At the recent Hazards XX conference in Manchester, the HSE presented a paper on the dangers of biodiesel manufacture. They are concerned about the risks from biodiesel esterification process, mainly from the use of caustics (NaOH, KOH), and from methanol (including inhalation and ingestion risks, and also the risks of fire and explosion). The caustic/ methanol mix (“methoxide”) can also pose health and safety risks.

There have been numerous incidents worldwide including:

► Fires and explosions from a variety of ignition sources, including leaks of methoxide onto electrical equipment; vapour being ignited by unprotected electrical equipment; failure to turn off heating element on reaction vessel; ignition of biodiesel during pumping into a road tanker (2 deaths); welding the top of a biodiesel storage tank while biodiesel was in the vessel (USA, 1 death); grinding operation on a vessel containing methanol causing an explosion.
► Burns from caustic substances including: uncontrolled exotherm of methoxide mix causing boil-out of vessel and burning operator; operator clearing caustic potash from a blocked reactor feed chute by using a screwdriver was burnt at the junction between glove and chemical suit, needing a skin graft

The paper HSE presented at the conference is not available for download, but most of the practical advice in that paper is included on their website at these two links:

► Domestic Production of Biodiese, Health and Safety Warning (also applies to manufacturers, and contains useful links to other guidance) http://www.hse.gov.uk/pubns/biodiesel.htm
► What HSE are looking for when they inspect a Biodiesel site: http://www.hse.gov.uk/foi/internalops/hid/spc/spcenf137.pdf

News article 4th June 2008