The future of fuel

The question of future vehicle technologies is at the front of many minds. As oil prices rise and demand for 'greener' cars increases, the best minds of the automotive industry have been tasked with changing the face of transport. One such mind belongs to Jamie Turner, chief engineer – powertrain research for Lotus Engineering. The array of competing technologies produced lead Turner to conclude that "In reality, the range of future transport technologies is going to be very mixed." Quite how mixed, however, is another question. Lotus Engineering's efforts in this direction include the Lotus Range Extender engine, which features an innovative architecture comprising an aluminum monoblock construction, integrating the cylinder block, cylinder head and exhaust manifold in one casting. This results in reduced engine mass (56 kg/123 lbs), assembly costs, package size and improved emissions and engine durability. In addition, the design of Lotus' Omnivore variable compression ratio, flex-fuel direct injection two-stroke engine, which achieves 10% improvement in fuel consumption compared to stratified direct injection engines. Two-stroke engine concepts are close to Turner's heart. He says: "The four-stroke engine is an automotive peculiarity. An engineer 100 years ago tasked to come up with the ideal automotive engine would not choose the four-stroke engine. While four-stroke engines are now very reliable and pretty clean, the elephant in the room is throttling loss at part-load, which is where vehicles run most of the time." By contrast, he claims, the two-stroke engine is much better suited to the automotive sector. He says: "The two-stroke engine doesn't scavenge its own energy, so there's no throttling loss. This was a clean sheet of paper design and all along we liked the two stroke because it's a much better match with how we use engines in the real world…two-strokes are the most efficient engines around!" Another innovation seen in the Omnivore is the homogenous charge compression ignition (HCCI), which allows the engine to operate without the need for the spark plug to ignite the fuel and air mixture in the cylinder – down to extremely light loads. Traditionally, this has been challenging but this combustion process results in ultra low emissions and has been achieved over a wide range of engine operating conditions. "It's theoretically a panacea," says Turner. These innovations do not mean, however, that Turner is dismissive of the idea of electric vehicles. He says: "Our view of the future electrification of vehicles is that the plug-in hybrids make a lot of sense." However, he does point out the core drawback of pure electric vehicles, saying: "The problem is that electrical storage is massively, massively expensive. In addition, the materials (such as cobalt) are rare and in unfriendly countries…Batteries currently cost $1000 per kWh and the most ambitious view is that we might get down to $300 per kWh. So, given that 1kWh of usable discharge gives you three or four miles on the drive cycle, $100 per mile of range is the cheapest it will ever be. "The other thing is that people don't know how long these batteries are going to last. The current assessment of the five-year value of an electric car is £3,000. At the moment, they can cost £25,000! I can't see how they're going to sell the thing beyond the early adopters." As for the possibility of hydrogen, Turner says wryly: "Hydrogen's a great technology for the future – and always will be." So what is the future for automotive technology? His view is firmly that the internal combustion engine is not going away. He says: "I've given up counting how many times I've been told that there's 'no silver bullet'. In my opinion, that's completely wrong. People have forgotten what happened at the dawn of the automotive industry. The internal combustion engine has killed the electric battery before – don't forget that. It is the silver bullet. The fuel's cheap and the engine's cheap. Economics and thermodynamics are on the side of the IC engine." The question of how fuel can be kept cheap as oil reserves decline is answered, Turner believes, by another fuel: methanol. He says: "An IC engine will burn a wide range of substances – ethanol, methanol, ammonia – but it's a question of what's miscible with gasoline or diesel. I propose methanol as the 'end game', because it's already a proven internal combustion engine fuel, can be synthesised from a huge range of feedstocks and by careful management of the production and use cycle could be made to be 100% carbon neutral. What's more, there is the possibility to manufacture all the fuel energy we need…After all, nuclear subs make methanol out of waste CO2 and hydrogen and just pump it out. It's been being done for 50 or 60 years." While alcohol fuels contain less energy than gasoline returning a shorter range for a given volume of fuel. However, Turner is dismissive of these arguments saying, "No-one really cares what volume of fuel is in their car? It is the energy they have bought. With modern, 'smart', fuel pumps it would be an easy matter to calibrate them to dispense fuel by energy content rather than volume." If Turner is right, then it would seem that the internal combustion engine will be with us for many more years to come.