Water and energy are inextricably linked, a concept referred to more and more commonly as the water-energy nexus. In short, it describes the interrelationship of water used in the generation of energy, and energy consumed in the use of water. Most forms of electricity generation require the use of water at some stage. For example, coal-fired power plants use vast amounts of water for cooling and even the manufacture of photovoltaic solar panels consume water. Likewise, energy is required to move, purify, store or do just about anything with water. For many water utilities, electricity is the number one cost center.?
Using less energy to transport water is one way water distribution can be made more efficient; losing less water in the course of transmission is another. Many water transmission lines in the United States are significantly deteriorated ? their average age is around 70 years, with many more than 100 years old. The U.S. Environmental Protection Agency (EPA) estimates that $650 billion in upgrades are needed to replace aging pipelines and satisfy new demand over the next 20 years.
The EPA has also stated that approximately 17 percent of treated water in the United States is lost due to leaking transmission pipes.?The same challenges are seen globally. It is estimated that the City of London – with even older pipelines than most here in the U.S. – loses almost 50 percent of its water. For water utilities that are already burdened with rising operational costs and shrinking revenues, leaking pipelines are taking an added toll.
To address both energy cost and water pipeline efficiency issues, Lucid Energy has developed a renewable energy system that utilizes a resource that water agencies already have at their disposal: water moving through pipelines. The LucidPipe Power System converts pressure available in water pipelines into usable or salable electricity. This patented, lift-based turbine technology has been the focus of the company’s development since 2007. ?
The In-Pipe Solution
The Lucid Spherical Turbine operates inside of a pipeline, generating power as it spins with minimal disruption to the water flow. It extracts pressure from the pipeline and could therefore be characterized similarly to a valve. Instead of burning off this pressure, the LucidPipe system converts it to electricity for onsite use or transmission to the grid. A LucidPipe system is complementary to most valve technologies and is usually installed upstream from a valve that is used to control flow rate or pressure. The technology is not so different in principal from conventional hydropower systems, except the turbine was specifically designed to operate within a water transmissi
on pipeline where most of the energy is used in the transport of water. Prototype systems and the first commercial system, installed near a valve in a Riverside Public Utilities (Riverside, Calif.) pipeline, have operated more than 15,000 hours and delivered more than 45 MWh of energy to the Riverside Public Utilities grid.
The LucidPipe system was developed and tested in a working water pipeline to offer water utilities a way to harness otherwise untapped energy lost in the course of normal operations. It was designed to reduce energy costs, improve the efficiency of pipeline operations and find new revenue streams to help water agencies fund the necessary growth and modernization of their infrastructure. A number of alternative and renewable energy sources are currently in use by water agencies worldwide, but few of these sources benefit operations through utilization of the water in the pipelines. A new tool for water resource management, LucidPipe also presents consistent, reliable and cost-effective means for renewable energy generation.
As part of an upcoming LucidPipe installation in Portland, Ore., historical flow data provided by the Portland Water Bureau was assessed in order to negotiate favorable electricity rates for a power purchase agreement (PPA) to sell energy directly to the electric utility. A similar assessment for a project with the San Antonio Water System led to a determination that the return would be more favorable when used to power equipment behind the meter.
How it Works
Most gravity-fed water pipelines utilize valves to control the flow of water and maintain safe operating pressures. Water distribution networks can thereby meet daily and seasonal variations in demand; removing more pressure when demand is low and less pressure when demand is high. While this is effective for controlling flow rates, energy dissipated in this way is not otherwise utilized and can lead to accelerated wear on valves. The LucidPipe Power System will extract pressure, converting energy removed from the pipeline to electricity and decreasing the rate of wear on downstream valves.
The LucidPipe system supports a wide range of operations, wherein it is possible to control the amount of pressure extracted. The amount of electricity produced by the system is as reliable and predictable as the flow of water in the pipe and presents water utilities with the option to produce zero-emissions electricity from an energy source already present in their networks. Compared to other sources of renewable energy, such as solar or wind that are weather-dependent, in-pipe hydropower offers a more controllable, consistent and cost-effective solution.
The turbine’s blades, or hydrofoils, generate lift as water flows over their surface. This force causes the turbine to rotate about its central shaft and allow mechanical energy to be transmitted as torque and RPM through the shaft. The maximum speed at which the turbine may spin is governed by the design of the hydrofoil and the velocity of the water column. The faster the turbine spins, the more pressure it will extract from the flow. Therefore, the natural limit imposed by hydrofoil design prevents a runaway situation and the potential for unexpected spikes in pressure extraction. In addition, an intelligent control system manages operation and adapts to changes based on flow conditions and input parameters from the pipeline operator. LucidPipe operation can be tailored to favor electricity generation, pressure extraction or both based on the preference and financial benefit to the operator or project owner.
Pipeline Efficiency
The LucidPipe system is scalable – multiple turbines may be incorporated as part of a single system. In this way, the installation can be customized to meet financial and operational requirements.? The number of turbines that can be supported is determined by analyzing expected flow rates, pressure available for extraction and the physical length of pipeline. It was determined that the upcoming installation in Portland could support a four-turbine system. Real-time performance data and measured conditions are to be delivered directly to the municipal SCADA infrastructure to further enhance control and visibility of pipeline operations.
Each turbine within a LucidPipe System can be deactivated independently. When turned off, the turbine stops spinning and very little pressure is extracted as water flows past. The characteristic range of pressure extraction for the system may be expressed similarly to that of a valve, making integration into operational pipelines straightforward. Fundamental operation of the pipeline does not change, only the location where the pressure drop occurs and in what form the extracted energy is now available. After a number of tests were performed in cooperation with Riverside Public Utilities and upstream pipeline operators, the LucidPipe system installed in the Gage Canal Pipeline was found to function almost transparently to normal operations. Only new positions for a downstream valve were needed to compensate for the pressure extracted by the LucidPipe system.?
Placing a turbine upstream from a valve to remove pressure reduces wear and tear on the valve, but it also helps reduce water leakage in the pipeline. The rate at which a pipeline leaks increases as its internal pressure (gage pressure) rises, and the pressure head inside a gravity-fed pipeline that transmits water over a long distance may rise to higher-than-necessary levels. A pressure reduction valve can be implemented at a point where the pressure is critically high in order to achieve safer or more cost-effective pressure levels downstream. Similarly, the LucidPipe system can be installed upstream to extract energy and lower the pressure along the entire length of pipeline. Less water lost to leakage has tangible benefits to a water utility’s bottom line.
The Bottom Line
The LucidPipe Power System, as a new technology that blurs the lines between energy generation and pipeline efficiency, can benefit any water utility. In addition to reducing pipeline leakage and reducing wear on the downstream valve, converting this energy to electricity is what makes this approach economical. Attractive returns on investment allow for a project finance model that benefits third party investors and water utilities alike. As an example, the Portland Water Bureau stands to benefit from reduced wear on a new downstream valve. It also benefits from a share of the revenue from electricity sales with the added benefit of private investment providing the upfront capital to pay for the equipment. Think of it as a novel way to finance improvements to aging infrastructure that benefits all parties involved.
Josh Thomas is the engineering program manager for Lucid Energy.
EDITOR’S NOTE: A previous online version of this story contained a factual error that has been omitted. The story included a?fact about water loss that stated the ?City of Boston loses as much as 30 percent of its?water due to leakage.? UIM has since learned that Boston?s unaccounted for water has, in fact, remained below 10 percent in recent years, according to the Boston Water and Sewer Commission.
