Thanks to its well interconnected electricity system, the United States may be able to meet a greater proportion of electricity demand using wind power than Europe can achieve, says National Grid, a major electricity transmission operator on both continents. The observation is one of a series made in a new report on the US market, "Transmission and Wind Energy: Capturing the Prevailing Winds for the Benefit of Customers." Commenting on perceived problems with wind's variable supply and the need for back-up power, the report points out that on regional power systems in Denmark, Germany and Spain in 2005 wind penetration reached 60%, 23% and 24%, respectively, compared with 5.1% in California and 3.3% in Texas. "Wind is not random. It can be forecasted with greater accuracy on shorter timescales. Such forecasting becomes essential with a higher penetration of wind resources on a system," states the report. Furthermore, "The additional amounts of dispatchable generation needed in association with wind power are modest [and] the additional costs associated with dispatchable generation do not destroy the economics of wind power." National Grid calls for a restructuring of market rules to eliminate the "imbalance" penalties which unintentionally hit wind. Beyond the integration issue, the report's key findings are also overwhelmingly in agreement with wind industry views. It says that wind is an economic power source with the added benefit of mitigating climate change. National Grid acknowledges that the interconnection and transmission industry, in which it conducts its core business, represents a major hurdle for wind power. It says the current US transmission system was not built to support competitive regional markets nor is it sufficient to integrate planned and potential new generation sources; additional transmission infrastructure will be required.