地热发电技术简介（英文版）_28页-4mb

Summary of Geothermal Power Technology Brief

Core Content

Geothermal energy is a renewable energy source that harnesses heat from the Earth's subsurface for direct use or electricity generation. It offers several advantages over other renewables, including consistent availability, lower lifecycle greenhouse gas emissions, and the ability to supply baseload electricity. Geothermal power generation primarily relies on medium- to high-temperature resources, which are typically found near volcanic activity, such as along plate boundaries, mid-oceanic ridges, and rift valleys.

Main Points and Key Information

1. Geothermal Power Overview

• Availability: Geothermal energy is available year-round, unlike solar and wind, which are intermittent.
• Applications: Used for heating, cooling, and electricity generation.
• Capacity Factors: Higher than many other renewables, allowing for reliable baseload power and flexibility in energy systems.
• Greenhouse Gas Emissions: Lower lifecycle emissions compared to fossil fuels, making it a cleaner energy option.

2. Technology Options

Geothermal power generation is based on four primary technologies:

• Direct Dry Steam Plants: Use high-pressure steam (≥150°C) directly to drive turbines. Steam must be at least 99.995% dry to avoid damage.
• Flash Plants: Most common type, using steam from high-temperature fluids (≥180°C). Steam is separated and re-injected after use.
• Binary Plants: Use lower-temperature geothermal fluids (100°C–170°C) to heat a secondary fluid in a closed loop, which then drives the turbine.
• Combined-Cycle or Hybrid Plants: Combine traditional Rankine cycles with binary cycles to use waste heat, increasing efficiency. Hybrid systems may integrate other energy sources like solar or biomass.

3. Global Status and Growth

• Installed Capacity (2016): 12.7 GW, with 80.9 TWh generated in 2015, representing about 0.3% of global electricity.
• Leading Countries: United States (2.5 GW), Philippines (1.9 GW), Indonesia (1.5 GW), Kenya (1.1 GW), and New Zealand (0.986 GW).
• Growth Trends: 901 MW added in 2016, the highest in 10 years, showing increasing interest in geothermal projects.

4. Costs

• Installed Costs: Range from USD 1870 to USD 5050 per kW, with binary plants being more expensive.
• Levelised Cost of Electricity (LCOE): Typically between USD 0.04 and USD 0.14 per kWh, depending on the project stage.
• Cost Reductions: Expected to continue through 2050, especially in flash and binary plants, with public and private sector collaboration playing a key role.

5. Potential and Barriers

• Technical Potential: Estimated at 240 GW for hydrothermal resources, with potential for even higher if deeper resources are accessed.
• Barriers:
  • Financial: High upfront costs and uncertain resource availability make it difficult to secure financing. Public funding and risk-sharing mechanisms can help.
  • Environmental: Impact assessments are required, and there are concerns about air emissions and land use.
  • Administrative: Lengthy licensing and permitting processes, and varying regulations across countries, can delay projects.

6. Enhanced Geothermal Systems (EGS)

• EGS enables access to deeper, non-conventional geothermal resources by creating artificial fractures in rock formations.
• Uses binary plants to generate power from hot brine, which is re-injected to maintain reservoir pressure.
• Pilot projects in France and the US have demonstrated the feasibility of EGS, though it is not yet commercial.

7. Global Geothermal Alliance

• Launched at COP21, it aims to accelerate geothermal deployment by fostering collaboration and investment.
• Aspirational goals include a five-fold increase in geothermal power capacity and more than two-fold growth in geothermal heating by 2030.

8. Opportunities for Growth

• Low-Temperature Bottoming Cycles: Increase efficiency by using waste steam in binary cycles.
• Co-Generation: Use of geothermal fluids for direct heating applications after steam extraction.
• Co-Produced Resources: Utilization of geothermal fluids generated as a by-product of oil and gas operations.
• Supercritical Systems: High-temperature systems (e.g., 374°C and 221 bar) that are still under research but could offer higher productivity.

Conclusion

Geothermal power has significant potential to contribute to sustainable energy systems, with a strong economic and environmental case. Despite its benefits, challenges such as high initial costs, regulatory hurdles, and environmental concerns must be addressed to unlock its full potential. Continued technological innovation, public-private partnerships, and supportive policies are essential for its expansion.