Millions of miles of pipelines and conduits across the U.S. serve municipal, agricultural and industrial purposes, and opportunities exists in all 50 states to harvest otherwise wasted energy using hydropower.
In a new report, researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory estimate that conduit hydropower, which uses water from structures such as water supply pipelines and irrigation canals, has the potential to add 1.41 GW of electricity to the country’s power grid.
“You can think of conduit hydropower as low-hanging fruit, and what has been started is a mere drop in the bucket,” said Shih-Chieh Kao, water power program manager at ORNL. “For all its benefits, the biggest barrier is a general lack of awareness of conduit hydropower’s potential.”
The process to develop conduit hydropower would be relatively easy. Facility operators could install hydropower generators at locations with excess hydraulic head. This could be coordinated with planned facility upgrades that replace aging infrastructure with more energy-efficient systems. Rural communities may benefit by adding small hydropower generation to existing infrastructure for net metering.
Because conduit hydropower taps into existing infrastructure with minimal environmental impacts, the permitting process has been streamlined. Through the Hydropower Regulatory Efficiency Act of 2013 and its amendments in America’s Water Infrastructure Act of 2018, the federal regulatory approval process can be completed in 45 days. More than 350 conduit hydropower projects have been permitted or constructed.
ORNL scientists conducted a systematic analysis of four conduit types — water supply pipelines, wastewater discharge, irrigation systems and thermoelectric cooling water discharge. For conduit hydropower to work, the water channel must have sufficient water flow and hydraulic head. Scientists analyzed this data as well as satellite imagery and topography to estimate the overall potential.
The potential for conduit hydropower was highest in five western states — California, Colorado, Washington, Nebraska and Oregon. All of these states have a large number of water conduits and their hilly terrain also provides the greatest hydraulic head.
Agricultural conduits such as ditches and channels for crop irrigation showed the greatest potential for hydropower among the three business sectors assessed, amounting to nearly half of all conduit hydropower capacity. The highest agricultural conduit potential was seen in Colorado, Washington, Nebraska, California, Oregon and Idaho. Irrigation and topography were primary drivers for this assessment.
Researchers also assessed drinking water supply and wastewater systems in the municipal sector. Conduit hydropower potential here was highest in California, which had twice that of the next-highest state, New York. Colorado, Utah, Washington, Oregon and Pennsylvania also showed potential for capacity generation in this sector.
Opportunities for conduit hydropower from industrial conduits, such as industrial pipelines or canals used at thermoelectric generating facilities, were present mostly in California, Texas, Missouri, New York and Maryland. However, these facilities also pose the greatest uncertainty due to higher economic and regulatory requirements.
The ORNL research team will facilitate further discussion with key stakeholders in water supply and delivery to raise the awareness of conduit hydropower and to understand how the community may overcome this hurdle to develop more conduit hydropower projects.
The study was supported by the Water Power Technologies Office in DOE’s Office of Energy Efficiency and Renewable Energy. UT-Battelle manages ORNL for DOE’s Office of Science.
