Energy storage enables renewables to be available to the grid around the clock, managing peaks and troughs in electricity demand. It also helps to balance microgrids and perform frequency regulation.
Technologies include lithium-ion batteries for homes and electric vehicles, compressed air energy storage (using the power of gravity), superconducting magnetic energy storage and thermal storage using water or molten salts.
Solar Photovoltaic (PV) Systems
All PV systems utilize solar panels to generate electricity from sunlight, but different types differ in the way the system captures, stores and delivers energy. This enables them to serve a wide range of residential and commercial applications including reducing dependence on utility rates and power grid vulnerabilities.
Solar cells convert sunlight into electric current using semiconductor material that creates electron-hole pairs with photons from the sun. This energy then flows into storage batteries or other DC devices for use during the night and on cloudy days.
PV systems with battery storage enable time-of-use optimization by capturing solar energy during expensive peak-rate periods and discharging it during off-peak hours, arbitraging electricity costs. They also provide backup energy for critical loads during extended grid outages, providing real savings to homeowners and businesses.
Hydrogen Fuel Cells
Fuel cells are electrochemical devices that combine hydrogen and oxygen to create water vapor, heat and electricity. Fuel cells emit only very small amounts of pollution (water vapor and heat) during operation. Fuel cell technology is considered a key component of industrial decarbonization and offers a clean alternative to traditional fossil fuels.
Hydrogen can be extracted from a variety of sources including fossil fuels, biomass or through low emission water electrolysis powered by renewable energy. Fuel cells supplied with green hydrogen can reduce industry reliance on fossil fuels and help achieve global climate goals.
The United States Government supports fuel cell development because they provide the opportunity to dramatically decrease our dependence on oil from politically unstable and unfriendly regions of the world. Also, when combined with a renewable system, hydrogen can eliminate the need for toxic batteries.
Capacitors
Capacitors may seem simple, but they’re vital for modern electronics and energy systems. They store and release electrical energy by accumulating electrons between two conductive plates separated by an insulating dielectric material.
When connected to a power supply, the free electrons on one plate of the capacitor move to the other under the action of an electric field, creating a charge. As the voltage of the power source increases, so does the amount of energy stored in the capacitor.
Capacitors are available in a variety of forms for different applications. Ceramic capacitors are small and stable, while electrolytic capacitors hold more charge and have polarity markings to indicate the right way to connect them (see #Polarity Marking). Other types of capacitors, such as advanced polypropylene and tantalum capacitors, offer a range of performance characteristics.
Thermal Storage
Thermal energy storage captures and stores heat or cold, using different materials and phase change processes. These include sensible heat storage, latent thermal energy storage and thermochemical heat storage. TES systems have distinct advantages in applications where long-duration energy storage is paramount, and they can be integrated with heating, cooling, and industrial processes.
This makes it a great option for district heating, industrial process heat, or large-scale solar power plants. But TES is also useful on the smaller scale, where it can help lower utility bills for homeowners.
Battery and thermal storage technologies exhibit different sustainability profiles, but they can be combined in hybrid systems that optimize energy management. This includes integrating batteries and TES systems with advanced control algorithms that coordinate charging, discharging and thermal management operations to maximize energy efficiency and savings.
Battery Storage
Battery storage systems are a key technology as we move away from fossil fuels. They allow renewables to be used at night or when the wind isn’t blowing, reducing our dependence on traditional backup power and helping us meet ambitious emissions targets.
These systems store electricity in lithium-ion batteries and convert it to alternating current (AC) to be used at sites. They can be grid scale or behind-the-meter and are often co-located with existing energy projects.
At a larger scale, these systems can be paired with solar farms or used to provide services like frequency regulation and spinning reserve. They can also help reduce the cost of electricity for consumers and support grid resilience and integration. They are silent and emit no pollution at the point of use.