On a flat piece of land in west Dublin, 96 black container like structures sit in perfectly straight rows.
A persistent hum is the only indicator of the electronic equipment packed inside.
Each cube is a battery storage unit, full of small lithium-ion batteries, just like the ones you find in your mobile phone.
The large boxes are surrounded by transformers, inverters and other equipment.
Together, the devices provide 30MW of electricity storage – enough to power 30,000 homes for up to two hours – for the grid.
The facility, which is nearly complete and ready for use, belongs to the ESB.
It is one of a number of companies, including Iberdrola, RWE and Statkraft, that have already or are currently developing more than a dozen such plants around the country.
The companies claim these plants will provide a crucial link in the chain that will ultimately result in Ireland moving its electricity generation capacity to fossil fuel free renewables.
“As we increase the level of wind penetration and solar penetration onto the system, we need to ensure the system is stable and we need to ensure that we deal with some of the intermittency associated with renewable energy,” said David Farrell, Head of Onshore Asset Development at the ESB.
“A battery like this does just that. It provides frequency response to any variations in the frequency and also if you have loads swings in the system. That’s really important for the grid’s stability.”
“It also provides a form of reserve capacity, so in the event there is a shortage of capacity in the system, this can provide, in this case, 30MW for two hours. And additionally to that it also provides the ability to store electricity when there is excess electricity on the system, it can be stored here and then at peak demand or when there is shortage it can be discharged onto the system.”
Energy storage is not new in Ireland – the 300MW pumped hydro station at Turlough Hill in Wicklow has been operating for nearly 50 years.
But in order to store enough power to run the country for just one day, we’d need 60 Turlough Hills.
So if we are to get rid of all the fossil fuels that our electricity is currently stored in and become fully reliant on what is at times unreliable renewables, we are going to need a lot more long-term sustainable energy storage options.
Larger battery storage plants are one option and plans are being developed here for units capable of storing many hours of power for when the wind stops blowing or the clouds cover the sun.
The ESB is currently installing the world’s largest flywheel in Moneypoint as part of a new Synchronous Compensator that will help smooth out grid imbalances.
Other technologies are also in the pipeline, but ultimately, experts think green hydrogen will be the medium to longer term answer.
“That means making electricity from water and renewable electricity,” said Professor Hannah Daly, from the Department of Engineering at University College Cork.
“When there is an overabundance of renewables we use the electricity to split the water molecule into hydrogen and oxygen and then we use that hydrogen as a way of storing energy for when we need it.”
“That can then go on to make transport fuels, to heat our homes and district heating.”
Of course, no new technology is entirely green.
So what about the environmental impact of these new solutions, like huge battery storage plants?
“No mining is environmentally friendly and the lithium and other precious minerals that go into batteries and other technologies for energy storage are not perfect,” Professor Daly said.
“But the impact of these things pales in comparison to the impact of drilling for fossil fuels, refining them, transporting them and then burning them. So we need to keep that in context.”
Although full of potential, the energy storage sector here is still very much in its infancy with around 500MW of combined capacity already delivered, growing to 800MW next year.
However, last year energy experts Baringa estimated that to hit the 80% renewable energy target by 2030 in Ireland and Northern Ireland, 1,700MW of battery storage would be needed across the island.
Around 60 more projects with a combined capacity of 2,500MW is in the pipeline, and the industry is confident of hitting its 2030 targets.
But it also says it needs policy and investment support from the state to make it happen.
“We don’t have Government targets for energy storage,” said Bobby Smith, head of Energy Storage Ireland.
“And that is needed to give that signal and drive the investment forward for the industry. There are some policies right now that could be upgraded or better implemented to help facilitate energy storage. Particularly around the ability of energy storage to get connections to the grid because there is a huge bottleneck at the moment.”
“And the ability of storage to participate fairly in the market.”
That’s because the market here has been designed for fossil fuel generators, Mr Smith said, making it difficult to slot new assets into the market.
“We’re going to have to do that, we are going to have upgrade our systems. And that comes down to stakeholders like Eirgrid, stakeholders like the CRU, to develop policies that better integrate energy storage.”
It seems that if Ireland gets its energy storage rollout right the opportunity could be enormous.
The EU estimates 435GW of capacity will be needed across the union by 2050.
Ireland has huge renewables potential, leaving it well placed to generate and store power for export.
This could potentially spark a whole new cleaner, greener energy industry here.