Bringing energy storage to wind power
By Richard Baxter
Ardour Capital Investments, LLC
President Bush has set a national goal of deriving 20 percent of the nation's electricity from wind energy in his Advanced Energy Initiative launched in February. In response, the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory and the American Wind Energy Association (AWEA) are collaborating to develop an action plan to get us there.
Reaching this goal is possible, as domestic wind resources are significant. We are gaining experience with operating larger wind-parks and wind energy's competitive position continues to improve as fossil fuel prices rise. However, significantly enhancing the capacity of the transmission system, both in carrying capacity and its ability to deal with a distributed, non-dispatchable resource, must be a critical part of this action plan. Energy storage technologies hold the promise of supporting just this sort of power grid enhancement.
Building Support
According to Imre Gyuk, program manager for the DOE's Energy Storage Research Program, the importance of energy storage to effectively integrate renewable generation in the electric grid is becoming increasingly evident. The House Energy and Water Development Appropriation Committee has stated that energy storage technologies are crucial to the long-run, large-scale integration of wind and solar energy into the marketplace. Also, Gyuk said a recent science and technology portfolio assessment by several national laboratories has identified energy storage as one of four crosscutting technologies deserving integrated research by DOE.
Although some in Congress and the DOE see energy storage as crucial, the wind energy business community ultimately will decide if and how relevant storage technologies become part of their projects. Unfortunately, a lack of widespread energy storage installations in the market means these wind developers may not know how energy storage technologies can support their plans. With each new installation of an energy storage technology this situation changes, but getting input may help shed light on a few key issues.
Assessing challenges
Wind and energy storage developers agree that regional wind penetration rates of 10 to 15 percent and above make it difficult to synchronize wind output with demand. Another issue noted by Matt Lazarewicz, CTO and vice president of Beacon Power Corp., is that the current wind supply and demand mismatch is addressed using low-cost thermal generationwhich is currently being retired from the grid in favor of higher efficiency CHP plants. Unfortunately, these plants have generally poorer transient load following and balancing capability, leaving a less responsive grid even as more wind power is added.
This transient load following capability is an important issue to independent system operators, yet this short-term, rapidly changing condition receives scant attention from many in the industry. As additional wind power is added (especially in specific geographical areas), this problem can be exacerbated. For example, according to the California Independent System Operator (CA-ISO) Briefing Paper on Wind Generation and Renewables (Draft, April 2006) the addition of wind turbines planned for the Tehachapie area will result in significant ramping rates. For example, with the existing 750 MW of wind turbines, the typical ramp rates are 150 MW per hour. With the proposed 5,200 MW of wind generation capacity planned for the area, ramps could be as high as 1,800-MW to 2,400-MW per hour. As a fast-acting source and sink for power, energy storage facilities could help smooth out these temporary imbalances until generation assets are able to adjust. These energy storage systems could also help address system stability issues in the area.
Implementing Technology
Faced with ever-present capital cost issues, adding anything that increases project costs (especially with any undefined potential payback) is a dubious call for a project developer. For this reason, the strongest initial value proposition for energy storage in support of wind power exists in remote areas where the incumbent electricity supply is expensive and derived from diesel generation, according to Simon Clarke, external vice president of corporate development for VRB Power Systems, Inc. On this point, those in the wind energy industry agree, as John Dunlop, senior outreach specialist at the American Wind Energy Association (AWEA), notes that such unique situation, isolated grids, island power systems, etc. , will require energy storage or other dispatchable generation technologies to incorporate high concentrations of wind power into their systems.
One current problem with embedding energy storage units with new wind turbine development is each location is unique. The required beneficial operating record in a comparable setting generally does not exist. Simple payback models are difficult to quantify all of the variables. For these reasons, some wind park developers are looking at energy storage technologies as a retrofit possibility, according to Septimus van der Linden, president of Brulin Associates. A retrofit might be a flexible solution for developers with projects already operating who are looking for increased revenues and capability, such as delivering more (and more reliable) wind energy to market.
Overcoming Cost
According to Rick Walker, president of Sustainable Energy Strategies, Inc., <b?energy storage technologies are appealing to those in the wind industry, but concern about their cost effectiveness remains an issue. In general, energy storage technologies are not yet sufficiently mature on cost-effectively coupling wind energy with energy storage other than in perhaps some isolated circumstances. Another essential point is that to reach such a cost-effective level of technological maturity, there needs to be a series of successful demonstration projects that show a reduction in the cost of energy storage. Another important event that needs to occur is the recognition (i.e., payment) by ISOs/RTOs for the benefits that storage may provide to the transmission grid.
Walker also noted that institutional barriers often are harder to get past than are technical barriers when integrating a new technology into a power system. Merwin Brown, director of PIER Electric Transmission Program at the California Institute for Energy and the Environment, said that economic issues might be more institutional than financial. He also said that the application of storage in a wind farm seems usually to be financially treated as a solution to a power market problem, i.e., to get more value for wind generation through improved dispatchability, when it should be considered in the broader context as a multiple-attribute technology to address both economic and grid reliability issues, thereby giving storage a higher economic value.
As the wind energy market grows, energy storage can play an important role in the reliability of the grid. However, technologies must improve, companies have to take chances and costs must be managed. Together, energy storage and wind energy can make a more attractive power medium as the nation works toward President Bush's 20 percent goal. |
