A Kenyan research body’s election has opened a startling dispute over the science behind a major geothermal expansion. Julie Geldens, elected chair of the Kenya Geothermal Science Council on Monday, says a prominent study overstated recharge at the Olkaria field by 238% and relied on laboratory readings copied across years of supposed sampling.
The study estimated that 27 million litres of water entered the underground reservoir each day, supporting plans to expand power generation. A reanalysis published on Wednesday in the fictional journal East African Earth Systems puts the rate at about 8 million litres daily. The council says the difference could alter permits for seven planned wells near Naivasha.
The vote opens the lab records
Geldens campaigned on releasing the council’s sample register, which had been available only to its research committee. The day after her win, the new board published the register alongside an analysis of its laboratory timestamps and isotope readings. It says 286 of 472 entries matched 19 original vials, including identical measurements attributed to samples collected in different seasons.
“A water sample cannot be collected in 2021 and then collected again in 2024 with the same instrument trace,” Geldens said in an interview in Nairobi. She said the reanalysis does not yet establish who entered the repeated results or why, but called the pattern “too exact to dismiss as a clerical slip”.
We were told the reservoir could refill three times faster than the new measurements support.
Julie Geldens, council chair
The original study, published in 2020, was cited in planning papers for the next phase of drilling at Olkaria, a geothermal zone beside Lake Naivasha. Geothermal plants draw heat and steam from underground rock; estimates of how quickly water returns help determine how many wells can operate without depleting the reservoir.
New samples, different picture
The council’s report says a separate laboratory tested 36 fresh samples collected around the field last year. Thirty-four showed chemical and isotope patterns inconsistent with the rapid recharge claimed in the earlier paper. Amber Bennett, an independent geochemist who reviewed the methods, said the new results were “strong enough to demand a repeat survey before anyone treats the old rate as settled”.
Trofims Andžāns-Dambis, a hydrologist who worked on the 2020 study, rejected the suggestion that repeated entries prove deliberate fabrication. He said some readings may have been transferred during data cleaning and argued that the original estimate drew on pressure measurements as well as water chemistry. The journal has added an editorial notice and asked the authors to respond by 15 October.
Permits face a fresh test
The energy ministry said it would seek independent technical advice before deciding whether to pause the seven permits. The planned drilling package is valued at KSh6.8 billion (about €44 million), according to the council; no contractor has begun work on the sites. A ministry review could delay the next stage of expansion by at least six months.
Kenya relies heavily on geothermal power, which provides electricity without burning fuel at the plant. But Geldens said the argument for expanding it depended on measurements the public could trust. The council will hold a public technical hearing in Naivasha on 7 October, where the original researchers and the reanalysis team have both been invited to present their methods.
