Improvement of Efficiency of Power Generation Facilities

Tohoku EPCo is trying to reduce the consumption of fossil fuels at thermal power stations and reduce CO2 emissions through careful maintenance and management of thermal efficiency at thermal power stations, safe and stable operation of nuclear power stations, improvement of capacity factors at geothermal power stations, and introduction of highly efficient equipment in hydroelectric power stations, etc.

Improvement of Thermal Efficiency at Thermal Power Stations

Higashi-Niigata Thermal Power Plant

Tohoku EPCo is making efforts to maintain the thermal efficiency of its thermal power stations at 40% or higher by utilizing to the greatest extent possible its highly efficient power plants such as Higashi-Niigata Thermal Power Station 4-1 System (826,000 kW) as a highly efficient LNG combined-cycle power plant that boasts the world's highest level of efficiency, Higashi-Niigata Thermal Power Station 3 System (1.09 million kW), Units 1 and 2 (1.2 million kW) of Noshiro Thermal Power Station, Units 1 and 2 (2 million kW) of Haramachi Thermal Power Station, etc.

Higashi-Niigata Thermal Power Station 4-1 System started commercial operation in 1999 and achieved highly efficient operation of more than 50%. Moreover, 4-2 System is slated to start commercial operation in December 2006. Together with 4-1 System, the thermal power station will be capable of generating 1.61 million kW.

The level of 50% thermal efficiency can reduce annual LNG consumption by about 370,000 tons and CO2 emissions by about 22% compared with the conventional type of LNG-fired power generation, making a great contribution to the prevention of global warming.

Thermal Efficiency of Thermal Power Plants

Safe and Stable Operation of Nuclear Power Stations

The capacity factor of our nuclear power stations in FY2005 stood at 47.3% because of shutdown of Onagawa Nuclear Power Station due to an earthquake in August 2005 in Miyagi prefecture. We will continue to exercise due care to ensure safety and maintain high capacity factors, while promoting the best power sources portfolio with nuclear power as the core in consideration of environmental adaptability, supply stability and operability.

Change in Capacity Factor for Nuclear Power Plants

Higashi-Niigata Thermal Power Station Wins Energy Conservation Center Japan Chairman Award at Nationwide Contest of Excellent Cases of Energy Conservation in FY2005

In February 2006, the combined cycle technology group of Higashi-Niigata Thermal Power Station won the Energy Conservation Center Japan Chairman Award at the Nationwide Contest of Excellent Cases of Energy Conservation in FY2005 for "Improvement of Operability of Loads at Power Stations through Introduction of New Combustor in Higashi-Niigata Thermal Power Station 3 System."

BOG* constantly generated at LNG bases was a factor that increased the minimum load of conventional power generation equipment during nighttime hours when electricity demand is little as BOG could not be burned in combined cycle equipment because of a combustion stability problem and was fully disposed of by conventional power generation equipment in the past.

"Improvement of Operability of Loads at Power Stations through Introduction of New Combustor in Higashi-Niigata Thermal Power Station 3 System" made it possible to improve the operability of Higashi-Niigata Thermal Power Station as a whole as it became possible to move loads to highly thermal-efficient combined cycle equipment and lower the minimum load of conventional power generation equipment as a result of the introduction of a new combustor capable of burning BOG in the gas turbine of Higashi-Niigata Thermal Power Station 3 System.

Consequently, it became possible to reduce fuel expenses through the improvement of thermal efficiency of Higashi-Niigata Thermal Power Station as a whole, and reduce environmental loads such as NOx and CO2, too.

*BOG (Boil Off Gas): A type of gas produced by agitation in LNG tanks and heat input from the air. BOG is mainly composed of methane.

	Takashi Ito Combined Cycle Technology Group Higashi-Niigata Thermal Power Station
Q.What is the effect of introduction of the new combustor? As a result of the introduction of the new combustor in the turbine of System 3, the operability of Higashi-Niigata Thermal Power Station as a whole could be improved. It has also become possible for the power station as a whole to reduce its LNG usage by about 6,780 tons a year, thanks to the difference in thermal efficiency that is improved by moving loads to the combined cycle equipment. At the same time, it has become possible to reduce CO2 emissions by about 18,000 tons a year.
New combustor (nozzle and inner cylinder) Q.What difficulty did you have in introducing the new combustor? To stably burn BOG that is composed mainly of combustion unstable methane in a gas turbine, we conducted joint research with the gas turbine manufacturers and repeated efforts to optimize the nozzle pore diameter and combustion air distribution through various combustion tests at a plant. As a result, we could achieve stable combustion of fuel gas that contains a high concentration of methane. 3 System's gas turbine Q.What is your future development? As for the new combustor that we have introduced this time, the cooling structure of the combustor itself is reinforced. Compared with conventional combustors, the service life of the new combustor is expected to be extended by 1.6 times as long on a design basis. From now on, we will accumulate track records of operation, evaluate the service life upon verification such as destructive inspection at the time of periodical inspection, etc., and pursue further cost reduction.

Improvement of Efficiency of Equipment at Geothermal Power Stations

Our geothermal power stations are also trying to improve their capacity factors by reducing the number of days of maintenance related work stoppage, etc.