Adding concentrated solar power plants to wind farms to achieve a good utility electrical load match

Abstract

Texas has the greatest installed wind turbine capacity of any state in the United States, but as the percentage of wind generation approaches 10% of the utilities total electrical generation (in 2012, the total wind generated electricity in Texas was 7.4%), it becomes increasingly difficult for the utility to balance the electrical load due to the mismatch between the wind farm (WF) generated electricity and the utility electrical loading. In this paper WF output was shown to be diurnally and seasonally mismatched with the utility electrical loading in the Texas Panhandle (e.g. Texas Panhandle has the highest wind energy resource in Texas). In addition, the wind farm output in the Texas Panhandle does not normally contribute significantly at the peak hourly electrical load, and the peak hourly electrical load is a major deciding factor for a utility to add new power plants. A financial analysis was also performed on all the renewable energy systems analyzed. Various ratios of wind farm output to concentrating solar power (CSP) parabolic trough plant output (with 6h of thermal storage) were calculated for the Texas Panhandle and compared to the utility electrical loading on an annual and peak monthly basis (each renewable energy system was analyzed at a 100MW rating). The 67MW wind farm and the 33MW CSP plant with 6h of thermal storage was approximately the best match to the utility electrical loading. The utility electrical load was also compared to: a 100MW WF, a 100MW CSP plant (with and without 6h thermal storage), and finally the 67MW WF with 33MW CSP plant (with 6h of thermal storage) on an annual, monthly, and peak hourly load basis. Typically for each month, the wind farm did not match the utility electrical loading except in the evening while the CSP plant (without storage) matched the utility electrical loading with the exception of in the evening. For the peak utility electrical loading months (July and August) and the days with the peak electrical loadings during those months, the 100MW CSP plant with 6h of thermal storage performed best in terms of supporting the utility electrical load (e.g. no wind farm). For the Texas Panhandle the estimated levelized cost of energy (LCOE) of a hybrid WF/CSP plant was in the range of $108/MWh to $129/MWh while the WF only system was estimated to be $64/MWh, but the benefits of adding CSP may justify the additional cost. Although the Texas Panhandle was the only location analyzed for combining CSP plants with WFs, the analysis described in this paper can be used for other regions, states, or countries.