Revival of Polyalkylene Glycols (PAGs) for Hydrogen-Fueled ICEs and Beyond
Electrically powered vehicles using lithium ion batteries or fuel cells represent the mainstream favored by politicians. Such green technologies require specific resources with limited availability, according to the recent report from May 2021 of the International Energy Agency (IEA). The scarcity of such resources will limit their upward market penetration. In consequence, internal combustion engines (ICE) fueled with hydrogen represent another option for CO2-neutral mobility. Hydrocarbon- or ester-based engine oils suffer from the water generated from the combustion of hydrogen inevitably leaked to the crankcase.
This calls for a base stock with a distinguished feature of intrinsic water solubility. Polyalkylene glycols (PAGs) are a class of such a base stock.
PAGs are well known to be the base oils with the lowest intrinsic friction. Today, their building blocks of n-butanol, ethylene oxide and propylene oxide can be made from renewable or biogenic resources, thus meeting sustainability and the requirements of a circular economy. Consequently, PAGs will have a low CO2 emissions factor. PAGs respond to the ecotoxicity criteria of environmentally acceptable lubricants. PAGs are available at large volumes, meet all the future attributes for engine and gear oils, and are worth being revived. Due to the polarities in each monomer, PAGs offer low to very low friction under the lubrication regimes of hydrodynamic and mixed/boundary lubrication. Comparative friction data determined by different tribometric equipment and bench tests will be shown.
