Innovative Upgrade Means More Clean Power at Twin Falls
The Twin Falls Powerhouse Redevelopment project by We Energies was a decade-long initiative to replace the aging, inefficient and increasingly unsafe powerhouse with a safe and efficient one. In the process, generation at the site was increased by 50 percent using about the same water flow.
The original hydropower station on the Menominee River that borders Wisconsin and Michigan’s Upper Peninsula was built in 1912. Until recently that powerhouse was still in operation, albeit very inefficiently.
Each unit of the original powerhouse had a nameplate capacity of 1.22 megawatts for a total capacity of 6.1 MW, but prior to the upgrade the existing turbines hadn’t been able to achieve nameplate capacity and significant maintenance was required just to keep the turbines operating. Simply starting and stopping a unit required a local operator.
“Through the Twin Falls Redevelopment, customers will benefit from another 100-plus years of renewable hydro electricity generated from a more efficient facility — one that offers 50 percent more generating capacity while using the same amount of water,” said Todd Jastremski, hydro operations asset manager at We Energies.
“Additionally, the reservoir created by the project will serve as a continued source of public recreation: fishing, kayaking, and water skiing being local favorite activities. Improved efficiency benefits the environment by reducing carbon and other emissions, and the ecosystem that was created more than 100 years ago through the construction of the original Twin Falls hydro project will remain unchanged.”
Through automation, the new powerhouse allows operators to control the turbines off-site. The digital controls have greatly improved the responsiveness of the powerhouse to meet flow conditions and respond to local demand.
But developing the new powerhouse was not without challenges. The site was difficult to excavate and the utility had an aggressive schedule coupled with a tight budget as well as high environmental protection standards. Moreover, the existing powerhouse needed to stay in operation while the project was under construction to minimize lost generation.
We Energies met the project’s challenges with creative solutions: controlling run-off to increase water quality protection; adapting construction plans to protect natural resources; avoiding changes of the impoundment level to reduce material costs; and eliminating the need for second-stage concrete to shorten the construction timeline.
We Energies also used a partnering approach to establish the overall budget for the project and provided incentives for the owner, contractor and engineer to deliver the project cost-efficiently.
“From an overall project approach, ‘budget conscious’ and ‘cost efficient’ are areas we always incorporate into project planning and execution,” Brad Smith, project manager at We Energies said. “We set an aggressive budget and timeline for the Twin Falls Redevelopment project and worked closely with our partners to commission the facility within the target schedule and budget.”
One of the utility’s partner organizations was the Wisconsin Department of Natural Resources.
“From planning through construction, We Energies provided best management practices for habitat protection, wildlife protection in construction zones, and fish and mussel relocation,” said Cheryl Laatsch, statewide Federal Energy Regulatory Commission coordinator at the Bureau of Environmental Analysis and Sustainability for Wisconsin’s DNR.
Another significant challenge for the project was developing a closed-loop cooling system that was reliable in a wide range of temperatures and eliminated the threat of zebra mussel infiltration. We Energies partnered with Canadian Hydro Components and Black & Veatch on the innovative system that cools the generator without the use of river water.
Zebra mussels are invasive and have been increasing in the river since the late 1980s. The mussels reproduce rapidly and attach themselves to metal and concrete surfaces. Worse, when they die, they leave behind hard shells that, over time, form a growing layer of organic material that can be very difficult to remove and is particularly troublesome for the cooling system’s heat transfer capability.
The cooling system is equipped with three different modes. During the winter, the system uses forced air to discharge heat from the cooling water into the powerhouse, which in turn is circulated to the lowest powerhouse level for heating. In the spring and fall, ambient temperatures are warm but sufficient for cooling using the turbine intake coils, reducing power required by the system. In the summer, when the powerhouse’s internal temperature is high, the system uses both the turbine intake cooling coils and the forced-air radiator to provide additional cooling.
In recognition of their work, We Energies received the National Hydropower Association’s 2017 Outstanding Stewards of America’s Waters award for operational excellence. The designation is given to projects that add value to the hydropower industry through technical contributions, innovation, engineering, upgrades and improvements, or technology breakthroughs.
“NHA is thrilled to present We Energies with the OSAW Award for Operational Excellence,” said Linda Church Ciocci, NHA’s Executive Director. “This award was designed to celebrate innovation and technical achievement, and We Energies’ Twin Falls project exemplifies each of these characteristics. As a result of We Energies’ commitment to increasing efficiency, while protecting environmental values, the communities they serve will continue to have access to clean, sustainable hydropower.”