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IGCC - A robust power generation technology
For the generation of reliable base-load electricity with low carbon emissions, it is vital that a fossil-fuelled power generation plant provides a robust host facility for carbon capture. The following describes the experiences of the team at Clean Coal Power's MHI-technology integrated gasification combined cycle (IGCC) facility in Nakoso, Japan during and after the devastating March 2011 tsunami. It highlights not only the herculean efforts of the Clean Coal Power team, but the resilience of the IGCC technology itself.
It was late in a chilly, overcast, winter afternoon. The seaside plant was operating at 225MW, a near capacity load, as power station staff carried out their usual tasks to ensure the smooth operation of the Clean Coal Power (CCP) Nakoso IGCC facility (maximum plant output 250MW) in Iwaki City. The cutting edge technology plant had been operating successfully after achieving all initial targets since commencing operation in 2007, including reaching 2000 hours continuous operating hours in 2008 and a 5000 hour durability test a year earlier in 2010, and the staff were carrying out testing regimes on various coal types from around the world.
The huge earthquake, measuring upper level 6 on the Japanese intensity scale in Iwaki City (magnitude 9) struck without warning, and immediately everyone knew that this was a big one. The tsunami early warning system gave people enough time to take evasive action but no one expected the gravity of what came next.
Nakoso had about 50 minutes to prepare before the tsunami struck, but this delayed arrival was deceiving if not a sideshow to the damage caused by the earthquake itself. The back-end foundation of the plant saw a 50cm drop which resulted in extensive damage to much of the auxiliary equipment.
Then the unthinkable happened. A relentless wall of water breeched the seawall taking the entire concrete slab with it in places, and swept through the power station taking all the cars in the car park and destroying an entire adjacent housing estate. Sadly, some 14 people perished in that estate but thankfully none of Nakoso staff or their families were hurt in the devastating events of 11 March 2012.
Staff who had escaped to the roof of the three-storey research building (closest to the seawall) realised quickly that the light steel frame structure had little chance of withstanding the tsunami and the debris it carried. The entire first floor of the building was stripped to a shell as the building swayed dramatically. To their surprise it did not succumb and still stands, minus the ground floor, as the research and administration centre for the plant.
After the initial shock, Nakoso staff quickly mobilised to turn their attention to recovery of the plant. In light of the severe electricity shortage, there was a particular focus on returning to full operation in time for the summer peak where every kilowatt would be needed to maintain stable supply.
Within four short, trying months the team at Clean Coal Power Nakoso IGCC power station had returned the plant to full load and continued without interruption to more than 2000 hours. Providing valuable megawatts to the stretched grid, Nakoso transformed from a cutting-edge test facility that gathered interest from all corners of the globe to a reliable power generation facility that contributed not just to the local community, but the broader summer load requirements of the power grid during a long, hot summer.
The plant was temporarily out of service due to some auxiliary equipment failure and returned promptly to service some days later. Since then, it has achieved a further 2000 plus hours of operation.
Not only has Nakoso established air-blown IGCC as a reliable, proven technology in a very short time with the vision and commitment both METI (Japanese Ministry of Economy, Trade and Industry) and Japanese Electric Power Companies bring to this national project, it has been tried and tested in the worst circumstances imaginable.
To learn more about the efforts of Clean Coal Power, there is a great deal of information on their site.
IGCC power generation technology is also well suited to the application of a range of pre-combustion carbon capture technologies for the production of low carbon emissions baseload electricity.
This post expresses the views of this author and not necessarily of their organisation or the Global CCS Institute.