Chapter 2:
Hydropower
In this chapter
Drought causes an annual cost of $1.8 billion in electricity generation
Based on 30-year averages, drought has had a persistent impact on hydroelectric generation in Türkiye. Both long-term and year-to-year declines in hydropower due to drought are compensated by natural gas power plants, increasing energy imports.
2.1
The impact of drought on hydropower is permanent
Hydropower has a long history in Türkiye. From the 1960s to the late 1990s, it accounted for up to 40% of electricity generation. Its share declined in the 2000s with the rise of natural gas. Nevertheless, hydropower continued to act as the backbone of renewable energy in Türkiye, maintaining a share between 16% and 30% during that period.
Over time, increasing electricity demand and the slowdown in new hydropower capacity additions have reduced its share in generation. In addition, drought has had a significant impact on power plants.
In Türkiye, drought has significantly reduced hydroelectric output over the past decade. Considering capacity utilisation rates over the last 30 years, the average capacity factor of hydroelectric plants fell from 38% in the 1996–2005 period to 26% over the past decade (See: Methodology).
A similar trend is observed in Türkiye’s three largest hydroelectric plants: Atatürk, Karakaya, and Keban dams.
When examining total electricity generation over the past 30 years, these dams show a consistent decline in output across each decade. Their average annual generation was 21.3 TWh in 1996–2005, which decreased to 18.7 TWh (-12%) between 2011–2020. Over the last decade, the average annual generation fell further to 15.1 TWh—29% lower than 20 years ago.
2.2
Decline in hydropower increases natural gas imports
In addition to its long-term effects, drought also causes short-term fluctuations in hydroelectric generation during dry years. These annual fluctuations can exceed 20 TWh, accounting for more than 5% of the country’s electricity consumption. For comparison, even the doubling of solar generation over the past two years resulted in an increase of 19 TWh. Therefore, drought-related declines pose a risk to Türkiye’s energy supply security.
In Türkiye, hydropower and natural gas plants effectively substitute for each other. When hydroelectric generation declines, natural gas plants compensate. When water availability is high, increased hydropower reduces the output of gas plants.
Although domestic natural gas production has increased in recent years, Türkiye remains heavily dependent on imports. In 2025, domestic gas production covered only 5% of total consumption. At the same time, drought reduced hydropower generation, resulting in increased natural gas consumption and energy imports.
Over the past 30 years, the 29% decline in generation (-6.2 TWh) at just the three largest hydroelectric plants has required compensation through natural gas plants, leading to an additional $400 million in annual gas imports. If all hydroelectric plants in Türkiye are assumed to be similarly affected, the long-term impact of drought on energy imports reaches an average of $1.8 billion per year (See: Methodology).
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