The US National Park Service, National Renewable Energy Laboratory, US Department of Energy and Princeton Power Systems collaborated to install a commercial scale Microgrid System on Alcatraz Island as a solution to high diesel fuel costs, pollution in the bay area, and high carbon emissions. When a ship’s anchor ruptured the underwater power lines in 1950, that linked the island to San Francisco, Alcatraz was forced to turn to diesel fuel and coal as its source of power. This has led to power costs of $0.76/kWh.

Microgrid Design:
This project reflects the National Park Service’s initiative to find an alternative way of powering the island in order to reduce fuel costs and pollution. A microgrid system, comprised of PPS inverters, a solar array, advanced lead-acid batteries, a PPS Site Controller, and back-up generators, was selected as a way to independently power the island. Designing and building the system on one of California’s and the U.S.’s most well-known historic landmarks with over 1 million visitors per year, created many challenges.

Component Placement: Preserving the island in pristine condition while completing the installation was the greatest challenge. Given that a system of this size requires a large construction effort, component placement was key. To prevent the solar array from being visible from San Francisco, it was placed on the roof of the prison in a flat configuration rather than a traditional angled configuration. The inverters, battery rack, and generators were placed in the old generator room, as this space is isolated and not accessible for tourists. The room was also protected from the harsh salt water envrionment.

Commissioning: The fragile natural environment and wildlife, particularly the birds (Alcatraz is an old Spanish word for pelican), added to the challenge. Extra attention was given to the solar panels after being damaged by rocks and shells dropped from overhead birds. Despite the coarse condition of the generator room, engineers were able to insulate the room to prevent future problems and ensure reliable long-term operation.