With the cost of crude oil on a relentless upward spiral, and HM government not showing any inclination to reduce the level of duty paid on every litre, it's not surprising that people are looking at using alternatives.

One alternative that has gained in popularity over the years partly due to its lower costs, but also due to the fact that it's considerably more environmentally friendly, is that of using cooking oil, or a refined version of it, as a partial or total replacement for diesel. Although this was initially thought of as something of a joke, it has been taken far more seriously of late.

Recent TV programmes have shown the process of the used oil being cleaned and refined and turned into diesel fuel, which have helped to raise the profile and credibility of Biodiesel.

For anyone unfamiliar with Biodiesel, it has been found that you can use domestic cooking oil in a diesel engine and that it will run in the normal way. But it seems that although you can use cooking oil straight from the container, prolonged use can cause problems in the engine.

One major problem is the reluctance of the engine to start when using none processed oils. Residues can also build up if the oil isn't treated and this can cause major problems and engine wear can be accelerated.

To overcome this there is a refining process and, once this is done, you will not only be able to run the engine on cooking oil, but the resultant emissions are far less hazardous than those from conventional fuels.

Currently the other major factor in favour of this particular fuel is that one source of the raw material (the cooking oil) can be supplied by the local chip shop or hotel kitchen. These users dispose of large quantities of used cooking oil almost every week and some find its disposal can prove to be a problem.

As a result users are not only reducing their costs and helping to reduce pollution, they are also recycling the used chip fat; and this all adds to the feel good factor.

As one might expect there is a price to pay for this method of running your engine. If you use almost any product as a fuel it is liable for the payment of excise duty to HM Customs and Excise.

Failure to do so can be very costly as it is an offence. The government has put in place new rates to cover such fuels and these are currently around 20p a litre, below that of ultra low sulphur diesel.

Reduced considerably However even after paying the duty on bio fuel users will still find their costs reduced considerably. A number of web sites quote prices of 50p - 75p per litre, which is well below the current pump prices.

And if proposed changes to duty on conventional diesel are made this difference with become even more significant.

Despite the fact that users will need to expend some degree of effort and planning in making the fuel for their engines the benefits, both to the pocket and the environment, cannot be overlooked my a growing number of people.

The actual production process requires methanol to be mixed with caustic soda, the amounts determined by initial tests on the raw materials. This catalyst mixture is then mixed with glycerine and the biodiesel mixture. After being well mixed, this concoction is then allowed to settle.

Eventually the glycerine will settle out and can be drained off. The remaining biodiesel can then be washed, by allowing water (which is denser), to work through the mixture taking any residues with it.

After draining off the water, you are left with Biodiesel.

Although it sounds complex (and these details must not be taken as full instructions) there are a growing number of businesses selling processing equipment, of varying degrees of complexity, on the Internet.

One company in particular sells systems that can produce between 45,000 and 30,000,000 litres per year. Full blown systems like this (assuming you have the space to set them up) start at just under £4000 and can produce 150 litres in eight to 12 hours, but there are enterprising souls on sites such as eBay who will sell you the know-how to make the fuel.

As well as a number of websites selling the items needed to produce Biodiesel, there are more and more giving advice and guidance. One reason for this could be an EU directive (Directive 2003/30/EU) that has set a target of 5.75% use of Biofuel by the end of 2010.

For the UK this would mean we would need about 800,000 tonnes of the fuel, most of which would need to be imported as we don't currently have the capacity to produce this much.

With this require-ment being set and covering all areas of transportation the market is ripe for those who want to get in on the ground floor.

Serious consideration A serious consideration before anyone starts to use this type fuel should be the age of the engine. There would seem to be no upper limit on the age of the engine running on cooking, or other none fossil fuel oil, but if an engine is new and still under a manufacturer's warranty, users may want to tread carefully.

Should they need to claim under the terms of the guarantee they might well find that the company will reject this as they were not using the correct fuel. With the possibility of many variations in the formulation of the fuel you can see why the manufacturers are cautious.

With this in mind we asked the views of one of the major players in the engine market.

Volvo Penta doesn't, at present, have an official line on this, other than the guidance provided by the parent company. With Volvo being a major supplier of engines to the road haulage sector the potential savings for these customers is significant and therefore the impact of biofuel use is greater.

Brian Hourican, of Volvo Penta's dealer and technical team, told us that the recommendations are that any biofuel must come from recognised suppliers. If the user does decide on using this fuel the limits are no more than 5% of the fuel can be anything other than normal diesel and the formulation must include all the recognised additives.

Hourican also pointed out that there are also amendments to the oil change schedules if using this sort of fuel. In short, if a user wants to knock up a batch in the shed, he or she can't expect the engine manufacturers to support any warranty.

Not wishing to be a prophet of doom, there does seem to be one thing that we may have overlooked.

There would seem to be a finite number of outlets disposing of cooking oil. Far fewer than the likely increase in the number of people with diesel engines who may want to run their vehicles or boats on biofuel. If this is the case and more people start to use this type of fuel it too could become scarce and as a result commercial users, who now throw used oil away, could begin charging.

We are not at this point at the moment and it may never come to this but, if only for the sake of the environment, we can only hope that even if charges are applied that more of this type of fuel is used. Although the first thought in many people's minds is the cost saving, the other - and one might say more important - saving is that of the environment.

Growing movement It would seem that there is a growing movement towards this type of fuel in all areas with the likes of DEFRA producing literature to encourage the farming community to grow more oil seed rape and other oil producing crops. With the groundswell of interest from the public and legislative changes being made it might be worth the UK marine industry keeping a close eye on this situation.

How long will it be before we see the first enterprising marina setting up a small processing plant in a currently empty building? If they already sell fuel they have the perfect outlet from which to make this fuel available and if the tax breaks are passed on they could undercut the conventional fuels.

One area that, although it's in something of a decline, would seem to have been overlooked is that of the commercial marine sector. With fishing and other commercial craft being far bigger users of marine diesel the cost savings for these guys will, it's safe to assume, be on a par with the road transport industry.

We might well find that this section of the marine industry leads the way and the recreational area will follow and benefit in the fullness of time.