HydroXS: unlocking distributed hydropower – International Water Power

InPipe Energy’s HydroXS pressure management and energy recovery system

Hydropower engineers know better than most that water doesn’t just sustain life – it protects and creates grid security. Yet, for all the innovation in turbines, storage, and dam optimization, one massive opportunity remains largely untapped: the enormous amounts of energy embedded in pressurized water pipelines.

Gregg Semler, CEO and founder of InPipe Energy, is changing that so utilities can reduce their energy costs and carbon emissions. Since Semler launched InPipe Energy in 2016, he has led the development of the HydroXS, a modular, in-conduit energy recovery system that generates grid-connected electricity by harvesting pressure differentials within water pipelines – without the environmental permitting hurdles associated with traditional hydro.

“At a time when the demand for energy is growing globally and infrastructure is aging, we’ve demonstrated how easy it is to retrofit water pipeline infrastructure to generate a new source of renewable energy,” says Semler. “It has all the benefits of hydroelectricity but it’s from an existing pipeline, so there is no environmental impact.“

A new approach to pressure management

At its core, InPipe’s HydroXS technology replaces traditional control valves with a micro-hydro turbine and generator designed to recover energy from pressure drops while maintaining flow regulation. The HydroXS is engineered to replicate the pressure-reducing function of control valves, integrating seamlessly into municipal, industrial, or agricultural pipeline infrastructure.

“Control valves in water systems reduce pressure by using a diaphragm or similar mechanism to burn off pressure through friction,” Semler explains. “We see that as wasted potential energy. We designed the HydroXS to precisely take that same pressure drop to spin a micro hydroelectric turbine and generate low-cost electricity – up to 2MW per unit, depending on hydraulic conditions.”

The HydroXS is available in seven standard configurations, accommodating pipe diameters from 5cm to 2.8m and flow rates between 75 and 2,500 liters per second, with operating pressure drops of 1.6 bar or more. These ranges make it viable for both high-capacity industrial infrastructure and smaller-scale municipal systems.

Each HydroXS unit comprises:

A hydro turbine and permanent magnet generator housed in a pressure-rated enclosure

An automated flow-control valve engineered to meet the same hydraulic standards as existing pressure regulation equipment

A smart control system with real-time telemetry on flow, pressure, generation output, and carbon offset

A grid-tied power panel that interfaces with utility systems via industry-standard net metering protocols

To minimize any adverse impact, the HydroXS is typically co-located in a bypass with existing valves, allowing for either manual or automated switching between traditional pressure management and power-generating operation.

Crucially, InPipe’s systems are designed for minimal civil works. In many cases, they’re retrofitted into existing vaults or installed in compact adjacent chambers, eliminating the need for above-ground infrastructure. This approach not only streamlines permitting but also reduces installation timelines and CAPEX.

“From the customer’s perspective, there is no operational impact on their operations,” says Semler. “The HydroXS mimics the impact of a valve only with added economic benefits.”

Performance and reliability

With over 10 years of runtime across multiple U.S. installations, the HydroXS has demonstrated >99% availability and minimal O&M requirements. Maintenance routines mirror those of standard valve and pump systems – quarterly inspections, basic lubrication, and filter changes—allowing utilities to rely on in-house personnel.

Case studies from Oregon and Washington illustrate both the reliability and versatility of the system:

In Hillsboro, Oregon, a HydroXS unit retrofitted into a municipal pipeline has generated 200,000 kWh annually for over five years with no outages. The energy offsets grid electricity demand from an adjacent sports complex, including EV charging, concessions and lighting systems.

In Skagit County, Washington, another installation delivers 104,000 kWh per year, feeding electricity back into the pumping station itself to reduce operational electricity costs from pumping.

InPipe offers multiple deployment models. Customers can purchase the system outright or opt for a power purchase agreement (PPA) under which InPipe installs, operates, and maintains the equipment and sells the electricity at a fixed rate over 15–20 years.

“This structure is familiar in the solar energy space, but it makes the economics very compelling compared to solar – especially for utilities or municipalities with tight capital budgets,” says Semler.

Depending on flow rate and energy prices, payback periods average three-to-five years, with levelized cost of energy (LCOE) between $0.05 and $0.06 per kWh, and potentially lower for large-scale sites. One HydroXS equates in energy output to acres of solar panels.

Importantly, the modular nature of the HydroXS allows for system wide deployment. Any point in a pipeline where pressure is intentionally reduced – through altitude changes, junction points, or end-of-line dissipation – becomes a candidate site for energy recovery. Multiple units can be distributed throughout a system to build up meaningful capacity and increasing the benefits.

A complement to renewables

While in-conduit hydropower is still gaining recognition, its operational profile complements that of traditional renewables. Unlike solar or wind, pressure recovery from water pipelines is non-intermittent. If water flows, power is generated – day or night, regardless of weather.

That consistency has opened the door to microgrid integration. HydroXS units can serve as a baseload anchor in distributed energy systems, especially when paired with battery storage. This could prove especially attractive in areas dependent on diesel backup generators, which are expensive to run and maintain, and carbon intensive.

“We’re working on replacing or supplementing diesel gensets with HydroXS and storage,” Semler explains. “That’s huge for resilience and security goals, especially in rural or infrastructure-critical environments like mining, agriculture, and data canters.”

InPipe’s systems are grid compatible, using standardized interconnection protocols modelled on those developed for distributed solar. Power is exported under net metering, and generation data can be tracked in real time via onboard telemetry. This includes flow rate, pressure, kWh output, and carbon emissions savings, offering customers a measurable path toward sustainability metrics.

Environmental considerations

From a regulatory standpoint, in-conduit hydropower benefits from a lighter footprint than traditional hydro projects – but it’s not without oversight.

In the US, systems must conform to electric utility interconnection rules, as well as drinking water standards where potable water is involved.

The HydroXS avoids the common environmental challenges of conventional hydropower: no dams, no diversion, no aquatic habitat disruption. As a result, it faces fewer permitting barriers and a clearer path to deployment.

“It’s an easier sell – both technically and politically,” Semler says. “Environmentalists really like the HydroXS. It’s the only source of electricity they’ve seen that has no environmental impact.”

From US to global opportunity

Until now, InPipe has focused primarily on the U.S. market, where more than 2.2 million miles of drinking water and wastewater pipelines represent a vast, underutilized energy resource. However, international demand is growing rapidly.

“We’re currently building our first internationally bound HydroXS system for a major industrial water user in Bangkok,” says Semler. “That will lead to a broader expansion into Southeast Asia and other emerging markets.”

Interest is also coming from Europe, where regulatory drivers around carbon accounting and grid flexibility are accelerating demand for decentralized renewables. InPipe sees strong alignment with European water utilities and industrial users looking to decarbonize without major infrastructure overhauls.

Semler is particularly keen to tap the agricultural, mining, and industrial cooling sectors, all of which rely heavily on pressurized water systems with recoverable energy potential. These are often gravity-fed, high-volume flows – ideal conditions for HydroXS deployment.

“We’ve seen great sites from mining, agriculture and data centers, where large amounts of water are being used in pipelines,” he says. “In those cases, the payback is even faster.”

Unlocking the potential of non-powered infrastructure

Beyond pressurized pipelines, Semler is evaluating the opportunity for the HydroXS in non-powered dams and conduits, particularly in the U.S., where over 90,000 dams exist – only 3% of which produce electricity.

“In-conduit hydropower could be a retrofit pathway for these sites,” he says. “We don’t require a full-scale build out with a powerhouse – just drop in the HydroXS on outlet works, drains, or bypasses where pressure exists.”

He acknowledges that working with federal bureaucracy remains a challenge – particularly with agencies like the Bureau of Reclamation and Army Corps of Engineers – but believes growing attention to energy security, grid resilience and energy demand will drive future policy shifts.

“There’s no reason why these assets shouldn’t be generating electricity. It’s low impact, it’s local, and it’s ready.”

The road ahead

Looking ahead, Semler envisions HydroXS evolving into a core component of distributed energy and storage networks, where water infrastructure can become an important asset for ensuring stability and resilience.

“Think of it as distributed pumped storage,” he says. “Every time water is released from a reservoir or tank, you can recover some of that energy. With two-way flow and storage integration, the same system could act as both a load and a generator. Increase the amount of water flowing out of the reservoir when you need it to balance the grid.”

This could be particularly valuable for urban utilities, where battery storage alone may not meet backup requirements, or for climate-sensitive infrastructure seeking redundancy during extreme weather events.

With rising electricity demand from electrification – especially in transport and data – engineers are increasingly being asked to find creative, low-impact generation options. InPipe’s HydroXS presents a plug-and-play solution for precisely that: clean, dispatchable power built directly into infrastructure that already exists.

As Semler puts it: “We’ve been burning off pressure in pipelines for centuries. Why not turn it into electricity?”