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Energy Storage Fact Sheet - EESI

Feb 6, 2019

The fact sheet from the Environmental and Energy Study Institute (EESI) discusses the growing importance of energy storage due to concerns about the environmental impacts of fossil fuels and the need for a more resilient energy grid.

The fact sheet from the Environmental and Energy Study Institute (EESI) discusses the growing importance of energy storage due to concerns about the environmental impacts of fossil fuels and the need for a more resilient energy grid. Energy storage can address the intermittency of renewable sources like solar and wind and can respond rapidly to demand fluctuations, reducing the need for backup power plants. Historically, batteries have been in use since the 1800s, and pumped-storage hydropower since the 1920s. However, the demand for a dynamic and cleaner grid has led to an increase in new energy storage projects and the development of better storage solutions. Energy storage can help meet peak electricity demand, provide grid resilience during extreme weather events, and support the integration of renewables. The International Energy Association estimates a need for 266 GW of energy storage by 2030 to keep global warming below 2 degrees Celsius.


The fact sheet also provides an overview of various energy storage technologies:


  1. Pumped-Storage Hydropower (PSH): Uses gravitational force to generate electricity by moving water between reservoirs at different elevations. It's the most popular form of energy storage in the U.S., accounting for 95% of utility-scale storage.

  2. Compressed Air Energy Storage (CAES): Involves pumping air into underground caverns during off-peak hours and releasing it to generate electricity when needed.

  3. Thermal Storage: Uses temperature to store energy. Materials like rocks or salts are heated and stored in insulated environments.

  4. Lithium-ion Batteries: Popular for grid storage and electric vehicles due to their high energy density.

  5. Lead-acid Batteries: Among the first battery technologies used but have a short cycle and calendar life.

  6. Flow Batteries: Suitable for longer energy storage durations.

  7. Solid State Batteries: Contain solid electrolytes, making them safer than liquid electrolytes.

  8. Hydrogen: Hydrogen fuel cells generate electricity by combining hydrogen and oxygen.

  9. Flywheels: Effective for load-leveling and load-shifting applications.


The fact sheet also touches upon the relationship between energy storage and electric vehicles (EVs). As EVs become more widespread, they will increase electricity demand, especially during peak times. Storage is essential for households generating their renewable electricity. Some EVs can also be used as back-up storage during grid failures or demand spikes.


In summary, energy storage plays a crucial role in ensuring a resilient, efficient, and sustainable energy grid. Different storage technologies offer varied benefits, and their adoption will be instrumental in supporting the growth of renewable energy and meeting future energy demands.


Read the fact sheet here:



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