There are about 1,800 sites in Alaska suitable for closed-loop pumped storage hydropower projects and many more suitable for open-loop pumped storage projects, according to Argonne National Laboratory.
“We are not assuming that projects will be developed on all 1,800 sites, but there are plenty of locations available for potential development,” Vladimir Koritarov, director of the Center for Energy, Environmental and Economic Systems Analysis in Argonne’s energy systems and infrastructure analysis division, said in a statement.
An open loop pumped hydro system uses a natural water source to create a lower reservoir.
Unlike other states, Alaska is not connected to an interstate electric grid, but consists of two transmission systems and more than 150 small, isolated systems serving remote communities. About 30 percent of the electricity generated in the state comes from renewable resources with the rest coming from fossil fuels.
Alaska also is warming faster than any other U.S. state, according to the Department of Agriculture, and suffering from coastal erosion, increased storm effects, sea ice retreat and permafrost melt.
To integrate more zero-carbon energy sources into Alaska’s energy systems, scientists are looking for cost effective ways to store energy to provide constant power when solar and wind are scarce.
For the report, The Prospects for Pumped Storage Hydropower in Alaska, Argonne scientists, in partnership with the Department of Energy’s National Renewable Energy Laboratory, created detailed models using the lab’s Argonne Low-Carbon Electricity Analysis Framework to simulate power system operations and planning and analyze projected electricity demand growth over the next 25 years, as well as the expected retirement of existing generators as they reach the end of their economic life.
The project was funded by DOE’s Water Power Technologies Office.
“One of the key findings of the A-LEAF modeling is that the Railbelt system will need both short- and long-duration energy storage in the future,” Koritarov said. “That storage will balance the operational variability of wind and solar generation and provide reliability and backup capacity for longer periods.”
The Railbelt transmission system comprises five regulated public utilities extending from Fairbanks to Anchorage and the Kenai Peninsula. About 80 percent of the Railbelt’s electricity comes from natural gas.
Pumped storage hydro candidate sites were part of the optimal capacity expansion solution in all scenarios analyzed for the Railbelt system, the study found, adding that, depending on the scenario, the new pumped storage hydro capacity that the model selected for the analysis period until 2046 ranged from 300 megawatts to 600 MW.
In addition, because of their small reservoir sizes and dam heights, many locations were identified as potentially suitable for small-scale pumped storage hydro systems. Nearly 50 percent of the identified potentially suitable small-scale pumped storage hydro sites are in Southeast Alaska, according to the report.
The model also selected lithium-ion batteries as a source of new generating capacity in all analyzed scenarios for the Railbelt system, indicating that the system will need a mix of short- and long-duration energy storage to support variable renewable energy sources, the study found.
As part of the study, NREL scientists evaluated Alaska’s remote areas that are powered by small isolated electrical grids using the Hybrid Optimization Model for Electric Renewables model.
The researchers analyzed the viability of small pumped storage projects in rural communities with at least 250 or more residents and identified 18 remote communities with potential for smaller pumped storage projects.
“For larger remote communities with higher diesel costs, results showed that pumped storage hydropower could be a cost-effective option depending on site-specific considerations such as renewable resources and constructability,” Rebecca Meadows, a NREL senior engineer, said in a statement.
In most cases, however, pumped storage hydropower may not be economically feasible for remote areas because of the high investment cost of small-size pumped storage projects, the researchers said, adding that lithium-ion battery storage may be more economically viable in rural areas seeking to lower electricity costs but would not provide longer duration storage economically.