Work will begin in July on an $84 million, 58-megawatt natural gas-fired plant near Huron, S.D. This flexible-capacity resource will provide energy as needed 24/7 for NorthWestern Energy's South Dakota customers.

Reciprocating internal combustion engine technology will replace the existing natural gas/diesel fuel-fired combustion turbines at the Huron Generating Station. The reciprocating engines are more efficient and use selective catalytic reduction and oxidation catalyst to control emissions. The plant design also includes several mitigation measures to reduce noise from the plant during operation.

Caterpillar Inc. was selected in April as the reciprocating engine supplier and Fagen Inc. of Granite Falls, Minn., was selected as the engineering, procurement and construction contractor.

Caterpillar is a global leader in reciprocating engine technology. The Cat engines are highly reliable and efficient with low emissions. The selected engines are capable of rapid ramping and multiple daily starts and stops. They have a proven track record of providing peaking power, baseload power and regulating power, which is required for integration of intermittent renewable resources, according to the company.

"Caterpillar's competitively priced equipment has a successful history of quality and performance and will be a generation asset meeting the energy needs of our South Dakota customers for decades," said Jim Williams, NorthWestern Energy director of Thermal and Wind Generation. "Fagen has a solid reputation as a superior EPC contractor. We are pleased to partner with both of these companies."

The new Cat engines will replace the existing units at the Huron Generating Station, one of which was installed in the early 1960s. When complete, the new plant will have a smaller footprint and a larger setback than the existing plant. Commercial operation of the new plant is scheduled for the end of 2021.

For more information, visit northwesternenergy.com.