Op-ed: Sustainable options for transporting the energy of natural gas

When Qatar began investing in power plants to convert its vast natural gas reserves to liquid natural gas, the fortunes of the country were dramatically changed. Suddenly, this form of energy could be converted into liquid form and transported worldwide to countries that needed it.

However, what if there were better ways to move all this energy? And, more to the point, what if there were more efficient and sustainable ways of doing this?

This is the issue we have tackled in the Sustainable Energy Program at the College of Science and Engineering at Hamad Bin Khalifa University. The technological barriers to energy transportation include low energy density, intermittent supply, and energy sources’ immobility. And a potential sustainable solution for overcoming these barriers is to use an effective and efficient energy carrier to store, transport, and distribute energy in a technically feasible manner.

Understanding that Qatar must adapt to global trends toward greater sustainability, we analyzed the five different liquid energy forms (liquid hydrogen, liquid ammonia, methanol, dimethyl ether (DME), and liquefied natural gas (LNG) that natural gas could be converted into, and looked at their environmental friendliness, physical efficiency, and cost-effectiveness.

Technically, during the supply chain, some liquefied energy mass is lost continuously due to the temperature difference between the liquefied energy carriers and the ambient, and these losses are called boil-off gas (BOG).

The generated BOG is treated differently either by flaring to the environment or capturing it for different purposes, such as power generation or re-liquefaction. We calculated the amount of BOG generated in different phases of the liquefied energy carrier supply chain. The implementation of a sensitivity analysis shows how BOG rates are affected under various parameters, namely ambient temperature, storage pressure, land storage time, ocean transportation time, heel percentage, and pumping time. A cost analysis was also performed to determine the cost of production and transportation of natural gas energy via liquefied energy carriers by accounting for the cost of BOG as well as the social cost of carbon within the production and transportation phases.

The research results showed that the methanol delivers the greatest mass, DME provides the most considerable energy, and hydrogen loses the highest mass as BOG during the supply chain if there is no BOG recovery process. The highest BOG generation mainly occurs during the ocean transportation phase, implying that ocean transportation time is the most critical parameter among the studied parameters.

When a ship's capacity increases from 100,000 m3 to 260,000 m3, the transportation cost of energy as LNG reduces by about 12.5 percent. DME and methanol can be more economical than LNG to transport the energy of natural gas for the same ship capacity. And given the ocean transportation costs for the energy of natural gas as liquid ammonia and liquid hydrogen, these forms – which are carbon-free and have no direct greenhouse gas emissions during utilization – can be alternative and cleaner options for short distances, enhancing the country's economy by diversifying its exports in the energy sector.

Addressing the environmental cost associated with producing and transporting the energy carriers can provide a clearer picture of which of these carriers meet the environmental regulations set by the International Maritime Organization. For example, including the social cost of carbon (SCC) within the total cost of transporting natural gas energy can become a decision parameter. As the social cost of carbon increases, LNG’s total transportation cost increases dramatically. This consideration favors liquid ammonia, methanol, and DME as an energy carrier of natural gas.

The conclusions pave the way for better optimization. We found that liquid hydrogen and liquid ammonia, the only two non-carbon-based forms, are best for the environment, but hydrogen loses the most energy during transport due to its thermophysical features. As for carbon-based forms, methanol has the best physical efficiency but is more complicated than dimethyl ether to transport over long distances. Each of these energy forms has its main uses – hydrogen for chemical feedstock, methanol for fuel, ammonia for fertilization and cooling – but the main point is to reduce carbon-based, fossil fuels used in power, heating and cooling, and transportation sectors.

This research will be instrumental in helping companies such as Qatar Petroleum, Nakilat and Qatar Gas optimize their operations with natural gas production. Countries such as Japan are leading the way in hydrogen-powered vehicles, and Australia is currently paving the way as a liquid hydrogen supplier.

This project generates optimism about the possibility that we can live more sustainably on renewable resources. The project was awarded Oman’s National Research Award 2020 as best published research led by a young researcher (non-PhD holder) in the Energy and Industry Field, for the research paper titled “Investigating the Technical Feasibility of Various Energy Carriers for Alternative and Sustainable Overseas Energy Transport Scenarios”, which was published in the Energy Conversion and Management journal by Elsevier.


Dr. Yusuf Bicer is an Assistant Professor at the College of Science and Engineering at Hamad Bin Khalifa University, where Mohammed Al-Breiki is a PhD student and researcher in the Sustainable Energy program.