Blog 13_ Energy Storage
"Explain what you mean by Energy Storage and why you think it is a key enabler for increasing levels of zero emissions Energy on the Grid".
We are facing five years of amber alerts on the Electricity Grid. Fortunately, Eirgrid are confident that interruption to supply is unlikely this winter. We could have been in a much better place if we had provided an adequate level of energy storage over the last number of years and it remains an urgent requirement as the net zero energy available to the Grid increases.
There are two categories of energy storage: short term storage and long term storage. By short term is meant storage for a number of hours say 3/4 hours, whereas long term storage is suitable for 3/4 days or even longer.Typically short term storage is provided by means of batteries which can be charged and then later discharged as required.There are various technology solutions suitable for use as long term storage but the one providing over 90% of storage in the world today is called pumped hydro storage. This is where there is a lake at the bottom of the mountain and a lake at the top. In some modern installations the lower lake is actually the sea. When there is excess energy available it can be diverted to pump water from the lower to the upper lake where it is stored as potential energy. Then later, when supply is tight, the water from the upper lake can roll down again to the lower lake through a turbine to generate electricity.
The present situation in Ireland is that we have a limited amount of battery storage and a single pumped hydro system (Turlough Hill). Two things about the battery storage: Firstly, since we have an all Island electricity system, some storage is in Northern Ireland and some is in the Republic. Without a satisfactory interconnector between the two jurisdictions, the effectiveness of the storage is reduced. Secondly, the battery storage is only partly state owned. Most systems are privately owned and operate on the basis of storage contracts from the Energy Regulator. However representatives of the industry have written media opinion pieces arguing that they would really like to operate differently. Instead of Grid storage contracts, they would like to do what every business does, namely to buy low and sell high. In this case they would be happy to use their technology to buy electricity from the Grid when it is cheap and then sell it back when it is expensive. Consequently, it's not clear how secure even our limited short term energy storage will be when the present contracts end.
I explained in an earlier blog how, as more and more renewable systems are connected to the grid, increasing amounts of the energy generated is wasted, reaching 8.5% in 2022 and probably more now. To eliminate this waste by urgently providing substantial levels of both short term and long term energy storage is long overdue and is now a policy imperative.
For more technical details see:
Engineers Ireland Yearbook 2025, "Why pumped hydroelectric energy storage is a perfect fit for Ireland's path to zero emissions electricity generation" Author: Chris Bakkala CEng MIEI