A low carbon alternative to HFO

A new biofuel combines high-performance energy output with immediate, significant emission reduction at low cost.

Jack Williams
Quadrise Fuels

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Article Summary

From commercial cruise liners to container ships, heavy fuel oil (HFO or bunker fuel) has been the primary choice of fuel in the maritime industry for decades. This low-cost, tar-like substance is widely available as leftovers from the oil refinery process but has significant environmental drawbacks as a fuel, whilst also being uneconomic for the refinery that supplies it (it sells at a discount to crude oil). HFO is considered by some to be a dirty and polluting fossil fuel. The International Maritime Organisation (IMO) is under increasing pressure to reduce the high levels of black carbon and NOx emitted by the sector as a result of burning HFO that contributes to global warming and smog.

IMO have also set a GHG emission reduction target of at least 50% by 2050. With potential future marine fuels such as hydrogen and methanol not yet technically or commercially viable on a large scale, there is a growing demand for a more sustainable HFO alternative that utilises well-known technologies and existing supply lines.

The solution
Decarbonisation of the marine industry is an urgent issue; however, the lifespan of a commercial vessel can last up to 30 years. Therefore, an alternative fuel must be suitable for use in existing engines whilst immediately supporting the transition towards net zero. Conversion to liquefied natural gas (LNG) is an option, which can provide around 20% CO2 savings on a well-to-wake basis over HFO. However, fuel storage temperature (-162°C) and operational modification requirements are a hinderance to its progress in the market. There is also an inherent risk of ‘methane slip’ during LNG use that can negate all of the GHG benefits, as methane is a very powerful GHG.
Emulsion fuel blending, the process of producing a stable mixture of water and oil for use in HFO applications, is increasingly being seen as an attractive option to bridge this gap. Quadrise’s leading emulsion fuel, MSAR, is cheaper than HFO and proven to increase engine efficiency as well as reducing energy consumption (it is low viscosity so does not need to be heated) and harmful NOx emissions compared with burning HFO. During MSAR production, heavy oil streams are taken directly from refinery rundown lines and mechanically milled into very fine droplets before being dispersed in a water-based solution.

The team behind MSAR have over 60 million tons of emulsion fuel supply experience. Following successful power plant trials, commercial trials on MSAR were very effectively carried out in recent years with Maersk Line on several commercial container ships, supplied from a Spanish refinery. To supply the fuel, Quadrise worked closely with Cepsa, a Spanish multinational oil and gas company, to install a commercial 6000 bpd MSAR Manufacturing Unit (MMU) (see Figure 1). The MMU was fully integrated into Cepsa’s existing refinery system and operated by Quadrise, utilising their visbreaker residue to produce MSAR fuel. The system was operational within nine months of signing agreements, proving that Quadrise has the expertise to rapidly install and manufacture emulsion fuels at commercial scale.

Quadrise’s new biofuel, bioMSAR, utilises the same technology and commercial emulsion fuel experience, and takes the environmental benefit  of this HFO alternative fuel one step further.

What is bioMSAR?
bioMSAR is an oil-in-water (OIW) emulsified synthetic biofuel comprising of heavy oils and residuals, glycerine (see Fact Box below), water and a small amount of chemical additives. It offers significant benefits over conventional HFO, including reduced emissions of CO2, NOx, SOx, lower particulates (including negligible black carbon), increased engine efficiency and reduced environmental risk in the unlikely event of an oil spill as it readily disperses in water.

Compared with LNG, it provides superior well-to-wake CO2 savings (due to the renewable glycerine component) whilst requiring little to no additional operational changes to burn efficiently within a HFO engine system. Importantly, there is also no risk of methane slip with bioMSAR.

bioMSAR is handled and stored at ambient temperatures (circa 20-30°C). This reduces the energy consumption required to store the fuel compared to HFO, which typically has to be heated to much higher temperatures (60-100°C) to be stored and pumped freely due to its high viscosity. 

OIW emulsion fuels require a small amount of proprietary additives to keep the resultant fuel extremely stable. This pre-atomisation increases the surface area of the oil droplets, enabling complete combustion of the fuel with next to no black carbon formation. The maritime industry is one of the largest sources of black carbon emissions, and MSAR or bioMSAR could be key to reducing this.
Finally, bioMSAR can be fine-tuned to a client’s carbon reduction targets (40% glycerine yields 26% lower CO2 emissions). The proportion of glycerine within the fuel can be altered to meet CO2 reduction targets at the optimum fuel cost.

Development at QRF
At the Quadrise Research Facility (QRF) in Essex, development of the new bioMSAR fuel has been extensive. Over 150 unique emulsions have been produced and tested to determine the ideal combination of fuel stability, effective combustion characteristics and emissions reduction. Following a successful in-house stability and handling testing programme, the next stage of bioMSAR development required demonstration in diesel engines.

bioMSAR engine testing
Quadrise’s engine technology partners, Aquafuel and VTT, are experts in the combustion of glycerine in diesel generators.
Results of bioMSAR testing at Aquafuel’s research facility have confirmed its viability as a high-performance alternative fuel in diesel generators. Testing has demonstrated increased engine efficiency using bioMSAR compared to diesel in a Cummins 4-stroke engine. NOx emissions are reduced by 20-25% as the water content of the fuel reduces its combustion temperature. Due to the pre-atomisation of the emulsion fuel, black carbon emissions were essentially zero.

Further testing of bioMSAR was conducted by VTT in Finland using a 1.6 MW Wärtsilä type-32, 4-stroke diesel engine. Once again, bioMSAR was tested using diesel as a reference fuel, and performed exceptionally well. Engine efficiency was consistently higher (up to 7%) at loads of 50-90%. Average CO2 emissions for bioMSAR on a well-to-wake basis were 580g CO2/kWh, compared to 782g CO2/kWh for diesel, representing a 26% decrease in CO2 output as a consequence of the renewable component of the fuel as well as its higher efficiency.

NOx emissions for bioMSAR were comparable to diesel and HFO. The level of smoke emissions were extremely low, as was unburned hydrocarbon emissions due to efficient combustion of the fuel. No operational issues were experienced when handling and burning the emulsion within the fuel injectors or pumps. There is also scope to improve on these successful test results through optimisation of engine parameters to reduce emissions further. These results represent important steps in demonstrating that this fuel is a viable commercial alternative to fossil fuels in the marine industry.

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