Click HERE to read Part One of our “More Than Just Storage” Blog Series
As we discussed in our last post, there’s more to our grids than supply and demand, power plants and wires. As power generation sources continue to diversify around the globe, the additional stabilizing and supporting benefits of Long Duration Energy Storage (LDES), and advanced compressed air energy storage (A-CAES) technology in particular, become even more important. The recent power outage in Spain and Portugal demonstrate this urgency in real world terms, when millions of people lost power in just five seconds.
Let’s dive into the other benefits of A-CAES.
4. Spinning & non-spinning reserve
How it works:
To balance ever-changing supply and demand for energy, all grid operators run different power markets to support their grids. Grid operators pay different power suppliers for the ability to provide power in a short period of time if required. These operating reserves provide power capacity to grids if demand or supply change unexpectedly. There are two types of reserves: spinning and non-spinning. Spinning reserves are already online and synchronized to the grid and can respond the fastest. Non-spinning reserves are not online or synchronized and take longer to respond to a grid’s needs.
Why it matters:
While grid operators can control supply, they have limited control over demand. Grid operators constantly need to balance the generating assets they control with the grid demand they generally don’t control. To ensure grid stability and prevent blackouts like those in Spain and Portugal, grid operators essentially need to pay generators to reserve capacity for their grid in case they urgently need it.
LDES solutions like Hydrostor’s A-CAES can multitask as more than just energy storage, providing both spinning and non-spinning reserves to grids. Hydrostor’s technology can provide backup power capable of coming online rapidly and even operate as low as 10% of its nameplate capacity, reserving 90% of its capacity for rapid response. While storage solutions like lithium ion batteries can provide slower non-spinning reserve, A-CAES can provide both, providing another essential solution for grid stability and support. In the case of the Iberian grid, more spinning reserve capacity could have greatly reduced the severity and duration of the blackouts.
5. Regulation up & regulation down
How it works:
Regulation up and regulation down function similarly to spinning and non-spinning reserves. Like balancing supply and demand, grid operators need to constantly ramp power up and down to balance and ensure frequency stability on the grid. In other words, grids need to adjust power generation and output with load fluctuations. To do this, regulation up involves increasing energy generation or discharging more energy and regulation down involves decreasing energy generation or discharging less energy to the grid to ensure this balance.
Why it matters:
What makes regulation up and regulation down complicated is that grid operators have a limited ability to control their loads and thus ensure the stability of grid frequency.
That’s where multi-tasking technologies like Hydrostor’s A-CAES can provide ancillary benefits beyond storage. Hydrostor’s technology is a rare exception: a load that grid operators can actually control. Hydrostor can offer regulation up and down services to grids because it controls its own facilities, with rapid response time and operational flexibility ensuring the ability to turn power up or down quickly as grid operators need. Hydrostor’s A-CAES can also provide Automatic Generator Control (AGC) to support regulation up and down, to allow autonomous response to rapid requests from the grid operator. In the case of the Iberian blackouts, additional regulation up and regulation down capacity, in addition to AGC support on the grid, could have reduced the severity of the event.
7. Transmission Alternatives
How it works:
Transmission deferral refers to the strategy of delaying capital-intensive transmission infrastructure projects, including building more power lines and substations, to serve growing demand. Instead, transmission deferral uses energy storage systems and other resources to balance the interconnection between energy demand and supply.
Why it matters:
While demand for energy continues to increase around the world, so too has the cost of grid infrastructure projects and upgrades.
The cost barriers of transmission investment hits communities like Broken Hill, New South Wales (NSW) Australia particularly hard. A small mining town at the end of an electrical network on a node by itself, the community and economy of Broken Hill is connected to the rest of the grid by a single 220 kilometer transmission line. In other words, Broken Hill has no energy redundancies. Whether it’s because of an accident or scheduled maintenance, when that single power line goes down the town of Broken Hill is completely without a reliable power supply – as happened in October 2024, at great cost to the community. And costs to build a new transmission line to the community are estimated to be extremely high – the Australia Energy Regulator’s (AER) current estimate for building new transmission lines in rural areas is $2.1 million per kilometer. This is where the strategy of transmission deferral comes in. Instead of building more transmission lines, investing in distributed energy resources like Hydrostor’s A-CAES technology can come with huge savings.
Similarly, transmission deferral solutions and mini- and micro-grids can help store and deploy abundant renewable energy that is currently going unused due to the heavy financial barriers to new transmission investment. Consider the power from rural wind farms in places like Ohio and Nebraska. Without additional transmission lines, a lot of that power gets curtailed and goes unused.
That’s where the strategy of transmission deferral once again steps in. Instead of letting that power go to waste, A-CAES can help grids and communities store that energy and deploy it on demand, at a fraction of the cost of new transmission lines.
The big picture
The benefits of LDES go far beyond simple energy storage, and A-CAES technology in particular can help support and stabilize grids by providing:
1. Inertia & frequency control
2. Voltage support
3. Black start
4. Spinning & non-spinning reserve
5. Regulation up & regulation down
6. Transmission deferral
While these ancillary benefits may seem like technical details, their value to the grid is immeasurable. A-CAES technology has the potential to be the multitasking infrastructure investment that meets the complex needs of communities, businesses and governments today – supporting, stabilizing, and securing grids around the world for generations to come.