Sosian Menengai Geothermal Energy, Kenya’s latest geothermal energy plant, is powered by modular know-how that maximizes effectivity, reduces prices, and enhances scalability.
Kenya’s scenic Rift Valley area is a literal hotbed of geothermal potential. A part of the huge East African Rift Valley System (EARS), a 6,400-kilometer (km) tectonic divergence that’s cleaving the African continent into two plates, Kenya’s Rift Valley varieties a vertical hall of intensive faulting and volcanic exercise, scorching springs, fumaroles, and sulfur-oozing fissures. However whereas the nation started geothermal exploration for energy growth within the Fifties, most of its investments have been centered on the Olkaria area located inside Hell’s Gate Nationwide Park close to the flamingo-flecked Lake Naivasha in Nakuru County. 5 of six geothermal energy stations in Olkaria are owned by KenGen (with a mixed capability of 799 MW), whereas Nevada-based Ormat Applied sciences owns a 150-MW plant. Olkaria crops in 2023 supplied practically 45% of Kenya’s whole technology, a sizeable contribution to the East African powerhouse’s meager 3.3-GW put in capability.
In 2008, the Geothermal Growth Co. (GDC), a state-owned special-purpose car tasked with accelerating the nation’s geothermal useful resource growth, expanded its focus to the Menengai area simply north of Olkaria, on the website of an enormous protect volcano with one of many greatest calderas on the planet. Whereas GDC says the Menengai advanced harbors a possible of 1,600 MW, its long-term purpose is to develop 465 MW of geothermal steam equal.
In 2013, it took step one to competitively award the primary three preliminary 35-MW energy initiatives on the advanced to a few unbiased energy producers (IPPs): Orpower 22 (a former subsidiary of New York agency Symbion now owned by China’s Kaishan Group), South African-based Quantum Energy East Africa (now majority owned by UK agency Globeleq), and Nairobi-headquartered Sosian Power. In August 2023, the primary of those initiatives—Menengai III, now formally generally known as the Sosian Menengai Geothermal Energy—wrapped up a 16-month development timeframe and started delivering first energy to the grid.
A Expertise Breakthrough
Sosian’s condensed timeframe is particularly beautiful on condition that conventional geothermal growth can exceed seven years. That is owing partly to a fancy course of that includes drilling and testing a number of wells, choosing a centralized energy plant location, ordering steam generators, and establishing intensive steam assortment and reinjection techniques. The normal strategy can also be ridden with dangers, together with important delays and inefficiencies, akin to power losses from steam stress drops, thermal losses over lengthy distances, and the underutilization of wells with various pressures.
Sosian, to some measure, had the good thing about the GDC’s public-private partnership mannequin for growing Menengai, below which the GDC assumes upfront dangers of geothermal growth. The state firm has additionally notably got down to develop the sector in 5 phases, beginning with a 105-MW “steam gross sales” mannequin, the place it provides steam from drilled wells to the facility crops through a 25-km steam gathering and piping system. As of 2023, GDC had drilled 53 wells with a possible of 169 MW.
Nonetheless, the facility plant’s success will also be attributed to a particular new geothermal growth course of launched by China’s Kaishan Group. Dr. Tang Yan, basic supervisor of Kaishan Group, recalled realizing the necessity for a dramatic shift at a 2015 geothermal convention in Melbourne, Australia, the place consultants mentioned the pitfalls of typical strategies. “I stated, ‘Why don’t you place an influence plant on the wellhead and do it part by part?’ ” he recounted.
Overcoming Conventional Challenges
Whereas the strategy proposed to assist incremental energy manufacturing from the beginning whereas offering income to assist future venture growth, Yan realized no know-how to assist the strategy was commercially accessible. Kaishan, which had then already begun its transition from an enormous Shanghai-headquartered air compressor maker to a diversified international firm, jumped into motion to leverage its 2012-developed Natural Rankine Cycle (ORC) expander and screw steam expander applied sciences.
The applied sciences—initially developed for waste warmth restoration from refineries and metal mills—allowed Kaishan to optimize geothermal energy technology by maximizing power output from various effectively circumstances, lowering inefficiencies, and enabling the event of 4 kinds of decentralized, modular energy crops which can be faster to deploy and extra adaptable to totally different geothermal fields, Yan informed POWER. “These modular energy crops embody the steam screw expander modular energy crops, the steam ORC modular energy crops, the brine ORC modular energy crops, and the steam and brine twin useful resource modular energy crops,” he defined.
Steam screw expanders are particularly designed to deal with moist or saturated steam, which is widespread in geothermal wells, successfully extracting power from a wider vary of effectively circumstances, together with wells with excessive non-condensable fuel (NCG) content material that is probably not appropriate for conventional generators. ORC techniques, in the meantime, are adept at changing lower-temperature steam and brine—byproducts that might in any other case go to waste—into further electrical energy, Yan stated.
As well as, Kaishan’s modular crops can be utilized to type hybrid cycles or thermal techniques to fulfill any manufacturing effectively circumstances, maximize their energy output, and eradicate low-head stress (WHP) wasted wells or idling wells. As a result of the applied sciences might be tailored to particular geothermal useful resource circumstances at totally different venture websites, they are often tailor-made to supply stellar effectivity, he stated. “We are able to enhance the effectively thermal effectivity of, for instance, medium enthalpy wells, to as much as 18% and 19%,” he stated. That compares to solely 8% to 12% for conventional centralized energy crops that solely use single-flash steam, he famous.
A Aggressive Edge for New Geothermal Energy
Kaishan rapidly expanded the area of interest know-how right into a profitable enterprise. Because it put on-line the primary of 4 phases of the 240-MW Sorik Marapi Geothermal Venture in Indonesia in 2018, it has constructed the 10-MW Sokoria Geothermal, additionally in Indonesia, alongside initiatives in Turkey, the U.S., and Hungary. At Sosian, Kaishan’s first venture in Kenya, the corporate served because the engineering, procurement, and development (EPC) contractor.
In keeping with Yan, Kaishan’s cost-effective value level proved a vital choice benefit. Kaishan’s EPC contract is valued at $65 million, in comparison with a $108 million EPC contract just lately awarded for Menengai II, one of many area’s three equally sized IPP initiatives. The worth distinction is rooted within the know-how choice, Yan defined. Whereas Sosian’s 35-MW venture was designed as a centralized energy plant, it’s powered by two steam screw expanders and three moist steam ORC modular energy crops.
Nonetheless, GDC’s steam accommodates 3.3% NCG—which represents a “enormous share,” he stated. If Sosian used conventional steam generators, they would wish to broaden steam at 6 bar absolute after which devour extra then 30 tons of steam per hour to take away NCG utilizing steam injectors and vacuum pumps. As an alternative, Sosian employs steam screw expanders and a backside cycle to deal with the saturated steam discharge, lowering the steam to atmospheric ranges all through all the course of whereas eliminating the parasitic energy sometimes consumed by vacuum techniques.
“The general effectivity in comparison with a conventional steam turbine is a big recreation changer for this website,” Yan stated. “The venture solely wanted a assure of 33.25 MW, and the goal was 35 MW, however we’re really producing 37 MW.” On the identical time, the venture doesn’t must buy the additional 10% of steam for a steam injector, placing much less of a burden on the GDC, he stated.
A Answer for Idled Wells
The modularity of the system additionally proved useful to hurry up development and, crucially, to beat provide chain and venture administration challenges posed by the COVID pandemic, Yan stated. Kaishan sometimes assembles the modules and conducts part testing in a manufacturing facility setting over six to 9 months, he stated. “After which, once we ship to the location, normally it takes a really brief time to place them collectively, and also you don’t must do any welding on the facility modules,” he added. “That’s generally the place high quality management generally is a problem,” he famous.
The success of the Sosian Menegai venture has up to now sparked important curiosity in Kenya’s geothermal business, Yan stated. A key purpose is that Kenya has loads of wells, and an estimated 25% to 30% of these wells is probably not supported by a steam assortment system, which is required by centralized steam generators. “They name them idled wells or wasted wells, they usually sit there and do nothing,” even when it was pricey to drill them, he stated. “However our know-how doesn’t have that limitation as a result of we are able to use any good stress, whether or not they can produce brine or steam.”
—Sonal Patel is a POWER senior editor (@sonalcpatel, @POWERmagazine).
