Alternatives to fossil fuel

Usually when we think of oil to burn in a boiler, we automatically think of mineral or diesel oil. This fossil fuel pumped from the ground is a non-renewable resource shipped at high cost (environmentally and economically) and which releases carbon dioxide into the atmosphere, adding to the concerns of global warming.

Oil-fuelled boilers, however, are not particularly fussy about what is burned to energise them – as long as it is a liquid and will release sufficient energy to heat water to the required temperature. Therefore any oily substance may be used.

Experiments worldwide with the use of the following oils have met with success:

animal fats,
babassu oil,
beechnut oil,
camelina oil,
castor oil,
chestnut oil,
cottonseed oil,
fish oil,
grapeseed oil,
hemp oil,
linseed oil,
lupin oil,
maize oil,
olive oil,
palm oil,
pea oil,
peanut oil,
poppy seed oil,
pumpkin oil,
rapeseed (canola) oil,
shea butter,
soybean oil and
sunflower seed oil.

Most of these oils have a higher viscosity than mineral oil. This is easily overcome either by the addition of a thinning agent, such as methanol, or by injecting pre-heated fuel into the boiler or both.

Knowing virtually any oil may be used in an oil fuelled boiler, Council undertook an investigation of alternative fuels that might:

readily replace the mineral fossil fuel presently used
would be a renewable resource
would be carbon neutral and
would not increase the cost of running the boilers.

It became obvious there is a plentiful supply of used cooking oil available, mainly from fast food shops. Once cleaned and de-watered by the supplier, this offers a suitable alternative source of energy for the oil-fuelled boilers.

Testing found that the fuel could be used, but it was best to modify the burners at each site. So a small heating unit is installed before the burner, to pre-heat the oil so that any animal fats also present are melted before reaching the burner. The animal fats are from meat cooked in the oil and these solidify at low temperatures.

Possibilities for the future
Many people believe trucks and cars with a diesel engine need diesel or mineral oil to run. But Rudolf Diesel, the inventor of the compression ignition engine developed his engine so that it would burn almost any inflammable material without the addition of a spark. The engine was designed to compress air in the cylinder to the extent that the heat emanating from the air would ignite the flammable substance. The first experiments used coal dust, but as this material was too explosive, mineral oil was used instead, with great success.

Experimentation established that any oil that could be injected into the cylinder would be suitable to run the diesel engine. In March 1912, Diesel himself said:

"... at the Paris exhibition in 1900 there was shown by the Otto Company a small Diesel engine, which, at the request of the French government, ran on … earth-nut or pea-nut oil, and worked so smoothly that only very few people were aware of it. The engine was constructed for using mineral oil, and sustainable and eco-friendly on vegetable oil without any alterations being made. The French government at the time thought of testing the applicability to power production of the …earth-nut, which grows in considerable quantities in their African colonies, and which can be easily cultivated there, because in this way the colonies could be supplied with power and industry from their own resources, without being compelled to buy and import coal or liquid fuel.

…the author resumed trials a few months ago. It has been proved that Diesel engines can be worked on earth nut oil without any difficulty, ….This oil is almost as effective as the natural mineral oils…

…similar successful experiments have also been made in St. Petersburg with castor oil and animal oils…

The fact that fat oils from vegetable sources can be used may seem insignificant today, but such oils may perhaps become in the course of time of the same importance as some natural mineral oils and tar products are now". Prophetic words for 1912.

As vegetable oil technology improves the product, it may be possible to change some of the other diesel engines operated by the Council to a renewable, carbon neutral resource, over and above the Bio-diesel 5 that we look forward to using.