Smoothing Wind Energy
Energy storage is often seen as the key to enabling greater penetration of renewable generation. One company, Xtreme Power, is getting the chance to demonstrate its large-scale, solid-state, power management system. The company provides dynamic power resources (DPRs) for utility-scale power management and energy storage systems.
I recently met with Darrell Hayslip, chief development officer for Xtreme Power, who discussed its work in integrating wind resources. Xtreme is collaborating with developer First Wind to deploy its technology at First Wind's Kaheawa Wind Project (KWP) and proposed Kahuka Wind Project. First Wind has a $117 million U.S. Department of Energy loan guarantee for the Kahuka project.
"Hawaii's winds are extremely variable, and with a weak grid, 30 megawatts of wind is a large percentage of the supply," he said.
The 30-megawatt Kaheawa Wind project is supported by a 1.5-megawatt energy storage and power management system. First Wind delivers power within strict ramping criteria and stores the energy generated during curtailment periods, when demand is low, for later use during peak periods.
First Wind also intends to incorporate a 10 megawatt-per-hour energy storage system from Xtreme Power in its DOE-financed Kahuku Wind project. The project is in its final permitting stages.
With more wind generation included in power systems areas nationally, wind is being used to bid into many day-ahead markets in regional transmission operations. The Xtreme system is interesting in that it can be used to mitigate forecasting error.
The company said its utility-scale storage system provides continuous adjustment of second-to-second intermittent output, controlling ramp rates (both up and down) during large changes in wind velocities and enabling the capture of curtailed output from wind generation, allowing stored energy to be used during periods of peak demand, Hayslip said.
And that's one more step on the road to having renewable generation occupy a more important place in a utility's portfolio.
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Comments
You can't store "power"
Please don't report power numbers for a system that stores energy.
The article mentions that the Kaheawa project has a 1.5 MW storage system: what is that supposed to mean?
If I run a 1.5MW turbine at full capacity, can this storage system store all the energy produced forever? No, because this would be infinite energy. Does it mean that it could store the amount of energy produced by an instantaneous 1.5MW rate? Maybe, but the system could then be useless because a system storing zero energy could meet that spec. Saying an energy storage system stores 1.5MW -- this is "power" not "energy" -- is nearly meaningless.
More than likely, the system can store the energy produced by a single 1.5 MW turbine for some hours, N; the amount of energy stored would then be 1.5*N MWh. This number does mean something because it's then possible to estimate how long the wind can die down before the lights go out. This is the answer to the question of how well the storage system solves the problem it was designed for.
OK, it's true that the Kahuku system is said to store "10 megawatt-per-hour." We could assume that at the end of that hour, the system can't store any more energy. But since the article starts out pretty shaky on units, it's hard to be confident in that guess.