This is regarding Greg Johnson's comment regarding whether the Ooi restarts had anything to do with actual shortages. His comment below:

"But suddenly, amazingly, after
starting only 1 of, 14 is it
? nuclear power plants, in the midst of a heat wave but with the peak of summer heat still to come, KEPCO apparently has not a 10% shortage but a surprisingly large surplus of electricity, so much that it is planning to shut down up to 8 conventional combustion powered electrical plants (see the link below).
http://osaka.yomiuri.co.jp/e-news/20120707-OYO1T00340.h
tm?from=main1
Clearly an electricity shortage was not the reason for the restart."

It should be pointed out that the article linked to mentions that Ooi
3 has a capacity of 1.18 GW, placing KEPCO's maximum capacity after the restart at 24.21-24.66 GW range.
That means that if power demand rises to that value KEPCO theoretically will be able to meet it and no outages occur.

Naturally, we live in the real world, so any sensible power utility wants to have excess capacity lying around to avoid brown-outs or worse if an unforeseen demand spike occurs. (This happens more often than you'd think. Britain is said to have experienced a massive spike during some footie world cup because the entire nation got up at once at half-time and put the kettle on to brew tea.) Demand projections are at
20.8-21.7 GW, says the article, so the math checks out for the usage rate of 84-89% (the article rounds to 85-88%).

Now, there are power plants and power plants. The 8 conventional plants mentioned by Mr Johnson are said in the article to have 3.84 GW of capacity, paling in comparison to the one nuclear reactor restarted at Ooi.
Take the 8 away and you get a maximum capacity figure roughly in line with demand projections.

The article does not mention how long these plants will be offline, i.e. if this is done for routine checks or not, and neither does it discuss how KEPCO will make up for the very likely supply shortfall.
Neither does it mention what KIND of power plants these are, e.g.
coal-fired ones typically used for baseload power or gas-powered ones that come on _under regular conditions (i.e. all reactors running)_ only during times of peak demand.That's ultimately sloppy journalism.
And the reason why sloppy journalism is bad in this case is because it does not mention that Japan has been firing all the conventional plants for months now to make up for the lost nuclear capacity. It is eye-wateringly expensive to run a peakload gas-fired plant all the time, because of the variable fuel costs.
Combustion needs to take place constantly because: No fuel, no power! And said fuel, i am sure that everybody on this forum will agree, needs to be bought against hard cash from abroad. Conventional power plants essentially burn money. Meanwhile, all the nuclear power plants gathering dust are loaded with fuel that's been bought and paid for already, awaiting political decisions to take them back online so that they can produce power and practically negligible variable costs.

As i said, the article itself does not mention what kind of plants these 8 were, nor how the potential supply-side shortfall would be met. But there is indeed plenty to at least suggest that KEPCO made a rational business decision that it (and its large-scale customers buying power at liberalized prices) was probably gagging for for months now. Frankly, i am not quite sure that under a completely liberalized electricity market the Japanese Main Street would have been all too upset about this, either. Come fall we'll see just how anti-nuclear the Japanese public REALLY is, when they will start having to pay for their perceptually safer, heavily CO2-polluting fossil-powered electricity.

None of the above is to suggest that obfuscation and mendacity Mr Johnson mentions does not exist in the Japanese nuclear sector in general, or that the Ooi restarts are shining examples of good governance. But the particular evidence tabled here points to something far less nefarious.

Sorry for the length.

Alex Luta,
PhD Cand,
Tokyo Institute of Technology