Hornblower Hybrid - Quietly exceeding expectations
An interview with Christopher Beck, port engineer for Alcatraz Cruises in San Francisco, about the company’s Hornblower Hybrid vessel
By Edward Lundquist
What makes the Hornblower Hybrid a “hybrid?”
We use a combination of diesel‐powered Tier 2 generators, electric motors, wind turbines and photo voltaic solar panels to charge batteries that provide power to all the functions of the vessel, including navigation systems, lighting, monitors and the variable frequency drive that controls the motors.
What kind of power systems does it have?
It has two Series 60 MTU Tier 2 diesel engines powering two Marathon 320 KW generators that provide power to two Yoskawa variable frequency drives, which control the output of two 400 HP electric motors connected directly to
conventional propellers. It also has a 380 V DC Battery bank that allows for a zero emission mode. The vessel also employs two 1.2 KW wind turbines and a 1.2 KW solar array.
Does it have a conventional engine/screw arrangement? Does it have an electric drive system?
We have an electric drive system for propulsion that uses a custom advanced power management system that regulates when and how the different power sources are used. For example, when the vessel is idling at the dock it can be operated with no diesel engine running. The motors will use energy that has been stored in batteries. The system that allows this flexibility is what allows us to drastically reduce the amount of fuel used and reduce the amount of emissions produced.
How often do you have to use the diesels?
The diesel engines are used when the boat runs between the shore and the island. The advantage of using electric motors is that we only need to run one generator to supply the vessel with enough electrical power to keep our schedule, instead of operating two diesel propulsion engines. This saves fuel and reduces the amount of emissions produced. When we are at the island or at the pier we operate on batteries or shore power, using no fuel and creating no emissions.
What other unique features does Hornblower Hybrid have?
We have worked to not only make the propulsion and power system more energy efficient, but have also used green products in the interior remodel of the vessel. The carpet is post consumer recycled materials. The countertops were created out of old vodka bottles and all interior signage is made from ‘Plyboo,’ a composite material made from sustainable products. All lighting has been upgraded to LED fixtures that require a fraction of the energy of standard bulbs.
We also work diligently at teaching the general public that rides the vessel about the benefits of this technology and what they can do themselves to help reduce their own carbon footprint. We do this through the use of informational signage, video presentations, and a gauge that shows the power system status of the vessel.
What was the business case for the “green” approach?
Part of our contract with the National Park Service to operate the transportation to Alcatraz included introducing a hybrid ferry. We have been interested in exploring new technologies and this contract gave us an opportunity to experiment with what type of components would make a hybrid vessel successful. Initially we looked into a solar-only option, but determined that wasn't the right solution for the San Francisco environment. We designed it to meet our needs here and that has proven to be a great foundation for more hybrid projects.
How many miles/hours logged since entering service?
1400 hours.
How has the plant functioned?
Exceptional, no issues.
Has it met expectations?
Yes, the Hornblower Hybrid has meet our expectations and has become the base design for our next two hybrid vessels, both of these vessel are currently under re-power, one for Statue Cruises and another for Alcatraz Cruises.
Any pleasant surprises?
What surprises me the most is how quiet it is to operate, as an engineer used to diesel propulsion it is still a little disconcerting to be moving on the water under our own power and not hear the sound of an engine. My other pleasant surprise is the amount of interest the general public express when they see the vessel for the first time, they always want to know what it is and how it works.
