CPS Energy explores new geomechanical pumped storage technology

CPS Energy explores new geomechanical pumped storage technology

CPS Energy, based in Texas, largest municipal electricity and natural gas company in the United States, entered into a 15-year commercial agreement to explore the installation of up to 15 MW of geomechanical pumped storage (GPS). The deal will kick off with a pioneering 1 MW project that will pump water from drilled wells and store it under pressure, providing up to 10 hours of long-term energy storage.

CPS Energy, which is owned by the city of San Antonio, disclosed the deal with Houston-based Quidnet Energy on March 7, noting that it had hired a technology think tank EPIcenter to support its decision-making process the new form of energy storage. Under the agreement, CPS Energy and Quidnet will build the initial 1 MW, 10-hour storage facility with a commercial operation date of 2024 at a site in Texas that is still under construction. Evaluation. A Quidnet spokesperson said POWER on the March 9 project the partners are evaluate several candidate sites in and around the greater San Antonio area.

However, the agreement also provides “time for both parties” to explore the technology. “CPS Energy will have the option to expand the project to provide 15MW as the project matures,” CPS Energy noted in a statement.

A marriage between electricity and oil and gas

Quidnet Energy’s GPS technology essentially leverages existing oil and gas drilling techniques and conventional drilling technology and hydroelectric equipment to facilitate closed-loop underground water systems designed to guard against evaporative losses.

The concept is based on three steps. When energy is abundant, it pumps water from a pond into a well and into layers of shale. The well, which is closed, keeps the stored energy under pressure between the rock layers “as long as needed”, Quidnet said.

But, “when electricity is needed, the well is opened to let pressurized water pass through a turbine to generate electricity, and return to the pond ready for the next cycle,” the company explained. . “The natural elasticity of the rock works as a spring and keeps the water under pressure until it is needed, at which time it is released by a hydroelectric turbine to generate electricity to send back to the grid.

A slide from a Quidnet presentation from a March 2021 event illustrates how geomechanical pumped storage (GPS) works. Courtesy of Quidnet Energy

The process involves drilling for depths between 1,000ft and 1,500ft to create a high-pressure ‘storage lens’ – essentially an underground reservoir – operating in impermeable, hydrocarbon-free rock,” Quidnet explained. Although the process uses wellbores and tools from the oil and gas industry, it is “quite different from hydraulic fracturing for oil and gas,” he noted.

The size of the storage lens depends on the storage depth and pressure,” the company said. “We store the energy by injecting water into the high pressure lens and send the electricity back to the grid by releasing the high pressure water to the surface via a turbine.” The process is more similar to pumped hydroelectric storage “but without the need for mountains, at a lower cost and in a highly modular way”, which allows the siting of several wells next to each other. The modules could share a surface basin to store low-pressure water, he noted.

The 1 MW facility will be Quidnet’s first commercial project. Bbacked by Bill Gates’ Breakthrough Energy Ventures, Evok Innovations, Trafigura and other investors, Quidnet has explored the feasibility of the technology with CPS and other partners since its inception in 2016. Although it has refined the technology with federal support from the US Department of Energy HydroWIRE Advanced Research Projects Initiative and Agency – Energy (ARPA-E) Duration Addition to Electricity Storage (DAYS) program, Quidnet has also secured state support from the New York State Energy Research and Development Authority and Emissions Reduction Alberta, among others.

In Texas, the company has test sites in Medina and San Saba counties. Quidnet also works in tandem on multiple drivers. A pilot project in Appalachia in Ohio is expected to help alleviate system peak load in PJM Interconnection, while another pilot project is being developed in rural upstate New York to potentially strengthen the regional network. But Quidnet’s potentially biggest project is being developed in Brooks, Alberta, where, armed with C$5 million in funding from the provincial government of Alberta, the company is explore a “multi-gigawatt” energy storage geological resource.

“Our wells in Ohio, New York and Alberta have allowed us to validate our ability to do geomechanical pumped storage in various basins,” Quidnet said. POWER when asked about the status of these projects. “Potential projects in these regions are in the early stages of our commercial pipeline.”

A low-cost profile

In November 2020, Quidnet CEO Joe Zhou told the CPS Board of Directors the main advantage of this technology is its low cost profile. “It’s really a marriage ultimately between pumped hydro storage and the oil and gas industry,” he said.

Compared to conventional pumped hydro, which would require sufficient elevation that CPS Energy cannot exploit given San Antonio’s terrain, “the civilian reach is much simpler and, therefore, the cost profile is much lower. for this form of storage,” Zhou said. Validation of the technology during a well-suggested active test “Storage pressures are comparable to the largest pumped storage facilities in the country,” he added.

The economics of the technology also offers a “structural cost advantage with lower installation costs per MW”, compared to peaking gas plants and other storage systems, Quidnet says on his site. “Long-term costs are expected to be half that of all other advanced storage technologies. »

Among its many other advantages over pumped storage hydropower is the fact that GPS modules – between 1 MW and 10 MW, depending on the resource – can be deployed in various geographic areas on small footprints to provide personalized network support. “Energy-storing rock bodies do not contain hydrocarbons and are found in abundance around the world, intersecting with major power transmission and distribution centers,” the company noted. Modules longer than ten hours can also be grouped together, “much like wind turbines – in larger configurations”, the company added.

Finally, the “simple approach” responds to established federal and state licensing structures, and its simple well construction techniques could allow new facilities to be added to the system in similar timeframes to renewable energy development, the company said. society. The San Antonio project, for example, already has a drilling permit granted by the Texas Railroad Commission, and the partners consulted with the Environmental Protection Agency and Texas Commission on Environmental Quality.

CPS Energy looking for long-term solutions

For CPS Energy, one of the main assets of the project is its potential as a new source of “reliable, safe and resilient service”. said Rudy Garza, Interim President and CEO of CPS Energy. “New technologies such as Quidnet’s GPS energy storage can improve reliability and enable us to expand our renewable energy resources and explore new technologies as we build our path for the future.” he declared. “Integrating Quidnet’s Texas energy storage solution allows us to create a cleaner solution [electricity] while supporting our local energy workforce and reducing costs for our customers. »

CPS Energy said the project will support its “Flexible Path” Resource Plan, according to which the electricity and gas company aims to reduce its net emissions by 80% by 2040 through a portfolio of “proven” technologies and new technologies. Corn Even today, CPS Energy relies heavily dependent on coal and natural gas for its electricity sales of around 27.5 TWh, it plans to shut down all of its coal-fired power plants while integrating new technologies like energy storage and electric vehicles, developing renewable resources and adding more programs and services such as energy efficiency and demand response.

By 2040, CPS aims to increase renewable energy by 127% while reducing gas and coal generation by 72% and 61%, respectively. A global request for proposals issued last year suggests the company is seeking up to 900 MW of solar resources, 50 MW of energy storage and up to 500 MW of firming capacity from all sources.

CPS Energy generated nearly two-thirds of its electricity from natural gas and nuclear, and one-fifth from coal in 2021. Courtesy: SPC Energy

Reliability is especially crucial for the company, given that it powers the electrical and natural gas infrastructure at Joint Base San Antonio, a collection of U.S. military installations including Lackland Air Force Base, Randolph Air Force Base, and Fort Sam Houston/Brooke Army Medical Center, it said.

CPS Energy’s decision to move forward with the Quidnet deal is also noteworthy because of its plans, for now, to use long-term debt to fund cost recovery for purchased power. and natural gas. The company suffered in particular increased purchased electricity and natural gas costs by approximately $1 billion as a result of the unprecedented wintertime power crisis that hit the Texas Electric Reliability Board in February 2021.

Sonal Patel is associate editor of POWER (@sonalcpatel, @POWERmagazine).