MERC Guide

Most Scope 1 emissions are from fuel consumed by an organisation’s vessels, vehicles and stationary engines. One way this can be addressed is to source more sustainable fuels.

There are two main ways that you can use more sustainable fuels. Firstly drop-in sustainable fuels, also known as low-carbon liquid fuels (LCLFs) are an obvious interim choice as they can be used in existing engines without modification (perhaps with some minor adjustments). The second approach is to find a renewable fuel that may require significant modifications to your existing engines, if not complete replacement of them.

The sorts of fuels that are worth considering here are:

• Biodiesel
  A first-generation biofuel, Australia’s biodiesel fuel standard covers diesel obtained from esterification of oil derived from plant and/or animal material. Most engine OEMs specify a maximum blend of 20% (known as ‘B20’), although you should always contact your engine OEM to be sure what is covered.

• Renewable diesel
  Almost indistinguishable chemically to fossil diesel. Most forms of this fit Australia’s paraffinic diesel standard, although there are some that can match the normal automotive diesel standard. Most engine OEMs support up to a 100% blend of renewable diesel (known as ‘RD100’), although custom blends can also be supported.

• Ethanol
  Another first-generation biofuel, ethanol is derived from plant sugars. It is commonly blended with petrol in a 10% blend (known as ‘E10’), and is supported by most engine OEMs, but some special engines can handle a higher blend of 85% ethanol (known as ‘E85’). Concerns have been raised by engine OEMs as to the suitability of ethanol in a maritime setting as it is highly hydrophillic (water-attracting) and hygroscopic (water-absorbing) and this can lead to water build up in petrol tanks and phase separation, which can cause engine damage.

• Renewable Methane (LNG)
  Some vessels have already converted their engines to run fully, or partially, off liquid natural gas (LNG) or methane. Renewable sources of methane exist, and this is a viable option if you can source the fuel reliably, and at a good price. Australia’s GreenPower has developed a Renewable Gas certification to support a book-and-claim system that lets methane purchasers buy renewable gas certificates to guarantee their use is covered by renewable sources of methane, without actually requiring the molecules used to be from renewable sources.

• Green Methanol
  Whilst this is a promising shipping fuel, there are few engine OEMs providing solutions in the scale of passenger vessels. There are also concerns with obtaining a reliable supply of green methanol as it is expensive to produce and has few practical use cases, therefore there is relatively low demand for it.

• Green Ammonia
  Green Ammonia is being investigated by some shipping companies (notably Fortescue) as a way of decarbonising international bulk shipping. Safety is a major issue for this type of fuel, as it is both highly toxic and flammable. Due to these concerns it is regarded as unsuitable for use on passenger vessels.