Colorado’s Flatiron turbine pumps water 297 feet uphill to Carter Lake, then generates electricity as it returns

Colorado’s pumped-storage hydropower uses a unique turbine to bridge power supply gaps.

America’s grid stability hangs in the balance as modern energy needs continue to increase to unprecedented highs.

Hydropower has historically played a vital role in electricity production, but its role has evolved.

Long-term economic barriers include degradation from repeated charging cycles, high procurement costs, and limited operational lifespans.

Now, flexible energy storage solutions have become critical to integrating renewable resources.

How does one of Colorado’s key diversion developments use reversible pumping to meet regional needs?

How hydropower’s role has evolved over the years

For a long time, hydropower has been a core pillar in the United States’ energy landscape.

Its first industrial milestone dates back to 1880. During this period, a water turbine powered a dynamo to light 16 lamps at a factory in Michigan.

Two years later, the first commercial plant in Appleton, Wisconsin, began selling electricity.

By the early twentieth century, hydroelectric infrastructure expanded significantly.

Beyond generating affordable electricity, these plants also helped with regional irrigation and flood control.

In the modern era, hydropower’s role has evolved as power demand surges while climate mandates push for decarbonization.

As digital and electric infrastructure expands across the U.S., renewable energy capacity deployment must accelerate.

Standard green energy sources such as solar and wind cannot bridge the nation’s growing power gap alone.

Their intermittency creates too frequent grid fluctuations, and battery storage systems present bottlenecks.

That is why hydroelectric facilities must integrate flexible systems to ensure grid reliability.

The challenges of conventional battery storage systems

Chemical battery storage has proven successful in addressing short-term intermittency issues.

However, these systems are increasingly facing notable deployment challenges across the U.S.

Chemical batteries require critical minerals for production, but mineral supply chain constraints have limited production scalability.

Long-term economic barriers include degradation from repeated charging cycles, high procurement costs, and limited operational lifespans.

Furthermore, these batteries typically supply only up to eight hours of storage, making them ineffective for multi-day power shortages.

Traditional hydropower is a proven alternative to these bottlenecks.

The American fleet maintains roughly 80,000 megawatts of capacity across 34 states.

Across the nation, many major hydropower projects are being upgraded.

Colorado itself has created a strong framework for flexible water and power management.

The U.S. Bureau of Reclamation is maximizing these assets by integrating flexible pumping systems into federal infrastructure.

A key feature includes the Flatiron Plant’s unique reversible pump-turbine, which helps strengthen regional grid reliability.

Using a specialized turbine to rewrite hydropower’s role

Colorado boasts an impressive hydropower capacity, with over 1,200 MW across more than 60 facilities.

The state’s standout development is the Colorado-Big Thompson Project. It is one of the biggest transmountain water diversion projects in the country.

It spans approximately 250 miles across Colorado, integrating over 100 structures.

Central to this network is the Flatiron Powerplant in Larimer County, southwest of Loveland, Colorado.

 

Its Unit 3 plays an essential role, consisting of a specialized 8,500-kilowatt reversible pump-turbine.

The dual-function operation of the reversible pump-turbine

When regional power demand drops, Unit 3 pumps water up to 297 feet from Flatiron Reservoir.

The water moves through the Carter Lake Pressure Conduit and Tunnel into Carter Lake Reservoir.

During peak demand hours, the flow is reversed, using gravity to force water from Carter Lake through the conduit.

This spins Unit 3 as a turbine-generator to generate electricity, then discharges into Flatiron Reservoir for downstream distribution.

The plant’s dual-function operation provides essential benefits to the regional energy grid and water supply.

By quickly releasing elevated stored water, the resulting energy absorbs grid fluctuations.

The reversible unit also handles bulk water transfer for municipal and agricultural supply. This eliminates the need for additional pumping and power generation facilities.

Ultimately, upgrading hydropower plants across the U.S. with this unique turbine will increase system reliability more cost-effectively.