Nov-2021

Well to wake and beyond

How can cleaner gas-to-liquid fuels help propel marine transportation in the lead up to mid-century decarbonisation solutions?

Susan Brownlow
Words for Industry

Article Summary

The risks of climate change now need little introduction. We are already starting to live with the impacts of a changing climate on communities, businesses and supply chains. The most recent Intergovernmental Panel on Climate Change (IPCC) report delivered the unnerving news that we now have less than a nine-year window to act on climate and limit global warming to 1.5°C. It made plain that limiting warming to 2°C will not be enough to prevent the most serious impacts to our way of life.

In 2021 we find ourselves at a critical turning point in the history of our relationship with crude-based fuels. In addition to the already much speculated date when the world will reach peak oil, increasingly stringent legislation to protect our environment and health is gradually resulting in the demise of conventional diesel fuels. To achieve a fully decarbonised economy by 2050 (and in the developing world by 2060), the world must electrify as many economic activities as possible through renewable energy, including wind, solar, green hydrogen and bioenergy.

However, due to the phenomenal investment required to make operational the infrastructure to support such a decarbonised energy system, alternative fuels — at least for an interim period — need to be considered. As an alternative next-generation fuel, gas-to-liquid (GTL) has the capacity to be such a transitional solution to reducing polluting emissions.

GTL: efficiency without toxicity
GTL technology converts natural gas into high-quality fuels, oils and lubricants, and even personal and home care products that would otherwise be made from crude oil. The benefit is that they not only have comparatively better combustion properties when used in diesel engines, but they contain none of the impurities and pollutants, such as sulphur, aromatics, metals and nitrogen, found in crude oil-based fuels.

Free of these contaminants, GTL fuels are non-toxic and biodegradable, and are significantly less harmful to both the environment and to human health. Studies undertaken at Shell have indicated that GTL fuels can reduce nitrogen oxide (NOx) emissions by 37% and particulate matter (PM) by 50% compared to conventional diesel — both known to aggravate respiratory conditions.1 And cleaner emissions mean better air quality.

Colourless and odourless, GTL fuel is an all-year round ‘winter-grade’ fuel, improving cold starts in engines. It also has greater ignition properties due to its higher cetane number, so delivers improved power and higher reliability than conventional diesel — ultimately meaning fewer breakdowns.

As the raw resource for GTL fuels, natural gas is also abundant, with new reserves continually being developed, and a plentiful supply available for decades to come. Add to this the fact that GTL fuel can be treated in many instances as a direct substitute for conventional diesel for most transportation types, without the need for engine modifications (known as a ‘drop-in’ fuel), and there is a very compelling proposition for GTL as an interim alternative. It is easy to recognise the huge potential for GTL as a clean transportation fuel source, particularly in highly populated areas.

GTL also has the advantage that it is easier and more economically viable to transport. Unlike liquefied natural gas (LNG), it remains in a liquid state at or close to ambient conditions. It doesn’t have to be maintained at -160⁰C to remain liquid and no special containers are required — just existing infrastructure.

Transportation applications
The continued dependence on refinery-produced crude products for fuelling the transportation sector is felt by many countries to be a threat to energy security, along with their associated detrimental environmental impacts and a potential drain on economic resources. By offering a practical alternative to diesel that helps to improve air quality without compromising efficiency, GTL has the potential to change the future of transportation fuel usage across the world.

The continued dependence on refinery-produced crude products for fuelling the transportation sector is felt by many countries to be a threat to energy security, along with their associated detrimental environmental impacts and a potential drain on economic resources. By offering a practical alternative to diesel that helps to improve air quality without compromising efficiency, GTL has the potential to change the future of transportation fuel usage across the world.

While many longer-term diesel transportation strategies at fleet level might elect to focus on engine modifications and even carbon offsetting, GTL fuel can be used in many circumstances as a direct replacement for conventional diesel fuels in heavy-duty and light-duty engines without the need for engine modifications, new infrastructure or vehicle investment. As a drop-in fuel, GTL is readily available now to make an immediate impact.

While supply of GTL to retail forecourts is far from established, GTL fuelling for heavy goods vehicles (HGVs) is starting to become available, with one of the primary benefits — apart from the environmental ones — being that little investment is needed in infrastructure modifications. And as a senior executive at Certas Energy, one of the largest fuel distributors in the United Kingdom, succinctly remarked, “as GTL is a drop-in fuel, every car is potentially a GTL car”, speculating that there is a powerful case for retail GTL as a solution to the demonisation of diesel engines.
However, it is in maritime transportation that GTL fuel may see its greatest uptake.

GTL for shipping
The maritime industry plays a very significant role in the world’s economy. While 90% of world trade, mainly undertaken by huge sea-going vessels such as cargo ships and crude tankers, is apparent to most people, there is a vast maritime sub-industry supporting their efforts — from pilot boats and docking tugs to barges and other small coastal vessels. Total maritime activity, therefore, is responsible for about 2.5% of global greenhouse emissions — or around 940 million tonnes of CO2 annually.2 With emissions consisting of sulphur oxides (SOx), carbon dioxide (CO2), nitrogen oxides (NOx) and particulate matter (PM) from diesel fuel used to power all these vessels, they are now under close scrutiny by environmental authorities globally.

Although LNG is increasingly being used to propel larger cargo ships in order to help combat marine emissions, an opportunity to use GTL as a drop-in fuel to power the many hundreds of thousands of smaller support boats and coastal craft has also been identified. The majority of these smaller vessels still use reciprocating diesel engines powered by intermediate or marine diesel fuel oils — otherwise known as ‘bunker oil’, derived from crude oil. These fuels produce high emissions, including CO2, NOx, SOx and PM.