The frequency frontier in Japan

After the Fukushima nuclear disaster, the utility company Tepco faced a problem: how to keep the lights on with the reactors off? Four of my students (Dan Bodley, Andrew Boudreau, Allison Dee, and Nick Phoutrides) found the answer. It boils down to “they didn’t.” But why they didn’t turns out to be very interesting. Preview: it was not because the nation of Japan lacked the excess capacity to replace nuclear electricity.

Japan is divided into 10 different utility areas.Tepco enjoyed 65 GW of capacity (17 from nuclear) and imported up to 13 GW. Typical summer peak demand ran around 61 GW. The quake took 17 GW of nuclear off-line, leaving 48 GW of local capacity under the heroic assumption that the utility could run all its non-nuclear plants at peak capacity.

OK ... so just import! Problem solved, no blackouts, all good. And if you just looked at the headline numbers, that would have been feasible, even with the national reactor shut-down.

Except there were two problems. First, the quake bady hit Tohoku — which normally provided all of Tepco’s imports — even worse than Tepco.

The second problem was the “frequency frontier” that ran roughly along the border between the Tepco-Tohoku service areas and the Hokuriku-Chubu service areas. Back when Japan first electrified, in the 19th century, General Electric supplied the Osaka utilities whereas the precursors to Tepco bought from Allgemeine Elektricitäts-Gesellschaft. AEG ran its equipment at 50Hz, whereas G.E. used 60Hz. The end result was the “frequency frontier” that bisects the country. There were three converter stations on the frontier, but their combined capacity came to only 1.2 GW. The end result was that Tepco’s maximum available peak import capacity declined from 13GW before the quake to only 7.3GW ... and that 7.3GW number, remember, was a maximum.

In short, Tepco faced a peak shortfall of 5.4 GW. Here is how that worked out: 47.7GW non-nuclear supply + 7.3GW imports − 60.4GW peak demand = (5.4GW). Tepco filled the gap by “conservation.” Why the scare quotes? Well, we normally think of conservation as turning off the AC, keeping lights low, taking the stairs, that sort of thing. We do not think of rolling blackouts as conservation. But rolling blackouts are indeed how Tepco reduced demand. In fact, Tepco exported 1.4GW to Tohoku in August 2011.

Running the company’s thermal plants at full speed meant importing a lot of liquified natural gas (LNG): Tepco’s imports jumped from 959 BCF in 2010 to 1,127 BCF in 2011. Fortunately for Tepco, its LNG facilities had a capacity of 2,785 BCF.(Of that, Tepco wholly owned two terminals capable of producing 1,287 BCF, with another 1,377 BCF of capacity in two terminals co-owned with Tokyo Gas. Tokyo Gas is the sole owner of the fifth; the gas company imports about 560 BCF per year in total.)

2012 appears to have been little different from 2011. Demand peaked at 50.8GW; Tepco had a cushion of 3.8GW on imports peaking at 6.9GW. But demand was held to 50.8 only by dint of blackouts. LNG imports remained about the same, at 1,120 BCF.

And so there you have it. On paper, Japan could handle taking nuclear off-line almost as easily as Germany. In practice, not so much, because of decisions made a century ago about sourcing electrical equipment from Germany and the United States. Economic history, it is an awesome field.

Comments

[Benjamin Skinner]

Rolling blackouts are a bit more extreme than opting to take the stairs, that's for sure.

[Robert Sneddon]

TEPCO brought a bunch of mothballed coal and oil-burning generating stations back on-stream in the year or so following the earthquake as the 13-month deadline for reactors still operating triggered the gradual shutdown of the rest of their nuclear fleet. Burning millions of tonnes of crude oil, bunker oil, coal and LNG have raised Japan's carbon emissions by more than 20% as well as damaging their GNP.

Japanese law requires all reactors must be shut down every 13 months for inspection and the utilities usually performed a refuelling operation at the same time. Restarting the reactors after this shutdown was usually done on the nod but it takes agreement by the national and local governments for this to happen and after what occurred at Fukushima Daiichi that permission was almost never granted. Only two of the Ohi reactors have been restarted after a paper safety exercise was carried out, the rest are still in cold shutdown and that includes all of the non-TEPCO reactors elsewhere in Japan, from Hokkaido to Kyushu.

[Noel Maurer]

True that! This is great detail that I should have included.

Japan had enough spare capacity (via very environmentally-unsound technologies) to prevent blackouts across the nation. Unfortunately, there was no way to get that to Tepco. Which is not to say that Tepco did not employ such unsound technologies! It certainly did.

And thank you for the details of the shutdown.