A water battery? It could happen soon

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Innovative applications to old technology hold the promise of developing a “water battery” that captures and stores energy, offering an environmentally friendly alternative to large battery plants as support systems to renewable energy projects.

The concept of a “water battery” is a new innovation that builds on a proven technology – pumped-storage hydro (PSH).

By moving water between two reservoirs at different elevations, PSH offers the flexibility to store excess energy during periods of low electricity demand and release that energy during periods of high electricity demand.

In today’s ongoing discussions of producing renewable, carbon-free, green energy that does not harm the environment, it is reasonable to examine PSH as an alternative to traditional battery plants with as-yet-unresolved waste streams concerns. While battery plants will continue to serve the industry, consideration of developing PSH “water battery” projects has gained momentum.

Ames Construction is one of several entities, along with major turbine-generator suppliers, that have invested the time and resources to develop potential PSH projects.

What if…

… We could make a new type of battery with internal material made of just water, eliminating the need for heavy metals like lead acid or lithium ions?
… The depth of discharge of this “magic battery” was negligible – it wouldn’t matter if the battery were discharged a little or all the way to its design limits?
… The round trip efficiency of the battery was 70% on megawatt usage and would make money back on power cost?
… The designed life of this battery was not dependent on the number of cycles it delivers?
… The storage materials used in this battery would never have to be captured, remanufactured or stored in a cubicle forever because of its hazardous properties?

Advances in PSH technology

Pumped-storage hydro technology has made incredible advancements in capabilities, from fast response to signals from the grid to providing grid-scale energy storage for as long as 10 to 12 hours. PSH is poised to elevate the grid capabilities in the U.S. Just as exciting is the prospect for developments in geographical locations that can support “closed loop” systems that can function without affecting existing bodies of water or adversely influencing the environment. Alone or in tandem in a potential series, these carbon-free plants will support continued construction of other renewable energy projects like wind and solar plants, along with minimizing the reliance on existing fossil fuel plants.

Pumped-storage hydro is the oldest technology with the highest capacity to store energy.

According to the 2016 Hydropower Vision Report and reprinted in the 2018 Pumped Storage Report by the National Hydropower Association, the U.S. Department of Energy (DOE) indicates that PSH is not properly valued in the energy wholesale market, which is making development of these plants more than challenging. Financial experts point to the lack of financial viability along with market uncertainty as the barrier to deployment of these advantageous projects.

Overcoming resistance to PSH development

Solar and wind power have been advancing during the past decade in remarkable fashion. They have responded to favorable tax incentives for renewable energy. PSH has not been included in these incentives, and efforts are under way to change that position. NHA has called for revisions of these policies, along with consistent treatment of hydropower and in particular PSH in its value in independent system operators (ISO) rules and definitions. Today, NHA is lobbying hard for a more efficient regulatory process and leveling the tax playing field for hydropower. NHA also strongly supports the initiatives of the DOE Water Power Technologies Office (WPTO) for more research and development of PSH and marine energy items.

In the past, extremely long project development timelines–often 10 years or more–have frustrated developers and investors alike. Within the U.S., a major PSH project has not been built in nearly two decades. Only one small-scale PSH project has been built: the 40-MW Lake Hodges plant, built by the San Diego County Water Authority (SDCWA) and completed in September 2012.

In 2018, a revised America’s Water Infrastructure Act (AWIA) was signed into law. The AWIA contained a number of key provisions for the hydropower industry. One encouraging measure is that the Federal Energy Regulatory Commission is working to establish an expedited two-year licensing process for closed-loop pumped-storage projects. These actions will diminish the permitting period compared to those seen previously. With the permitting period diminishing, the design and construction portions of the projects become the longest timelines for the development of new PSH facilities.

Oldest technology, highest storage capacity

It is vital to the nation and the environment that new PSH development begins soon. The well-known “Duck Curve” graph, courtesy of the CAISO (California Independent System Operator), depicts the net demand on the electrical grid. The graph reveals that, only seven to eight years ago, the net electric demand curve was basic. We had dispatchable energy generation, meaning that grid operators could turn the generators on and off. With the addition of a large amount of solar power panels, along with additional non-dispatchable wind, the net demand during the daylight hours simply indicates the added renewable sources produce too much power together with respect to today’s demand. Projections without a mitigating factor reveal spikes and demand that reach to nearly zero and potentially beyond zero. PSH can help this problem – it is the oldest technology with the highest capacity to store energy.

At the state levels, renewable energy standards have become common. A PSH plant’s ability to provide firm capacity, voltage support, frequency response and energy storage is becoming increasingly apparent and valuable to the electric grid.

PSH delivers hazard-free energy storage

A PSH project simply uses water and gravity to generate and store energy. Neither water nor gravity produce hazards when used appropriately and scientifically.

In a PSH facility, one megawatt spent on pumping water is returned with the efficiency of about 70% currently. How many cycles can be run before the water for the battery wears out?  An infinite number of cycles can be run in a PSH facility. There is no limit to its lifecycle. For decades, we have used and treated wastewater over and over again and have never worn out the water. Pumping and generation equipment have finite lives, while hydropower has been kind to the human race for hundreds of years.

Several PSH projects are under development in the western part of the U.S. alone. Each plant is estimated to have a capacity of at least 400 MW. At least one of them – the Gordon Butte PSH Project – has advanced to the final stages of design, is located on private land, and the project has been licensed by FERC. The project is moving toward financing and construction start as contractors and suppliers have confirmed their firm cost estimates for construction and equipment. Current efforts including finalizing the schedule for construction. All items are currently in action with Copenhagen Infrastructure Partners, who indicated with their press release of June 2019 that they have entered an agreement securing equity investment capital for the project. The same developer, Absaroka Energy, is also working with state and federal agencies, local landowners, environmental groups and other interested stakeholders on several other PSH projects in the surrounding western states and other environmentally positive endeavors. 

Currently, 56 GW of PSH is planned or under construction throughout the world with zero under construction currently in the U.S. It is important to the hydro industry – and our country – that we continue our work together to begin to develop grid-scale PSH again.


David Gatto is business development manager, hydroelectric and water, for Ames Construction, a full-service heavy civil and industrial general contractor serving multiple markets throughout North America. In business for nearly six decades, Ames began performing hydropower work in the 1980s, with expertise in constructing complex water-related projects throughout the U.S.

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