The research into sustainable alcohols is progressing at Lotus’ Hethel headquarters in Norfolk, UK and involves input from the Royal Society of Chemistry’s Alternative Fuel Symposium Series; the Low Carbon Vehicles Innovation Platform, developed by the Technology Strategy Board; and direct discussions with the University of Sheffield.

An alcohol-based fuel derived renewably from atmospheric CO₂ would allow society to transfer relatively easily to sustainable, carbon-neutral internal combustion. However, the supply infrastructure investment from governments and fuel companies could take 15 to 20 years, the company notes.

The Lotus Exige 270E Tri-fuel. The Exige 270E Tri-fuel is built to the lightest specification possible without resorting to expensive and rare materials. The performance improvements of using synthetic alcohol have been made through increasing the power of the engine without increasing its weight and therefore the overall weight of the car.

The heart of the Exige 270E Tri-fuel is the Lotus 4-cylinder, 1.8 liter 2ZZ-GE VVTL-i engine equipped with a modified Roots-type supercharger (with a sealed-for-life internal mechanism) and air-to-air intercooler package from the Exige S. The Exige 270E Tri-fuel offers peak power of 270 hp (201 kW) at 8,000 rpm, an increase of 19% (51 hp, 39 kW) over the standard gasoline Exige S and develops torque of 184 lb-ft (260 Nm) at 5,500 rpm, up 14% (25 lb-ft, 45 Nm ). Maximum engine speed is 8,000 rpm (8,500 rpm transient for up to 2 seconds).

Methanol and ethanol give more power when burned in the engine than conventional gasoline fuel. The performance benefits come largely from the high heats of vaporization of methanol and ethanol, which give strong charge-cooling effects, and the increased octane ratings.

There are other secondary thermodynamic effects. Methanol’s higher heat of vaporization leads to a slightly higher performance relative to ethanol. All charge air ducting has been kept as short as possible with large diameter pipes making sure that the bends in these ducts are not too tight, to the benefit of throttle response and efficiency. The Roots-type Eaton M62 supercharger is turned by the crankshaft, and has an integral bypass valve for part load operation.

The 2ZZ VVTL-i engine has two cam profiles—a high speed cam and a low speed cam. The seamless switch point between these two cams is completely variable depending upon driving conditions and engine load. This gives the Lotus Exige 270E Tri-fuel a smooth and linear surge of power from idle speeds all the way to the maximum 8,500rpm. Six fuel injectors have been fitted to increase fuel flow to the engine at normal and higher engine speeds and loads.

Synthetic methanol cycle. Click to enlarge.

Synthetic methanol. Methanol (CH₃OH) can be produced synthetically from CO₂ and hydrogen. Lotus asserts that ultimately, emerging processes to recover atmospheric CO₂ will provide the required carbon that can entirely balance the CO₂ emissions at the tailpipe that result from the internal combustion of synthetic methanol, according to Lotus. The result is that a car running on synthetic methanol, such as the Exige 270E Tri-fuel would be environmentally neutral.

Synthetic methanol would use similar engines and fuel systems to those in current cars; and synthetic methanol can be stored, transported and retailed in much the same way as today’s liquid fuels such as gasoline and diesel.

Synthetic methanol also possesses properties better suited to internal combustion than today’s liquid fuels, giving improved performance and thermal efficiencies. And it is ideal for pressure-charging (turbocharging and supercharging) already being introduced by manufacturers to downsize engines in a bid to improve fuel consumption.

At present, the motor industry is seeking a route to reduce CO₂ emissions just at the tailpipe; this focus is far too narrow. A sustainable alcohol such as synthetic methanol has the potential to reduce the overall CO₂ footprint of internal combustion vehicles towards zero. Produced through CO₂ recovered from the atmosphere and given a tax incentive, it immediately becomes a green, cheap and more desirable fuel. For those compelling reasons motorists, legislators and car manufacturers must switch to a sustainable alcohol like synthetic methanol.

—Mike Kimberley, Chief Executive Officer of Group Lotus plc

We believe that, technically, there are a small number of significant but by no means insurmountable hurdles to the adoption of synthetic methanol as the staple future fuel for internal combustion. We are some way into a number of extensive research projects but of course, we understand that further research needs to be undertaken to fully overcome potential challenges that may arise.

—Geraint Castleton-White, Head of Powertrain at Lotus Engineering

Lotus believes that the most likely future pathway for the mass-production of methanol is by using electrochemical techniques to combine oxygen, hydrogen and carbon. Carbon could be sourced from carbon dioxide recovered from the atmosphere using either large scale extraction facilities or biomass. Oxygen would be taken from the atmosphere already contained in the CO₂ molecule. Hydrogen would be acquired through the electrolysis of water. Synthetic methanol can also be supplemented by production from biomass sources where properly sustainable.

Techniques for the production of synthetic methanol through the extraction of atmospheric CO₂ are well developed and understood but are not being employed on an industrial scale. An early solution, according to Lotus, would be the co-location of a nuclear or hydroelectric powerplant with a conventional power station—the hydrogen generated by hydrolysis of water would be combined with CO₂ from either fossil or biomass sources to make liquid methanol. In the future, large volumes of CO₂ could be extracted directly from the atmosphere.

Lotus Engineering regards sustainable alcohols as the third step in a process towards carbon neutral driving. The current E85 (85% ethanol and 15% gasoline) based movement represents the first stage in building momentum towards sustainable fuels. The valuable learning from the current bioethanol vehicles on the market means that synthetic methanol would easily be managed technically and within the existing transport, storage and distribution infrastructure. The steps towards a synthetic methanol economy for transportation fuels could be as follows:

• 1st Generation: there is a handful of current bioethanol models on sale around the world. These cars run on E85 bioethanol, which is produced from valuable arable crops (food). This is unsustainable in the short and medium term as global demand for fuel will outstrip the supply available from farmland to the detriment of food production, but is a necessary step in the evolution of the market.

• 2nd Generation: the next generation bioethanol fuels will be based on biomass waste, for example crop stubble, waste vegetable-based oils and any biodegradable waste matter. This is thought also to be unsustainable in the medium- to long-term as the required volume of biomass increases beyond that which can be supplied.

• 3rd Generation: sustainable alcohols such as synthetic methanol can be introduced due to its miscibility with ethanol and gasoline. This fuel can be produced from entirely sustainable, readily available inputs, with an environmentally neutral overall impact.

• 4th Generation: Direct Methanol Fuel Cells: over the longer term, sustainable alcohols in internal combustion will facilitate the soft introduction of direct methanol fuel cells as a long term sustainable future fuel. This will only be possible with pure methanol pumps on the forecourt which internal combustion engines can bring forward due to their ability to consume a mixture of fuels.

Lotus Engineering strongly believes governments, fuel suppliers and car manufacturers all have a key role to play in the adoption of sustainable alcohols. If car manufacturers were incentivized to produce next generation models for introduction over the next 5 to 10 years as flex-fuel vehicles capable of running on any mix of gasoline and bioethanol, there would be no need for an unfeasible instant global changeover. Late software changes can permit the introduction of methanol and fortunately, E85 bioethanol and subsequently synthetic methanol can be introduced gradually to the marketplace, due to their miscibility.

Resources

• Ohla, G.A., Goeppert, A, and Surya Prakash, G.K. Beyond Oil and Gas: The Methanol Economy. Wiley-VCH Verlag GmbH & Co. KgaA, Weinheim, Germany. 2006. ISBN 3-527-31275-7.

• Pearson, R.J., and Turner, J.W.G, Exploitation of energy resources and future automotive fuels. SAE paper number 2007-01-0034, SAE Fuels and Emissions Conference, Cape Town, 23rd - 25th Jan., 2007.

• Pearson, R.J., and Turner J.W.G., Bio-alcohols and their role in the transition to the use of synthetic alcohols for mobility. I.Mech.E. Seminar: Biofuels or future transport and mobility. Hethel Engineering Centre, Norwich, 20th September 2007.

• Turner, J.W.G., Pearson, R.J., Holland, B., and Peck, A., Alcohol-based fuels in high-performance engines. SAE paper number 2007-01-0056, SAE Fuels and Emissions Conference, Cape Town, 23rd - 25th Jan., 2007.

• Turner, J.W.G., Peck, A., and Pearson, R.J., Flex-Fuel vehicle development to expedite alcohols as the basis of a viable negative-CO₂ energy economy. Paper number 07APAC-31. Submitted to 14th Asia Pacific Automotive Conference, Hollywood, CA, USA, August 5th-8th, 2007.