Combining smart pressure control with micro hydro tech

7 July 2021

A new pressure reducing valve that combines smart pressure control with micro hydro technology has been developed to meet both the water and energy challenges facing water utilities. Jennifer Allen Newton, President of Bluehouse Consulting Group, reports

Municipal water agencies are finding themselves at the centre of the two biggest resource challenges on the planet: water and energy. They are facing rising operational costs, declining revenues and ageing infrastructure that needs repair. Up to 3.5% of total US electricity consumption is used for water, including pumping and large-scale conveyance, according to the US Department of Energy ‘s Water Energy Nexus report. Rising energy costs hit municipal water agencies particularly hard, as energy is typically their second largest expense – up to 40% of the agency’s budget. Municipalities are also under increasing pressure to meet renewable energy mandates and climate action goals.

All this puts conservation, loss prevention and economics at the top of water industry priorities. 

On the water side of the equation, precise pressure management is a critical function, as too much pressure in pipelines can cause excess wear and lead to water loss. Water agencies typically use pressure reducing valves (PRV) to ensure water is delivered at the appropriate pressure. 

There are more than two million of these valves in use across the US alone. But embedded in that pressure reduction is a significant, untapped opportunity for water agencies to capture this excess pressure and produce renewable energy to improve resilience.


With 100,000 residents, Hillsboro, a suburb of Portland in Oregon, gets most of its water from the nearby Tualatin river. It is treated and then pumped up to reservoirs at elevation for gravity-fed delivery to homes and businesses. The pumping process is energy-intensive and at the mercy of rising energy prices.

“We’re always looking for ways to deliver water more efficiently to our rate payers but finding the most practical and cost-effective lever is key,” says Eric Hielema, Water Department Engineering Manager for the City of Hillsboro. 

When Hielema and his team learned about an innovative new solution coming out of research at Oregon State University, that addresses both pressure management and energy production, they were immediately interested.  

InPipe Energy was funding the development of its In-PRV – a new pressure recovery valve that combines smart pressure control with micro hydro technologies to meet both the water and energy challenges facing water departments. 

“Electricity is a large cost for water utilities and often relies on methods that aren’t sustainable, such as the burning of coal, but there’s also untapped energy embedded in all that gravity-fed water as it flows downhill from reservoirs,” said Hielema. “With a traditional PRV, all of that kinetic energy is not used to its full potential.”

“The In-PRV is a turnkey, end-to-end solution that controls pressure precisely, but it converts excess pressure to carbon-free electricity,” said Gregg Semler, President and CEO of InPipe Energy. “It’s a new tool that water departments can use for pressure management and to generate revenue, to reduce operating costs and re-invest the dollars into other programmes like water conservation or new infrastructure.”

According to a Climate Impact Report by Boundless Impact Research and Analytics, a 100kW In-PRV can save 550 tons of CO2 per year and has a three to four times higher return on carbon compared to solar or small wind systems. Considering full deployment of InPipe Energy’s In-PRV technology at the global scale, Boundless Impact estimates that 1.75 giga tonnes of CO2 equivalent could be saved per year – equivalent to 4300 billion driven miles in an average passenger car. 

Such savings were music to the ears of Hillsboro’s water managers. The department purchased the In-PRV in February 2020 and the installation was completed in September 2020 at the Gordon Faber Recreation Complex. Because of the system’s attractive profile for renewable energy generation, Hillsboro partnered with Portland General Electric, their utility provider and Energy Trust of Oregon to help fund the project. 

Control box for the In-PRV, which is installed in a small below-ground vault at the Gordon Faber Recreation Complex in Hillsboro, Oregon

The In-PRV’s sensors and software are integrated into the SCADA system, allowing Hillsboro Water to manage pressure, flow and electricity production 24/7. This, combined with the system’s ability to control pressure at both high and low flows, helps the city streamline operations, save water and extend the life of their infrastructure.

“This system functions as a PRV but what excites me about it is that we’re taking energy that is traditionally wasted and we’re generating electricity from it,” said Hielema.

The system is on target to generate an estimated 200,000kWh of electricity per year that is fed back into the grid, offsetting Hillboro’s cost of energy and helping to power the lights, concessions, and charging fleets at electric vehicle charging stations at the recreation complex. This single In-PRV generates enough electricity to power 20 homes, which amounts to about a million dollars’ worth of electricity over the life of the project. 

The City of Hillsboro expects payback on their investment within three years, but the return on this investment is more than financial. The system is also helping the city meet its climate action goals by reducing more than 162,000 pounds of carbon annually. 

“The In-PRV hydroelectric system provides a practical way for us to capture energy that’s already in our system, and we’re using it to reduce our operating costs, which benefits the ratepayers and helps the city meet its climate action goals,” said Hielema.

The In-PRV in Hillsboro, Oregon is the first in a city water pipeline

Large-scale projects

Conduit, or in-pipe hydropower has been used in a few large-scale projects around the country, including the LucidPipe Power System installed in a water pipeline in Portland, Oregon. 

Semler, InPipe Energy’s founder, is the former CEO of Lucid Energy, which developed the Portland system. Over the past decade he has met with hundreds of water managers across the country to better understand their greatest needs and obstacles.

“Water agencies are mission driven – they deliver clean, safe drinking water – and they aren’t going to embrace anything that puts their operational focus at risk,” said Semler. “That’s why we set out to create a turnkey product that fits seamlessly into a water utility’s current operations.”

InPipe Energy spent four years following a nine-step product development process prescribed by the Department of Energy and independent technology and innovation consultancy Isle Utilities. They worked with Oregon State University’s Mechanical, Industrial, and Manufacturing Engineering department to develop, prototype and validate the In-PRV. With the Hillsboro project, the In-PRV went from technology readiness level 6 (TRL 6) to TRL 8, the last and final step before full commercialisation. 

“We designed the system so that it can be installed quickly, easily, and cost-effectively throughout water systems with smaller-diameter pipelines and wherever pressure must be reduced,” said Semler. “But the beauty of the In-PRV is that it can also be used in other types of pressurised pipelines, such as penstocks in more traditional hydropower facilities, providing a way to harvest even more electricity from moving water.”

Isle Utilities completed a technology readiness assessment of the In-PRV and concluded: “InPipe’s system is a straightforward approach to renewable energy from an untapped resource. It utilises proven technologies such as hydroelectric turbines and induction type generators. At a time where conserving and generating clean energy are high priorities around the globe, InPipe Energy has introduced a simple and low-cost strategy to achieve both objectives.”

With the In-PRV, Hillsboro Water can monitor pressure, flow and electricity production 24/7


The Hillsboro In-PRV installation is the first in a city water pipeline, and several other In-PRV installations are slated in the coming year in Oregon, Washington, Texas, Utah and California.

With full deployment of the In-PRV by US water agencies, InPipe Energy estimates that $230 billion in new revenue could be recovered in energy savings over the next 30 years while preserving the life of water infrastructure and reducing leaks through more precise pressure management. This, along with eliminating tonnes of carbon emissions, would go a long way toward improving resilience, reducing the carbon footprint for water and ensuring safe, clean drinking water for all Americans.  

“As a water utility, in order to stay cost-effective for ratepayers, we have to make sustainable, long-term investments that look forward 50 years instead of 20 years,” said Hielema. “With the In-PRV we can generate electricity from a resource that is otherwise wasted. It’s an innovative technology that water utilities all across the country can easily deploy in order to improve their resilience.”


How the In-PRV pressure recovery valve works

The In-PRV can be installed wherever there are water systems that use valves to control pressure, and it can also be used in other gravity fed systems. It is co-located in a bypass, making it easy to install onto an existing or new pipeline with minimal impact on water operations. A sensor continuously monitors flow and pressure. As water flow is diverted through, the In-PRV reduces pressure using proprietary micro hydro and control technology to the precise level required by the water utility, and the excess pressure is converted into electricity that can be used on site or fed to the grid for net-metering. Grid interconnection is similar to solar systems.

The system’s precision pressure management eliminates chatter, vibration and pressure pulses that can lead to leaks and water loss, which helps extend the life of infrastructure. It provides redundancy for existing valves and gives water managers precise control over the pressure in the pipeline during both high and low-flows – something older PRVs don’t provide with as much resolution. The system’s dashboard provides real-time, continuous data on flow, upstream/downstream pressure and energy production. 

The In-PRV from InPipe Energy




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