Distributed Electric Power Storage

The storage of electrical power has been an age-old challenge facing the electricity industry. A number of electric utilities are now in the process of placing equipment in residential areas that is capable of storing several hours of electricity supply. These localized or distributed technologies include lithium ion batteries and underground compressed air storage. The lithium ion batteries are usually configured in storage units of 10 batteries, are approximately the size of a typical pad-mounted transformer, and have a capacity of 1 to 2 MW of power for a few hours. Underground compressed air storage uses compressed air pumped into underground formations that is pressurized and released later to drive a turbine that produces electricity. Underground compressed air storage typically provides several hours to several days of storage.

Distributed Storage Benefits

Distributed storage is offers the potential to provide:

• Back-up power in the event of widespread system outages. Studies suggest that just 4 hours of back-up power could prevent 90 percent of the outages experienced by most customers.
• Peak shaving at less than high peak-time rates.
• Stabilization during dips in grid signal frequency.

From a more holistic perspective, distributed storage also enhances the viability of renewable energy resources. Renewable sources such as wind and solar are often viewed as variable or non-firm sources with respect to providing consistent levels of power. Distributed storage in combination with distributed renewable resources is seen as feasible alternatives to fossil generation by providing a “buffer” during periods of renewable power generation fluctuations.

Barriers to Widespread Implementation

As a developing capability and technology, there are a number of barriers to successful implementation of distributed power storage, namely:

• Initial costs still present challenges in justifying investments in the context of alternative supply costs, and
• Current regulations encourage investments in least cost generation supplies, which continue to be predominantly central generating resources.

As pilot efforts at implementing these technologies provide insights to further technology and the drive for clean, renewable energy increases, these barriers will be addressed and scalable, more cost-effective alternatives will likely be developed.