Even after a century of experience with this reliable renewable resource, significant opportunities still exist to expand the nation’s hydropower resources
Advances in Hydroelectric Power Generation
Dr. Raj Shah, Andrew Kim, Mrinaleni Das and Rahul Khandekar | Koehler Instrument Company
Hydropower’s energy source comes from the energy of water moving from higher to lower elevations, mainly from rivers and reservoirs. Reservoir hydropower plants rely on the stored energy in the reservoir, while river power plants harness energy from the flow of the river. Hydropower is currently the largest renewable energy source in the electricity sector as it relies on stable rainfall patterns. However, there are some negative effects of hydropower. Droughts can negatively impact it. The basic physical structures needed to create hydropower can adversely impact ecosystems. For this reason, small-scale hydro reactors are preferable and especially suitable for remote location communities.
Hydropower Technology Development
Hydroelectric power produces 6.3% of the nation’s total electricity and is the largest source of renewable electricity . Even after a century of experience with this reliable renewable resource, significant opportunities still exist to expand the nation’s hydropower resources through non-powered dams, water conveyance systems, pumped storage hydropower, and new site development. The Water Power Program (WPP) supports the hydropower industry through the development of key components as well as identifying key areas where hydropower generation can be enhanced. Pumped-storage (PS) hydropower acts as utility-scale grid storage technology and is therefore an important piece of DOE’s renewable energy portfolio. The WPP can play an essential role in showing the benefits of PS hydropower as part of our clean energy future – acting as a renewable form of grid stabilization and an enabler for renewables (such as wind or solar). The US outlines key activities that can help accelerate pumped-storage development in the United States.
Adding additional hydropower generation will create a large economic benefit by revitalizing the domestic and hydropower industry.
Low Head Hydropower
Across the country (US), there are opportunities at low head sites to add new hydropower generating capabilities (i.e., those that operate with a change in elevation ranging from 2 to 20 meters). These types of waterways are often present across diverse areas of the United States. The Water Power Program(WPP) invests in innovative low-head hydropower R&D, such as Percheron’s Power installation of the nation’s first Archimedes Screw System. The project shows that the low-head technology is simple, robust, and economical.
Figure 1: Archimedes Screw System design .
Figure 2: The first image shows a schematic diagram of the run-of-river hydroelectricity. The second image shows a micro hydropower system (ultra-low head). This image shows how the powerhouse of low head hydropower systems from rivers functions .
Materials and Manufacturing
WPP helps improve performance and lowers the costs of hydropower by testing new materials. The research found reducing the life-cycle cost of turbine runners, draft tubes, and penstocks comes from new materials and advanced coatings. R&D is looking for new ways to generate efficiency and reliability.
WPP is working its best to develop and test new technologies that can reduce construction costs; increase areas for installation and plant growth factors; reduce risk; and improve the quality–environmental performance attribute of the energy produced. Areas of focus include water-use optimization, advanced materials application, and water power grid services assessment. For example, existing hydropower facilities in the United States show signs of deterioration, and the data used to evaluate these facilities is outdated. WPP is working with partners to update the information to understand the declines in electricity generation, capacity factors, and facility availability.
Technology Development Accomplishments
The program has numerous accomplishments in hydropower technology development. The projects below highlight just a few of the program’s new opportunities and recent successes in cost reductions, water-use optimization, and facility upgrades.
New Opportunities for Advanced Hydropower R&D:
After more than a decade, in 2011, WPP released its first example of hydropower R&D after revamping its hydropower technologies. These projects aim to reduce the costs of hydropower technologies and demonstrate the dynamic grid benefits of advanced hydropower technologies. For example, Natel Energy designed, built, and commissioned a protected powertrain for the Schneider Linear hydro engine. By reducing interest rates and maintenance costs, this powertrain enables the development of new low-head hydropower capacity.
Optimizing Hydropower Systems for Power and Environment:
WPP teamed with U.S. national laboratories to develop the Water-Use Optimization Toolset (WUOT), a suite of advanced, integrated analytical tools. WUOT assists with operating hydropower plants more efficiently, resulting in environmental benefits from improved hydropower operations and planning. WUOT includes tools for hydrologic forecasting, seasonal hydro-systems analysis, day-ahead scheduling, real-time operations, and environmental performance operations. The following locations are demonstrating WUOT:
The Oroville Complex on the Feather River in California
The Colorado River of the River Storage Project
The dam in the Susquehanna River in Maryland
Figure 3: Oroville Complex (California) .
Revitalizing American Infrastructure
WPP completed three hydropower efficiency projects with overwhelming success – resulting in an increase of more than 3,000 megawatt-hours per year .
Figure 4: Hydropower efficiency project generating over 3,000 megawatt-hours per year .
The Los Alamos County Department of Public Utilities installed a low-flow turbine in its Hydroelectric facility in New Mexico. The new turbine boosts overall facility output from 13.8 megawatts to 16.8 megawatts .
The City of Boulder in Colorado completed a modernization project to its Boulder Canyon Hydroelectric Project by installing a new turbine unit. The new unit resulted in a 30% increase in generation and an 18-48% increase in turbine efficiency .
The City of Tacoma installed two Francis turbine/generator units at Cushman Damn in Washington. The new units add 3.6 megawatts of electrical generation annually .
Tides can create a head difference when combined with a barrage or a lagoon. Even though tidal energy is not a major source of electricity today, it has the potential to be a significant contributor in the future. A positive of tidal energy is that it is more predictable than the wind or the sun. However, a main disadvantage is that it is relatively hard to find a site with strong tidal flow velocity and is expensive compared to other energy sources.
In recent years, technological improvements/developments have allowed for a higher capacity for tidal power than previously assumed. Significant design improvements include dynamic tidal power and lagoons because of their new axial and cross-flow turbines. With this, economic and environmental costs can be brought down to competitive levels.
Figure 5: Example of a tidal energy construction 
Marine and hydrokinetic technology are one of promising advances in hydropower. These devices capture energy from waves or tides of the oceans. Additionally, MHK power sources/devices are commonly located near the outline of the US. In addition, MHK power sources have the potential to power millions of homes every year .
Most hydroelectric power sources require freshwater, but MHK does not. With using seawater, it can generate huge amounts of potential hydropower from its vast size and the technologies applied to it.
Five Promising Water Power Technologies
The world’s first hydroelectric plant in Appleton, Wisconsin, started illuminating the home of the plant builder and a nearby building on Sept. 30, 1882. Afterward, there was the development of more hydropower plants and an increase in size. Today more than 2,500 hydropower plants generate clean, reliable, and renewable energy across America . However, this was not the end for hydropower technology. To further realize its potential, new challenges and resource types must be discovered and used in ways to connect streams to oceans. These are five promising water-powered technologies under research now:
Although hydropower electricity is the least expensive source of energy, manufacturing a plant may be costly. Today’s technology allows for reduced manufacturing costs and installation fees. One answer to this is modular hydropower which allows for assembly off site and integration into new sites and greater capacity factors for plants.
Modular hydropower systems allow for lower construction costs and reduced environmental impacts. For example, a 24 foot long and 16 foot high prototype dam, was built in Mass. as part of the HydroNext Initiative to lower costs, improve performance, and promote environmental stewardship of hydropower development.
Powering non-powered dams
Currently, hydropower ranks number 1 in being a renewable energy source. However, thousands of dams still don’t produce power. Adding generation equipment can add up to 12 GW of hydropower capacity, and using existing dam infrastructure can lower construction costs and reduce permitting time – meaning hydropower is added faster . Because roughly 50% of hydropower capacity is owned by the US government, federal dams represent a big portion of developed non-powered dams .
Pumped Storage Hydropower
Pumped-storage hydropower (PSH) is a big battery. It allows water to go to a higher elevation, which can then be released to turn turbines and meet energy demands. As the largest form of energy storage, PSH helps stabilize America’s power grid. It can respond quickly to power outages or grid instability and may balance variable generation from wind and solar. The country’s PSH plants help make the electric grid reliable and resilient, but Energy-funded research shows we can add even larger amounts of new, low-cost, and flexible PSH.
To produce electricity from tides that occur worldwide, there needs to be a sixteen-foot gap between high and low tides. Currently, tidal power plant conditions are good in the Pacific Northwest and Atlantic Northeast. The Energy Department has discovered techniques to develop new ways to install, maintain, and decommission tidal power plants. Recently, the Energy Department funded Verdant Power, Inc. to optimize a way to deploy and retrieve three tidal turbines together as a single system with an on-water operation without support.
Ocean waves store enormous amounts of energy. The challenge for scientists - and a focus of the Energy Department – is developing technology that can safely, reliably, and cost-effectively convert wave energy into usable electricity. But once that’s done, wave energy can supply power to major cities and distributed applications – like naval bases. To solve this problem, the Energy Department-funded an 18-month public competition that ended with the prize winner Aqua harmonics. They demonstrated a five-fold increase in the energy capture potential of their MHK device.
Six Emerging Hydropower Technology Trends
Emerging technological trends aimed at increasing hydropower’s flexibility, efficiency and cost-effectiveness were the subject of a workshop organized by the European Commission Joint Centre (JRC).
Two of the paper’s authors present the spotlighted research and development trends. These technologies cover hydropower flexibility, digitalization, storage and variable speed turbines, generators with current-controlled rotors, and novel small-scale and fish-friendly technologies.
Climate change mitigation strategies require a high share of renewable energy resources. The variable generation of RES requires that new hydropower technologies provide greater flexibility over a range of hydraulic conditions.
Some of the most salient technologies under development are stabilizer fins, J-grooves, air injection/admission, axial water injection with high/low velocity and low/high discharge, tangential water injection at a cone wall, two-phase air-water injection along the axis, hydroelectric energy storage, battery hybrids and smart modeling to increase operating range and unit flexibility.
Real-world data allows the upgrade of hydropower turbines so they can support advanced grid services without interfering with stations’ reliability and safety. Hydropower digitalization allows 42 TWh to be added to the hydropower energy production system . The benefits are cost-effectiveness and less greenhouse gas emissions (from hydropower turbines).
Energy storage and variable speed turbines
Pumped hydropower storage (PHS) is needed as there is an increase in variable RES in power systems. PHS plants can operate in turbine and pump mode during peak regulation times. Fixed or variable speed turbines enhance this. Speed variation has two components: converter-fed synchronous machines, i.e., machines whose stator is driven by frequency, and double-fed induction machines, i.e., electric machines fed by AC currents in both stator and rotor windings. The Goldisthal PHS plant in Germany was the first large speed hydropower plant in Europe equipped with 265 MW pumped-storage units .
Generators with current controlled rotors
Novel power electronics with current-controlled power supplies can ensure better control of electrical machines, for example, during the start and stop phases. For example, the hydropower plant Frades II plant in Portugal is equipped with two-pump turbines, and an AC-excitation system controls the rotor power of the induction-motor generator.
Novel small scale hydropower technologies
Small-scale hydropower allows for mini-grid and rural electrification strategies. For example, water wheels, turbines, and advanced designs and operation strategies for pumps (PATs) are being introduced and designed to conform to the new ways of machine learning. PATs can also operate in turbine mode, making them hybrid. An example of a PAT is the Deriaz turbine. Although used in bigger hydropower plants, it is a water turbine with high heads to make it more suitable for inclined waterways.
Fish-friendly hydropower technologies
The design stage of a plant helps keep it sustainable due to environmental concerns regarding hydropower. Fish friendly turbines today include vortex turbines, water wheels, Archimedes screws, Alden turbines and the minimum gap header turbine.
Future of Hydroelectric Power
Hydropower generation has many positive outcomes and some negative outcomes. Advances in hydropower generation will allow for fewer problems and better/more efficient outcomes.
For example, drought-related losses can be recouped, and efficiency can be increased by modernizing existing hydropower infrastructure and ensuring that plants can operate for many decades to come.
In the next 10 years, $127 billion will be spent on modernizing old plants. That accounts for nearly one fourth of total global hydropower investment and nearly 90% of the investment in Europe and North America .
In other countries besides the USA, investment is going towards new plants. Large projects in Asia and Africa will account for over 75% of hydropower capacity through 2030, but some worry about the environmental effects.
Run-of-river facilities have less impact on the environment since they have no reservoir, but because output depends on seasonal flow, they cannot generate energy on demand. Run of river hydropower is expected to account for 13% of total capacity additions this decade, while traditional hydropower will make up 56% and pumped hydro 29% .
But overall, hydropower growth is slowing and is set to contract by 23% by 2030 . Reversing this trend will depend on the regulatory and permitting processes and setting high sustainability standards and emissions measuring programs to ensure community acceptance. A shorter development timeline would help developers obtain power purchase agreements, thereby incentivizing investment since returns would be guaranteed.
Finding the right incentives for hydropower and pumped storage development will be critical in weaning the world off fossil fuels, accordingly, done sustainably.
Dr. Raj Shah is a Director at Koehler Instrument Company in New York, where he has worked for the last 27 years. He is an elected Fellow by his peers at IChemE, CMI, STLE, AIC, NLGI, INSTMC, Institute of Physics, The Energy Institute and The Royal Society of Chemistry. An ASTM Eagle award recipient, Dr. Shah recently coedited the bestseller, “Fuels and Lubricants handbook”, details of which are available at ASTM’s Long-Awaited Fuels and Lubricants Handbook 2nd Edition Now Available (https://bit.ly/3u2e6GY). He earned his doctorate in Chemical Engineering from The Pennsylvania State University and is a Fellow from The Chartered Management Institute, London. Dr. Shah is also a Chartered Scientist with the Science Council, a Chartered Petroleum Engineer with the Energy Institute and a Chartered Engineer with the Engineering council, UK. Dr. Shah was recently granted the honourific of “Eminent engineer” with Tau beta Pi, the largest engineering society in the USA. He is on the Advisory board of directors at Farmingdale university (Mechanical Technology ) , Auburn Univ
( Tribology ), SUNY, Farmingdale, (Engineering Management) and State university of NY, Stony Brook ( Chemical engineering/ Material Science and engineering). An Adjunct Professor at the State University of New York, Stony Brook, in the Department of Material Science and Chemical engineering, Raj also has over 550 publications and has been active in the energy industry for over 3 decades. More information on Raj can be found at https://bit.ly/3QvfaLX
Mrinaleni das, Andrew Kim and Rahul Khandekar are all part of a thriving internship program at Koehler Instrument company which encourages students to explore renewable and alternative resources for energy
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The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag
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