On May 9, 2005, Dora Yen-Nakafuji, a member of the Research and Development Office in the Technology Systems Division of the California Energy Commission, presented a 31-page white paper "California Wind Resources" at the Intra-State Integrated Energy Policy Report (IEPR) Workshop in Sacramento, California.

The white paper provides an estimate of the wind resources within the state that are potentially available, noting that the gross estimates are unconstrained by technical, economic or environmental requirements.

The report found that California continues to be a leader in installed wind capacity with just over 2,000 MW, and observed that the potential exists to double this amount in the next five years.

Moreover, new turbines will be able to generate power in wind speeds of 5 m/s (11 mph), at which time California would have the potential for 31 GW of turbines at 30 m hub height, which would cover 1.2 percent of the land area. At 50 m height, the potential increases to 56 GW in low-speed areas and 10 GW in high-speed regions, with annual generation of 213,214 GWh.

At a height of 100 m, the state could have 127 GW of turbines in low-speed regions and 21 GW in high-speed, generating 479,362 GWh a year from turbines on 5.7 percent of the land area.

California has one of the most diverse electricity supply systems in the nation with a large potential to generate electricity from renewable sources, such as wind, biomass, geothermal, hydroelectric and solar, according to the paper. Currently, renewable resources provide approximately eleven percent of the state's electricity mix. In the future, renewable resources will play an even larger role in providing bulk electricity for the state.

California's Renewable Portfolio Standard (RPS) established in 2002 by Senate Bill 1078 (SB1078, Sher, Chapter 516, Statutes of 2002) requires electricity providers to procure at least one percent of their electricity supplies from renewable resources so as to achieve a twenty percent renewable mix by no later than 2017. More recently, the California Energy Commission, the California Public Utilities Commission, and the California Power Authority approved the Energy Action Plan (EAP), accelerating the 20 percent target date to 2010.

The challenge now facing the state will be how best to integrate and manage renewable energy resources with traditional generation while ensuring a reliable electrical system.

Existing utility-scale wind generation facilities are found in five major resource areas, of which three (Altamont, Tehachapi and San Gorgonio) account for 95 percent of all commercial wind power generation in the state and 11 percent of the world’s wind-generated electricity. With an average California household using 6,500 kWh of electricity per year, the 3.5 billion kWh of annual output from wind provides electricity for 530,000 homes.

Domestic turbines accounted for 67 percent of total installed capacity in 1985, compared with only 37 percent in 2001, and 35 percent of US-made turbines manufactured in the 1980s and 1990s remain in operation in California.

In the last few years, wind turbines have become sufficiently powerful, reliable, efficient, and cost-effective to rank them among the most appealing options for new power generation facilities. Furthermore, wind power has been the fastest-growing energy source for over ten years, and its growth is accelerating with continuing advancements.

The capacity factors of California’s wind turbines range from 10 percent to 41 percent, and recent improvements have increased that capacity factor by 8 percent. The current industry trend is toward larger and taller turbines. Driven in part by the economies of scale and by the offshore turbine market, the cost of energy for these mammoth systems is nearing an impressive $0.04/kW with capacity factors in the range of 38 - 40 percent.

Although many of the power qualities with existing wind technology have been addressed, issues related to increasing intermittent wind resources are introducing new challenges, according to the paper. Though new technologies are on the horizon, several barriers combine to limit the number of areas to generate power form renewable resources such as wind. These barriers include transmission capacity constraints, intermittency management issues, and occasionally perceptions, which combine to limit available areas of renewable resources like wind.”

The report suggests that the dispatchability of wind will be improved by locating turbines closer to strategic locations in the grid, and recent improvements in a number of aspects of wind energy mean that California wind resources need to be routinely assessed.

The paper also presents the estimated technical wind potential in states sharing borders with California, assuming an average 37 percent capacity factor. In Arizona, the potential is 1,540 MW which would provide 5,000 GWh/year; in Nevada it is 17,000 MW (55,000 GWh/year; and in Oregon it is 21,600 MW (70,000 GWh/year).

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The full report, "California Wind Resources" (report # CEC-500-2005-071-D) can be found on-line at: http://energy.ca.gov/2005publications/CEC-500-2005-071/CEC-500-2005-071-D.PDF

The author, Dora Yen-Nakafuji, can be reached at dyen@energy.state.ca.us

An article about the report appeared in the July 13, 2005 issue of "Refocus Weekly" which was posted on-line at: http://www.sparksdata.co.uk/refocus/redesign/showdoc.asp?docid=51418704&accnum=1