Overview/Objective
For more than a century, hydropower has served as an important renewable energy source. A new report released by the US Department of Energy’s Oak Ridge National Laboratory (ORNL) assesses the potential to generate electricity from new hydropower operations along existing water conduits in the municipal, agricultural, and industrial sectors throughout the United States. These conduits include pipelines, irrigation canals, and other water channels.
More than 350 conduit hydropower projects have received federal regulatory approval since 2013. Conduit hydropower installations are typically small, with minimal environmental impacts and a simplified permitting process. They offer the potential to generate new electricity for the grid and new revenue for water system operators.
To quantify the potential for further conduit hydropower development, the ORNL research team conducted a systematic nationwide analysis, evaluating four categories of conduits:
- Water supply pipelines for municipal and industrial uses
- Wastewater discharge conduits from municipal and industrial systems
- Agricultural water conduits: irrigation canals, ditches, and pipelines
- Thermoelectric power plant cooling water discharge conduits
For each type of conduit, the team developed and implemented a method to estimate hydraulic head and annual water flows – and in turn the hydropower potential – at specific sites, based on analyses of satellite imagery, topography, and existing datasets on water systems and power plants. These methods support a consistent, replicable evaluation of conduit hydropower potential across the nation, though they are not sufficiently accurate to inform project-specific feasibility assessments or investment decisions.
Results
The analysis conservatively estimates that new conduit hydropower has the potential to add a total of 1.41 gigawatts of electricity to the US power grid, more than two-and-a-half times the current installed conduit capacity of 512 megawatts. The agricultural sector accounts for nearly half the potential for new conduit hydropower development, 662 megawatts, followed by the industrial (378 MW) and municipal (374 MW) sectors.
The potential for conduit hydropower development in the agricultural sector was greatest in states with a combination of a large amount of irrigated acreage and hilly or mountainous terrain. Colorado had the most conduit potential, 154 MW, followed by Washington, Nebraska, California, Idaho, and Oregon.
In the municipal sector, conduit potential scaled generally with population – which is roughly proportional to flows in municipal water and wastewater systems – and terrain. The study found California to have more than twice the conduit development potential, 109 MW, than the second-ranked state, New York, which was followed by Colorado, Utah, Washington, Oregon, and Pennsylvania. Municipal water supply systems accounted for 90% of the total potential, compared with 10% for wastewater systems, due mainly to the greater water pressure in closed pipelines in water supply systems. However, in nine states, primarily in the Midwest, potential from wastewater systems may exceed that of water supply systems.
Industrial conduit hydropower potential was greatest in California, followed by Texas, Missouri, New York, and Maryland. Of the three sectors evaluated, the industrial sector has the greatest uncertainty, as most of the measured conduit potential, 60%, was associated with cooling water discharges from thermoelectric power plants. There are multiple potential economic and regulatory obstacles to conduit hydropower development at such sites, and, to the authors’ knowledge, there are as yet no projects of this type in the United States (though successful projects have been built in Europe).
Impact
The study found opportunities for conduit hydropower development in every state. In general, the western states have the largest resource potential, with the highest total capacity potential in California, followed by Colorado, Washington, Nebraska, and Oregon. The state-level potential reflects suitable topography to provide hydraulic head, and the scale of water supply.
Next Steps
Despite the abundance of potentially feasible sites and the relatively simple permitting process, conduit hydropower faces a number of challenges, including a lack of awareness of the technology, and needs for better understanding of the economics of conduit hydropower projects, site-specific information to inform investment decisions, and technical advances to support the integration of conduit hydropower into water systems as aging infrastructure is upgraded. Further research can help answer these questions and promote the growth of this valuable hydropower resource in our future grids.
Get Involved
If you have questions or would like to be added to the mailing list for updates on this work and notices of public events, please email kaos@ornl.gov or ltryba@kearnswest.com. In the coming year, the research team will be hosting multiple webinars on this work and leading discussions at conferences.
