Ask the average person about rechargeable batteries and their first thought will likely be of their cell phone: In the last 10 years, smartphones have changed our everyday lives thanks to the lithium-ion batteries that keep them running no matter where we are. Those batteries have become so important that most of us have a constant background thought: “How long can I go before I have to charge my battery?”
But for the power grid, batteries are starting to perform a service that’s going to be just as impactful as the growth of the mobile phone industry. This revolution will be about more than providing energy when we’re unplugged. When batteries are widely deployed across the grid, it will pave the way for exponential growth in renewable energy.
The challenge from increasing levels of power generation from wind and solar is that they’re intermittent — you can’t control when and where the wind will blow or the sun will shine. For more than 100 years, the grid has operated by relying on controlling power generation to match demand and keep the grid running. As clean but unpredictable and uncontrollable sources start to become a larger part of the energy matrix, batteries can help keep the grid in balance.
Large-scale battery energy storage capacity is rapidly rising, at decreasing costs, mostly due to lithium-ion batteries — large versions of the batteries in most cell phones. In the United States, as much as 1,800 megawatts of new energy storage will be online by 2021, an eightfold increase from 2016 levels, according to GTM Research. The resulting 5,900 megawatt-hours of stored electricity will help address power outages, reduce peak demand charges and improve grid reliability. While the U.S. is a more advanced region in terms of markets and regulations for storage, it still has a ways to go for a countrywide, fully developed market. This also holds true for Europe, where a nascent market in the U.K. is expanding to Germany, Spain, Italy with other areas, including Australia, Asia, and the Middle East following quickly.
Energy storage is becoming even more compelling as the economics of batteries improve. The cost of storage at the cell level has dropped to less than $300 per kWh today from more than $2,000 per kWh in 2008. This unprecedented price drop has been driven by the wide adoption of electric vehicles, which use the same type of battery cells. Technical advances will drive that price even lower, making energy storage even more appealing.
Today there is a wide array of battery energy storage applications throughout the energy grid, from large networks to community microgrids. With large grid systems, batteries can be attached directly to generation sources such as wind turbines and solar panels to store and release excess electricity that the grid can’t absorb in that moment or even be used in hybridizing conventional power generation (gas engines or turbines) in order to enhance the flexibility of and speed of response to grid intermittency. Alternatively, large battery energy storage systems can be directly connected to transmission and distribution networks to even out any production and consumption imbalance and support grid operations with response times as fast as a quarter of a second. Batteries can also be installed on industrial buildings, or even homes, to sustain consumption peaks or maximize the output of rooftop solar. Battery energy storage is also becoming an essential part of a growing number of microgrids — community-type networks of electricity users with a local source of supply that can work independently while being attached to the national grid. The integration of storage at the center of a microgrid, can allow that microgrid to rely almost exclusively on renewable sources, providing sustainability and economic advantages for the communities it supports.
Whatever the application, batteries alone can’t do the job. You need a complete energy storage system to enable dynamic grid controls that provide sub-second response times. GE’s Grid Solutions business has been deploying energy storage systems throughout the last decade and has learned a lot about how to provide the best solutions to optimize the battery system. This kind of knowledge is crucial because without it, you risk harming the batteries through improper charging and recharging patterns, forcing power operators to prematurely replace these expensive batteries.
On the grid, storage systems need to be optimized to last 10 to 20 years with the minimal amount of battery use possible in order to be cost-effective. Operators need to size the energy storage system to make sure it will have a long-term guaranteed capacity, notwithstanding the natural battery degradation that comes from the foreseen usage pattern. These battery systems need to have all the latest power conversion technologies and software controls to maximize the batteries’ functionalities and help them interact with the network control logic. GE’s Grid Solutions software has been globally deployed to allow generation, transmission and distribution utilities to optimally manage key functions such as how fast batteries discharge to the grid and how quickly a turbine needs to ramp up from being idle. For example, advanced utility operations software is helping the California Independent System Operator to visualize what’s happening on the grid. If the frequency on the power lines drops due to intermittency of a renewable source, the California ISO can send a signal to batteries installed on turbines to keep the amount of power racing through the lines steady. It’s a balancing act that’s similar to how a hybrid car balances its varying power needs by sometimes drawing from its battery and sometimes from its supply of gasoline.
Energy storage has its uses in conventional power generation systems, such as gas-fired power plants, as well. GE recently proved energy storage can perform one of the hardest jobs in the power business: a black start (rebooting an idle power plant without using the external transmission network). On May 10, GE’s battery system was used to restart the Imperial Irrigation District’s El Centro Generating Station in California — a first-of-its-kind demonstration.
Establishing the world’s first battery storage and gas turbine hybrid GE’s unique solution allows a power plant to shut down completely instead of idling during off-peak hours, and can use the battery as a standby to cover a sudden, unexpected need for electricity. It’s a combination that lowers fuel costs and reduces emissions.
As we know from our cell phones, one concern with lithium-ion batteries is that they show signs of aging — capacity deterioration is noticeable after just one year. However, power controls can preserve battery health and slow battery degradation. To combat capacity deterioration, GE is leveraging its Predix analytics platform to develop Digital Twins of the battery storage system, enabling operators to make real-time operational adjustments optimizing battery performance while minimizing degradation.
Just as cell phone batteries have evolved to provide greater performance, research in battery technologies continues to reveal new innovations and much promise on the horizon. Likewise, in energy storage we’re in the midst of an evolution that will move us from the age of the passive battery to the time of smart storage.