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Verified Technologies for SmartWay and Clean Diesel

Foss Maritime / AKA Technology—XeroPoint Hybrid Tugboat Retrofit System

This retrofit technology is included on EPA's Verified Technologies List for Clean Diesel.

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Technology specifications

Engine Model/Application

Harbor tugboat vessels with auxiliary generator engines, rated horsepower range between 100 and 750 hp and main propulsion engines up to 5,000 hp each

Retrofit Fuel, Max Sulfur 15 parts per million (ppm)
Reduction in particulate matter (PM)a 25%
Reduction in nitrogen oxide (NOx) 30%
Reduction in hydrocarbons (HC) 15%
Reduction in carbon monoxide (CO) 35%
Reduction in carbon monoxide (CO2) 30%

In the application described above, XeroPoint demonstrated a 30% fuel savings. 

This technology is approved for Foss Maritime Company and Aspin Kemp & Associates (Foss Maritime / AKA) XeroPoint Hybrid Tugboat Retrofit System.  The XeroPoint system replaces one of the boat's auxiliary engines and generator sets with a suitably sized new larger generator set and new larger horsepower engine that must comply with current model year EPA emission standards.  The XeroPoint system includes the main hybrid switchboard, DCDC converter cabinet, junction boxes, wheelhouse hybrid control, hybrid E-stop panels, clutches, energy management system, 24V DC uninterruptible power supply and optional batteries.  The XeroPoint system uses Programmable Logic Controllers (PLCs) that are custom programmed to manage and control engine and motor speeds based on throttle demand and the selected mode of operation. The PLC will also control ancillary systems such as environmental (fans, heaters, water cooling), battery monitoring, clutch operation, system monitoring and data logging. The optional batteries are expected to yield minimal emission reduction benefits except in cases where the vessel has access to on-shore power. 

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Criteria to achieve emission reductions

The following criteria must be met in order for appropriately retrofitted vessels to achieve the aforementioned emission reductions: 

  1. Prior to installation, Foss Maritime / AKA must determine final sizing and any energy storage system configuration to satisfy application-specific requirements. 
  2. With the main propulsion engines off, vessel speed is dependent on the XeroPoint system sizing. 
  3. Fuel savings and emission benefits are dependent on reduced operation of the main propulsion engines and operation with the XeroPoint system in transit, idle and stopped modes. 
  4. With the installation of a new generator set Foss Maritime / AKA must incorporate a new engine that complies with current model year EPA emission standards. 
  5. The servicing dealer must follow specific installation instructions approved by Foss Maritime / AKA and validate the necessary components to ensure the proper fuel delivery, power, torque and speed, per federal, state or local regulations. The dealer must submit a validation form to Foss Maritime / AKA to receive a label for the XeroPoint system.
  6. Operating conditions and maintenance requirements of engines and engine components are to be conducted according to manufacturer specifications and are unchanged by the use of the XeroPoint system. 
  7.  The XeroPoint system is designed to be installed on commercial vessels with trained and properly credentialed crew. As such the crews need to have the capability required for operating the system and conducting routine maintenance. Additionally, Foss Maritime / AKA will provide system training as part of the installation.  For major repair work, an electrical technician with training and experience on the system is required. 
  8. Foss Maritime / AKA and the vessel owner must evaluate battery technology options for the specific vessel.  EPA is not specifying a battery technology, rather it is the responsibility of Foss Maritime / AKA and the vessel owner to select a technology based on the individual preference and performance requirements.
  9. Batteries are not required for the operation of a XeroPoint system. However, for systems with optional batteries the XeroPoint system must include a battery monitoring system to warn operators of any necessary actions to ensure the proper operation of the batteries.
  10. For systems with optional batteries the owner’s manual must include maintenance procedures which must include battery safety precautions and the disposition of the batteries.
  11. Batteries and shore-power capability are optional, and could potentially help further reduce emissions and fuel consumption in applications with increased vessel idle time. 
  12. The engine must be operated on ultra-low sulfur diesel fuel (ULSD) of 15 ppm or less. 

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Verification Letter from EPA

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