Large-scale energy storage is practical and cost-effective soon might be within reach as well. Some technologies that can store sizeable amounts of intermittent power are already deployed. Elon Musk, CEO of Tesla Motors, unveiled the company’s sleek new Powerwall, a rechargeable lithium-ion battery designed for residential use.
Among the top trends in energy storage are solar + storage and an increase in mandates for utility-scale storage. Solar + storage applications are often predicated on price arbitrage, that is, a difference between peak and off-peak prices that allows the user to store cheaper, off-peak electricity and consume or sell more expensive peak power.
In Germany Sonnen is combining solar with storage and with digital controls to create microgrids that allows members to share renewable power in a way that the company says will make conventional utilities obsolete.
Other energy storage technologies are poised for growth in 2016 as the world continues its shift to greener grid powered by more intermittent energy forms, like wind and solar. Lets look at these other energy storage technologies:
Pumped hydro: The oldest, cheapest and most established of the storage technologies. Pumped hydro works by pumping water from a lower elevation reservoir to a higher elevation reservoir and then releasing it and allowing gravity to pull the water through a turbine and create energy. Pumped hydro represents 99 percent of the bulk energy storage capacity in the world today.
Flow batteries: Using a variety of different chemical combinations, a typical flow battery is made up of two tanks of liquids that are pumped past a membrane held between two electrodes. When the chemicals combine with the electrodes they produce electricity. Flow batteries are generally used in larger stationary applications, such as the grid for balancing or off-grid for power supply.
Lead-acid batteries: Made up of plates of lead and lead oxide that sit in a bath of electrolyte solution, the batteries are able to give quick short bursts of energy. These are the oldest types of rechargeable batteries.
Deep-cycle batteries: A type of lead-acid battery that uses a thicker lead plate and requires less maintenance. These are used in off-grid situations for charging, for example, cell phone towers or for backup power. Deep-cycle batteries can also be used for grid energy storage. Trojan’s Smart Carbon batteries (pictured) are an example of a deep-cycle battery.
Power-to-Gas: A technique that uses hydrogen fuel cells to produce energy. The benefit is that the hydrogen can be created from excess wind power and stored in tanks to be used days, weeks, even months later.
Compressed Air Energy Storage (CAES): CAES plants use ambient air that is compressed and pumped into a tank and are used when excess power is available. To deploy the energy, the air is heated and released, which turns a turbine to produce electricity. A very large CAES project has been proposed outside of Los Angeles, California.
Flywheels: A flywheel is a rotating mechanical device that is used to store rotational energy that can be called up instantaneously. Flywheels contain a constantly spinning mass which, when called upon to produce energy, turns a device similar to a turbine to produce energy thus slowing down the spinning mass. To be recharged, the device uses a motor to bring the mass back up to its rotational speed again.
Energy storage also becomes more important the farther you are from the electrical grid. Remote rural areas that are disconnected from the larger electrical grid system can benefit from energy storage and ensure power stability, just like you depend on the batteries in your flashlight while camping.
Sanjith S. Shetty