• Turkey’s geothermal power plants release CO2, says EBRD study
  • Country has set a target to install 1 gigawatt by 2023

Geothermal wells usually provide a steady supply of clean energy flowing from the natural heat of the Earth. In Turkey, because of a quirk in the geology, some of those wells pollute as much as coal-fired power plants.

The nation has a layer of subterranean limestone, which lets loose carbon dioxide when it comes in contact with steam as hot as 280 degrees Celsius (536 Fahrenheit) tapped by geothermal wells, according to a report commissioned by the European Bank for Reconstruction and Development, a government-backed institution helping fund the projects.

The results mark a rare example where renewable energy is producing a greenhouse gas. They’re disputed by at least one of the companies singled out in the EBRD report and have prompted the industry to search for ways to pare its emissions. They’ve also put a spotlight Turkey’s ambition to boost geothermal capacity 60 percent by 2023, making it one of the world’s top markets for the technology. The standard-setting Climate Bond Initiative said none of the projects pass its sustainability criteria.

“It is clear that in some areas of Turkey, the present concentration of CO2 is quite high,” said Adonai Herrera-Martinez, director of energy efficiency and climate change at the EBRD in Turkey. “There is a clear momentum by all parties to actually understand how to manage this.”

Geothermal plants tap hot water and steam from deep underground to drive electric turbines. The liquid is injected back into the ground, but gases that come up with steam escape. In Turkey, the problem comes from a band of limestone prevailing in western Anatolia where most of the wells are drilled. Limestone is mostly calcium carbonate and breaks down into carbon dioxide and other calcium compounds when heated.

The previously unreleased study, which was obtained by Bloomberg News, was prepared for the EBRD by Ernst & Young LLP, Ecofys International BV and the Middle East Technical University in Istanbul. It evaluated projects by Turkish companies including Zorlu Enerji Elektrik Uretim AS, Gurmat Elektrik Uretim AS, Kipas Holding AS’s Maren Enerji, Menderes Geothermal Elektrik AS, and Enda Enerji Holding AS. At least 12 geothermal plants working in Turkey didn’t release their emissions results and weren’t included.

Disputed Findings

Zorlu Enerji, an electric utility based in Istanbul, debated the validity of the report, saying its emissions are closer to those of a plant fired by natural gas than coal. It has invested more than $900 million in geothermal, drawing part of its funding from Japan Bank of International Cooperation. It sells some of its CO2 to Linde Gaz, the Turkish branch of Munich-based Linde AG, which supplies the beverage industry.

“I don’t see that this is a major problem,” said Ibrahim Sinan Ak, general manager of Zorlu Energy, in a phone interview.

Gurmat, a developer based in Ankara, is studying how to inject the CO2 it produces back into the ground, according to Ali Karaduman, the company’s general manager. It’s also considering selling the gas to greenhouses, which can use it to stimulate plant growth. All the CO2 from its five plants is now released into the atmosphere.

The other three companies named in the report didn’t respond to requests for comment.

The report puts development banks in an uncomfortable position, since they assess projects based on environmental criteria including carbon emissions. The EBRD in January set aside $100 million to lend for geothermal projects in Turkey. It also partnered with the World Bank’s Clean Technology Fund to spend another $25 million on exploring for further geothermal capacity in Turkey.

The EBRD commissioned the report on emissions to identify ways to store or use carbon produced by the wells. It suggests the flow of CO2 from geothermal wells may naturally decline with age. Of the 10 plants assessed, all except one produced as much or more CO2 than an average coal plant generating the same amount of power.

“Most geothermal power plants are producing very clean energy,” said Magnus Gehringer, a former adviser at the World Bank and chief executive officer of Washington-based consulting firm Consent Energy LLC. “Turkey is the only place that I know of with the CO2 problem.”

Japan Bank for International Cooperation, isn’t aware of the contents of the EBRD report, according to its spokesman Junsuke Arita. Its overseas geothermal projects must be in line with the institution’s environmental and social guidelines, he said. The bank provided $16.7 million in financing for a Zorlu Energy project.

Growing Ambition

Turkey is aiming for a total of 1,000 megawatts of geothermal capacity by 2023, almost as much as a single nuclear reactor generates. The country currently has 614 megawatts of geothermal capacity, a fraction of its 67,000 megawatts of generation capacity, according to Bloomberg New Energy Finance.

The Climate Bond Initiative, a London-based researcher that sets voluntary standards for the green bonds used to finance many developments, said none of Turkey’s geothermal projects qualify for the seal of approval.

“Geothermal with high levels of emissions are not going to help you in the long run,” said CBI Chief Executive Officer Sean Kidney.

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