Ameren Missouri, a unit of Ameren Corp., says it has entered into an agreement to acquire a 400 megawatt (MW) wind farm in northeast Missouri to be built by Terra-Gen.

The deal is an early step in implementing the utility's Integrated Resource Plan, which follows Missouri's Renewable Energy Standard passed by voters in 2008. Planned investments by the utility include approximately $1 billion to build wind generation projects in Missouri and possibly neighboring states, resulting in at least 700 MW of new wind generating capacity by 2020. The Terra-Gen wind farm would meet more than half of that planned capacity, the utility says.

Groundbreaking is expected in summer 2019. The wind farm will consist of 175 wind turbines that will stand more than 450 feet above the ground.

Terra-Gen owns 1,051 MW of wind, geothermal and solar generating capacity in operation across 25 renewable power facilities throughout the western United States with a focus on California. The company's web site says its business units operate and maintain 2,000 MW of renewable projects. The company primarily sells the output of the renewable energy projects to utilities and power cooperatives under long-term power purchase agreements.

The wind farm is enabled in part by the expanded transmission capacity made possible by the Mark Twain Transmission Project, approved in January by the Missouri Public Service Commission. The transmission project has a targeted in-service date of December 2019.

The a 96-mile-long, 345 kilovolt (kV) transmission line and substation will run from Palmyra to Kirksville in Missouri and north to the Iowa border. Nearly all of the line will be co-located on existing rights of way. It will share existing right of way on Northeast Missouri Electric Power Cooperative’s 161,000 kV line between Palmyra and Kirksville and Ameren Missouri’s 161 kV line from Kirksville to the Iowa border.

The wind farm transaction is subject to a number of conditions, including regulatory approval and obtaining an acceptable Midcontinent Independent System Operator transmission interconnection agreement.

Ameren Missouri says it also expects to add 100 MW of solar-generated energy over the next 10 years, with 50 MW targeted to come online by 2025.