The case for methanol, part one: Introduction
Fossil fuels in the form of petrol, diesel and natural gas have classically been the mainstay of road transport for many decades. Indeed, engine development has continued throughout this time to optimise the use of such fuels. Fuel consumption has improved dramatically, and thanks mainly to mandatory legislation, exhaust emissions have improved likewise.
However, we still need further improvement. The emissions from diesel fuels have been improved, but there is still too much NOx and minute particles of carbon, and while petrol is considerably better in these aspects, it still leads to a greater release of carbon dioxide into the atmosphere, relative to diesel fuel. Apart from the small amounts of biodiesel and bioethanol that are blended within current road fuels, the vast proportion of the fuel is fossil derived and thus may contribute to climate change.
Methanol has long been known as a viable fuel for spark ignition engines. It has a very high-octane rating of about 110, significantly higher than conventional fuels, thus enabling higher compression ratios to be used. Methanol fuel is extensively used in the motor racing industry, due to its high performance, energy efficiency and as a bonus, the emissions are clean compared with long chain hydrocarbon fuel.
The one drawback it has in practical terms is the difficulty in starting the engine initially. Methanol is a pure compound and its vapour pressure is determined solely by the ambient temperature. If the vapour pressure at a given temperature is below the lower flammability limit, then the engine will not start. This is not a problem for petrol because petrol is a mixture of many hydrocarbons including propane and butane which are normally gaseous at ambient temperature. Avocet Natural Capital have an additive which is wholly soluble in methanol and which circumvents this problem.
While methanol is a very good fuel for spark ignition engines, Regrettably, this is not true for compression ignition engines. It has a very low cetane value, circa 5, which is well below the minimum required for regular use in diesel engines – circa 51, whether automotive or static. However, a cetane enhancer was developed in the 1990s by ICI which was demonstrated to run very successfully in diesel engine vehicles, as proven by extensive testing in both California and Sweden.
Unfortunately for that product, the production costs were high, the price of methanol was high, the cost of diesel was low and there was no environmental appetite or political support for this very expensive fuel. The project was consequently discontinued. Times have changed. Methanol is now very cheap, diesel has bad press and improvements to the process for manufacture of the additive has enabled the production of a methanol-based fuel that is easily cost effective per mile travelled and has very “green” credentials. Avocet Natural Capital plc have developed this technology and have an improved process for the manufacture of the additive so that a new environmentally clean fuel can now be produced economically.