Naturally, it depends. As storage technology continues to evolve, energy suppliers and consumers alike are presented with increasing options for deployment. Latest and greatest solutions that take advantage of technology breakthroughs are exciting, but determining when, and in what kind of technology to invest can be a challenge.
For instance, earlier this year, scientists at the University of Southern California developed a new redox flow battery. The benefits are that this battery is based on low-cost and readily available materials and can recharge hundreds of times with virtually no loss of power. Sounds impressive, but does that mean it’s the right storage solution for every case?
Again, it depends.
When considering existing and emerging storage technologies, you must also consider the use of such technology in each case. As a consultant to electric utilities, we consider all applications; small-scale batteries in homes and businesses that link up to deliver kilowatts of capacity, as well as grid-scale batteries rated in megawatts. After use is determined, our next analysis is how any new technology will achieve a client’s objectives and impact reliability, capacity, resiliency, power quality, and overall grid and operational flexibility.
A new class of asset
As an industry, our understanding of storage has matured over time. Now we are starting to think of storage as a separate class of energy assets with multiple technologies creating the systemic solution-set. It’s the same thinking as ‘generation-as-an-asset-class’ where coal, gas, hydro, wind, solar, nuclear, etc., are selected for their use-case within the whole energy system. This ‘energy mix’ supplies systems with a diversity of fuels and technologies to reduce reliance on a single element in the system, while affording utilities operational flexibility. The same will be true of storage, and policy is starting to align with this thinking.
We have come to acknowledge that no single storage technology holds all the answers. Each of the many storage technologies used or in development today have their own optimal operating conditions. Apart from varying construction and O&M costs, the main parameters distinguishing storage technologies are capacity (how much energy is stored) and output (the maximum amount of power that can be produced at any point). Additionally, energy storage has the capability to provide other services that are unique to its fast response rate, such as frequency regulation and inertia to improve grid stability and back up power to increase resiliency.
Ramp-rate and utilization aren’t only for generators
Ramp-rate is another key factor in determining which storage technology is best in each case. In broad-brush terms, electrochemical systems (vs. electromechanical) are quicker to ramp-up to power because they forego the mechanical inertia that must be overcome in electromechanical systems. Another point is that storage doesn’t necessarily follow the same economies of scale as traditional generation. As a general rule, battery storage has better economics the closer it is to the load – in part because you get better utilization of the asset’s potential at that point. So, bigger isn’t always better.
Storage is not a uniform technology, and its intended use is fundamental in deciding what technology to choose. As new technologies are tested and deployed, we’re finding alternative ways to fulfill many use cases. Even though there’s no silver storage bullet, we get closer to our targets when we analyze the use-cases for each opportunity.