The Scottish archipelago Orkney is taking steps to adopt a hydrogen-based energy system that feeds off excess tidal generation from the European Marine Energy Centre (EMEC).
The tidal and wave energy test station is due to install a 500-kilowatt ITM Power polymer electrolyte membrane electrolyzer, with integrated compression and up to 500 kilos of storage, in the first quarter of 2017, said Lisa MacKenzie, marketing and communications officer.
The £1.79 million (USD $2.77 million) electrolyzer, with a generation capacity of 220 kilos of hydrogen per day, will also mop up excess power from a community wind turbine owned by local renewable energy developer Eday Renewable Energy.
Later in the first half of the year, EMEC, which is located on the island of Eday in Orkney’s North Isles, will install a 75-kilowatt fuel cell from an unspecified vendor at the pier at Kirkwall, the capital of Orkney, on the island of Mainland.
The fuel cell is being installed as part of a project called Orkney Surf and Turf, which will use hydrogen generated by the Orkney-based electrolyzer to provide auxiliary power for ferries docking at Kirkwall.
It is also part of a wider plan allowing EMEC to gain experience in hydrogen storage that can then be applied to projects elsewhere, particularly in shipping. “The vision in the future is to have hydrogen-powered vessels,” MacKenzie told GTM.
“The issue we have is that hydrogen-powered vessels don’t exist. Part of the Surf and Turf project is to develop the fuel cell technology to a standard that could be used at sea.”
At the same time, a separate project, called BIG HIT, will see the local council in Orkney introduce electric vehicles with fuel-cell range extenders that could also run off the hydrogen produced at EMEC.
The BIG HIT project includes the installation of a second 1-megawatt electrolyzer on the island of Shapinsay, between Eday and Mainland. The Shapinsay electrolyzer will be powered by a community wind project on the island.
EMEC, which is the world’s most prestigious test center for tidal turbine and wave energy technologies, chose to focus on hydrogen after reviewing a number of options for storing energy, initially as a way to get energy back to mainland Britain.
The presence of grid-connected pilots from tidal turbine developers such as Nautricity and OpenHydro, along with community wind power and more than 1,000 residential-scale wind and solar plants, means Orkney already produces more renewable energy than it can use.
But the island group, which includes 20 inhabited islands, only has two 33-kilovolt subsea cable connections to Thurso on the north Scottish coast, which makes it difficult to export energy when the tidal arrays are working a full capacity.
The plan over a year ago was to find a way of storing the excess energy while tides were coming in or going out, and then releasing it to the grid during slack periods.
The center needed multi-megawatt-hour storage with a duration of several hours or even days, which ruled out battery systems.
Similarly, two other bulk power management technologies, pumped hydro and compressed air energy storage, were not viable on the Orkney archipelago because of geographical constraints. “That’s why we’ve had to look elsewhere,” said MacKenzie.
In any event, she said: “We’re not looking to put the power back into the grid anymore. It’s no longer all about storage, although the initial driver was to seek to store electricity between tides.”
Besides being used for transportation, hydrogen from Orkney could be used industrially, for example as a chemical feedstock, food additive or fertilizer ingredient. “Orkney could act as a case study for rural environments elsewhere,” said MacKenzie.
Nevertheless, it remains to be seen whether other regions will embrace hydrogen as readily as Orkney is.
Carlos García Buitrón, managing director of the Spanish renewable energy provider Ecovatios, said: “I’m no expert, but what I can say is that in mobility, at least, hydrogen has always appeared to be the future, but we’ve seen lithium batteries overtaking it. Few seem to be considering it now in this field.”