INSIGHT: Can a Green/Conventional Methanol Blend Be a Sound Transitional Fuel?

Estimated total Well-to-Wake GHG emissions for a methanol dual fuel vessel on a single hypothetical Singapore-Rotterdam voyage for different fuelling options. Image Credit: Eddy Van Bouwel

According to Clarksons Research, 125 methanol dual fuel vessels were ordered in 2023. When using green methanol, these vessels should be able to very substantially reduce their GHG footprint.

Actual use of green methanol remains very limited at this stage, as availability is limited and it comes at a cost substantially higher than the cost of conventional fuel oil. In the absence of regulations that effectively help to close the cost gap, use of green methanol will remain limited.

But some are considering green/conventional methanol blends in the interim.

As conventional methanol has a higher well-to-wake GHG footprint than VLSFO, this would not be a good idea.

GHG Comparison

Conventional methanol is widely available, with a global production around 170 million mt/year. But with an estimated Well-to-Wake (WtW) GHG footprint of 102/g CO2eq, it leads to GHG emissions that are about 11% higher than the WtW emissions of conventional fuel oil.

Therefore conventional methanol cannot play a role in decarbonizing shipping emissions.

Green methanol, on the other hand, can be produced from biogas (bio-methanol) or can be synthesized by using renewable hydrogen and CO2 from a renewable carbon source (e-methanol).

The GHG footprint of green methanol will vary depending upon the detailed production pathway that has been used.

Recently a 20/80 green/conventional methanol blend has been used in a bunkering operation in Singapore. Such a blend has an estimated WtW GHG footprint of about 82.5 g CO2/MJ, which is around 10% lower than VLSFO.

At first sight, this looks like an attractive transitional fuel to bridge the period until sufficient green methanol becomes available at commercially attractive prices. But using such a blend would mean that a substantial volume of conventional methanol would find its way into ships' tanks, and this would actually be counterproductive from an overall GHG emission perspective.

Lower emissions could be achieved by using a smaller volume of pure green methanol, and using conventional fuel oil to meet the remainder of propulsion energy requirements, making use of the dual-fuel capability of current methanol fueled vessels.

While using a 20/80 green conventional methanol blend would lead to a saving of around 10% versus using fuel oil, savings would be around 20% if a ship were to use green methanol for part of the voyage and switch to fuel oil for the remainder of the voyage.

In other words, WtW GHG savings would be twice as high when using a mix of green methanol and fuel oil versus using a 20/80 green/conventional methanol blend.

One obvious advantage of using a green/conventional methanol blend is that it avoids the need to switch fuels during a voyage. While technically possible, a switch during a voyage requires a strict
procedure to be followed in order to avoid any risk of engine damage or worse, a black-out.

Furthermore, use of methanol leads to lower NOx and SO2 emissions. But the additional overall GHG emissions versus using a mix of green methanol and conventional fuel oil is substantial.

It may make sense to use of green/conventional methanol blends for testing and market development purposes. But it does not seem to be good idea to develop green/conventional methanol blends into mainstream transitional fuels. With a bit of planning, ships should be able to alternate voyages on fuel oil with voyages on pure green methanol in case they prefer to avoid the need for fuel switching while sailing.

Delivering the IMO GHG strategy will be challenging, and regulations to encourage ships to use fuels with the lowest possible overall GHG footprint will unavoidably introduce complexity. The details of such a regulatory framework will need to be well considered to make sure that ships will make proper fuel choices to decarbonise shipping as effectively and efficiently as possible.

What may sound like a good idea at first, may not be such a good idea when considering all the details.

That is the case for blends of green and conventional methanol. While they would lead to lower GHG emissions than using fuel oil only, they would lead to higher overall emissions compared to using green methanol only and complementing it with fuel oil.

This is quite different from the case of LNG, where blends of bio- and fossil LNG would lead to lower overall emissions versus using a mix of bio-LNG and fuel oil.

To view a longer version of this article with supporting materials, including some regulatory considerations, click here.