Rural Pumped Storage Hydropower

 

An infographic explaining how PSH works

What is Pumped Storage Hydropower? 

Wind energy generation has steadily decreased in cost in recent years, and is now competitive with electricity even in large markets where other sources like natural gas are readily available.  In rural Alaska, where wind energy is in many cases abundant and communities depend on expensive and difficult to supply diesel generators, wind energy (and to a lesser extent solar) is very likely to be a step forward.

However, wind and solar energy are too variable to provide reliable electricity on their own. They must be balanced either with other energy generation or with large-scale storage. One technology that can fill this role is Pumped Storage Hydropower (PSH). 

Unlike conventional hydroelectric power, PSH is an off-river closed or semi-closed loop system that transfers water between two reservoirs; one at high elevation, and another at low elevation, connected by a penstock or tunnel.  It acts like a battery to store wind, solar or other variable energy for when it’s most needed. 

When electricity is needed, but wind or solar energy is not available, water from the upper reservoir can be released, drawn by gravity through a turbine to generate energy, and recaptured in the lower reservoir.  Likewise, when wind or solar energy is available, but demand for electricity is low, it can be used to pump water back uphill to refill the upper reservoir, thus storing that energy for when it’s needed, and the cycle begins again. 

PSH is a proven technology that currently accounts for around  95% of energy storage worldwide. PSH has a much longer lifespan of 50 or more years and a significantly lower per kWh cost compared to lithium-ion batteries with a lifespan of between 8 and 15 years at a higher per kWh cost (see Table 1). 

A graph showing the comparative costs of different energy storage options
Table 1. Relative per kWh cost of short-term lithium battery, short-term Pumped Energy Storage and Long-term Pumped Energy Storage as of 2020.
Image of water being piped from a reservoir

Pumped Storage Hydropower in Rural Alaska

Alaska has an abundance of wind, water, summer solar and rugged terrain, ideal conditions for Pumped Storage Hydropower. 

At the end of 2020 ALICE was awarded a grant from the Denali Commission to look into small-scale PSH as a cost-effective means of closing the gap for rural communities to fully transition to renewable powered energy.

The ALICE PSH team has identified dozens of potential sites for small-scale wind/PHS systems adjacent to existing reservoirs, lakes, rivers and even seawater.  Our priority now is to work with local Native Village Councils, Cities, utility managers and interested regional and local entities to better understand the current and future energy needs of communities, how PSH might best complement existing microgrid operations and identify local siting concerns that might conflict with cultural, subsistence or other resources so that we can fine-tune our final prospect designs and begin to engage directly with interested parties.

Please use the comment form below to send your welcomed feedback, questions and inquiries.

To learn more, click on the links below:

 

Draft map of potential small-scale PSH-renewable energy microgrid prospects in rural Alaska.
Draft map of potential small-scale PSH-renewable energy microgrid prospects in rural Alaska.

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