, with uncertain returns due to resource variability.
- Ongoing upkeep is also expensive, as corrosion, scaling, and specialized labor raise operational costs .
6. Location Dependency
- Geothermal resources are only viable in specific geological locations—often near tectonic plate boundaries or volcanic areas – limiting widespread deployment.
7. Environmental Emissions & Water Usage
- Although emissions are lower than fossil fuels, geothermal facilities may release CO₂, H₂S, and other gases unless properly contained.
- Some plants consume large volumes of freshwater for cooling and processes, straining local water supplies in arid areas .
8. Regulatory, Social & Financial Barriers
- Permitting and regulation can be lengthy and complex, especially for new EGS projects on public land .
- Public opposition stems from concerns about induced quakes, emissions, or landscape impacts.
- Investment risk is high due to exploration uncertainty and long return periods, limiting private financing.