Duke Energy is now part of the next wave of clean energy technology: Energy storage, which gives utilities and large industrials the flexibility they need to respond to power shortages and price spikes. As for Duke, it is installing batteries at a wind farm in Texas to harness excess energy there that would be discharged during peak periods.
It is a budding concept, which is considered critical to building out the smart grid. In essence, it would add new efficiencies and thereby make room for alternative sources of power. Utilities may have excess generation that serves to firm up the system in case of a failure, or during peak demand. An energy storage device would give those power companies the latitude to keep that energy when it is not needed and to release it when the demand for it is highest.
According to the Department of Energy, the technology has a lot of market potential and environmental benefits. It can help utilities avoid downtime and thereby save billions in repairs and lost opportunities while also allowing such companies to sell blocks of peak power at premium prices.
Environmentally, it will facilitate the development of more wind and solar power, although the wind power sector says it needs no such leaps to keep growing. It says that wind power simply replaces electricity generated by base-load systems.
Energy storage research is moving forward. In November 2009, the Energy Department said it would put up $22 million to install large-scale batteries to install a 36-megawatt capacity system for Duke’s project there. The utility will invest $22 million of its own money. When complete in 2012, the battery storage system that is being designed by Xtreme Power will be one of the world’s largest.
By comparison, most such trials taking place today store about 1 megawatt. Some are larger as is a project in New York State that is 20 megawatts. That one is being built by Beacon Power and is using flywheel-based storage that can ramp up quickly when supply and demand are imbalanced.
Altogether, the federal stimulus plan is providing $185 million to 16 energy storage demonstration projects. Meantime, the Energy Department's Office of Science is also working to advance battery technologies.
“Bringing more efficiency and reliability to the grid will help cut costs for consumers and power a cleaner energy future,” says Energy Secretary Steven Chu.
To be clear, storage devices come in many forms: The most prevalent ones today are batteries that are the size of a house. They link to the transmission grid where they siphon off power and store it, such as the one used by Duke. That process can occur at night when the cost of electricity is lowest and it can be dispatched during the day when prices rise. Then there’s the fast-response flywheels, and a deviation of that called kinetic energy storage that is practical for short-term needs.
Beyond those tools, there's also compressed air energy storage that holds air underground and releases it in heated form to create electricity. And there’s the mature pumped hydro storage, whereby turbines push water into reservoirs at night and then let it go during the day when demand is highest.
The younger products are now relatively expensive and it is still unknown how they would operate in a commercial setting. If they are to be cost effective, they must be able to offer other services, say experts. Until then, the federal government will partner with private industry to help foster this sector.
Recently, the Energy Department awarded a $17 million loan guarantee to AES to support the construction of a 20-megawatt capacity energy storage system using lithium-ion batteries. The project is purported to bring about efficiencies to the grid in Johnson City, New York, allowing more room for green electrons. It will also reduce carbon emissions, AES says, by storing the energy and using it later -- as opposed to firing up a fossil fuel plant to kick in when the wind is not blowing.
Balancing the electricity load is a difficult job. Storage devices, if they can be shown to work at commercial scale, would be a huge boon to an industry -- and an economy -- trying to advance renewable power.
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