Over the next few weeks as one strolls or drives along the Embarcadero by Hornblower Cruises’ Grape Street Pier, passersby should stop and take a look at the unlikely sight of a pair of 10-foot-high, white and blue turbines twirling atop a tour boat emblazoned with the logo Alcatraz Cruises. This is the first-ever hybrid ferry operating in the United States – and quite possibly the wave of the future. The turbines were built in San Diego at Helix Wind, under the Coronado Bridge. Now visiting San Diego through Sunday, Jan. 3, the eco-friendly Hornblower Hybrid is the first of Hornblower Cruises’ planned fleet of “green” alternative-powered ferries and tour boats. Based in San Francisco, the vessel normally ferries tourists for the National Park Service (NPS) from Pier 33 to Alcatraz and Angel Island. “We made a commitment to do this for the NPS,” said Jim Unger, Hornblower Cruises & Events vice president and San Diego general manager. “One of the most important reasons that (the ship) is down here is to show off our technology and create interest in our technology partners and customers.” Unger said the firm plans to convert the San Diego-based Adventure Hornblower to green power, whether hybrid, hydrogen fuel cell or a more advanced technology, within a few years. Each conversion, he said, builds upon previous lessons learned. The Hornblower Hybrid, a 10-year-old catamaran originally built as a diving vessel in the Gulf of Mexico, was converted at Bayside Boatworks in Sausalito to run on a mixture of electric, solar and wind power with a boost from diesel-powered generators to provide back-up power as needed. In addition to electric shore power for use dockside, it boasts a whimsical fifth source of power: a stationary bicycle that passengers can pedal to add their personal power to the ship’s energy grid. The 64-foot ship’s computerized “brain” directs power from all sources to charge the bank of 64 marine-grade batteries housed under the salon deck and then distributes electricity to the vessel’s motors, navigation systems, lighting and other operating systems. “It’s mostly a sensing and switching system, like a Prius,” Unger said. “At times of lesser need when the batteries are fully charged it will go offline. It determines that (distribution) even when we’re on shore power.” The Hybrid features several flat-panel displays — called the “Prius gauge” — in the pilothouse, showing energy generation and distribution so that passengers can monitor power flow. Once underway, the ultra-quiet Hybrid can cruise at 6-7 knots using only renewable energy. To boost speed to 10 knots, as needed on its 56-hour voyage down the coast or for maneuvering in tight docking quarters, the Hybrid draws on its environmentally-advanced supplemental Tier 2 diesel generators, which sip only six gallons of fuel per hour, compared to the more than 30 gallons per hour for conventional generators. The Hybrid’s other eco-friendly features include interior carpeting made from recycled materials, countertops crafted from recycled blue Skyy Vodka bottles, energy-saving LED lighting using a total of only 150 watts and signage made from plyboo, a combination of plywood, bamboo and recyclable ink. “Everything we did in building this boat is consistent with the ideas of sustainability,” Unger said. Hornblower also favors use of local boatyards and contractors for conversion and maintenance of its vessels. Just as the San Francisco-based Hybrid was overhauled in the Bay Area, the next project — conversion of a 600-passenger ship incorporating a hydrogen fuel cell in its renewable power systems to ferry Statue of Liberty visitors in New York Harbor — will be undertaken at a yard in nearby Connecticut. When the Adventure Hornblower is converted to green power, Unger said he plans to use a San Diego boatyard. The Hybrid’s $4.5 million conversion, funded entirely by Hornblower, was designed in-house by Cameron Clark, Hornblower’s director of environmental affairs and special projects at Alcatraz Cruises, a Hornblower subsidiary.  Installation of the new systems took only about 30 days, said Hybrid Capt. Aaron Warren, who was involved in the construction. Warren captains the boat on cruises and brought her to San Diego. The Hybrid can accommodate 149 passengers as a ferry and up to 110 for a cocktail party. During the Hybrid’s six-week visit to San Diego, Hornblower is offering the public special two-hour Happy Hour and Eco Bay cruises aboard the Hybrid on Dec. 17, 19 and 26. The trip is $40 for adults and $35 for children for Hybrid Happy Hour and includes light hors d’oeuvres and music. For the Hybrid Eco Bay Cruise, the cost is $30 for adults and $15 for children. The Hybrid is also participating in the San Diego Bay Parade of Lights and is welcoming passengers Dec. 20 with holiday appetizers and desserts at rates of $69 for adults and $49 children. For more information and reservations, call (888) 467-6256, or visit www.hornblower.com and click on San Diego and “local events.” The Hybrid departs the Hornblower dock off Harbor Drive at Grape Street.