All flowing water contains energy. Water utilities increasingly try to take advantage of it.
In fact, in-conduit hydropower plays a small yet growing role for utilities looking to control energy costs and operate more sustainably. Real-world case studies show how the technology can have financial and environmental benefits and how monetary and regulatory incentives are driving its adoption.
Among companies helping utilities put their water to work is InPipe Energy, which offers the HydroXS energy recovery system. The technology converts excess water pressure into around-the-clock renewable power.
The company reports that the system is deployed in Oregon, Washington, Colorado and California and has achieved 99% uptime. The technology replicates the function of a control valve, creating precise pressure management and flow control. Instead of differential pressure being “burned off,” it creates renewable energy. This reduces operating costs, saves water, cuts carbon emissions and helps extend infrastructure life.
Given the thousands of miles of water pipeline in place, the company sees major potential for the technology. Gregg Semler, CEO and founder, talked about the offering in an interview with Treatment Plant Operator.
TPO: What was the motivation for bringing this technology to market?
Semler: I’ve spent 20 years building energy and water companies. As I learned how water treatment facilities and municipal water systems work, I thought about how to generate renewable energy from pipelines that would be consistent, predictable and low-cost, and would have no environmental impact. I was motivated by the idea of an energy source that utilities could use to reduce operating costs and improve energy security at a time when energy costs were rising. We need to find ways to reduce those costs, which are starting to affect affordability.
TPO: What differentiates this technology from a hydroturbine?
Semler: Most people think InPipe is building a new kind of turbine. But in my conception, the water industry is made up of pipes, pumps and valves, and I wanted to create a valve. Water utilities use valves to manage flow and ensure that their customers receive water at the right pressure. Micro-hydroturbines are great at generating electricity, they’re very efficient and well understood, but they’re not precise enough in managing flow and pressure. Our idea was to integrate a control valve with a micro-hydroturbine and so deliver precise flow and pressure management, plus energy and the economic benefit of reducing cost.
TPO: In basic terms, how does the HydroXS system work?
Semler: It has three components. First, it integrates a control valve with a micro-hydroturbine and generator. Second, there is a control system that constantly monitors the flow and pressure in the pipeline, making sure that the HydroXS is operating compatibly with the utility’s requirements. It also integrates with a SCADA system. And third, a power panel collects the generated electricity, which can be used in the facility or exported to the utility grid.
TPO: Where in the process would this technology typically be deployed?
Semler: It can be used in any place where water is under pressure in a pipeline. We’re typically looking at gravity-fed systems — places where customers are using flow-control valves, pressure-reducing valves or other kinds of control valves. Common locations would be downstream of a water tower, reservoir or storage tank. Those are obvious places where utilities are wasting pressure that could be used to generate electricity.
TPO: Does this product have applications outside the water utility industry?
Semler: Yes. It can be applied in industry where they use water in a cooling loop, where they pump the water uphill and use it to cool the facility, and then it comes back gravity-fed. Food processing, data centers, agriculture, mining, all these and other industries use water in pipelines under pressure.
TPO: How much energy can this technology generate?
Semler: We make seven sizes of the HydroXS, and they integrate with pipe diameters from 4 inches to 110 inches. It’s not the pipe diameter that really matters. The amount of power we can produce is a function of the flow of the water and how much pressure we can take out, times efficiency. The systems are 80% efficient. We don’t change the flow of the water, but we do take out pressure to produce electricity. Our units range in capacity from 10 kW (enough for 10 homes) to 2 MW (enough for 2,000 homes). All that energy comes from wasted pressure in a single valve.
TPO: What kind of application would provide 2 MW of capacity?
Semler: We see it in large industrial water systems. You need maybe 10 mgd of flow to get to that level. Mostly, our systems yield about 100 kW to 500 kW.
TPO: How easy is the technology for plant personnel to learn and operate?
Semler: It’s very easy. We work with leading companies in the industry to manufacture our system, so customers are very familiar with most of the components. They know the brand names, and they know how they work.
TPO: What maintenance does the system require?
Semler: It is maintained in the same basic way as a control valve or a pump, with a scheduled protocol: Grease the bearings, make sure there is no water on the floor, no overheating and no excess noise. We have over 10 years of operating experience with our technology in the field, with 99% availability. And that is with customers doing the maintenance.
TPO: How are the hydroturbine and control valve deployed in the pipe?
Semler: Utility operators don’t like putting devices in the pipes, and so we install our technology in a bypass. That provides redundancy and also allows them to manage the new technology. They may ask, ‘What if the product doesn’t work?’ And the answer is, it’s in a bypass, so the existing system is still there. If our product doesn’t work, they can isolate it and go back to where they were. But we’ve found that typically the HydroXS in the bypass becomes the main pipeline, and the legacy pipeline becomes the backup.
TPO: How does the technology integrate with SCADA?
Semler: The SCADA is connected to the HydroXS through a smart control system and sensors. We have meters and sensors that constantly monitor the flow and pressure in the pipeline. We use control technology that meets the customer’s standards. Meanwhile, the power panel meets all the standards for safety and reliability established for the solar energy. So power utilities find our technology safe and acceptable for export of electricity to the grid.
TPO: Is there a specific “sweet spot” in terms of size or type of facility for which this product is best suited?
Semler: Not really. Water is conveyed similarly all over the world. We work with small cities, big cities, large industrial facilities. It really depends on what their hydraulics are — how much water they deliver and how they deliver it.
TPO: What is an example of where this product has operated successfully?
Semler: A good example is the city of Mount Vernon in Washington. The Skagit Public Utility District there has been using a HydroXS system for about four years where they fill an underground storage tank co-located at a pumping facility. When filling the tank with water, they generate electricity, offsetting some of the cost of operating their pumps. We’re now working with them at another location where they will pull a cable to a nearby high school to power electric vehicle charging stations.
TPO: How can customers document the benefits of the technology?
Semler: Data is increasingly important to our customers. We provide real-time data on flow, pressure and energy generation. We also provide carbon emissions data, so that if they have net-zero energy goals or climate goals, they can report to the EPA or to their customers about how they’re doing on a sustainability basis.
