NAIROBI, Kenya -- Blackouts are a regular occurrence here and throughout Africa, and the problem is getting worse. Nairobi goes dark not for its lack of coal or natural gas, but for a lack of water. Hydroelectric dams generate more than 60 percent of Kenya's power, much of it coming from a string of dams along the Tana River. During the 2009 dry spell, rationing was the rule and some sections of the city had power for just two days a week. A deepening drought cycle now threatens to spread Kenya's energy crisis beyond its borders to other parts of Africa, especially Tanzania and Ethiopia. "We in Kenya today are seriously concerned about energy security," conceded Ministry of Finance Secretary Joseph Kinyua during a recent energy conference here.