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We've all seen the massive damns and aqueducts that provide power to cities around the world,
but there's an untapped potential beneath our cities. Gallons of high-pressure water
flowing through our water pipe infrastructure every day; wasted energy dissipating through
pressure-reducing valves and canal drops. It's possible to recover some of that energy
and put it to use. Imagine your toilet generating energy with every flush ... okay, maybe that's
not the best imagery for this ... let's explore energy recovery hydropower and how it could
be a game-changer in micro hydropower.
I'm Matt Ferrell ... welcome to Undecided.
Harnessing the power of water isn't a new concept. Between 202 BC and 8 AD, during the
Han Dynasty in China, trip hammers powered by water wheels were used to pound and hull
grain and break ore. The Greeks also captured the power of water for milling thousands of
years ago. However, it was only in the nineteen century that hydraulic turbines started to
be developed. Since then, we've been producing clean energy from the force of water, and
this power source accounts for 60% of all renewable electricity we consumed in 2020.
But the energy generating potential of hydropower isn't limited to our current hydroelectric
options like canals and damns.
In drinking water distribution and supply networks of cities, industries, and farms,
water coming from reservoirs reaches high speeds and pressure. So before it can enter
our homes and businesses, where it flows through much smaller pipes, the water's speed and
pressure has to be reduced in water treatment plants in order to protect pipelines and equipment.
The usual solution is to install Pressure Reduction Valves (PRV). These devices release
the pressure from the water, but they also lose all that usable energy. However, there
is a small but growing move towards converting that wasted pressure into electricity and
feeding it back into the grid, creating clean, usable, renewable energy that would otherwise
be lost. This approach is called energy recovery hydropower.
This is a subset of conduit hydropower that harnesses the energy released by PRVs in current,
pressurized, man-made water systems already diverting water from a natural waterway for
consumption. These systems generally include a micro-turbine, generator, sensors, processors,
electronic controls, and communications equipment that operate continuously and autonomously
within the water utility infrastructure. So here's how it works.
Usually, the control systems of water treatment facilities get data about pressure and speed
from sensors that constantly monitor the water flow in the pipeline and send that information
to the operators to control the PRVs. Energy recovery systems are usually connected parallel
to those systems. The diverted and parallel water flow drives a micro-hydro turbine that's
combined with pressure control to produce and feed renewable energy into the grid. Control
valves ensure that the diverted water flows back into the main pipeline at the correct
pressure.
Unlike intermittent renewables like solar power, one of the benefits here is 24/7 operation
all year long. And from a system level point of view, these turbines could replace PRVs,
using the turbine itself as a flow control device. You'd simplify the overall system
design, have high efficiency and reliability, and take advantage of the existing structure
... all without negative environmental impacts. But redundancy wins out here. In order to
ensure the safety of the treatment plant or distribution network, the turbine is usually
placed in parallel with a PRV to ensure that if either is offline for any reason, water
can still be treated and delivered to consumers.
There are quite a few applications for this type of recovery system: municipal drinking
water delivery, waste water treatment applications, transferring of raw water to water treatment
facilities, and transfer of water from one reservoir, tank, holding source, to another.
All these harness the power of gravity to function. The electricity that's produced
by the energy recovery turbines can be utilized to power a water treatment facility to balance
their annual energy consumption. On top of that, excess electricity can be sold directly
to the grid with a power purchase agreement.
Several companies around the globe have been developing energy recovery hydropower systems,
and a great example is SOAR. This American company develops different types of hydro
turbines, and works closely with each customer to provide the ideal solution for their needs.
Their In-Line model is designed specifically for each site in order to achieve maximum
efficiency, but shares a number of common parts for competitive pricing and quick lead
times. These turbines are designed to recover power at flow rates between 500 to 30,000
gallons per minute (GPM). Their higher operational flow rates gives them a lot of flexibility
for what they can support, like public water supplies, agriculture, tunnels, canals, or
aqueducts.
The company also offers Canyon® Pump Turbines, which are simple, robust and cost effective
pump-as-turbines (PATs). Think of it like regen braking on an EV. Instead of using energy
to run a pump rotor to push water out, the water flows in the other direction spinning
the pump rotor in the opposite direction, which allows the motor to operate as a generator.
Since they aren't site-specific, PATs usually achieve lower efficiencies but at the same
time it reduces installation time and cost.
Canyon® Pump Turbines can be installed in any water delivery network with excess pressure
and are well suited for sites that have a relatively constant flow rate. SOAR offers
pump turbine packages for both on- and off-grid applications with outputs ranging from 5 kilowatts
to 350 kilowatts and supports 500-9,000 GPM flow rates.
They also produce a low-power, plug-and-play energy recovery turbine with a maximum power
output of 300 watts. Pico Hydro Turbines are designed for power generation in new or existing
water networks and they're ideal for powering monitoring equipment, sump pumps, lighting,
blowers, fans, and any devices that operate under 24VDC. Any excess power is stored in
a battery charging system.
A great example of this was installed in Oregon for a company that wanted to power a system
for remote monitoring and controlling drinking water flow rates. The challenge the company
had was that there wasn't available power in the area, and connecting to the local grid
was too expensive. SOAR's system currently generates and stores enough power to run the
equipment and shuts itself down to extend system life when power isn't needed. The utility's
now able to send data to their headquarters for analysis and adjust the flow rates remotely.
One of the leaders in this area with several projects already developed is Rentricity.
They're currently producing two in-pipe hydro energy recovery systems. One is their customizable
Flow-to-Wire™ system, which is designed for 30kW to 350kW use cases. The other is
the Sustainable Energy and Monitoring Systems (SEMS™). This recently launched plug-and-play
system is designed for applications in the 5kW to 30kW range.
Their energy recovery systems are designed to last 40 years with low operation and maintenance
costs, which makes them a pretty durable and reliable solution for energy recovery. A nice
perk is that this equipment can provide extra revenue.
For example, in 2014 the company installed a $500,000 system in Halifax, which was the
first city in Canada to exploit in-pipe power. Since the system was commissioned, the 31-kilowatt
turbine has generated about 225,000 kilowatt-hours and $30,000 of revenue per year from selling
excess power. In Westmorland County, Pennsylvania, Rentricity installed a system that was estimated
to produce 250 megawatt-hours a year, saving $40,000 in electricity costs annually. In
that project, the Municipal Authority of Westmorland County awarded a state grant of over $200,000,
for an accelerated payback, which provided final costs around $0.04/kWh.
InPipe Energy, a Portland-based company is also betting on the energy recovery hydropower
concept. They've installed their In-PRV technology to produce up to 200,000 kWh of electricity
annually for lighting, electric vehicle (EV) charging stations and concessions at Hillsboro’s
90-acre Gordon Faber Recreation Complex, which includes the 7,000-seat Hillsboro Stadium.
The system bypasses an existing PRV and rather than dissipating the pressure, it converts
it into electricity. The total budget for the hydropower project is $509,000, and the
city got two renewable energy grants from PGE and Oregon Energy Trust, which covered
70% of the project cost.
According to Solar Impulse, In-PRV has a payback time ranging from 4 to 5 years and a cost
of electricity of 0.03-0.05 cents per kilowatt-hour. On top of that, for every kilowatt-hour generated
from their system, it's the equivalent of saving 553 tons of CO2e per year.
At the beginning of the video I brought up the vision of an electricity-generating toilet.
And I'm bringing it up again because it's actually possible. I don't think you'd want
to, but it's possible.
Leviathan Energy manufactures the Benkatina in-pipe turbine that can fit limited space
and variable flows. Their unit is about 100 cm in size and currently produces up to 10
kilowatts. An interesting feature of Benkatina turbines is that it operates at variable water
flows and uses an air bubble to prevent water interference on the blades. It's already achieved
high efficiency at low flows (55% at 1 kilowatt of output, 61% at 5 kilowatts of output).
With that small size it could be installed in conjunction with a toilet to harness energy
from water with each flush to produce electricity. Of course, it wouldn't be a great amount of
energy, but instead of flushing all that energy potential down the toilet ... why not?
So far we've only seen a slow, growing trend in energy recovery hydropower, but some policies
are being developed to foster the technology since it has such a high electricity potential.
The California Energy Commission (CEC)-funded research that completed in 2006 estimated
that California has 255 MW of undeveloped conduit hydropower potential. In the state,
energy recovery hydropower projects are eligible for funding through the Self-Generation Incentive
Program for $0.60/watt. In addition to that, California has a feed-in-tariff that includes
energy recovery hydropower projects less than 3 MW with a payment rate of 8.9 cents/kWh.
The Colorado Department of Agriculture (CDA) published a study estimating that Colorado
has approximately 30 MW of conduit hydropower potential ... and that's only counting agricultural
irrigation systems across the state. Because of that they started an incentive program
that provides technical assistance and grants for project development.
The primary market driver for energy recovery hydropower is the opportunity for water system
operators to lower operational costs by offsetting energy use costs. In the U.S., energy consumption
by water utilities represents 30%–40% of a city's energy costs, mainly from water pumping.
So why not install energy recovery turbines and tap into that wasted potential? And in
some cases, produce a surplus that can be sold back to the grid. Energy conservation
and renewable energy doesn't have to be a one size fits all approach. It's not just
wind turbines and solar panels that can solve our energy needs.
If you'd like to dig a little deeper into electricity and how generators work, I'd strongly
recommend checking out the Electricity and Magnetism course at Brilliant. In order to
watch this very video there's an electric generator out there somewhere spinning away
powering the servers ... and powering or charging up the device you're using to watch it. You'll
learn all about the principles behind how that all works, like Maxwell's equations.
But if that short circuits your brain a little bit, don't worry because they have over 60
courses including topics in computer science, quantum mechanics, and mathematics. They've
got something for everybody.
All of the concepts are taught through fun and interactive challenges to help you understand
the "why" of something ... not just the "how." It helps to develop your intuition, which
is my favorite part about Brilliant and taps into the way I learn ... and just makes it
fun.
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I can't get the toilet generator out of my head. Put a USB port on the lid, plug in your
phone and start flushing to charge it up. That's a horrible idea. What do you think
of energy recovery hydropower? And do you know of any other unique technologies like
this that I should look into? Jump into the comments and let me know. If you liked this
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all of my patrons and to all of you for watching. I’ll see you in the next one.