Turn Red Hill into a pumped storage power station

By Aaron Sewake, the Honolulu Civil Beat

April 3, 2022

The US Department of Defense has just announced that it will be closing the fuel storage facility at Red Hill. Now the tedious inspection of the pipelines, the emptying of the tanks and the cleaning of the system begins.

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After years of struggle and advocacy by numerous community groups and government officials, this may seem like the finish line of a year-long marathon.

However, we as a community should stop thinking about what’s next.

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Personally, I would hate to see it go to waste and would love to put it to good use instead.

Given the design of the plant and our needs as a community, I believe it would be best to convert the fuel plant to a pumped storage power plant.

Pumped storage power plants are an energy storage technology that has been in use for over a hundred years. It uses two reservoirs at different elevations connected by pipes known as the penstock.

A pump/turbine near the lower reservoir uses surplus renewable energy or cheaper off-peak energy to pump water from the lower reservoir to the upper reservoir during periods of low energy demand. As energy demand increases, water is released from the upper reservoir to flow through the turbine, converting gravitational potential energy into electricity.

battery storage

PSH is the largest capacity energy storage technology currently available. According to the US Energy Information Administration, the round-trip efficiency of PSH is about 80%, which is equivalent to utility-scale battery storage.

A major benefit of PSH over battery storage is its ability to store energy for long periods of time. Batteries are good for short-term storage and constant cycling, but will slowly discharge over time even when not in use.

The US Department of Defense has ordered the permanent closure of the Red Hill fuel depot. Could it be repurposed to produce energy for Oahu? Courtesy US Navy/2022

However, water stored in tanks can easily be stored for months to years. This makes PSH well suited for the long-term storage of emergency energy, e.g. B. longer periods of low solar or wind production, or for shifting energy from periods of high production, such as summer, to periods of low production, such as winter.

Much of the infrastructure for such a facility already exists. The existing fuel tanks would serve as the upper reservoir, while the piping and tunnel system would serve as the penstock.

A new lower reservoir and a new pumping and power station would need to be built, which would probably be the largest cost of this project. Rather than building a traditional reservoir dug out of the ground and open to the air, prefabricated tanks like those already used for water and fuel storage can be set up and linked together like the Red Hill tanks.

This closed loop system would greatly reduce water loss through evaporation and is immune to drought conditions. Also, the facility can be easily scaled up by adding new tanks to increase capacity if needed in the future.

The interconnected tank system also improves serviceability by allowing individual tanks to be isolated and drained for cleaning and maintenance without disrupting operation of the plant as a whole.

However, this option would require a lot of space to accommodate the necessary infrastructure, space that is at a premium on this island.

Another possible, albeit highly unorthodox, alternative for a pumped storage power plant is to use the ocean as the lower reservoir. This has only been done once in the world at the Okinawa Yanbaru power plant.

Instead of storing water in tanks in the lower reservoir, water would be pumped and dumped directly to and from Pearl Harbor. This would result in significant space savings.

Of course, the obvious challenge with this option is the increased maintenance costs due to corrosive seawater and barnacle growth. The Okinawa plant used fiberglass-reinforced plastic tubing, which resists corrosion, and stainless steel turbine blades to solve this problem.

Some of the increased maintenance costs could also be mitigated by reducing the infrastructure required as there is no need for a lower reservoir. These numbers need to be quantified to determine which option makes more financial sense.

A system connected to the ocean would still raise the question of possible leaks affecting the aquifer. A serious discussion would need to take place with the Board of Water Supply to determine what, if any, precautions and design features would be acceptable.

Without their consent, this option is a non-starter. If BWS is okay, then there’s also the question of what impact the constant pumping and dumping might be having on both wildlife and operations at Pearl Harbor.

There are many environmental questions that would need to be answered if the ocean were to be used as the lower reservoir, so any work on this option would definitely take longer to assess what impact these might have, further increasing costs.

Much of the infrastructure for such a facility already exists.

Regardless of which option is chosen, I believe that converting the Red Hill fuel plant to a pumped storage facility would be the best decision the Navy could make for the future of the plant. It would provide much-needed energy storage capacity that could power the entire island of Oahu, and it fits perfectly with the Navy’s goal of increasing renewable energy use and reducing reliance on imported oil.

The increased storage capacity would allow more intermittent energy projects, such as rooftop solar and the recently proposed offshore wind projects, to be brought onto the grid by buffering the fluctuations in production and providing a smoother, more consistent power output.

With no geothermal or nuclear production planned for Oahu, adding a renewable source of solid, shippable energy in the form of PSH would greatly improve the resilience of our grid.

We have a unique opportunity to transform a historically damaging facility into clean energy that will benefit both the Navy and our community for years to come.

I beseech the Navy, City and State to consider this proposal and invest in our future.

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