Storage encompasses a broad range of technologies ranging from chemical, electrical, thermal, electrochemical and mechanical. Each of these technologies has different characteristics and capabilities in terms of speed of response and storage capacity which means they can provide a variety
of valuable services to the power system.
Frequency Response
Lithium ion battery energy storage systems (LI BESS) are the most common type of grid-scale batteries at present and are already operational worldwide. They are predominantly used to provide fast acting frequency response and reserve grid services that can replace the need to use fossil fuel generators for these services.
For example, to ensure the stability of the system in case of a sudden disruption to power generation or demand, such as a large generator failing unexpectedly, the TSOs must make sure that there is sufficient reserve back up power on the system at all times. This reserve power must be available at a moment’s notice and currently the TSOs meet the majority of their reserve requirement from fossil fuel generators. This means that out-of-merit fossil fuel generators are often constrained on or run inefficiently just so they are available to provide this immediate reserve back up.
LI BESS can replace the need to use fossil fuel generators for reserve and fast frequency response as they are available nearly all the time and can respond to tiny frequency deviations in milliseconds, thus helping to manage system stability. This has huge benefits in terms of system cost savings, emissions reductions and lower renewable curtailment as demonstrated in a study carried out by energy experts Baringa (Store, Respond and Save) which you can read in our publications section.
Reducing Electricity Prices
Storage technologies with multiple hours duration can reduce electricity prices by storing energy at low price/cost periods and discharging it at as a cheaper and cleaner alternative to fossil fuel generators in high price/cost periods.
For example, electricity demand tends to have a consistent profile day to day characterised by the lowest demand at night with a gradual ramp up in the morning, with another fairly steep demand rise in the early evening, in line with peoples’ activities at home. Generation has to be scheduled to meet this demand profile, with the most generation needed to meet the evening peak. This also tends to be when the most expensive electricity prices are seen as expensive gas or diesel peaking generators are often brought on just for a couple of hours to meet this evening demand.
Multi-hour energy storage systems can replace these peaking generators as they can discharge energy over this short evening peak timeframe to help meet demand. Energy storage systems active in this market generally
charge when electricity prices are low, which is typically when renewable generation is high, and discharge at times of peak demand. This removes the need to turn on expensive fossil fuel peaking plant, lowers costs to consumers and reduces overall power sector emissions
Energy Storage as an Alternative Network Solution
Energy storage technologies could also be used to provide a non-wires alternative to network build out to help mitigate peak transmission or distribution network congestion. As the electrification of heat and transport adds additional demand to an already constrained grid, energy storage offers a potentially cheaper network reinforcement solution to network operators for the benefit of all users.
For instance, deployment of storage in large demand centres such as Dublin can help avoid network congestion during peak hours and reduce or defer the need for network reinforcement. Behind the meter electricity storage schemes will also have a role to play in managing energy balancing and network congestion, increasing the overall utility of existing grid infrastructure.
Long-Term Storage
To achieve a decarbonised energy sector a cost-effective means for the long-term storage of large volumes of renewable energy will be required. Technologies such as pumped hydro, compressed air energy storage, liquid air energy storage etc. already offer potential options. Electrolysis may provide a scalable alternative solution, whereby surplus or dedicated renewable generation is used to produce hydrogen gas, which is then stored and transported, potentially via existing gas infrastructure, as a ‘clean’ fuel for use in the electricity, heat and transport sectors.
Significant research and development is ongoing across the world on the development of a ‘hydrogen economy’ and it could prove an ideal solution for the all-island Irish market, improving energy sustainability and security, while also facilitating achievement of long-term decarbonisation goals.