1. 1 Transmission Development at Ameren and in the Midwest ISO Mid-America Regulatory Conference Maureen A. Borkowski June 8, 2010

2. 2 Ameren Company Statistics Total Assets Total Revenues Employees Electric Customers Gas Customers Service Area Generation Peak Load (2006) Transmission Miles 2009 $23 Billion $ 7 Billion 9,200 2.4 Million 1.0 Million 64,000 Sq. Miles 16,200 MW 18,265 MW 7,500

3. 3 Transmission Planning Challenges The four Ameren Utilities in MO and IL are Transmission Owning members of the Midwest ISO Ameren plans its transmission as an integrated system  to continue to provide reliable service to customers,  to be more environmentally responsible by enabling growth in renewables,  to improve the efficiency of the delivery system,  to reduce congestion in wholesale markets,  to provide flexibility in response to climate legislation. Current challenges in the Midwest ISO include:  Uncertainty regarding Renewable Standards, climate legislation, load growth, fuel prices, etc.  Piecemeal approach to transmission expansion for new generation interconnections  Potential retirements of generating units due to low market prices and environmental requirements  Congestion in and across organized markets during both on and off peak conditions  Unit commitment, dispatch and minimum load problems due to renewable growth

4. 4 New Projects at Prevailing Voltages Midwest ISO Regional Generation Outlet Study

5. 5 Prevailing Voltages plus DC

6. 6 Midwest ISO Regional Generation Outlet Study New Projects Primarily 765kV

7. 7 Cost Allocation Objectives To encourage needed transmission development in order to provide reliable service and promote efficient market operations. To provide appropriate locational signals for new generation development. To equitably assign the costs of new transmission to those who derive benefits from its development.

8. 8 How does MISO measure up? MISO will file on July 15 Current proposal  No change to Reliability or Regionally Beneficial Projects  Multi-Value Projects –80% to all loads based on MWH –20% to all generators based on MW capacity  Generator Interconnection –345 kV & greater: 90% “higher of” and 10% load ratio share –< 345 kV: 100% “higher of” network upgrades or MVP charge Reliability projects are already addressed MVP concept should help get needed projects built, but criteria need to be defined “Higher of” for new generation gives some incentive for locational decision-making Shortcomings:  Proposal does not attempt to define who benefits to equitably assign costs, particularly with regard to existing generators.  Cost assignment to generators will likely have negative market impacts as well.

9. 9 Going Forward The Midwest needs transmission development to maintain reliable, efficient and environmentally responsible electric service and to promote economic development. Plans need to provide sustainable benefits across a diverse set of potential futures. Cost allocation must encourage new transmission development not impede it.