In-Conduit Hydro

Water flowing through California's aqueducts and other channel systems is an underused renewable electricity source in the state, according to the California Energy Commission.

A "renaissance" in turbine technologies over the past decade has increased the amount of power that could be generated using flowing water in California's aqueducts, ditches and other channels, according to a study by the California Energy Commission.

Water that moves through California's channel systems has the potential to generate an additional 414 MW of renewable power for the state, according to the CEC. The in-conduit hydropower could provide renewable energy that is not fundamentally intermittent, which is an aspect of other renewable resources like solar and wind, the CEC's report says.

Furthermore, in-conduit hydropower has minimal environmental impacts when compared with large hydropower systems, since its equipment is installed in existing water infrastructure, according to the report.

But despite its strong market potential, in-conduit hydropower is largely unused in the state. Project development has been slow over the past 10 years for many reasons, including a lack of knowledge about aspects of a project's life cycle; complex California ISO implementation and metering requirements; and interconnection rules that are not streamlined for reactive power generation projects, such as in-conduit hydroelectric projects, according to the report.

To address some of these issues, the CEC wrote a guidebook and created a business-case assessment tool that can help municipalities and agencies move projects forward. The guidebook includes information on conventional and emerging in-conduit turbine technologies, potential project sites, current regulatory and permitting requirements, interconnection processes, project financial viability assessments, and environmental benefits from greenhouse gas emission reductions.

The state's large investor-owned utilities count little, if any, in-conduit hydropower toward their renewables portfolio standard requirements. RPS amounts were 0.1 percent for Southern California Edison and none for both Pacific Gas & Electric and San Diego Gas and Electric, according to the California PUC's 2019 RPS annual report.

California currently has about 343 MW of installed in-conduit hydropower capacity, but the substantial evolution of turbine technologies over the last decade has the potential to more than double that amount, according to the report. New turbine technologies have resulted in equipment with improved performance, modularity, portability and scalability, the report says.

One of these advanced turbines—called a hydrokinetic turbine—generates electricity from the kinetic energy of moving water instead of the potential energy from static water. Hydrokinetic turbines are modeled after wind turbines and include axial-flow turbines, which have rotor shafts that are positioned parallel to the water current, and cross-flow turbines, which are positioned either vertically or horizontally.

In-conduit hydropower projects are typically financially feasible if total project costs are in the range of $5,000 to $15,000 per kW, with a payback period of fewer than 15 years, the report says. A project's cost can be offset by grants available through the CPUC's Self-Generation Incentive Program, according to the CEC.

Staff Writer

David Krause is an energy reporter covering the California Energy Commission and Air Resources Board. He writes about transportation, climate change, utilities, and wildfires. He has an MFA in Writing, an MA in English, and a BS in Civil Engineering.