Lignin as cetane booster for methanol and ethanol

A know drawback of methanol or ethanol as a fuel for compression ignition engines are is their intrinsically low cetane number. This means that under normal operating conditions such fuels will not auto-ignite. A commercially available work-around is found in so-called dual-fuel engines, whereby the low cetane base fuel is ignited by injecting a second, higher cetane pilot fuel. Apart from the resulting increased capital expenditure required for a dual-fuel architecture, operating costs can also be higher as two different fuels need to be bunkered throughout the lifetime of the vessel. There are some chemical solutions on the market in the form of alcohol soluble ignition improvers, with a polyethylene glycol derivative branded as Beraid® perhaps being the most well known of which. Our earlier work demonstrated that certain lignin monomers could boost the cetane number of both methanol and ethanol. This paper will build further on these findings, not only by benchmarking the cetane number boosting performance of lignin versus that offered by Beraid®, but also by measuring ignition delays for various concentrations of lignin in ethanol in an optical spray combustion chamber, modeled on a real 2-stroke marine engine. The results definitively prove that alcohol soluble lignin is more than just a source of sustainable calories, but an effective performance additive with the promise of facilitating pilotless alcohol ignition in 2-stroke marine engines.