The installation of 1,300 solar panels on Alcatraz Island in San Francisco Bay has been completed, powering lights and appliances that for 75 years were powered by diesel fuel ferried across the bay.
NREL recently helped the National Park Service and the DOE Federal Emergency Management Program convert the island’s electricity source from diesel fuel to photovoltaic panels on the rooftop of the Cellhouse building.
Now a 307-kilowatt photovoltaic array sits on the roof of the main Cellhouse building, attached to two 2,000-amp-hour battery strings and an inverter plant. The new 1,300-panel system produces close to 400,000 kilowatt-hours of electricity a year, reducing carbon dioxide emissions by about 337,000 kilograms a year and reducing the time the generator runs from 100% to 40%. The NPS also made some energy efficiency changes, such as better light bulbs and changes in operation to reduce energy consumption.
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.
A massive solar battery system helps power the island when the sun doesn’t shine, hidden from the view of the 1.4 million visitors the island and prison get each year.
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.
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) 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.
The design assistance NREL provides for FEMP includes modeling, monitoring, analysis, and alternative financing assistance to support energy conservation and renewable energy projects in federal buildings.
