Ireland’s targets, while ambitious, will most likely encounter several issues in the coming years, not least of which are system non-synchronous penetration (SNSP) limits (high concentrations of non-synchronous generators operating on the grid), infrequency events, and, due to recent geopolitical events, insecurity of supply. Wind and solar generators are typically non-synchronous.

Previously, Ireland had mixed success in reaching its 2020 renewable energy share targets, and while it did achieve its transport target, it just missed its electricity target and fell short of its overall goal. 

The increasing proportion of renewable energy in electricity production poses growing challenges for transmission system operators (TSOs). Since solar and wind power are subject to weather-dependent fluctuations, the Irish TSO needs to find a means for controlling infeed more flexibly and avoiding expensive network interventions to stabilise the power grid. 

If more wind power is generated than can be transported, wind turbines need to be curtailed. Until recently this energy would have remained unused since there were no individual storage systems available for large volumes of power. 

However, among the available energy storage systems, electric batteries exhibit considerable potential for application to the Irish grid. As the majority of Ireland’s renewable supply is in the west, and demand in the east, electrical energy storage is attractive because it provides a flexible installation near generation sites, modularisation to scale to the size required, rapid frequency event response and relatively short construction cycles. 

The benefits that energy storage can deliver in terms of consumer savings, reduced carbon emissions and reduced curtailment of renewable energy are one of the key aims of the current government’s Target Climate Action Plan.

Energy storage technologies such as lithium-ion battery energy storage systems (LI-BESS) can provide a safe and reliable role in the operation of a grid with high levels of renewable energy integration that the Irish market operator is currently striving for. LI-BESS are the most common type of grid-scale batteries at present and are already available worldwide, with up to four hour’s storage duration. 

They are predominantly suited to providing fast-acting frequency responses and reserve grid capacity that can replace the need to use fossil fuel generators for these services. Out of merit fossil fuel generators are often constrained on or run inefficiently so that they are available to provide this immediate reserve back up and maintain the required frequency.

However, the current technology is subject to increased degradation with cycling and therefore may only be suitable as a shorter-term solution.

Due to Ireland’s relatively isolated electrical grid relative to the wider European market, renewable energy sources, such as wind and solar, face several obstacles, including curtailment, where the generated energy exceeds local demand and production must be reduced because of limited transmission capacity. As renewable energy production not only varies from day to day but season to season, this must be used as soon as it’s generated because the island of Ireland’s grid has very little storage capacity beyond the single pumped hydro site of Turlough Hill power station.

Battery storage, in this instance, is the most obvious solution. If Ireland was able to install enough grid-scale battery storage capacity to meet demand and supply, then we would become less dependent on the use of curtailment.

A growing number of batteries are available for not only storing electricity from the grid, but also from a home’s solar panels. These newer and smaller ‘smart’ batteries, whether in the form of home mounted or, for example, Tesla electric vehicles (EVs), can store solar power generated from a home’s array or draw power from the grid when there is an excess and is relatively cheap. This energy can then either be used in the home later, or if the grid operator allows, sold back to the grid at a higher price in times of high national demand.

These virtual power plant (VPP) services that can help balance the grid are rapidly evolving. Other methods include microgrids with local independent grid networks, peer-to-peer trading where a blockchain-like technology can be used, and communal energy supply with battery owners sharing their electricity. Systems such as these take advantage of smart meters and may include the time of use pricing, where the cost of power is based on low or high national demand. 

Currently, in Ireland, there are unresolved issues around the finer details of operating these new technologies, for example, whether ‘re-exported’ electricity should be eligible for payments. 

In the electrical energy transformation process, grid-level energy storage system plays an essential role in balancing power generation and utilisation. As the penetration of EVs continues to rise, and lithium-ion production sees efficiency gains and greater economies of scale, the production costs for the battery packs as the core component of battery storage systems will continue to decline. 

With energy demand rising in Ireland and the government pushing to increase the number of renewables in the system, each day there is an ever increasing need to invest in energy storage technologies as these are a key enabler to a decarbonised electricity system, and their deployment supports renewable energy policy objectives by providing a multitude of valuable services.

The views and opinions expressed in this article are strictly those of the author only and are not necessarily given or endorsed by or on behalf of the Energy Institute.