"Due to the breakdowns at Songas' plant and Kihansi (hydroelectric dam), the national grid has an 80 MW power deficit," Tanzania State House said in a statement.
The statement said President Jakaya Kikwete had ordered the reopening of a private firm, Independent Power Tanzania Limited (IPTL), which is involved in a court case to wind up its operations. The plant can generate up to 100 MW of electricity.
"The availability of power from IPTL will ease pressure on the technicians now working to repair the Songas and Kihansi plants and allow them to do their work in a more calm environment," State House said.
TANESCO said it expects to have its 45 MW gas plant running by November, while the broken 60 MW hydro plant is expected to resume generation in December.
Tanzania also suffered serious power cuts in 2006 after a drought slashed hydroelectric power production.
Tanzanians are angry at the present rationing, which sometimes runs beyond the scheduled 14 hours a day.
"Recalling marathon blackouts of past years, we have to wonder how many more years of darkness and forced work stoppages we will have to endure," privately owned Thisday newspaper said in an editorial.
In the longer term, the east African economy plans to add another 100 MW natural gas plant in Dar es Salaam and another of 60 MW running on heavy fuel oil in northwest Tanzania.
TANESCO said the country was producing an average 697 MW against a suppressed demand of 714 MW. It says it expects demand to rise to 769 MW in 2009. The country currently has an installed capacity of 964 MW.
Just 14 percent of its 40 million people connected to the grid, and demand is growing by 10 to 15 percent annually.