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Fuels forMEDIA. thoughtPOWER Wayne Ward reports on the various technologies lining up to see motor racing past the fossil-fuelONLINE age hat is alternative energy? From Race Engine bioethanol and biodiesel. Indeed, there are a number of successful Technology’s point of view, it is energyHIGH that is not REPUBLISHED race engines that have been converted to run on fuels which are necessarily created from fossil or synthetic sources. either entirely biofuels or have a large proportion of biofuel content. So, we might include solar energy, energy stored BioethanolOR is the best known of the biofuels; your average ‘man on Win batteries and capacitors, flywheels, energy in the exhaust gases of combustion devices, energy in the form of biofuels such as bioethanol, Fig. 1 – The American Le Mans Series encourages OF BE alternative fuels. The Mazda-powered Dyson Racing and the output of fuel cells. machine ran on a mix of bioethanol and biobutanol We don’t aim to pass judgement on the rights and wrongs of in 2010 (Courtesy of Advanced Engine Research) electricity generation for electric race series; the term ‘zero-emission vehicle’ is a controversial one. Nevertheless, the time will come when most of our electricity generation will be from non-fossilTO sources, and our road transport is predicted to be largely of the purely PRINTelectric type within a few decades. It is inconceivable that motor racing won’t follow this trend and, as we shall see, there are those in the forefront who are already racing in the pure electric arena. We need to deal here not only with the source of theIN energy, but its storage and conversion to motiveNOT thrust. An electric motor is not generally a device for energy storage, but rather a means of converting stored chemical energy into kinetic energy. Where energy is stored by mechanical means, a transmission is the means by which energy is capturedPROPERTY and released. Alternative fuels Of those technologies that readers of Race Engine Technology are familiar with, the internal combustion engine is the best known. There are many options for converting existing engines or designing new ones to run on what might be termed ‘alternative fuels’ such as 28 28-35 RET053.indd 28 22/03/2011 12:01 FOCUS : ALTERNATIVE ENERGY the street’ will probably have heard of it for one of two reasons – the between synthetic ethanol and bioethanol. Bioethanol is produced by fact that it can be used as a fuel, or the ongoing political debate about fermentation of much longer molecules (sugars and starches) that we its production. Biodiesel is also well-known; it can be produced from find in quantity in certain crops. The argument about so-called fuel both animal and vegetable fats. crops displacing food crops as we try to become less dependant on There are a number of ‘E’ fuels containing bioethanol mixed with fossil sources of fuel has led to a lot of money being spent on r&d to gasoline. E5 contains 5% bioethanol, E10 contains 10% bioethanol, produce the cellulosic alcohols mentioned above. and so on. Fuels containing less than 10% of ethanol are popular Cellulose isn’t readily digestible by humans, and we call it ‘fibre’ for a number of reasons. First, they can be used in unmodified or ‘roughage’. It is treated as a waste product generally in terms of gasoline engines. Second, they can be helpful in cleaning up exhaust food, although it does haveMEDIA. a number of important uses. Cellulose is a emissions, and for this reason they are mandated in certain parts of the substance where a great number of organic units are joined together. It world. E15 is a popular fuel blend, and in 2011 NASCAR will run with is not fermentable without pre-treatment to break it down into sugars E15 fuel where the 15% ethanol is biofuel made from corn grown in and starches. The attraction of cellulose is that it is abundant; about a the US. third of all plant matter is cellulose, but the quantity varies from plant Ethanol has a higher octane rating than gasoline, so engines running to plant. a fuel with some ethanol content can run a higher compression ratio, As a race fuel, pure bioethanol requires some changes to the and many of us will be familiar with the positive effect of compression operating conditions of the engine, as well as some understanding ratio on engine efficiency and output. of the properties of the fuel from the series organisers. The fuel has E85 is a blend of gasoline with 85% ethanol, and some teams in a much lower energy density than gasoline or diesel, so to produce the American Le Mans Series have used this fuel with the ethanol competitive power you need to use more fuel. This might require content being of the cellulosic type. Cellulosic ethanol is made from POWERthe rule-makers to allow users of biofuels to run a bigger tank to the cellulose in plant matter, and therefore many types of vegetation be competitive. For example, in endurance racing, a given size of and waste from arable farming can be used, although the vegetation fuel tank containing E85 will take the car far fewer laps than one requires more processing to produce the sugars used in the alcohol containing gasoline. Tanks of different fuels containing the same production process.’ quantity of energy will have different masses, so to balance car ‘Conventional’ bioethanol is produced from sources such as corn performance where differentONLINE fuels are used in one race class is not and sugar cane; there is some controversy here over the merits of straightforward. displacing food crops in order to grow fuel. All types of simple, Beyond bioethanol, there are other alcohol fuels in use in racing. short-chain alcohols, whether produced by industrial synthesisHIGH or REPUBLISHED Again in endurance racing, the Mazda two-litre turbo engine being by biological methods (fermentation using bacteria or yeast) are raced in the American Le Mans Series has been successful while chemically identical. Once refined, it is not possible to differentiate running onOR alcohol fuels. In 2010 it ran a mixture of ethanol and biobutanol (Fig. 1). OF BE There are some unusual facts concerning butanol. It can take a number of forms, as it is the first of the alcohols where the chain doesn’t necessarily have to be a straight line. It can take a tetrahedral form called t-butanol, which is a solid at room temperature, although this is miscible in ethanol. Another interesting fact is that, while it isn’t TO safe to eat or drink, it is allowed in countries such as the US and Japan PRINTas a food additive to enhance flavour. Butanol fuels have several advantages over bioethanol. They can be run in gasoline engines with very little or no modification, and its energy density (in terms of energy per litre of liquid) is much IN closer to that of gasoline than is the case for ethanol. In fact, the NOT specific energy of butanol fuel (measured in energy in the fuel per kilogramme of air consumed by the engine at stoichiometric conditions) exceeds that of gasoline. Oil company BP has developed both biobutanol-blend road fuels and the ethanol-butanol mix used in endurance racing. PROPERTY The ethanol-butanol mix improves on the poor energy density of ethanol and the octane rating of butanol. The octane rating of butanol is very similar to gasoline, although lower, and the ethanol boosts this, allowing it to run happily in a high-compression air-restricted turbocharged application. As motor racing and production engines move inexorably toward small, light, highly boosted turbocharged t 29 28-35 RET053.indd 29 22/03/2011 12:01 FOCUS : ALTERNATIVE ENERGY Hybrid technologies The recovery of braking energy is one area where racing is very much in the vanguard. Providing that the rules encourage – or at least do not stifle – such developments, this is something we will see increase in use in the coming years. The ACO, which organises the Le Mans 24 Hour race and whose regulations form the basis of the various other endurance series running globally, has come up with a carefully considered set of rules that seem to encourage hybrid technology, and it should be applauded for this move. However, theMEDIA. ACO has not given an automatic entry to an LM P1 gasoline-electric hybrid entry for the 2011 race. There are a number of variations on the recovery, storage and re-use of braking energy, but all have the same theme. They seek to reduce the amount of kinetic energy converted to heat and dissipated by the brake system, and use the recovered energy at an advantageous time. In roadcars, the general aim of such systems is to have a car with a Fig. 2 – Zytek’s permanent-magnet three-phase motor technology small engine that feels like it has a big engine when we put our foot has been developed over many years. This motor is the basis for a hybrid endurance prototype to be raced in 2011 (Courtesy of Zytek Automotive) down. In racing, the aim of an unfettered set of regulations would surely be to increase acceleration and decrease lap time. It is likely engines, any biofuels developed need to be able to cope with the though that racing, in seeking to present a more environmentally particular needs of such engines. Knock resistance is one of the most POWERfriendly image to the public – and in trying to become a more relevant important parameters, and a high octane rating is essential in this arena for the development of technology – will frame its regulations respect.

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