Lange II Generating Station in Rapid City

What is Lange II?

We're developing the Lange II Generating Station — a new 99-megawatt natural gas-fired electric generation facility in Rapid City, South Dakota. This facility is designed to meet the growing energy demands of our customers in South Dakota and eastern Wyoming from the upcoming retirement of older units. It will feature six dual-fuel Reciprocating Internal Combustion Engines (RICE) that can operate on both natural gas and diesel, giving us the flexibility to reliably serve our customers under a range of conditions.

Lange II will be a critical resource for our system, helping us serve customers cost-effectively while enhancing reliability. It's located next to our existing Lange facility on Deadwood Avenue in Rapid City. We've already completed significant site preparation, including grading and infrastructure setup. We're investing an estimated $280 million in this project, which will bring important economic benefits to the local community through job creation and increased tax revenue. We plan to begin construction in the third quarter of 2025 and expect commercial operations to begin in the second half of 2026.

Key points

We're committed to providing energy that's safe, reliable, and cost-effective. The Lange II Generating Station reflects that commitment — chosen as the best option to support our system and the region's energy needs.

The RICE engines at Lange II are designed to start up quickly and deliver power right when it’s needed most — especially during times of high demand. They’ll run primarily on natural gas, which supports our efforts to reduce emissions and helps us use more renewable energy efficiently. This makes our power grid more reliable and more sustainable.

Beyond its technical and environmental benefits, Lange II is a long-term investment in the region’s energy infrastructure and economic future.

Milestones

Frequently asked questions

What is the anticipated environmental impact of this project?

The Lange II Generating Station and its RICE generators will have minimal emissions, limited water usage, and no solid waste generated.

Will there be increased traffic on Deadwood Avenue?

Minimal long-term traffic impact; construction-related traffic will be coordinated with the city.

What is the economic impact locally?

The Lange II Generating Station is a multi-million-dollar investment into the local area. At the peak of construction, we expect approximately 200 workers on-site. Once operational, the facility will support a smaller, ongoing team of about 2–3 permanent technicians.

What is dispatchable power?

Dispatchable power is electricity that can be turned on or off — or adjusted up or down — whenever it's needed.

Think of it like a faucet: you can open it to let more water flow, close it to stop the flow, or adjust it to get just the right amount. Electricity demand goes up and down throughout the day — we typically use more in the morning and evening, and less at night.

Dispatchable power helps fill those gaps and keeps the lights on.

Examples of dispatchable power sources include:

• Natural gas plants
• Hydropower
• Coal plants
• Battery storage