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Tuesday, 1 September 2015

How nuclear-free Japan made it through hottest summer yet without brownouts

TOKYO — The nation’s nuclear power generators having been shut down since 2011. Summer temperatures, with their commensurate power demand, have been climbing. Yet warnings at the time of the nuclear plant shutdowns, to the effect that the aging thermal generators would not be able to meet peak demands, have not come to pass.

What’s made it possible to keep the juice flowing? J-Cast News (Aug 27) reports that one factor has been the growing use of solar power, which when demand is highest during daylight hours has been pitching in to keep the air conditioners chugging along.

During two straight weeks of sunny weather, and particularly from July 31 to August 7—during a record-breaking string of eight consecutive “moshobi,” during which daytime peak temperatures in Tokyo surpassed 35 degrees Celsius—the power suppliers came through with flying colors.

According to Tokyo Electric Power Co (TEPCO), a new record of 29.57 million kilowatts of power demand was set at 1 p.m. on August 7. Fortunately even without nuclear power, use of outside suppliers to supplement TEPCO’s power generated in-house meant that usage by its own thermal plants reached 92% of capacity, leaving it with a surplus of 8%.

From the beginning of August, a source within the power industry revealed that “as we’re getting lots of solar power from noontime, there’s no problem, even without the nuclear reactors. They’re supplying enough that we can even hold back on the thermal generator output.”

What’s so remarkable was that in addition to the 23.84 million kilowatts being produced by TEPCO’s own generators, 9.91 million kilowatts, or about 20% of the total, were supplied by outside companies, which TEPCO has contracted to buy at fixed prices. A good portion of these are sourced from solar or wind power.

As of the end of June this year, some 7.9 million kilowatts of solar and other forms of renewable energy are serving TEPCO’s network, which on sunny days are calculated to be capable of supplying the amount of power provided by the nuclear plants. About half of the 9.91 million kilowatts provided by the outside suppliers is said to be sourced from solar power.

The situation is similar in other regional power utilities. On Aug 4 at 4 p.m., the time of highest power demand in Kansai reached 25.57 million kilowatts. Of Kansai Electric Power Co’s 27.81 million kilowatts maximum capacity, 6.34 million kilowatts are supplied to KEPCO by outside firms, again about half of which is solar energy.

The day of highest demand for Kyushu Electric Power Co, Aug 6 at 4 p.m., was 15 million kilowatts. Its peak capability is 17.21 million kilowatts, of which 4.70 million are sourced from outside suppliers—nearly as much as the 5.17 million the island’s five nuclear generators used to produce.

The J-Cast News reporter reminds readers that once night falls, solar power generation naturally drops to zero, and that output also declines on cloudy days. But fortunately the kind of hot, sunny afternoons when power demand is at its highest, coincide with the time when solar power generation is at its most efficient. What’s more, buying power from these suppliers lowers the burden on the power utilities’ thermal reactors and helps reduce energy consumption, so it’s not a bad thing at all.

That said, solar is not a perfect solution, since demand for air conditioning on some days does not taper off quickly with the coming of darkness. Still, its contribution to the power grid during this past month has turned out to be an unexpected and pleasant surprise.

Source: Japan Today
http://www.japantoday.com/category/kuchikomi/view/how-nuclear-free-japan-made-it-through-hottest-summer-yet-without-brownouts
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