Utility Integration Issues

In the near-future, it is likely that wind energy's primary market will be niches that recognize values in addition to cost. Nonetheless, the primary economic product from wind energy is electricity, and as such, a primary market is the electric power generation industry. Barring large policy changes, such as a carbon tax, the principal value of wind energy a s an electric generator, without storage facilities, is as a fuel saver. That is, wind energy generation must be used whe n it is available, thereby displacing energy (and variable operating expenses) that would have otherwise been provide d by conventional generation. Because of its intermittent nature, any additional value of wind-generated electricit y beyond fuel savings and variable operating expenses will vary depending on (1) site-specific characteristics of the wind resource, and (2) utility load and other characteristics of the electric distribution system. For instance, the ability t o site windpower closer to the end user (a "distributed" application) may increase its value to the utility.

Statistically, a windfarm can displace a fraction of the capital cost of some new conventional plant. The critica l question, which depends on the correlation of the wind resource with utility demand, is: "How much capacity does a windfarm displace and how much is it worth?" This analytical issue is often termed the capacity credit issue, and ca n be characterized as firm, dispatchable capacity vs. any as-delevered capacity. Although capacity credit for wind energy is often not accepted by electric utilities, research by NREL [1], Grubb and Halberg in Europe, [2,3], and Henry Kelley at the Office of Technology Assessment suggests that virtually any wind installation merits a capacity credit. As an alternative, hybrid wind/gas or wind/storage systems could earn full capacity credit.

The annual energy generated from the wind can be estimated with some certainty, on a long-term basis. In addition , some locations can have a degree of predictability on a daily or hourly basis. These include islands with trade wind s or sites such as the California passes, where winds are caused by the predictable inrush of cooler coastal air as th e mountain desert air is warmed and rises. Thus, it is possible for windfarms to get some capacity credit in thes e locations. Based on these examples, utility operation and wind valuation are affected by wind forecasting ability . Researchers in wind prediction are now beginning to explore techniques which would allow the utility dispatcher t o gauge the availability of his wind power plant over the next 6 to 36 hours. In the future, the ability to predict wind s on relatively longer time scales will improve, potentially allowing windfarms to be operated with greater certainty , thereby increasing their value. Due to the regional variations in the amount and levels of the wind power resource, and to the other regional variations determining the competitive market for power generation, wind technology will achieve different levels of regional market penetration.

Analysts often quote penetration limits for wind capacity of 5 to 20 percent of installed conventional capacity [4]. This is based on a combination of longer-term system integration limits, such as those discussed above, and syste m operational limits on the second-to-hour time scale, such as generation control, load following, unit commitment , reserve requirement, and system voltage regulation. A recent study by NREL indicates that hardware and syste m design advances can address most of the technical concerns resulting from interfacing intermittent renewable generation technologies with the electric system [5]. U.S. studies have shown that a 5 percent penetration level has virtually n o effect on system operations, while estimates of the impact of larger numbers appear to be largely speculative. Othe r work by Grubb and Halberg [2,3] in Europe confirmed that no absolute physical limit exists to the fraction of win d penetration on a large power system. Rather, with increasing penetration, the fuel and capacity savings begin t o decrease, so that the system limits are economic rather than physical. Regardless, as Grubb points out, the penetration of wind energy in the U.S. must be much larger before its value begins to degrade in the electric system.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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