NAIROBI, Feb 9 (Reuters) - Africa-focused power firm Globeleq, owned by British and Norwegian development finance institutions, has awarded Japan's Toyota Tsusho a contract to build a 35 megawatt $(MW)$ geothermal power plant in Kenya, the two companies said on Thursday.

The plant, to be based in Menengai in Nakuru County, will add to Kenya's installed capacity of 3,321 MW, 90% of which is from renewable sources, according to government statistics.

Construction of the project, valued at $108 million, is expected to start in the first quarter of this year and go into commercial operation in 2025, Globeleq and Toyota Tsusho said in a joint statement.

The electricity will be sold to the country's sole power distributor Kenya Power under a 25-year contract, while the geothermal steam to run the plant will be supplied by state-owned Geothermal Development Corporation for the same period, they said.

Kenya Electricity Generating Company , 70%-owned by the government, already produces 799 MW from its geothermal power plants, while energy firm Ormat Technologies produces 152 MW.

Globeleq is 70% owned by Britain's British International Investment and the rest is held by Norway's Norfund.

(Reporting by George Obulutsa; editing by Anait Miridzhanian and Jason Neely)

((george.obulutsa@thomsonreuters.com; Reuters Messaging: george.obulutsa.thomsonreuters.com@reuters.net))