Currently the generation of high quality foamed products from aerosol packaging and refillable devices (e.g. whippers) relies upon the use of dissolved or liquefied gases acting as both propellants and blowing/foaming agents. Such gases include nitrous oxide and volatile organic compounds (VOCs); butane, propane, DME, isobutane. Many of these gases were implemented as propellants after the 1987 ban on Chlorofluorocarbons (CFCs), responsible for ozone layer depletion.
However, these current propellant gases are of increasing concern due their role in global warming, smog formation, and poor air quality (indoor and outdoor). Unlike compressed air or nitrogen, these gases are not circular in their use. They are additive to, and polluting the natural atmosphere of the planet. These gases have a wider environmental footprint associated with raw material extraction, synthesis, transportation, storage and disposal. This has lead to legislative bodies around the world implementing increasingly stringent restrictions on the use and emission of nitrous oxide and VOCs more generally.
As well as their role in the generation of poor air quality, nitrous oxide and butane are also illegally used as recreational drugs, or for substance abuse. Both the UK and European Parliaments have discussed proposals to ban or limit the sale of nitrous oxide whipper bulbs to reduce recreational use. As a result the Netherlands have imposed a ban on nitrous oxide sales other than to licensed medical, industrial, and food users from the 1st January 2023. It is anticipated that the UK will enact a similar ban.
Safety and Recycling
The VOC propellants used in aerosol cans are highly flammable making their industrial use hazardous and expensive. Additionally, nitrous oxide, though not flammable, acts as a flame accelerant, enhancing the combustibility of other materials. Many recycling facilities do not wish to accept aerosol cans due to the risk of fire or explosion posed by residual liquefied or dissolved gas propellant. Thus steel, aluminium and PET cans, which may be recycled, will go to landfill.
Over the past five years the commodity cost of petrochemically derived gases such as butane, propane and DME has risen significantly, as has the price of ammonium nitrate used to manufacture nitrous oxide. These increasing commodity costs, combined with increased energy costs, and supply chain uncertainty may make some products economically and environmentally unsustainable. Moving to compressed gas propellants, such as air or nitrogen, removes reliance on fossil and mineral derived feedstocks. Since compressed air and nitrogen can be drawn directly from the atmosphere they could be produced locally to the end user.