This article originally appeared in The Conversation. It is licensed CC-BY-ND. Click here for original.

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Japan was the third-largest producer of nuclear power in the world in 2011. Then, on March 11 of that year, an earthquake of magnitude 9 was followed by a catastrophic tsunami, resulting in the first nuclear disaster of the 21st century – at the Fukushima Daiichi power station. The country’s nuclear plants were shut down, and within a year Japan had become the world’s second biggest importer of fossil fuels.

Before the tsunami, nuclear power provided 25% of Japan’s electricity, and a strategic plan was in place to expand this to 50%. Japan has few fossil-fuel resources of its own, so most of the resulting shortfall in electricity was made up by burning imported coal, oil and gas – an unsustainable solution from both environmental and economic perspectives.

But on a group of islands to the west, tidal power may offer part of the solution to the country’s energy needs.

A renewable future

By 2030, the Japanese government plans once more for nuclear power to provide around 21% of the nation’s electricity – which is highly controversial – but also stipulates (see page 8) that 22-24% should be delivered by renewable energy sources. At a local scale, two prefectural governments, Fukushima and Nagano, have pledged that all of their electricity will come from renewables by 2050.

Most of the new renewable energy available in 2030 is likely to be solar and wind, along with existing hydropower, but some contribution from the tides is possible. To this end, a zone in the Goto Islands of Nagasaki Prefecture has been designated for tidal energy development, and a cluster of companies plans to install the first turbine in 2019. This project will be of the tidal stream type, where underwater turbines are placed in the free flow without any dam or barrage, similar to the MeyGen project in Scotland.

Installing a tidal stream turbine base at the MeyGen project off the coast of Caithness in northeast Scotland.
MeyGen/Atlantis Resources

When tidal turbines are placed in a channel, they remove energy from the flow. This causes it to slow, and represents a partial blockage of that channel. In turn, that means that the behaviour of the tides in an area after turbines are installed can be different to how it was before. Understanding and predicting this change is important for estimating both how much energy is available and the impacts of removing it; if there are too many turbines, the flow could slow too much and much less power would be generated.

Going with the flow

My recent work, in collaboration with researchers in Scotland and Japan, involved using a computer simulation of tidal flow around the Goto Islands to investigate the effects of installing large numbers of turbines.

We estimated that between 24 and 79 MW of power could be generated from the designated area. The reason for this range is because the number of turbines that are used will ultimately depend on economic considerations. The first few will offer the most benefit, while later ones will suffer from diminishing returns. Tens of megawatts represents a very small contribution to Japan’s overall electricity needs, but a very large chunk of the local demand in these islands.

A number of parallel channels run through the Goto archipelago, of which two are within the tidal energy zone. In situations like this, it is common to find that adding turbines to one channel simply causes the water to flow by a different route. That means that to harvest energy efficiently we need to collect it from all the channels at once – an expensive proposition for a new technology.

In the Goto Islands, all the channels run parallel but separate to each other, never merging or meeting, so they can each be exploited without affecting the others.
Elsevier, Author provided

However, our modelling shows (see sections 4 and 7.2) that the parallel channels in Goto do not behave this way; instead, they are independent of each other. The reason for this unusual behaviour lies in the geometry of the islands.

Partially blocking a channel causes water levels to rise a little behind the blockage. The interactions that we see elsewhere in the world are a result of this extra water “spilling” into other channels. In Goto, because all of the channels run separately from one end to the other without meeting or merging, and because their mouths are spaced well apart, there is no way for this “overspill” to occur. Consequently, any or all of the channels can be exploited without affecting the others, which should make the area more attractive for commercial development.

If the relatively small-scale development in Goto is a success, it could act as a proving ground and a springboard, leading to the use of tidal energy in other locations all over Japan. And for a country ambivalent about its return to dependence on nuclear power, additional contributions from renewable energy will be welcome.

The most recent is my second journal article as lead author, and one that I’m quite proud of. It covers the work that I did in Japan last year, and in the months after returning, on the tidal energy resource of the Goto Islands of Nagasaki Prefecture. We produced estimates of the amount of power that could be obtained – which is mostly of interest for the people planning tidal development in that archipelago – but of more general interest are the findings about inter-channel interactions. The Goto Islands have several parallel channels that could contain turbines.  When this arrangement has been studied in other places, it has usually been found that putting tidal turbines in one channel causes flow to divert into the others, and hence that to reach the full potential for power we would have to put turbines in every channel. Goto doesn’t behave like that – instead, the channels have very little effect on each other – and in the paper we looked a little into why that is. My thanks are due, of course, to my co-authors on this work, both in Scotland and Japan.

Plot showing the mean power available from various numbers of turbines in the channels of the Goto Islands, using simplified M2 tides.

Just a few weeks ago I attended the EWTEC conference in Cork and presented this paper on Lashy Sound, which is a channel with strong tides in the Northern part of Orkney. In this work, I used very similar methods to those that were developed in Japan to look at the tidal resource – in this case, not for realistic turbine developments but in terms of the theoretical maximum available power if we didn’t care about things like environmental impact, or allowing ships through. Unsurprisingly, it looks like achieving this maximum yield would have some significant impacts. I also considered the more plausible scenario of a smaller tidal farm, similar to the 30MW one that has been planned for the area, and was able to show that its effects would be small and confined to Lashy Sound itself – something that’s important when other potential tidal energy sites are just a few km away in neighbouring channels.

Both of these papers are available for free at the links above, or at the publications page on this site.

“The Konpon Daitō is the tallest building in Kōyasan… In later centuries the Konpon Daitō was destroyed in fires caused by lightning striking five times, and rebuilt each time. After the great fire of 1843, only the foundation stones remained. The existing building was rebuilt in 1937.”

Some people just don’t seem to get the message!

But it illustrates a wider observation, which is that in Japan an ancient wooden temple or other structure can still be ancient even if it has been rebuilt many times, the latest sometimes being quite recent. Indeed, it is tradition that some of the most important temples are deliberately torn down and rebuilt every few decades. Other places are “renovated” every 50 years in a way that pretty much entails dismantling them and putting them back together again, replacing timber wherever it is no longer sound. These processes don’t cause anybody to think of them as modern structures.

Kokura-jō: Four hundred years old, or sixty?

A similar concept applies to castles. Castles in Japan were made of wood, and thus prone to being burnt down – sometimes by accident, sometimes by the enemies of the occupants, and sometimes by the occupants themselves on the occasion of their departure. When one visits a castle one tends to find a litany of all the times they were destroyed and rebuilt. It’s not unusual for the last rebuilding to have been in the 1950s or 60s, out of reinforced concrete, but they’re not really thought of as replicas.

There’s a strong element of My Grandfather’s Axe here. It’s echoed to some degree in descriptions of British churches (and occasionally pubs), which tend to go “There has been a church here since 1273…”, but the British think in terms of the site: there was a church here, but it was not this church. The Japanese view of it, at least as I perceived it through the flaws of translations, is that it’s the same building. It’s as though it’s the notion of the building that’s important, rather than its physical or material structure.

Ise Grand Shrine: Two thousand years old, but rebuilt every twenty. Photo: Flickr user Kzaral, licensed CC-BY 2.0

But travelling around the country, it struck me that infrastructure in Japan is visible, and they don’t seem to be ashamed of it. Streets have their power lines overhead, rather than buried – like much of America, but strange and messy-looking to a European eye. In areas suitable for heavy industry, there is heavy industry. One sees large power plants, chemical plants, gas storage tanks, etc., close to populated areas, with no attempt to disguise them. Plans for any of these facilities would cause uproar in the UK.
Most towns, even agricultural ones in pristine valleys, have one or two large radio masts, painted red and white, rising out of a municipal building (often one belonging to the former state telecoms company, or sometimes a post office). Some of these are festooned with microwave dishes, but most just have cellphone antennae now; I suspect that they are the relic of an extensive microwave network that has since been replaced, but they haven’t been torn down. Contrast to the arguments in the UK that led to some cellphone masts being disguised as metallic trees.

Photo: Wikimedia commons, user Prosperosity. Licensed CC BY-SA 3.0.

There isn’t much onshore wind power, and I don’t know why that is – but I don’t think it’s likely to be about visual impact, since everywhere one sees electricity transmission lines “marching across the landscape”, with the towers once again painted bright red and white. It’s notable that – in a way that will be familiar to everybody who has lived near such things – after a few days they stop being obtrusive, and become a part of the landscape that is largely filtered out of conscious perception.
The shinkansen, built from the 1960s to the 2000s, zooms across the whole country on elevated tracks, visible for miles in every direction. Recently there have been complaints about noise from high speed trains, and as a result the latest line has noise barriers – which help with the noise but make the tracks themselves more visually obtrusive. Contrast with the “debate” about HS2.

I’m not praising or criticising the British or Japanese attitude here, and I don’t feel that I understand enough to hazard any guesses in public as to the reasons behind the differences, but I found them very striking.

I’m on my way home, and I have very mixed feelings. After two months I’m ready to resume “normal” life, to see friends and family, to speak English without always gauging how much I should slow and simplify my language according to the listener, and to sleep in my own bed. Probably for about a week. On the other hand, I will miss Japan. It’s a fascinating place, and while I understand it a lot better than I did eight weeks ago, there’s a long way to go on that front.

I hope I have the opportunity to return one day.

The grand torii at Miyajima. Photo: Jordy Meow, CC BY-SA-3.0. Original here.

After leaving Fukuoka on Saturday my first stop was the island of Miyajima, literally “Shrine island”. At one time the whole island was considered too sacred for common people to set foot upon, so the famous “floating” temple, with its maritime torii, was constructed on stilts on the coast. I took a cable car to the top of the island’s hightest peak (about 530m) and admired the view right across the Seto Inland Sea. I decided to walk down, but had not anticipated the Japanese penchant for steps… where in Europe the gradient would have resulted in a winding, cliffhugging path, here it was basically a 2.5km staircase. My right knee was not impressed.

At Miyajima I felt a kind of reverse culture shock. For the last six weeks the number of white people I’ve met is in the low double digits, and the number with really fluent English somewhat lower. Here, suddenly, everywhere I look there are people from all over the world. Perhaps this shouldn’t be surprising at one of the country’s top tourist attractions on a Saturday in summer…

The grand shrine at Izumo. Photo: miya.m, CC BY-SA 3.0. Original here.

Two days later, after a stop in the hill town of Tsuwano and then a day of travel problems caused by heavy rain, I arrived in Izumo. I visited an Edo-period silver mining area, now a World Heritage Site. Considering its status, there were surprisingly few visitors, and apart from myself I only spotted one group of non-Japanese. In contrast to a few days earlier, things felt more like they had before… apparently the foreigners don’t reach too far beyond the major cities and the shinkansen lines. Later I visited Izumo-taisha, arguably the second most important Shinto shrine and said to be the oldest. Again, I was the only obvious foreigner. I have the feeling that most Brits, and others, visit Tokyo->Kyoto->Hiroshima and then go home.

I’ll be joining them for the rest of my trip: today I’ll be travelling to Kyoto, and eventually east to Nagoya and Tokyo.

N700-series train. Photo: author

Japan’s Shinkansen (bullet train) system is famous, and rightly so – it was one of the first high-speed railways in the world (the first on dedicated track), and as new sections have been built over the years it has stayed at the forefront of technology.

Interestingly, its origins parallel events in British Rail somewhat. Each country was faced with an old network with winding, low-speed routes. Development of the Shinkansen started about a decade earlier than development of the APT, and went in a different direction: the British, with standard-gauge track that was speed-limited by passenger comfort, did the early work on tilting. The Japanese had a mountainous country full of narrow-gauge railway, and so opted for a completely new high speed system with dedicated (standard-gauge) track, minimum bend radii, maximum slopes, and so forth. The APT was of course an unsuccessful project (although the technology that it developed lived on), but the first shinkansen sets[1] arrived a decade before the HST and had around the same service speed of 200kph.

0 series, the first shinkansen train, in the 1960s. Photo: Roger Wollstadt, CC-BY-SA 2.0; original at Flikr

That was 55 years ago, and since then things have diverged… Shinkansen upgrades have pushed its speed on new routes up to 300kph, while UK speeds on old track have remained topped-out at what they were in the 70s. Meanwhile, using technological ideas that originated on the APT project, Japan now has “limited express” trains, the fastest to use the old narrow-gauge track, that tilt and run at 200kph (125mph).

Recently, long distance rail here has faced some of the same challenges that it does in the UK. Shinkansen tickets are really expensive, akin to on-peak British ones bought without any advance purchase discount, and low-cost air travel has been eroding the market. Nearly all of Japan’s sleeper trains have vanished, and the air route between Fukuoka and Tokyo is apparently the second busiest in the world, despite a high speed line running underneath that (for a city-centre to city-centre journey) doesn’t take much longer. This feels sad, and in energy terms must be bonkers.

Fortunately, if one has a JR Rail Pass (only available to foreign visitors, and only if bought outside Japan), things are really cheap. So bullet trains, here I come!

Two N700-series trains at Kagoshima station. Photo: Author

[1] If you’re wondering where the name “bullet train” came from, it’s not a direct translation – “shinkansen” just means something along the lines of “new trunk line”… but just look at that first train‘s nose!

Six weeks here has been a short enough time that I still feel new, and still wish that I had a few more weeks available, to do more work and to explore the area further; but it’s also a long enough time that I’ve made some local friends, and will feel sorry to leave. This afternoon I walked home the long way, and I found myself taking special note of the sights and sounds along the route, trying to fix them in memory. This has been a short chapter in my life, but a chapter nonetheless.

Tomorrow I am putting work largely on hold and going on a two-week holiday around Japan. I’ll probably write a little bit about it as I do (for those who are really not interested in my holiday diaries, forgive me – I’ll return to more subject-focused topics in a fortnight’s time). After that it’s back to Scotland, and a return to the reality that I have a looming thesis submission deadline, meaning that while I do plan to further analyse and to write up what I’ve been doing in Fukuoka, I have to be very careful how much time I spend on it.

On Saturday I sent off for Kagoshima, which is the port city at the southern end of the main islands of Japan. I booked a slow route, on vintage trains running through the interior – a landscape of never-ending lush, green, forested hills and mountains.

After reaching a main station the day started on a shinkansen, because I needed to cover some distance to reach the other railways. There are many good things that I could say about the “bullet trains”, but one thing that they are not good for is sightseeing. The Kyushu shinkansen in particular spends perhaps 1/3 of its length in tunnels, due to the terrain of the island, and for much of the rest of the time it hides behind noise barriers. This makes a lot of sense for everybody except the passengers, but for those on board it means that one can’t see much!

I disembarked at Shin-Yatsushiro, transferred from the new to the old station, and found myself on a lonely platform in the middle of nowhere, looking out across fields. After a short wait my next vehicle arrived in the form of a steam train! I’m not sure how old the locomotive was (although it was far from modern – we’re not talking post-war steam here), but the carriages behind it were thoroughly modern, freshly designed for a tourist line. At the rear of the train was an “observation lounge”, which was of course rapidly packed with people, with windows on three sides and sofas and armchairs from which to watch the scenery go by. I’m less fussed about old trains, and indeed steam locomotion, than many, but a train with a separate loco and a clear view out the back is a pleasant novelty in modern times. An unfortunate side effect of steam power was the number of shouty kids running around… We puffed our way along a steep-sided river valley, swapping sides occasionally, until we reached the smallish hill town of Hitoyoshi and disembarked. At some point I noticed that for the first time since my arrival in Japan, we had left overhead electrification behind.

The next two trains were nearly identical on the outside, although with different interiors: the “Isaburo” and “Hayato No Kaze” expresses were both operated by 1970s DMUs with thoroughly rebuilt interiors, in one case described by the railway company as “Meiji-period”. Unfortunately the brief given to the interior designer seemed to have neglected to mention the scenic-railway, sightseeing nature of these trains, because the fitout included such authentic features as high-backed seats, quality hardwood privacy screens, and other such luxuries that prevented one from actually seeing out of the windows very easily! Nevertheless, this train followed an impressive mountain railway, climbing through Japan’s only railway spiral (where the line crosses over itself) and two switchbacks (where instead of going around hairpin bends, it simply switches direction and goes up Z-shaped sets of tracks and points) to reach a station at more than 500m above sea level. A couple of times we stopped for 5-10 minutes at rural stations with wooden buildings that could easily be a hundred or more years old, where the locals set out souvenir stalls on the platform. This sort of rural railway is a world away from the urban commuter networks elsewhere in Japan.

Here are some poor-quality phonecam pictures from the journey; better photos will follow at a later date…

Eventually, the second of the trains descended from the hills to the southern coast, and followed the bay around towards Kagoshima. The defining feature of this area is the looming mass of the volcano Sakurajima – so named because it was an island in the bay  until it made itself a bridge in 1914. Said bay is itself a coastal caldera from a far more ancient mountain. Sakurajima is much closer to town than Vesuvius is to Napoli, and unlike its European cousin it is active – sufficiently so that hiking near the crater has been prohibited for the last couple of months – but Kagoshima does have the partial protection of a mile and a half of sea between it and the volcano.

It so happened that I had arrived on the evening of Kagoshima’s annual fireworks display, which was a source of delight. The next morning I visited the Museum of the Meiji Restoration, where I was struck by how very recent Japan’s modernisation and industrialisation was, compared to Europe and America. Then it was onwards to the shinkansen station, where the distance that had taken most of the previous day to cover was devoured in just an hour and a half of smooth comfort to deliver me home – that’s the power of 160mph travel!

Here are some phonecam pictures from Kagoshima:

A few minutes ago my officemate came over and asked “did you feel that? I think there was a small earthquake”. I checked the app’s log, and sure enough the seismometer network reported a “Level 3” event, Magnitude 4.2, beneath the slopes of a volcano about 60 miles away.

My first potentially-noticable earthquake, and I missed it! I feel faintly disappointed; while I certainly hope that a major quake is a part of Japanese life that I do not get to experience, I’d quite like to feel a minor, non-dangerous one.

It does, perhaps, vindicate my change of weekend plans – I had hoped to go and visit that very volcano, but for the last few weeks the area within 1km of the active crater has been closed for safety reasons…