# Rolling Hills Wind Farm

MISO asset profile · https://askthegrid.com/assets/facilities/rolling-hills-wind-farm

## Current generation inventory

EIA plant 57501 · Inventory reporting month: 2026-08.

- wind: 484.2 MW operating nameplate
- Capacity basis: operating_generator_nameplate_mw
- Source inventory: [EIA-860M workbook (preliminary)](https://www.eia.gov/electricity/data/eia860m/xls/august_generator2026.xlsx)
- Inventory retrieved: 2026-10-10T02:12:40.665346+00:00
- Filed coordinate (longitude, latitude): -94.7744, 41.1973
- OSM extract: 2026-10-08T20:21:06Z
- OSM mapped edit: 2024-03-25 04:13:53+00:00
- Map prepared: 2026-10-10T02:28:21.842378+00:00

Battery power (MW) and stored energy (MWh) are separate measures. Shared physical-site membership does not establish electrical connectivity, settlement or a common export limit.

## Reviewed overview

Rolling Hills Wind Farm is a 484.2 MW onshore wind turbine plant in Cass County. Rolling Hills is a MidAmerican Energy wind project in Adair, Adams and Cass counties in Iowa. The original 443.9 MW build used 193 Siemens SWT-2.3-101 turbines, installed by Mortenson Construction. In 2019 MidAmerican selected Siemens Gamesa to repower the project with 163 SG 2.7-129 and 18 SWT-2.3-108 turbines, a 429.3 MW order that was the largest repowering in North America to date, with commissioning expected in late 2021.

## Reviewed metrics

- **Nameplate capacity:** 484.2 MW — Canonical EIA plant baseline.
- **Registry anchor:** Plant 57501 — plant-57501

## Facts

- **Technology:** Onshore Wind Turbine
- **Operator:** MidAmerican Energy Co

## Related parties

- **Owner / developer:** MidAmerican Energy Company — owner ([source](https://www.midamericanenergy.com))
- **Equipment supplier:** Siemens Gamesa — equipment_supplier ([source](https://www.siemensgamesa.com))
- **Equipment supplier:** Siemens Energy — equipment_supplier ([source](https://www.siemens-energy.com))
- **Construction contractor:** Mortenson Construction — construction_contractor ([source](https://www.mortenson.com))

## Sources

- [prnewswire.com](https://www.prnewswire.com/news-releases/midamerican-energy-siemens-energy-and-mortenson-construction-celebrate-renewable-energy-at-rolling-hills-wind-project-126279873.html) — prnewswire.com · public_source — Source retained for exact-record publication review.
- [siemensgamesa.com](https://www.siemensgamesa.com/global/en/home/press-releases/190702-siemens-gamesa-onshore-projetct-usa-midamerican-energy.html) — siemensgamesa.com · public_source — Source retained for exact-record publication review.

---

Canonical page: https://askthegrid.com/assets/facilities/rolling-hills-wind-farm
Website: [MidAmerican Energy Company](https://www.midamericanenergy.com)

Source: Ask the Grid — https://askthegrid.com/