Shipping faces the grand challenge of decarbonization and energy transition that will require industry-wide efforts on the technical and operational fronts.

CLEOS was formed as a collaboration between three Greek shipping companies, GasLog, Drylog and Olympic Shipping, with the purpose to perform research and development, and offer advisory services regarding decarbonization.

These include energy efficiency technologies, alternative fuels, power generation and propulsion systems, emissions control and aftertreatment, carbon capture, and other solutions pertaining to marine vessels.

Our objective is to assist the owned and managed fleet of the group to navigate the emerging energy transition landscape, comply with future regulations, and become an industry leader in adoption of state-of-the-art technology.

Company Ownership and Structure

Collaboration between three Greek shipping companies


Gaslog is a leading global provider of LNG shipping services. It delivers natural gas that is helping the world transition to a lower carbon future, making LNG shipping safer, cleaner and more efficient.


Drylog Ltd. is a dry bulk shipping company established in 2001 as a fully owned subsidiary of Ceres Shipping Ltd., controlling a fleet of between 70 and 80 owned and time-chartered bulk carriers.

Olympic Shipping

Olympic Shipping is a subsidiary of the Onassis Foundation and owner of 18 crude oil tankers, assembling a great team of senior level experts and the most promising young professionals.

Mission & Objectives


  • Research and propose safe, commercially viable and customized technologies, and/or practices towards a Net-Zero Carbon Maritime Industry
  • Increase competitiveness, sustainability and resilience of the client-companies through innovation
  • Promote collaboration and partnerships with key regulators, policy makers, investors, and customers towards defining appropriate best practices, policies and regulations
  • Enhance knowledge-base of the client-companies through training and skills transfer


  • Perform and coordinate research and development work in the fields of energy, fuels and decarbonisation technologies for the maritime sector
  • Provide consulting services on decarbonisation strategies to the CLEOS shareholders
  • Promote the commercial exploitation of technologies developed by CLEOS


George Skevis, Ph.D., DIC

General Manager

George Skevis is a Mechanical Engineer with expertise in novel combustion concepts, combustion chemistry of conventional and alternative fuels, emissions control and aftertreatment, and carbon capture and sequestration. Prior to joining CLEOS, George was a Principal Researcher at CERTH and has served in multiple research and academic roles. He holds a Ph.D. in Mechanical Engineering from the Imperial College London.

Sotiris Mamalis, Ph.D.

Senior Development Engineer

Sotiris Mamalis is a Mechanical Engineer with expertise in power generation and propulsion systems. He has performed research on internal combustion engines using conventional and alternative fuels. Prior to joining CLEOS, Sotiris completed an academic tenure in the United States and served in sustainability roles in the maritime industry. He holds a Ph.D. in Mechanical Engineering from the University of Michigan.

News & Articles

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The Outlook of Biofuels for Shipping – Opportunities and Challenges

In the recent MEPC 80, the International Maritime Organization (IMO) enhanced the targets for decarbonizing shipping, by mandating a 20% reduction in absolute GHG emissions by 2030 (striving for 30%) and a 70% reduction by 2040 (striving for 80%).


Zefirou 8, Paleo Faliro 175 64, Athens, Greece