The term “sustainable energy technology” often conjures images of towering wind turbines and dazzling rows of solar panels. Yet one less spectacular technology has emerged as a key piece in the clean energy jigsaw: renewable energy storage. Industry experts now see building energy storage infrastructure as a critical step for scaling renewables like solar and wind power.
Renewable Energy Variability and Storage
Why is renewable energy storage so important in determining the extent to which we can rely on wind and solar power for our energy needs?
These leading renewables are variable by nature, fluctuating with the weather and the time of day. Since these energy sources cannot be raised or lowered as demand fluctuates, the power grid must be able to regulate the amount of electricity it delivers to businesses and homes. This kind of regulation is not a problem for coal-fired plants, but coal is a top contributor to pollution and global warming. Other power generation sources that sometimes play a role in clean energy conversations, such as nuclear power and natural gas, can also be turned off and on, though they are not without controversy.
Large utility-scale battery storage systems allow renewable energy generated at one time to be discharged later, as needed. While lithium-ion batteries currently dominate the storage market, lead-acid, redox flow, and molten salt batteries have their own benefits and drawbacks, according to the National Renewable Energy Laboratory.
The Future of Renewable Energy Storage
Falling battery prices and the increasing penetration of wind and solar power could see an increase in the world’s storage capacity over the next two decades, from 545 megawatt hours to 2,857 gigawatt hours. The cost of lithium-ion batteries has dropped by 80% over the past five years.
Significant battery storage projects have already been deployed in the US, Japan, Germany, the UK, and Australia. Among the most promising projects in terms of capacity is the Hornsdale Wind Farm in Australia. Completed in November 2017, the project expanded by 50% last year, owing its success to the substantial local demand for stable renewable energy.
This year, the University of South Carolina (USC) developed battery storage technology that could outperform the one pioneered at Hornsdale. Researchers at USC claim their iron-AQDS battery can recharge hundreds of times with negligible loss of power.
In contrast with massive storage facilities like Hornsdale, small-scale battery storage is another important development. So-called behind-the-meter (BTM) batteries connect to the back of the utility meters of business and residential users. Australia is targeting the rollout of one million BTMs by 2025, which would represent a significant leap from just 21,000 BTMs in 2017.
One challenge for renewable energy storage is where to put the batteries themselves. In the face of obstacles like population density and environmental restrictions, some states are turning to otherwise unused landfills to house their battery infrastructure. Another question for renewable energy advocates to resolve is the recycling of spent batteries, a necessary step for keeping the environmental impact of the technology positive. Companies like Li-Cycle are developing battery cycling solutions in anticipation of an urgent need as more batteries come to support the renewable energy transition.