Before commencing any practical work, it is of the utmost importance to understand the risks involved with making biodiesel. Safety can only be achieved when the biodiesel maker has been fully briefed regarding hazards and the safe working practices that ensure risks are minimised. Here follows a risk analysis that provides a safety model for small-scale biodiesel making.
Risk analysis
Biodiesel production involves using:
- dangerous chemicals
- slippery oils
- heavy containers
- the application of heat
- electricity
Each of the above aspects will be dealt with in more detail.
Dangerous chemicals
The following chemicals will be used:
- methanol (CH3OH) – technical grade 98-99%. This is a clear, colourless, odourless liquid (see data sheet for more details). It is highly flammable and has the added problem that the flame is invisible. You can become intoxicated on the fumes and also absorb it through your skin. Methanol kills receptor nerves, which means that you won’t necessarily feel it burning your skin. Always work in a well-ventilated area with gloves, long-sleeved top and eye protection. Ensure that no hot surfaces are present as a splash could auto-ignite. Do not lean over large containers as the fumes are odourless and intoxication could result. Do not smoke in the presence of methanol. Make sure that you have a source of running water nearby. Wash off any methanol that comes into contact with skin or eyes with copious amounts of water, and seek medical advice. Note that conventional vapour masks are of no use when dealing with methanol however serious they look. Methanol handling should wherever possible use sealed systems.
- potassium hydroxide (KOH) – 100% (flake). This is a white flaked solid (at room temperature) that is violently caustic (see attached data sheet). It will cause severe burns if it contacts your skin. The tiniest speck in your eye will cause terrible damage and could easily result in blindness. The best case scenario is a three-month heal period. Always wear gloves (chemically-resistant nitrile rubber) and eye protection (preferably full face protection) when handling this chemical. Also, wear an apron and a sleeved shirt. If handling a larger quantity (if transferring from a sack to smaller containers for example) then also wear a mask. It is preferable to sodium hydroxide because the flakes are heavier and less likely to get airborne. It is also slightly less toxic than sodium hydroxide. Potassium hydroxide can be neutralized with vinegar (acetic acid). Keep a squeezy bottle (maybe a washing-up liquid bottle) of vinegar handy at all times. If any specks fall outside of their intended vessel then give them a squirt of vinegar. Immerse all implements in vinegar after they’ve been in contact with either the potassium or sodium hydroxide (or methoxide as described later).
- sodium hydroxide (NaOH) – 100% (granules). Our process descriptions are generally oriented towards the use of potassium hydroxide rather than sodium hydroxide. Risks are as for potassium hydroxide but the size of the grains make it more hazardous.
- sulphuric acid (H2SO4) – 98%. Our process does not use sulphuric acid, but this information is included in case you intend to use other recipes which require it. It is an orangey-yellow liquid that smells of sulphur. It is very acidic and will cause severe burns to skin and eyes. Wear an apron, nitrile rubber gloves and full face protection. Avoid inhaling fumes.
All of the above chemicals must be kept off the skin, and out of your eyes, and must not be inhaled – whether vapour or dust. It is important to read the data sheets.
These chemicals are best decanted into small containers in a lab situation. This minimises the risk of spillages that are difficult to manage. Spill management equipment must be at hand in sufficient quantities to contain the quantities that are present. This can be as simple as a bin of sawdust, a broom, and a scoop. Also, an eyewash station must be available with tops ‘cracked’ and ready for use, and in addition a source of running water nearby. We like to have a hose fitted with a trigger spray attachment constantly to hand. Take care not to splash liquids when stirring or mixing.
Store chemicals in a cool, dry, locked area. Use labels to denote the contents in containers. There should also be labels on the store room door to inform people of the potential hazards.
Emergency first-aid procedures relating to biodiesel
- ingestion: rinse mouth with water and seek medical help
- eyes: rinse with water for 15 mins and seek medical help
- skin: wash with soap and water
Slippery oils
The use of any oil presents a risk of slipping – either slipping over, or losing grip on things due to slippery hands. Making biodiesel can be a very messy business. Floors must be kept free of oil either by covering any spills with an absorbent material e.g. cardboard / sawdust, or with the use of oil absorbing granules. Glassware must be continually wiped (sometimes with solvent) to keep it free of oil. Handling glassware with oily gloves presents a very real risk of dropping containers and spilling dangerous chemicals. Use paper wipes to clean containers.
Heavy containers
Care must be taken when lifting any heavy item. Lift with bent legs and a straight back. If an item is too heavy for an individual then use team-lifting techniques. Keep the load as close to the body as possible.
Application of heat
During the biodiesel production process, heat is used to de-water and heat oil. This involves heating cooking oil to over 50ºC. Great care must be taken to avoid spilling hot oil. Only use heating appliances that don’t involve flames e.g. electric elements or hot plates or remote boilers transferring heat via a liquid. Use thermostats to control maximum temperatures where possible. Don’t leave vessels of oil during heating – it’s easy to become distracted and forget them. Install a smoke alarm in the laboratory area. Always have a source of cold water to quench burns. Don’t overfill vessels with oil – it tends to spit and writhe on heating.
Electricity
Use a power supply that is protected by an RCD (circuit breaker). Keep the work area clear of trailing leads that may make a trip hazard or knock things over. Be careful not to sever leads with heavy sharp objects.
Other sensible precautions
- A-well designed work area goes a long way towards minimising risks. Keep the heat and oily operations (dirty area) well away from the chemical (clean) area. Ensure that there is enough space, and stable work surfaces.
- Keep a CO2, foam (don’t use foam on an electrical fire) or dry powderfire extinguisherhandyat all times (near the exit). Be aware that the blast from a CO2 extinguisher can knock over a burning vessel making matters worse – use it from a distance slowly approaching the fire. If you don’t feel confident to tackle the fire then follow the procedure for evacuating the building and call the fire service.
- Keep all rubbish in a metal lidded bin.
- Be mindful at all times. Tell other people in your building what you are doing.
- Dispose of rags soaked in biodiesel. Because biodiesel is made from plants, it can oxidize over time, which can produce heat – theoretically enough heat in a pile of rags to spontaneously combust and cause a fire.