Offshore
Opening page: To avoid costly underwater cables, PowerX has developed the Power ARK, where energy transfer vessels will carry the daily electricity needs of Japan through grid batteries.
focusing on renewables. For a country completely surrounded by water, accustomed to strong gusts, wind farms are the obvious candidate. But with craggy mountains limiting investment on the Japanese mainland, and deep trenches making construction equally tricky offshore, actually building the turbines to nourish the world’s fifth-largest emitter of greenhouse gases isn’t easy. That’s where Ito and his colleagues come in. With a remarkable plan to transport offshore energy on ships, PowerX could yet transform Japan’s energy portfolio – and even send oil wars to oblivion.
22,000
Japanese households could have their daily energy needs met by the electricity transported by each PowerX vessel.
200MWh
The amount of electricity the 100 grid batteries onboard each PowerX vessel can contain. PowerX
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Deep trouble “Destroy a country,” says an old Japanese proverb, “but its mountains and rivers remain.” The people here know that better than most: beyond the famous Mount Fuji, flanked by its ocean of conifers and cypresses, 80% of Japan is covered by uplands. This leaves precious little room for urban or industrial development. Japan’s towns and cities are squeezed on to just 4% of the land, and whatever remains is generally left to agriculture. It goes without saying, then, that Japan is no place for mammoth onshore wind farms so common in Flanders or the Romanian steppe. The geography of Japan’s coastlines is just as frustrating. Even five minutes from shore, says Ito, the sea plummets to depths of 3,000ft. To put that into perspective, that’s five times deeper than many typical coastlines in Europe. Of course, this makes fixed- bottom turbines impossible, with floating platforms the only viable alternative. But getting renewable energy from these floating turbines to Japanese consumers is challenging too. For starters, Ito emphasises that laying underwater cables at the necessary depth is painfully expensive. For another, fixing problems deep below the surface can take weeks. And given Japan sits on a huge tectonic fault, cables are bound to break eventually. “The Japanese government is predicting a very large earthquake to hit along a couple hundred kilometres- worth of coastline,” Ito says. “If that happens, and you’ve got multiple wind farms, they’re all going to go out when you need power most – in a disaster.” These environmental barriers have stymied investment in Japanese wind energy. The government has certainly made the right noises here. Among other things, Tokyo aims to invest over $100bn in wind and solar generation by 2030, a figure that could soon supply 24% of the country’s energy needs. In truth, however, progress has been far slower. At the moment, just 10% of Japan’s electricity is created by renewables. Of that figure, solar panels often get more attention. Snaking electricity cables 50–100km to a floating wind farm is simply too cumbersome, even though Japan’s climate is far more suited to wind turbines. According to one recent estimate, after all, Japan has 608GW of offshore wind capacity – more than the entire global wind output in 2018.
Ship-shape
In some ways, Masahiro Ito feels like an unlikely figure to revolutionise the Japanese wind sector. He started his first business, a software start-up, in 2000, and for years worked in industries as varied as fashion and automobiles. Turbines and floating platforms were notable mainly by their absence. Yet as Ito explains, it would be the relative triviality of his early career that ultimately led him towards co-founding PowerX. “There’s got to be something bigger,” he recalls thinking. “And I realised that climate change and carbon neutral goals are all super important.”
However it emerged, in any case, PowerX’s actual programme is alluringly simple. Dispensing with underwater cables, the company instead aims to transport energy on enormous battery ships. Known as the Power ARK – and about 100m in length – these ‘power transfer vessels’ will hold 100 grid batteries, together capable of carrying 200MWh of electricity. That’s the equivalent to the daily energy needs of 22,000 Japanese households. Rather than directly docking with individual turbines, moreover, the ships would instead approach a nearby barge. From there, a stabilised crane would drop cables on to the ship, before finally transferring precious wind power into the ship’s batteries. The immediate benefits of this approach are obvious. Expensive and unreliable cables would be rendered irrelevant, while the PowerX ships, sleek and black like something out of a Bond movie, could quickly charge up after an earthquake or storm. More broadly, it’s obvious that Ito and his colleagues have battled to drag their vision into the real world. Working with a UK naval engineering expert, for instance, the Power ARK is designed with Japan’s coastal waters in mind. As Ito puts it, “We’ve determined that the ship will pitch and roll to a certain degree – it’s designed to be stable enough that the cranes can compensate for that roll.” Other details of PowerX’s story are impressive too. Because the electricity platforms will be stationed downwind of the turbines themselves, Ito envisions that once the cranes have attached their cables, the latter could be let loose. While its batteries are being charged, a Power ARK would “drift away” from the platform, using its thrusters to stay close while also saving energy. At the same time, PowerX has considered the question of weather. Unsurprisingly, the Power ARK’s floating embrace could go wrong in a storm – hardly an immaterial point, given the country faces over 25 typhoons each year. Conversely, it makes little sense to deploy a ship if there’s no energy to collect. As Ito notes, turbines often enjoy “uptimes” of just 40%. Not that the situation is hopeless. PowerX plans to use sophisticated modelling to
World Wind Technology /
www.worldwind-technology.com
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