It has been 40 years since it was designated a U.S. national park, but the spirits of "Machine Gun Kelly," Al Capone, and the "Birdman of Alcatraz" still haunt the cellblocks at Alcatraz Prison, according to local folklore. And even now, the desolate, inescapable penitentiary is nearly as major a landmark as the Golden Gate Bridge—visible to the north of the span on a nearby island known as “The Rock” in the middle of San Francisco Bay. 

Gloomy is the adjective we would most likely associate with the old prison—but, situated as it is on the highest point of 22-acre Alcatraz Island, it actually is well-insolated. It is so bright, in fact, that 1,300 solar panels have been installed on the roof of the main Cellhouse building—and now are powering lights and appliances that for three-quarters of a century were powered by diesel fuel ferried across the bay.

The 307-kilowatt (kW) photovoltaic (PV) solar array is attached to two 2,000-ampere-hour battery strings and an inverter plant—producing close to 400,000 kilowatt-hours (KWh) of electricity a year, reducing carbon dioxide (CO2) emissions by about 337,000 kilograms a year, and reducing the time the generator runs from 100 percent to 40 percent. The NPS also made some energy efficiency changes, such as better light bulbs and changes in operation, to reduce energy consumption.

What’s more, a massive solar battery system helps power the island when the sun doesn't shine — and it, too, is hidden from the view of the 1.4 million visitors the island and prison get each year. Surplus electricity generated by the solar panels at peak is sent to a 2-megawatt-hour (MWh) valve-regulated lead-acid (VRLA or “sealed” ) battery pack, which was installed next to the island’s new power plant

The panels are part of an effort by the National Park Service (NPS) and the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to bring clean energy to national parks and landmarks. The $3.6 million project was funded by the American Reinvestment and Recovery Act — and, importantly, it is saving money.

The cost of transporting diesel fuel to the island (maintenance costs and the price of the fuel itself) boosted the cost of electricity for the island to about 76 cents a kilowatt-hour, said Andy Walker, a senior engineer and task leader for design assistance in the DOE Federal Energy Management Program (FEMP) at NREL. The PV project brings that cost to 71 cents a kilowatt-hour–and that includes the capital costs of buying the solar panels and erecting them on roofs. With diesel fuel use eliminated, there is far less corrosion of pipes and smokestacks, and less pollution in the bay.

A Long Time Coming

The project was a long time coming. NREL's involvement began in 1995, when FEMP enlisted NREL's Applying Technologies team to monitor the strength of the sun at the island, do a feasibility study, and mock up what a solar installation would look like from up close and from across the bay. FEMP and the NPS contracted with the Sacramento Municipal Utility District (SMUD (News - Alert)) to install PV on Alcatraz's New Industries Building and sell power to NPS for a penny less per-kilowatt-hour than what it was costing for diesel electricity.

SMUD got as far as putting a new roof on Alcatraz's New Industries Building and installing roof stanchions to hold the solar panels. But a historic landmark group protested that the solar panels would be too visible. They could be seen by tourists from an exit door in the exercise yard — and that would mar the historic nature of the New Industries Building, where Al Capone once worked a sewing machine, and Machine Gun Kelly did the laundry.

The Cellhouse became a possible alternative because its roof was less visible from the ground or from the bay. The NPS asked SMUD to put the panels on the Cellhouse roof, but SMUD wanted a guarantee that this time the panels would be up for good. The best the NPS's Advisory Council for Historic Preservation could say was that it had "no objections at this time" to the solar panels being on the Cellhouse roof. That wasn't enough assurance for the utility, and it dropped out of the project.

When Recovery Act funds became available, the Alcatraz project got new life.

"It's ironic," Walker said, "because when the National Park Service was contemplating doing it on its own, they assumed that the Cellhouse would be considered more iconic than the New Industries building." It turned out that there were fewer objections to panels being on the Cellhouse.

The NPS envisioned solar panels on both the New Industries Building and the Cellhouse, but problems with nesting birds and the visibility of the panels delayed installation, said NREL's Byron Stafford. Happily, the progress made by the PV industry over the years — primarily higher-efficiency PV panels — made it possible to put the entire PV system on the roof of the Cellhouse, where it is less visible.

Kent Brogger, the former project manager at Alcatraz t for the NPS, commented, “The expertise of NREL has been of great value" in coming up with a green solution for an island so isolated that electricity needs had been provided by diesel generators.

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