Two US transmission organisations are ready to move forward with competitive power markets approved by the Federal Energy Regulatory Commission (FERC), but so far only one exempts intermittent resources, such as wind power, from imbalance penalties. The MidWest Independent System Operator (ISO) began testing a new power market this month that it intends to fully implement December 1. The market will trade in a way similar to the PJM Interconnection for Pennsylvania-New Jersey-Maryland, New York and New England markets, says the ISO's James Torgerson. In a draft tariff, the ISO proposes an exemption from trading penalties for resources certified as intermittent if they fail to meet their scheduled energy deliveries for reasons not within the generator's control. Such penalties can significantly increase the delivered cost of wind power (Windpower Monthly, February 2004). The draft will not be final until December. The second ISO, the Southwest Power Pool (SPP) was given regional transmission organisation status in February by FERC. But the federal regulator is allowing SPP to wait until November before it completes plans for a real-time balancing market, as well as real-time and day-ahead markets. In its order, FERC does not mention how SPP should treat intermittent resources, but SPP's Stacey Duckett says, with Zilkha's 64 MW Blue Canyon project now online in Oklahoma where SPP serves, how wind resources are treated is a growing issue that the ISO hopes to resolve by the end of the year.