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energy storage ship PowerX Ark offshore wind
This sleek trimaran is equipped with a utility-scale energy storage system for harvesting electricity from offshore wind farms (Power Ark screenshot via PowerX).


Seagoing Energy Storage Ship Meets The Offshore Wind Transmission Challenge

The sleek new Power Ark trimaran envisioned by PowerX will sport a utility-scale energy storage system for harvesting electricity from offshore wind farms.

The Japanese startup PowerX launched in March 2021 with the ambitious idea of offloading electricity from offshore wind turbines, without having to lay new undersea cables. All you need is a boat with some giant batteries to collect the clean kilowatts and ship them back to shore. The devil is in the details, but PowerX aims for its new Power Ark vessel to hit the waves within the next three years.

A Boatload Of Energy Storage For Offshore Wind Farms

Not to be confused with the similarly named Brooklyn-based smart home device company raising funds on Kickstarter, the PowerX company of Japan describes Power Ark as a “power transfer ship” engineered to ferry electricity from offshore wind farms to practically anywhere a ship can go.

Aside from potentially cutting the overall cost of constructing a wind farm, the Power Ark solution would help alleviate growing concerns over the vulnerability of undersea cables to sabotage. Underseas cables have also raised environmental concerns.

There being no such thing as a free lunch, maritime traffic also raises security and environmental issues. However, all else being equal, flexibility in destination and use of existing port infrastructure are two points in the Power Ark’s favor.

The Power Ark Energy Storage Ship: Look Ma, No Undersea Cables

PowerX outlined its plans in a press release last August. The company took particular note of the Power Ark concept in the context of Japan’s clean energy goals. According to PowerX, Japan will need to push its offshore wind sector far past its existing capacity of 20 megawatts, to attain 10 gigawatts by 2030 and up to 34 gigawatts by 2040.

That means more undersea cables along with the wind turbines, which provides PowerX a hook upon which to hang its hat.

“An undersea power cable typically requires expensive construction that comes with substantial environmental impacts. Comparatively, the Power Transfer Vessel stands out as it is resilient to natural disasters, requires less time and cost for development, leaves minimal impact on the environment, and therefore is able to expand the potential of offshore wind power significantly,” PowerX explains.

Power Ark could also potentially import clean kilowatts from elsewhere around the world into Japan. As the company points out, Japan already relies on ships to import almost 85% of its fuel for power generation.

Energy Storage To Sail The 7 Seas

One complication that comes to mind is the amount of time needed to harvest electricity by the megawatt from wind turbines on the open seas. In addition to the technology challenges, labor shortages in the global maritime sector could put a kink in the plans, though automation could help resolve that issue.

Another challenge is the amount of power needed to propel a large ship loaded with batteries. Apparently the plan is to use electricity from the batteries, supplemented with biodiesel for longer voyages.

The biodiesel angle sounds less than optimal in terms of producing the lowest possible carbon footprint, but it’s possible that PowerX may shift the plan as new low-carbon maritime technologies emerge.

One option that looks increasingly feasible is to install the latest generation of high-tech sails, enabling wind power to do some of the heavy lifting. Leading players in the shipping industry are also beginning to pivot into green ammonia as a carbon-free fuel, though the issue of nitrogen oxide emissions needs to be addressed.

Regardless, if all goes according to plan, the first energy storage ship in the PowerX series will be a prototype-scale trimaran dubbed Power ARK 100, a name that reflects its length of just over 100 meters and the goal of equipping it with 100 grid-scale batteries (a trimaran is a three-hulled vessel, a configuration that is considered practically unsinkable).

One hundred is also the capacity of the ship in terms of TEU (twenty-foot equivalent unit), which is a unit of measurement based on the dimensions of a standard 20-foot shipping container. One hundred TEU is fairly small, considering that the container ships of today can carry thousands of TEU, but it’s still a pretty big boat.

This Could Actually Happen

In addition to building the boat, PowerX also plans to manufacture its own batteries in-house, with assembly taking place in Japan. The company aims to supply its Power Ark ships as well as other use cases, including  EV fast-charging, grid, and marine batteries, with a production goal of 5 gigawatt-hours annually by 2028.

That’s a pretty tall order, but PowerX appears to have its ducks in the water.

On December 3, PowerX let slip that it has partnered with the leading maritime engineering company Imabari Shipbuilding Group, to develop a prototype Power Ark with a 220-megawatt marine energy storage system on board by the end of 2025, with plans for scale-up after that.

Last week, PowerX also announced that it has recruited the leading classification society DNV onto its seagoing battery venture. DNV will collaborate on technical assessments of both the Power Ark and the energy storage system. DNV is known for its work in the renewable energy field, and PowerX anticipates that it could develop a new class notation for safety validation and other regulatory issues, smoothing the path to global implementation of the Power Ark model.

Offshore Wind Hearts Energy Storage

PowerX could soon find itself busier than expected. Floating wind turbine technology is enabling wind farms to be constructed farther from shore and in deeper waters, two factors that could complicate the construction of new undersea cables.

Engineers are also developing new ways to squeeze more clean power out of offshore wind farms. In addition to an ongoing series of larger, more powerful offshore wind turbines, some of the latest developments include doubling two wind turbines onto one offshore platform or adding solar panels. The addition of wave energy to wind farms provides another opportunity for growth.

The wave energy field is also expanding as a standalone technology. That could translate into additional opportunities for PowerX, especially in protected nature conservation areas where opposition to new undersea cables would be difficult if not impossible to overcome.

Here in the US, coastal states have barely begun to tap the potential for adding offshore wind farms to the nation’s energy profile, but major new projects are finally slipping into the pipeline and the US Department of Energy is already trying to assess the impact on the nation’s transmission infrastructure. Don’t be surprised if creative solutions like seagoing energy storage pop up here, too.

Follow me on Twitter @TinaMCasey.

Image (screenshot): Energy storage vessel for offshore wind farms courtesy of PowerX.

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Written By

Tina specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.


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