PARIS SHOW: Five-year timeframe for gas turbines

Basically a range-extending hybrid, the concept car features gas-turbine engines to generate electricity for the motors that drive the car. Gas turbine technology has been tried in cars as far back as the 1950s, but among other stumbling blocks, the engines just didn't spool up fast enough to provide the right level of driveability for the road. As a device to generate power however, the gas turbine engine is an excellent choice. It's simpler than a piston engine, with fewer moving parts, and it tends to be less sensitive to fuel quality.

Tony Harper, Jaguar's Head of Research & Advanced System Engineering, was at the Paris show where the C-X75 debuted, to promote the new car and the technology behind it. When the Carsales Network caught up with him, the immediate question arising concerned Jaguar's rationale. Why has the prestige manufacturer gone with gas turbines when other companies are working on hydrogen fuel cells?

"Hydrogen as a ubiquitous fuel is a long way off," Harper answered, "...in terms of infrastructure to bring it to cars -- and also it's not very well proven as a low CO2 'energy vector', as we call it, because the CO2 produced in that chain is just not in the car, it's in generating the hydrogen in the first place. At the moment, there isn't a large-scale production method for hydrogen that doesn't produce more CO2 than other ways of propelling cars. You can do it on a small scale, but who knows how that's going to go?

"When we were looking at this car [C-X75], we were looking at it predominantly as an electric supercar -- with about a 60, 70-mile range [roughly 100-115km], because that's what most people do most of the time, under a 60-mile range. Then you say: 'well okay, but we want [it] to be a true Jaguar in the 'beautiful, fast' category, so it's got to have mind-bending performance and it can't have a limited range any more than a car does today'.

"So what you then look for, technology-wise, is you want a range-extender and a power-extender, which is very light and has high power density, because there are other ways of producing that power, but they're big and heavy -- and that would compromise the car...

"That takes you to quite a narrow set of options. The gas turbine is the lightest and the most power-dense of those options. Also it's the most technologically 'stretchy' and one of the things we wanted to do with the C-X75 was to push that. It was deliberately a concept car and so we wanted range-extension and power-extension technology in there, which was 'concept-car-esque'."

If gas turbines in a hybrid-drive system are better for the environment on a well-to-wheel measure, does Jaguar anticipate other manufacturers following the company's lead -- as an alternative to hydrogen?

"I don't think everyone is going to hydrogen," responded Harper, neatly avoiding speculation as to how other companies might respond, but insinuating that gas-turbine/hybrid technology would make a lot more sense for companies investigating alternative energy drivetrain systems for future products.

Harper subsequently cites other companies that are already looking at practical and economically viable alternatives to fuel cells as range-extending units. These include Audi's concept car with a rotary petrol engine in the same role. By implication, the gas-turbine solution fits Jaguar's brand image and performance requirements best.

"There will be a number of different answers to that question, depending on the type of car you're designing, the characteristics you want it to have and what most people do with the car most of the time. I personally think that in this particular case, the world isn't going to converge on one answer. The thing that characterises the whole low-carbon debate... is that everyone seems to acknowledge that we're going to have horses for courses. This is the horse for our course..."

Asked for an estimation of the lead-time for gas-turbine technology in a car you can drive, Harper provided a number that seems enticingly close: perhaps as soon as five years into the future.

"We would say that in terms of developing the system, the gas-turbine and the generator system together, we're some two years away from having that -- as we call it -- implementation-ready... and then there's a task of integrating that technology into the vehicle and doing all of the robustness work that you need to bring that to market. That would be an additional three-year period, so we are at least five years away -- and that's of course if every egg is a bird on the development path."

That's R&D time, which is not necessarily linear like real time, but does that mean Jaguar would head down that path led by the ultimate goal of placing a gas-turbine/hybrid-drive vehicle into production? What about the cost of parts and engineering? Will Jaguar rely on its prestige status to charge over the odds for this technology if it were to go into production?

"In terms of the inherent cost of the gas-turbine unit, actually it's not high," says Harper. "The number of moving parts is very low -- and if you were to look at a gas turbine, in one hand, and then you put a high-tech, multi-valve petrol engine and an eight-speed transmission in the other hand, there's a lot more complication and parts in that [than there is in the gas-turbine unit]."

So production is possible -- and in the relatively near future -- but would Jaguar also consider selling the technology under licence to other car companies?

"It's now a matter of public record that Tata Group have taken a stake in the company that produces those gas turbines [Bladon Jets], so we do see exploitation beyond our use and perhaps even beyond automotive applications."

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