Water pipes hold flood of untapped electricity potential

1.41GW, in fact – enough to power around one million homes

There is a wealth of untapped hydroelectric potential in the United States – around 1.41GW of energy flowing through pipes, irrigation channels, and aqueducts.

Scientists at Oak Ridge National Laboratory (ORNL) reached this conclusion after what they described as a first-of-its-kind study examining the potential power generation of small and micro-scale hydroelectric generators bolted on to existing water infrastructure.

Using both existing data from water regulators and "novel remote sensing and feature detection techniques," the ORNL team said it was taking the first step in not only understanding the US's untapped conduit hydropower potential, but also to raise awareness that such a power source exists. 

"For all its benefits, the biggest barrier is a general lack of awareness of conduit hydropower's potential," said Shih-Chieh Kao, ORNL's water power program manager. 

That's not to say conduit hydropower isn't being used in the US – it is, but it's only generating around 530MW nationwide, ORNL said in the study [PDF]. That 1.41GW, on the other hand, could power more than a million homes. 

Who forgot about all that pressurized, flowing water?

Hydroelectric power is facing serious challenges as climate change and overuse begin to drain rivers. Additional projects that would put water-intensive semiconductor fabs in locations like Texas, where water is already scarce, have been facing increased criticism as well.

Power generation in an increasingly electricity-fueled future will likely rely on distributed energy resources (DERs) that produce small amounts of clean energy for local consumption. Conduit hydropower is simply the distributed answer to large-scale dams. 

"The undeveloped potential presents a great opportunity to develop clean and renewable hydroelectric energy across the nation," the ORNL team said in the study.

For the sake of generating power, ORNL said it considers any "manmade water conveyance that is operated for the distribution of water for agricultural, municipal, or industrial consumption and not primarily for the generation of electricity" as a tappable source. Most deployments would tend toward the very small scale – existing conduit hydro projects top out at less than 10MW, the team explains. 

Most of the power generated by such small facilities would go toward stabilizing microgrids and offsetting energy needs for water system operators, which ORNL said is typically a significant portion of their costs. Conduit hydro systems could also be net metered, meaning unused energy could be returned to the grid for further cost offsets, ORNL said.

Further, as water infrastructure ages and need replaced, that upgrade can include some power generation potential. "Tapping conduit hydropower from water distribution systems can be a sustainable long-term water and energy supply solution," the ORNL team said.

Like most things, this'll take time

Most of the potential to generate electricity from water distribution infrastructure can be found in western states like California, Colorado, and Washington, all of which have miles of water conduits mostly used for agriculture, and lots of mountains where water flows freely downhill.

But ORNL's study didn't focus on specific locations and "may not identify accurate site-specific opportunities that are more suitable to support further feasibility assessments and investment decisions." 

In other words, this isn't going to happen overnight. 

Toss in a lack of public awareness and a dearth of "consistent and equitable incentives compared with other renewable resources," and you have a recipe for a technology that goes unnoticed despite its potential benefits.

ORNL said that there's yet another reason to consider getting conduit hydroelectric generators plugged into grids: the 1.41GW figure is probably way lower than the actual potential.

"The authors attempted to incorporate a variety of data and approaches to estimate the national conduit hydropower potentials, but the significant data gaps still represent a major hurdle to capturing the full resource potential," the researchers said. 

"Given these uncounted opportunities" – which ORNL said includes self-supplied water withdrawals, incorrect coordinates on maps used for estimates, and other things unmeasurable in a broad study like this – "there could be more conduit hydropower than … estimated in this study." ®