Tokyo in a power crunch

On March 22, 2022 the Tokyo Electric Power Corporation (Tepco) warned electricity consumers in east Japan about the risk of rolling blackouts from a tight supply situation. The recent M7.3 quake near Sendai had knocked several of Tepco’s thermal power plants offline, which left the company in a difficult situation when a cold spell with snow flakes hit the region of the capital. Demand at times exceeded generation capacity and only the availability of pumped hydro storage saved the day before measures to curb demand such as turning down heating and switching off lights averted an outage.

No doubt this experience will increase pressure to restart more nuclear power stations that have been shuttered since the tsunami and nuclear meltdowns in Fukushima in March 2011. Before the nuclear disaster about 30% of Japanese generating capacity were nuclear; now only about 10% comes from restarted nuclear reactors. The current high prices of natural gas will further enhance the attraction of nuclear, at least in the eyes of anyone whose financial interests are tied to the balance sheet of the utility companies, such as their individual and institutional shareholders.

However, that is not the whole story.

While eastern Japan was in a power crunch, western Japan has ample spare capacity, as did Hokkaido. Why could this power not be used in Tokyo? You would have thought Japan would have learnt its lesson from the 3/11 disaster in 2011 and addressed it in the decade since then, but you would be wrong: Japanese electricity markets are still split between a handful of regional near-monopolies with minimal interchange capacities between them. For example, the Hokkaido grid has a generating capacity of 7.5 GW but only 0.6 GW of interchange capacity with Honshu (8% of the total). Tepco supplies up to 47 GW to customers in its area but can only exchange up to 1.2 GW with major utilities in the west of Japan. This leaves little margin when earthquakes or weather events with a regional impact hit supplies.

By contrast, China has built huge high voltage direct current (HVDC) transmission lines between the industrialized coastal cities on one side and hydroelectric power stations near the Tibetan plateau and solar and wind farms in the arid north on the other. Many of these lines are longer than the distance from Tokyo to Hokkaido, let alone Tokyo to Kansai. The Chinese government understands that if it wants to wean itself from the dependence of dirty coal or imported oil and gas then it will need to vastly increase power transfer capacity from the interior of the country where renewables are available to the densely populated urban areas near the coast lines.

Japan is actually in a similar situation. The elephant in the room that nobody wants to talk about is offshore wind. While European countries and the US are building up tens of Gigawatts of offshore wind power capacity, Japan has very little installed capacity, particularly offshore. The entire conversations seems to be about nuclear vs. solar vs. gas vs. coal, leaving out one of the most promising renewable energy sources available to Japan. So far the regulatory hurdles for erecting and connecting wind turbines in Japan have been high and that has left wind as an also ran compared to much more widely deployed solar. However, solar does not provide power at all hours. Wind would complement it.

Much of the European wind power capacity is installed offshore where wind speeds tend to be high and more consistent than onshore. This is where the largest and most economical turbine models tend to be used. By contrast, almost 99% of Japan’s wind power capacity is still onshore. A cumulative total of only 51.6 MW of offshore wind capacity was installed at the end of 2021 while total installed wind power capacity was 4.6 GW. Meanwhile the UK had 24.7 GW of wind power capacity, Spain 27.1 GW and Germany 62.2 GW. China is in a league of its own with 282 GW, more than all of Europe combined. Japan’s installed wind power base is less than that of small European countries such as Belgium (4.7 GW) that have relatively short coast lines and tiny EEZs: Japan’s EEZ of 4,479,388 km2 is over 1000 times larger than Belgium’s at 3,447 km2!

Japan is really only starting to build up offshore wind capacity, with projects off the coasts of Akita, Chiba and Nagasaki getting under way in the last two years. By 2030 its goal is for 10 GW of offshore capacity either installed or under construction which is still tiny compared to the already installed base of Germany, Spain or the UK.

Unlike fossil fuel or nuclear power stations, wind turbines are not location independent. They will be installed where wind conditions are favourable, where the sea is not too deep and connections to the coastal grid are cost-effective. To make the most of the wind conditions, the grid will need to be greatly expanded to allow large amounts of power to be transferred from regions with plenty of wind to regions with many consumers. This will be quite different from the current model where utility companies try to generate all the power they need within their own region, which is why there is only limited interchange capacity to help out if one company loses a large part of its generating capacity as happened in the recent quake or after 3/11.

Japan needs to start building high capacity long distance HVDC power lines like China has in order to enable a transition to zero carbon electricity. The fragmented power markets dominated by local utility companies are an obstacle to this transition as the interests of the regional companies seeking profits from existing investments in their area are not aligned with the interests of the consumers who want reliable green energy regardless of where it comes from.

Japan quickly needs to remove regulatory obstacles to expanding wind power and then invest to build a HVDC backbone to connect renewable power generation with consumers.

Hokkaido wind power for Japanese energy

Nikkei reports (“Japan pushes for undersea cables to solve wind power puzzle”, 2022-01-02) that the government is allocating 5 billion yen (about US$43 million) in its supplementary budged for a feasibility study for a 4 GW high voltage direct current (HVDC) link between the power grids of the northern island of Hokkaido and the main island of Honshu, where most of Japan’s population lives. This would be by far the biggest HVDC link ever built in Japan. The Japanese government wants to generate 45 GW of power from offshore wind in 2040, up to about a third of which (14.65 GW) is to be produced in Hokkaido. The development plan lists several promising offshore areas along the southwest coast of Hokkaido.

For this power to be available to consumers outside the northern prefecture, it would need to be exported via a HVDC link. This is the preferred technology for shifting large amounts of power over long distances, especially between AC grids not synchronized with each others or operating on different frequencies. Since 2019 there have been two 300 MW HVDC links between the two islands. Their combined capacity is to be doubled to 1.2 GW by 2028.

Japan has relatively little capacity for transferring power between its regional grids. This is because its grids used to be operated by regional monopolies that had little incentive to ever import or export power. This lack of interconnect capacity became a major problem following the power shortage after the 2011 Tohoku earthquake and tsunami when less affected areas could not help out the most affected region. There is a conflict of interest between the local utility companies and the country as a whole. Tepco owns a lot of nuclear power stations, expensive infrastructure with huge sunk costs. It would rather generate power from these plants than pay another supplier from outside its area for renewable energy. However, many of these power stations have yet to be restarted since their shutdown following the Fukushima meltdowns. By restricting how much power can be imported from other grids, Tepco can put pressure on regulators to allow it to restart more reactors to ensure a stable supply of power. On the other hand, expanding interconnect capacity would ease the pressure. Which side will the Japanese government take?

A related issue is the variable output of renewable power sources. Long distance transmission will make it easier to compensate for local weather patterns by shifting power between different regions, which allows a larger share of renewable energy to become part of the mix without having to resort to either energy storage or peaker plants (e.g. gas turbines to cover peak loads). That again means Tepco loses leverage to maintain coal and other fossil fuel powered generating capacity as insurance against shortfalls of renewable energy.

China, one of Japan’s main economic rivals in the world, has pursued a completely different course. Over the past decade it has aggressively expanded long distance HVDC links to stabilize its grid. Japan operates a single HVDC link of at least 1 GW, a 1.4 GW link between Honshu and Shikoku that started operating in 2000. All other links are only in the several 100 MW range and most of those are not long distance lines but back-to-back local interconnects, for example between the 50 Hz grid of eastern Japan and the 60 Hz grid of western Japan near Nagoya. By contrast, China has built over 20 HVDC links over 1 GW, mostly with a capacity of 3 GW or more. Many of the biggest projects cover distances of 1,000 to 2,000 km. This allows China to supply it coastal megacities with hydroelectric power from its southeastern mountains or from other power sources from its arid central parts. China is the world leader in wind power. Its windiest parts are along its border to Mongolia and on the Tibetan plateau. Large scale HVDC is key to China’s energy policy for the 21st century.

An alternative to shifting power long distance is to use it to locally generate hydrogen from water (“green hydrogen”) and feed it into pipelines or use it to make ammonia. This makes some sense for applications that already use hydrogen, such as the fertilizer industry or for carbon free alternatives to existing technology, such as direct reduction of iron ore for steel making without using coking coal. However, it makes little sense to use green hydrogen for power generation: if you convert electricity to hydrogen which you then use to generate electricity, more than 70 percent of energy is lost in the process while less than 30 percent remains. By contrast, batteries are 90 percent efficient. Therefore, if excess wind or solar power is used to produce hydrogen, that resource should best be used by industries that directly consume hydrogen, until all fossil fuel currently used for such purposes has been replaced.

If Hokkaido had a surplus of hydrogen from wind power, it would make more sense to have it consumed by steel works and fertilizer plants built in the prefecture rather than sending it through a pipeline to Honshu.

Although green hydrogen or ammonia can be used as fuel in thermal power plants in place of coal or LNG, it would be a terribly wasteful use. Because of the huge conversion losses, we would need three times more wind or solar power to end up with the same amount of usable electricity than if we used grid-scale battery storage to absorb any surplus and make it available when needed. This advantage makes grid-scale battery storage a strategic technology.

Most existing Li-ion batteries depend on relatively scarce resources such as cobalt, nickel and lithium. Lithium-iron-phosphate (LFP) batteries only require lithium and widely available materials, while sodium ion batteries use only readily available raw materials. Japan will need to invest in high capacity long distance HVDC links as well as in battery storage to speed up its transition to a carbon neutral economy.

Releasing Tritium-tainted Water from Fukushima 1

The Japanese government has approved a plan by Tepco to release more than a million tons of water stored in tanks at the site of the Fukushima 1 nuclear power station. The water is supposed to be gradually released into the ocean starting two years from now.

Currently about 1.2 million t of contaminated water are stored on site, an amount that is increasing by about 170 t per day. Tepco is expected to run out of space at the end of 2022. Water is being injected into severely damaged reactors on the site to cool the remains of nuclear fuel left inside. It leaks back out, mingles with ground water that seeps in and is then purified through a filtration system called ALPS. This removes most of the radioactive contamination, but leaves tritium, a radioactive isotope of hydrogen which can not be chemically removed from water. So it ends up in the storage tanks.

Proponents of the release argue that tritium poses little hazard in small quantities. Radiation from tritium is so weak, it only travels for a couple of mm through air and it is stopped by the dead cells on the outside of human skin. Even if ingested it does not accumulate in the human body.

The water released will be diluted to levels so low it would meet drinking water standards in Japan and in other countries. Opponents fear an economic backlash against local fisheries or argue in principle that Japan has no right to contaminate the Pacific ocean, which is not just their territorial waters but shared by many other countries.

Proponents call such criticism hypocritical, given that many other countries, including the Republic of Korea, routinely release tritium into the ocean from their own nuclear facilities.

The issue is complicated. First of all, whether the danger from the water release is real or exaggerated, fishermen will suffer economically because consumers will end up avoiding fish from Fukushima more than they already do, even if it was safe to eat. If the release is unavoidable, the fishermen should receive compensation for their economic losses. That is only fair.

The truth about the water is not black or white. The 1.2 million t of water that has accumulated over the past decade was treated in different ways at different times. Some may indeed contain only those low levels of tritium as a contaminant, but other tanks will hold water that still has significant amounts of caesium, strontium and other dangerous isotopes that unlike tritium can accumulate in organisms and pose long term hazards. More purification and testing will definitely be needed before a release can take place. As Motoko Rich and Makiko Inoue reported for the New York Times in 2019:

Until last year, Tepco indicated that with the vast majority of the water, all but one type of radioactive material — tritium, an isotope of hydrogen that experts say poses a relatively low risk to human health — had been removed to levels deemed safe for discharge under Japanese government standards.

But last summer, the power company acknowledged that only about a fifth of the stored water had been effectively treated.

Last month, the Ministry of Economy, Trade and Industry briefed reporters and diplomats about the water stored in Fukushima. More than three-quarters of it, the ministry said, still contains radioactive material other than tritium — and at higher levels than the government considers safe for human health.

The authorities say that in the early years of processing the deluge of water flowing through the reactors, Tepco did not change filters in the decontamination system frequently enough. The company said it would re-treat the water to filter out the bulk of the nuclear particles, making it safe to release into the ocean.
(New York Times, 2019-12-23)

Long term there is no real alternative to releasing the water. Once its radioactivity has been reduced to only tritium, dilution and disposal at sea should pose little risk.

The challenge however is that Tepco and the government have a public trust problem, at home and abroad. How do we know the water released will be as clean as claimed?

Any release process needs to be transparent and independently verified to make sure there are no shortcuts or other shenanigans.

See also:

Tepco drowning in radioactive water

A recent leak of 300 tons of highly radioactive water at Fukushima No. 1 has highlighted the long term problems that Tokyo Electric Power Co. (Tepco) is facing in its struggle to manage the crisis at the wrecked nuclear power station (see Japan Times, 2013-08-21). One massive steel tank had been leaking as much as 10 tons of water a day for a month before the leak was noticed. The water level in the tank dropped by 3 m before anyone noticed. It is not clear yet how the water is escaping.

The water in the tank has been used for cooling the melted reactor cores. Consequently it is highly radioactive from strontium, cesium and tritium. At a distance of 50 cm, as much as 100 millisieverts per hour (mSv/h) were measured. That means a nuclear worker there would absorb as much radiation in one hour as is legally permitted over a total of 5 years.

You might think that with a witches’ brew like that on its hands, Tepco would take every possible precaution to prevent leaks and to monitor fluid levels. Tepco uses both welded steel tanks and temporary tanks for storing contaminated water at Fukushima No. 1. Welded tanks are supposed to be stronger and more leak proof, whereas temporary tanks can be bolted together quickly from sheet metal and plastic. About one third of the over 1000 tanks at Fukushima No. 1 are temporary tanks, including the one that recently leaked. Tanks of this type have been used at the site since December 2011 and they are supposed to last five years before needing repair or replacement. So far 4 of these tanks have leaked, yet Tepco is planning to install even more temporary tanks for storing water. I guess they must be cheaper.

I am curious why the leaks were not detected sooner. Are there no monitoring devices installed that can automatically report water levels?

Tepco is planning to treat the water in the tanks with its ALPS filtering system, which can remove radioactive cesium and strontium from the water, but not tritium. It was meant to start operating this month, but after problems it is now expected to not resume operation until December.

Even after treatment, Tepco will have a water problem. Any water pumped from the turbine halls that has been in contact with the reactor basements has elevated levels of radioactive tritium. No chemical removal system exists for tritium, as it’s an isotope of hydrogen, one of the two elements that make up water. Tepco can not simply evaporate water from those tanks to reduce volume and concentrate contaminants into a smaller volume, as the tritium would be released with water vapour and come down as rain again elsewhere. So what is it going to do? Release it into the atmosphere slowly? Dilute it with sea water? Or store hundreds of thousands of tons of water for hundreds of years? Neither alternative seems very appealing.

Japan without nuclear power

Since last weekend, Japan is without a single nuclear power station feeding power into the grid, the first time in 42 years. All 50 nuclear power stations are currently off-line (this count does not include the 4 wrecked reactors in Fukushima I, which are no longer officially counted — it used to be 54 nuclear power stations).

Some of these power stations were shut down because of problems after the March 11, 2011 earthquake and tsunami. Others were taken offline one by one for routine inspections and maintenance but have not been started up again, which would only happen with the consent of nearby local governments. That consent has not been forthcoming.

Electrical utilities and the government are raising concerns about a power shortage when the summer heat sets in, which usually results in peak usage for air conditioners. Critics of nuclear power see an opportunity for a quick exit from nuclear power. Others are concerned that if the government rushes to bring power stations back online before the summer without safety upgrades and a change in the regulatory regime, a unique chance to prevent the next nuclear disaster will be squandered. If upgrades and reforms don’t happen when the memory of Fukushima is still relatively fresh, what’s the chance of it happening a few years down the road?

The utility companies are facing high costs from buying more fossil fuels for gas and oil fired thermal power stations to cover the demand; restarting the nuclear power stations would keep those costs in check. But that is only part of the reason they are keen on a restart. The sooner they can return to the pre-Fukushima state of power generation, the less leverage governments and the public have for making them accept new rules, such as retrofitting filters for emergency venting systems or a permanent shutdown of the oldest and seismically most vulnerable stations. Because of this it’s in the interest of the utilities to paint as bleak a picture of the situation as possible. Japan would be smart to proceed cautiously and not miss a unique chance to fix the problems that are the root cause of the Fukushima disaster and of disasters still waiting to happen.

Fukushima “cold shutdown” announcement up to 25 years too soon

The Japanese government has announced that the wrecked Fukushima Daiichi power station has reached a “cold shutdown”. The BBC quotes Prime Minister Noda:

“The nuclear reactors have reached a state of cold shutdown and therefore we can now confirm that we have come to the end of the accident phase of the actual reactors.”

It is meaningless to still use the term “cold shutdown” for a reactor in which the fuel rods and containment vessel have lost their integrity. It’s like saying the bleeding has been stopped in an injured patient who had actually bled to death.

The normal definition of “cold shutdown” is when, after the chain reaction has been stopped, decay heat inside the fuel rods has been reduced enough that the cooling water temperature finally drops below 100 C. This means the cooling water no longer boils at atmospheric pressure, making it possible to open the pressure vessel cap and remove the fuel rods from the reactor core into the spent fuel pool. After that the reactor core no longer needs to be cooled.

Only units 4, 5 and 6 have reached a genuine cold shutdown. Unit 4 had been shut down for repairs in 2010 and did not contain any fuel at the time of the accident. In units 5 and 6 a single emergency diesel survived the tsunami and prevented a meltdown there.

In units 1, 2 and 3 of Fukushima Daiichi the fuel melted, dropped to the bottom of the reactor pressure vessel and penetrated it. The melted rods then dripped down onto the concrete floor of the containment vessel and are assumed to have partly melted into the concrete up to an unknown depth.

While in a regular cold shutdown fuel can be unloaded within weeks, the Japanese government estimates it may take as much as 25 years before all fuel will have been removed. The technology to remove fuel in the state it’s in now does not even exist yet and will have to be developed from scratch. Even the most optimistic schedule puts it at 5 years, during which time the reactors will have to be cooled 24 hours a day, with no new earthquakes damaging them or knocking out cooling again, no major corrosion problems, no clogged water pipes, etc.

In my opinion, the announcement of a “cold shutdown” at Fukushima Daiichi is greatly exaggerated and was made mainly for political purposes. More than anything, it is meant to provide political cover for restarting other idled nuclear power stations during the coming year.

Radiation maps for Eastern Japan

The Japanese government has released updated radiation maps for Eastern Japan from its helicopter survey. The maps now cover prefectures as far west as Gifu and as far north as Iwate and Akita. Previously there was map data only for Tokohoku (excluding Aomori) and the Kanto area. The PDF can be downloaded here.

The previous set of maps documented caesium contamination and background radiation levels in Fukushima, Tochigi, Miyagi, Ibaraki, Chiba, Saitama, Tokyo and Kanagawa. The latest set adds maps for Iwate, Shizuoka, Nagano, Yamanashi, Gifu and Toyama. Akita, Yamagata and Niigata have also been surveyed and are shown on the overview map.

The most heavily contaminated areas are in the eastern half of Fukushima prefecture, within about 80 km of the wrecked nuclear power stations. The southern part of Miyagi to the north and the northern part of Ibaraki to the south also took a hit.

A major radioactive plume moved south-west from Fukushima, polluting the northern half of Tochigi and the northern and western part of Gunma. A separate plume reached the southern part of Ibaraki, the north-west of Chiba and the eastern part of Tokyo.

There is also some caesium in the mountainous far west of Tokyo and Saitama that extended from Tochigi, but most of Saitama, Tokyo and Kanagawa seem relatively OK, as are Shizuoka, Yamanashi, Nagano, Gifu, Tokyama, Niigata, Yamagata and Akita. There is some fallout in a strip from southern Iwate to northern Miyagi, while central Miyagi and the rest of Iwate look clean. There is no published data for Aomori and Hokkaido yet, but based on the distance and the absence of significant pollution in Akita and adjacent parts of Iwate they will probably be fine.

The maps only give the overall picture, as there may be local hotspots in areas that are relatively clean overall, based on rainfall and wind patterns as well as soil and vegetation that can retain more or less fallout.

Update 2011-12-06:
The ministry has also published radiation maps for Aichi, Aomori, Ishikawa and Fukui prefecture.

How (not) to decontaminate Japan

An article in Japan Times (2011-11-09, “Scrub homes, denude trees to wash cesium fears away”) provided advice on how to decontaminate areas affected by nuclear fallout, such as in Fukushima, Tochigi and northern Chiba prefecture. Most of the advice is sound, but some is downright alarming:

As for trees, it’s best to remove all their leaves because of the likelyhood they contain large amounts of cesium, Higaki [of University of Tokyo] said.
(…)
What should you do with the soil and leaves?
(…)
Leaves and weeds can be disposed of as burnable garbage, a Fukushima official said.

So let me get this right: you should collect all those leaves because they contain so much radioactive cesium (cesium 134 has a half life of 2 years and cesium 137 of 29 years). And then, when you have all that cesium in plastic garbage bags, you have it sent to the local garbage incinerator, so the carefully collected cesium gets spread over the whole neighbourhood again via the incinerator smokestack. That makes no sense at all.

My Terra-P dosimeter (MKS-05) by Ecotest

Yesterday my geiger counter arrived here in Japan. It is a Terra-P dosimeter made by Ecotest, a company based in L’viv/Ukraine, about 300 km west of Chernobyl.

I bought the device on eBay from a supplier in Australia for US$399 including shipping. It arrived within 9 days and seems to work well. Although the buttons on my Terra-P are labelled in Cyrillic (either Russian or Ukrainian) and so is the manual, English manuals for it are easy to find online, so that’s not really a problem.

The Terra-P is a consumer grade dosimeter, so it’s not quite as versatile or as precise as professional devices costing $1000 or more, but it covers the basics very well. Its power source are two AAA-batteries, accessible via a lid at the back of the unit, which are easy to replace. It measures gamma rays and is suitable for checking for caesium contamination.

The user interface consists of an LCD, two buttons and speaker. One push of the right hand button (“режим” = mode) switches the dosimeter on and puts it into the measuring mode. The display switches to a microsievert per hour (µSv/h) readout. For the first 70 seconds the resulting number blinks, as it averages the dose over that period and the number gradually becomes more meaningful. After the initial sampling period, the number displayed will always be the average of the last 70 seconds, so you can move it from location to location and will get a decent result provided you wait for about a minute.

After several minutes the device enters power save mode, in which it continues counting radioactive decays, but the LCD is off and less power is used. To turn it off completely when it’s active, push the mode button once more and then push and hold it for four seconds, until the LCD blanks.

The Terra-P also has a user-settable alarm threshold (default: 0.30 µSv/h) and a clock mode. The built-in speaker usually makes one click for every gamma photon detected and sounds an alarm if the radiation exceeds the alarm threshold.

Checking my home after unpacking the device, I found the radiation level was a little higher than the 0.055 µSv/h reported for Tokyo by the local government, but still somewhat lower than the 0.10 µSv/h in my home town in Germany. On the other hand, I was relieved to see the wooden deck outside our living room was no more radioactive than inside the house. As expected, the gutters at the edge of the road, where rain water drains into the sewers, was more radioactive, with about 0.20 µSv/h, which is still far from alarming.

See also:

Radiation map of Japan

The Japanese government has published online map data about radiation levels in Eastern Japan. You can zoom in and out, scroll around and select data from:

  • Background radiation in microsievert per hour
  • Contamination by caesium 134 and 137 combined (Cs-134+Cs-137) in becquerel per square metre
  • Contamination by caesium 134 (Cs-134) in becquerel per square metre
  • Contamination by caesium 137 (Cs-137) in becquerel per square metre

The data was collected via helicopter flights carrying instruments that detect gamma radiation of different energy spectrums, allowing a breakdown by isotopes causing it.

There are the following data sets:

  • April 29
  • May 26
  • July 2
  • Miyagi prefecture, July 2
  • Tochigi prefecture, July 16
  • Ibaraki prefecture, August 2
  • Chiba and Saitama prefecture, September 12
  • Tokyo and Kanagawa prefecture, September 18

Click on this link:

either the online maps or download PDF files of the maps and click on “同意する” (“I do agree”, the left button) to get access.

The government is planning to extend the radiation survey to the whole of Japan, not just within about 250 km of the wrecked reactors as is currently the case.

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