World Leading Marine CNG Ship Design

CNG Optimum

GEV’s CNG Optimum ship is the next generation of Marine CNG  transportation and the result of two decades of developing a low-cost, volume efficient CNG ship design. The CNG Optimum ship is now construction ready with GEV seeking to commercialise CNG projects using an integrated ‘Pipe to Pipe’ Business Model which includes loading, shipping and unloading.

The CNG Optimum ship design maximizes the amount of Compressed Natural Gas that can be stored within the hull of a ship, with a capacity of 200 million standard cubic feet. The Optimum containment system is constructed using hexagonal close-packed, high strength pipes that run the entire length of the ship’s cargo hold. The simplicity of the design and the invention of a mechanism to clamp the gas storage pipes so tightly together that they become locked together as one, allows this design to meet all classification requirements.


American Bureau of Shipping (ABS) issued its formal letter in January 2019 granting approval for construction of the CNG Optimum ship as designed, subject to continued compliance with applicable ABS Rules and Guidelines. Approval of the CNG Optimum ship design follows the completion in December 2018 of the extensive work program including; prototype testing of the Optimum system, review and verification of the design, review of the safety studies and a Hazard and Operability Analysis (HAZOP). Granting of the letter of approval by ABS is a major milestone for GEV and the culmination of three years of effort.

Base CNG Optimum ship design with principal particulars per CIMC Raffles general arrangement drawings.

CNG Optimum ship designed for offshore loading applications. CNG ship is equipped with bow thrusters as part of Dynamic Positioning (DP) requirements and compatible to load gas via a Submerged Turret Loading (STL) system or Single Anchor Loading (SAL) system. The preferred loading system is subject to met-ocean conditions, particularly wave height.


CNG Optimum Design & Construction Partners


GEV’s shipping team is supported by a team of global experts in the design and construction of the CNG Optimum ship, including Clarksons Platou as our Ship Broker & Financial Advisor, SeaQuest Marine as our Lead Technical Consultant and Yantai CIMC Raffles Offshore as the Shipyard for construction.

In July 2019, GEV entered into a Letter of Intent with Yantai CIMC Raffles Offshore to build the CNG Optimum 200MMscf ship. 

GEV and CIMC Raffles will now work towards a binding shipbuilding Engineering, Procurement & Construction contract, employing GEV’s CNG Optimum design, for 4 firm CNG Optimum ships, with the option for GEV to order up to an additional 4 ships.

The selection of CIMC Raffles has been driven by the commercial terms under the LOI. CIMC Raffles has a strong track record, delivering in excess of US$6 Billion in EPC contracts since 2012. CIMC has the required gas expertise, large in house design and gas handling department having built the first and only marine CNG carrier in 2016.

Environmental Benefits

CNG Optimum holds the potential to commercialise a new global industry for the bulk transport of natural gas in regional applications. Natural gas is a vital component of a sustainable energy future, being the transition fuel to renewables. It is the fuel of choice for thermal power generation in many industries because it is cost effective, easy to handle and efficient.

Natural gas usage will replace coal and heavy fuel oil in power plants. This switch in power generation has the greatest short term impact – significantly reducing all polluting emissions and improving air quality.

How Natural Gas compares to Fuel Oil when used for power generation:

  • Reduces Carbon Dioxide (CO2) by 29%
  • Reduces Oxides of Nitrogen (NOx) by 78%
  • Reduces Oxides of Sulphur (SOx) by 99.9%
  • Reduces Particulates by 90%

Marine CNG not only supports the expansion of natural gas usage by land-based customers but enhances the marine environment as well. CNG Optimum ships will be among the cleanest running in the world, equipped with dual fuel engines which run on natural gas from their own cargo. The total amount of gas consumed by a fleet of CNG ships is approximately 2% of the loaded gas. There is no boil off, discharge or recycling since the gas is stored at ambient temperatures in a closed system.