As we’ve talked about in the past, energy storage is especially important for the development of renewable energy sources, such as wind and solar power. Since not every day is particularly sunny or windy, these energy sources aren’t always available, and energy storage can help address any intermittency. Additionally, the demand for electricity varies throughout each day. Energy storage can also often respond rapidly to large fluctuations in demand, making the grid more responsive, and reducing the need for backup power plants. 

There are many different ways of storing energy. Below is a list of some of today’s top technologies that can currently provide large storage capacities:

  • Thermal Energy Storage

      • Thermal energy storage facilities use temperature (heating and cooling methods) to store and release energy. Rocks, salts, water, and other materials are heated and kept in insulated environments in order to store energy. When energy needs to be generated, the thermal energy is released by pumping cold water onto the hot rocks, salts, or hot water in order to produce steam, which spins turbines

  • Pumped Hydroelectric

      • During off-peak hours, turbines pump water to an elevated reservoir using excess electricity. When electricity demand increases, the retained water is released from the reservoir so that it can flow down through a turbine and generate electricity
      • Pumped hydroelectric facilities are the most common form of energy storage on the grid and account for over 95% of the storage in use today

  • Batteries

    • Lithium-Ion Batteries
          • Compared to other battery options, lithium-ion batteries have high energy density and are lightweight
          • These are undoubtedly the most popular battery storage option today and control more than 90% of the global grid battery storage market
    • Flow Batteries
          • Although not quite as popular, flow batteries are an alternative to lithium-ion batteries.
          • These only make up less than 5% of the battery market
          • Flow batteries have relatively low energy densities and have long life cycles, which makes them ideal for supplying continuous power. As such, they tend to be used in energy storage projects that necessitate longer energy storage durations
    • Solid State Batteries
          • When it comes to large-scale grid storage, solid-state batteries have the upper hand compared to lithium-ion batteries. Solid-state batteries consist of solid electrolytes. Solid electrolytes have higher energy densities and are much less prone to fires than liquid electrolytes (which are found in lithium-ion batteries)
          • However, because it’s not as developed, solid-state battery technology is more expensive than lithium-ion battery technology
          • These types of batteries are great for large-scale grid applications because of their smaller volumes and higher safety

  • Flywheels

      • Flywheel energy storage operates by accelerating a rotor to high speed and maintaining the power as rotating energy. The flywheel rotational speed is reduced and accelerated when the stored energy is drawn from the system
      • Flywheels are recognized for their long-life cycle, high-energy density, low maintenance costs, and prompt response speeds
      • Although they’re effective for load-leveling and load-shifting applications, they’re not suitable for long-term energy storage

  • Compressed Air Storage (CAES)

    • With this type of energy storage, air is pumped into an underground hole during off-peak hours, and when energy is needed, the air from the underground cave is released back up into the facility, where it’s heated, and the resulting expansion turns a generator
    • While this process typically utilizes natural gas, CAES triples the energy output of facilities using solely natural gas. In fact, CAES can achieve up to 70% energy efficiency when the heat from the air pressure is retained (efficiency is otherwise between 42% and 55%)

According to the U.S. Department of Energy, as of March 2018, the United States had over 25 gigawatts of electrical energy storage capacity. 94% of that total was in the form of pumped hydroelectric storage, and most of that pumped hydroelectric capacity was installed in the 1970s. The 6% of other storage capacity is in the form of battery, thermal storage, compressed air, and flywheel, which is depicted in the graph below.

If we want to combat climate change and build a more sustainable future for our planet, we need to start relying more heavily on renewable energy. Because it allows us to better manage our power supply in order to create a more resilient energy infrastructure, energy storage (such as the technologies outlined above) will play a significant role.

Want to help create a more sustainable future? Start with the energy you use in your home. Kiwi Energy offers environmentally-focused energy plans to help you reduce your impact.