Storing Wind Energy Underground

Wind turbinesWind is the fastest growing energy source in the United States. Over the last five years, wind energy output has increased tenfold. Unlike most other forms of energy used to produce electricity, wind is a variable energy source. Some wind energy may be wasted when too much energy is produced and more energy might be needed when there is not ample wind available.

A very promising technology is being developed called compressed air energy storage (CAES) that can store large quantities of wind energy. Surplus wind energy is used to pump air into layers of porous sandstone in the earth below. This underground cavern is sealed with dense shale and acts like a huge balloon. When demand for energy increases, air flows up into a natural gas-fired turbine, boosting its efficiency by 60% or more.

This technology is being implemented at the Iowa Stored Energy Park in Dallas Center, Iowa. The energy park is scheduled to be complete in 2011 after 8 years of construction. This 268-megawatt system will cost $200 million to construct, with funding from the Energy Department and municipal utilities across Iowa, North Dakota, South Dakota and Minnesota.

Batteries are also being developed that can store wind energy. American Electric Power and Siemens Wind Power are experimenting with large-scale batteries that could store a megawatt of energy. Such technologies are very pricey and could have a high environmental price tag and have a much smaller storage capacity than CAES.

The future looks bright for compressed air energy storage and wind energy. Being able to store off-peak wind energy until demand and electric rates are higher allows wind energy to be a more lucrative and consistent energy source.

About the Author

is passionate about the new green economy and renewable energy. Sarah’s experience includes work with small-scale solar energy installations and utility-scale wind farms. She earned an MBA in sustainable management from the Presidio Graduate School and is a co-founder of Trees Across the Miles, an urban reforestation initiative. When she can escape the internet vortex, she enjoys playing in the forest, paddling down rivers, or twisting into yoga poses.