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Author: John Coxon

Source: Autoindustry

Publication Date: 23^rd August 2006

Bioethanol was used by a prototype at Le Mans in 2003 and 2004 while in 2007 it will be the fuel of the Indy 500. In the meantime it is being exploited by a competitor in the UK’s high profile British Touring Car Championship: John Coxon explores how.

Bioethanol, as you might guess, is just another form of ethanol or ethyl alcohol, albeit one manufactured in a more environmentally friendly way. Not to be confused with methanol (CH3OH), ethanol (C2H5OH) is generally produced by reacting ethane, a downstream product from an oil refinery, with steam over a catalyst. Made in this way, ethanol is not considered to have anything other than a negative impact on the environment. Bioethanol is different. It is produced by the fermentation of sugars and starches from beets, grain or preferably agricultural waste such as wood, brewery waste, paper waste and many types of vegetable waste sometimes referred to as biomass. Manufactured using this technique, the greenhouse gas, carbon dioxide, absorbed during the growing stage can be offset against that produced by its manufacture (that is - farming), distribution and use. The fuel can therefore claim to have a positive environmental impact, reducing the carbon dioxide that would have been otherwise created but since the manufacture and distribution still create CO2, not rendering it neutral. Even so, as a renewable fuel, if a little expensive to produce, bioethanol has much to offer a world under environmental threat.

The use of ethanol as an automotive fuel is far from new. In the early history of the internal combustion engine, pioneers experimented with a wide range of blends of hydrocarbons, alcohols, ethers and other organic solvents. In the nineteen twenties when the phenomena of detonation and preignition in engines was at last being understood, and the mushrooming demand for hydrocarbon fuels was finally being satisfied by the petrochemical industry, alcohol-gasoline blends started slowly disappearing from the market.

Even so, factory racing teams in Europe were still using ethanol - benzole (a mixture of benzene, zylene and toluene) - gasoline blends. However by the middle of the following decade ethanol had been almost totally replaced by the more superior (in terms of specific energy and performance) methanol.

In the latter part of the twentieth century ethanol made a comeback not specifically as fuel for racing but as a method of reducing dependency on fossil fuel imports in areas of the world that do not have their own oil supplies. Brazil is perhaps the most well known of these but at some stage Sweden, the United States, France and Spain have all had similar ethanol - gasoline blend programmes based on 85% ethanol/15% gasoline (E85).

Inspired by these sort of initiatives and supported by government funding through the Motorsport Development Board, in the UK the Energy Efficiency Motorsport (EEMS) project has been created. This project aims to “place a premium on the efficient use of resources, to encourage the development of alternative fuels and powertrain technologies and, most of all, to put energy efficiency at the heart of modern motorsport – all without compromising the sporting spectacle.”

By providing assistance in the form of grants an objective of EEMS is to use motorsport to accelerate the development and public acceptance of alternative ‘green’ automotive technologies. One such grant was made to Team Nasamax, which used a bioethanol-fuelled Cosworth 2.65 litre (Indy-derived) V8 engine in a Reynard LMP1 to contest the 2003 Le Mans 24 Hour race.

Following a difficult debut Nasamax returned in 2004 with its car revised to the latest ACO chassis rules and now carrying a 4.0 litre Judd V10 engine. To offset the greater mass of fuel its use of bioethanol called for, the ACO had permitted its fuel tank to be increased from 90 to 135 litres and the team to exploit a larger diameter refuelling hose. Thus equipped the uniquely bioethanolpropelled machine managed a creditable 17th place finish in spite of losing much time in the pits later traced to an electrical problem.

Although Nasamax did not find the funding to compete again in 2005, this year we had a taste of the future at Indianapolis when an ethanol blend-powered IRL car did some demonstration laps on Carb Day. Following the gasoline price shock over the last few years and the lack of refining capacity, which threatens availability, the Indy Racing League has seen fit to migrate from methanol to road car fuel of the future, bioethanol.

Methanol is produced from the fossil fuel, natural gas. In 2006 the IRL will use a 10% bioethanol/90% methanol blend and then in 2007 it will be 100% bioethanol. At a time when the oxygenate, MTBE, has been phased out of road gasoline (in the US only) to be replaced by bioethanol, this must be seen as a master stroke since it not only diffuses the critics of motorsport but also supports the farming community of the mid-west. It could be claimed that, as it was in the past, once again racing is being used to “improve the breed.”

Meantime, in 2005 the attention of those interested in bioethanol was transferred to the British Touring Car Championship. Here was to be found a relative novice onto the scene, Lincolnshire farmer’s daughter, Fiona Leggate. Having secured the backing of EEMS, long time BTCC participant Triple Eight Race Engineering converted one of its 2004 championshipwinning Vauxhall Astras to run on bioethanol for her use. The engine was supplied by the Magny Cours, France-based tuning outfit Sodemo and day-to-day race preparation was contracted to Tech-Speed of Leamington Spa, England. The car was set to start racing in the middle of the BTCC season, at Croft on July 17/18.

Before we go any further it behoves me to mention that any bioethanol intended for use as a fuel will, to discourage drinking, have certain de-naturants or poisons blended into it. If this were not enough the UK authorities also insist on the addition of a product known as ‘Biterex’ or denatonium benzoate. Claimed by its manufacturer to be the bitterest substance in the world, it is totally intolerable by most people and animals at only one part in a million. I haven’t tried it but I am prepared to take their word for it!

In order to fully understand the characteristics of bioethanol it is perhaps useful to compare it with those more familiar fuels, gasoline and methanol (Table 1). In simplistic terms the properties of bioethanol fall somewhere between the two. With a calorific value about 60% of that of gasoline and an air fuel ratio at maximum power of around 7:1, specific fuel consumption will be somewhere between 1.5-2 times that of our normal gasoline.

Thus, for a given race mileage the bioethanol car will require a 50% bigger fuel tank. Perhaps more critical for our BTCC sprint car, this implies carrying more fuel weight. In the case of endurance racing, when refuelling is required, larger bore fuel nozzles will be required to allow refuelling in the same period of time as any gasoline car. As we have noted, this was a concession the ACO made to Nasamax in 2004.

	Units	Typical Racing Gasoline	Bioethanol	Methanol
Lower Heating Value	MJ/kg	43.5	26.8	19.7
Heat of Vapourization	MJ/kg	0.3	0.93	1.17
Stoichiometric Air Fuel Ratio		14.7	8.95	6.45
Specific Energy at Stoichometry	MJ/kg	2.96	2.99	3.06
Air Fuel Ratio at Max Power		12.0	7.0	4.0
Specific Energy at Max. Power	MJ/kg	3.6	3.8	4.97
Boiling Point	°C	35-205	78	65
RON		100-102	112-120	115-130
MON		88-90	95-106	95-103
Oxygen content	Wt%	2.7	34.8	50
Density	G/L	735-775	790	790
Reid Vapour Pressure	kPa	40-60	20	36

Table 1 - Comparison of bioethanol and methanol with gasoline

PARAMETER	Units	Min.	Max.
Density	g/ml	0.735	0.775
Evaporated at 70oC	%	15.0	47.0
Evaporated at 100oC	%	46.0	70.0
Evaporated at 180oC	%	85.0
Final Boiling Pt.	°C		205.0
Research Octane No		100.0	102.0
Motor Octane No.		88.0	90.0
Sensitivity		11.0
Reid Vapour Pressure	kPa	40.0	60.0
Benzene	%v/v		0.1
Oxygen content	%mass		2.7
Lead	g/L		0.002
Sulphur	mg/kg		10

Table 2 - 2005 BTCC Fuel Specification

While methanol fuel provides the advantage of being able to run optimum (for power) air-fuel mixtures of 40% greater than stoichiometric, bioethanol cannot benefit from this and so the specific energy at maximum power is much closer to that of gasoline.

With the heat of vaporisation for bioethanol only slightly less than for methanol, but only 20% excess fuel for maximum performance, the opportunity for inlet charge temperature reduction is much less. Balancing these factors with the intake air displacement effect of the greater flow rate of fuel, and at the maximum engine compression ratio of 12.0:1 permitted by BTCC regulations, I would dare to suggest that the engine power target should be similar to that produced when running on gasoline. This would seem to concur with the claimed power output of the bioethanol-fuelled Astra 2.0 litre four-cylinder, which is between 290 and 300 bhp.

At the outset of the Astra programme and with the learning curve so steep, Sodemo approached BTCC fuel supplier Petrochem Carless for a range of bioethanol/gasoline blends of 5%, 30%, 60%, 90% and as near as possible 100% bioethanol. The remit was to keep the specification as close to that of the regulation fuel (Table 2). However, Mike Jardine of Petrochem Carless says: “fuel blending is not just a case of taking 5% or 30% of bioethanol and mixing it with 95% or 70% gasoline. In order to get an acceptable fuel, the lack of volatility of the bioethanol (RVP 20 kPa) has to be counterbalanced by the addition of other gasoline components and yet still keep the fuel as far as possible within the octane limits.”

That to date the Tech-Speed team has had no fuel related issues says much about the blending skills of the people at Petrochem Carless. For a high-speed racing engine, the speed of combustion is a key factor. Short ignition delays and fast burn rates ensure complete combustion and good performance figures. While the lower alcohols are reputed to have faster burn rates than gasoline, the longer ignition delays involved with the pure product can sometimes give the appearance of slow combustion. The addition of 10-15% gasoline to our bioethanol can assist this, which is most probably why the team reported maximum engine power at 90%. When running on 100% bioethanol, engine performance dropped by 5%.

Since bioethanol is a single boiling point fluid and unlike gasoline lacking a range of boiling points or distillation curve characteristic, it can sometimes be very difficult to carburate in cold or inclement weathers. Fortunately most modern racing cars are fuel injected and so the issues are not so great but nevertheless at low ambient temperatures, cold starting can be difficult. Road going cars these days have to be so very exhaust emission clean, even during the first cranking cycle of a cold start, whereas a racing car can use calibration strategies that would be totally unacceptable in the wider environment.

In the case of the Tech-Speed car, during the first cranking revolution fuel is injected without ignition in order to ‘wet’ the manifold walls. Only on the second revolution is the ignition switched on, when the appropriate rich mixture that has been produced should fire. This strategy seems to work well (albeit at the ambient temperatures of a British summer) since Fiona and her mechanics reported no cold start concerns.

The team started at Croft with a 30% mix, rising via a 60% step to 90% for the season finale at Brands Hatch in early October. Tech- Speed boss Marvin Humphries was keen to assure me that there are no special handling issues with the fuel. “Apart from ensuring that the fuel container tops are sealed tight so that moisture cannot enter – bioethanol has great affinity for water – and that the fuel is not accidentally spilled – it is also a wonderful paint stripper!”

Discussing the modifications to the car with Marvin, he had to admit that there were surprisingly few. Although bioethanol is corrosive in nature and particularly so when blended with gasoline, modern racing systems should be capable of coping with the majority of the specific requirements.

In particular the braided steel Aeroquip hose with PTFE inner lining and anodised aluminium fittings equipping the Astra is resistant to the effects of the fuel. The fuel tank, although it looks nothing out of the ordinary, was a bespoke model supplied by Premier. This, the company claims, is totally resistant to the fuel. It is the product of its experience with another race team over the past 18 months. The trick, I was told, is in the vulcanising process when bonding the rubber layers together at the seams.

As already mentioned, bioethanol has a great affinity for water. A certain amount (less than 0.5%) is almost always present in commercial fuels. This is principally due to manufacturing and transport issues, which would be difficult, not to say expensive to rectify. However, higher levels of water can lead to a phenomenon known as phase separation in gasoline/bioethanol blends, although this is more likely in large storage tanks when the fuel is stored for some time.

The presence of water can also have other effects. In particular water can contribute to metal corrosion and galvanic couple effects between electrochemically dissimilar alloys in the fuel system. Metals like zinc, brass, magnesium and copper should not be situated anywhere in the system. Even some alloys of aluminium can corrode under the right conditions.

The general advice for both methanol and ethanol/bioethanol is to use only either stainless steel or anodised metals (particularly in the case of aluminium). When buying such items as fuel injectors, pressure regulators, pumps and filters, always specify compatibility with the fuel you will be using. Whether or not it is strictly necessary, it may also be wise to flush out the alcohol blend by running the engine with normal gasoline at idle at the end of the day.

In addition, alcohols have very high solvent powers particularly if blended with gasoline products. When in contact with certain elastomers they can cause problems: fuel lines and ‘O’ ring seals can swell and rubber components can embrittle depending upon the temperature. In the case of bioethanol, Vitons (the DuPont tradename for fluorohydrocarbon elastomers) are particularly suited to its use and should give little trouble.

So how did the Astra fare over the last part of the season? Best place finishes of fifth and sixth at Silverstone suggest that the fuel has some kind of future in motorsport. True these performances may have flattered but bearing in mind Fiona’s lack of experience, steady on-going development and adjustments to the weight limits could encourage further environmentally aware racers into the BTCC.

Added to the database on 23^rd August 2006